Biogeochemistry

7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 765

Part 2 Biogeochemistry

RMZ-M&G 2004, 51 766 PART 2 BIOGEOCHEMISTRY

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 767 Methyl Mercury and Sulfate-Reducing Bacteria in the Floating Macrophyte Rizosphere from an Amazonian Floodplain Lake, Bolivia

DARIO ACHA1, VOLGA INIGUEZ1, MARC ROULET2, JEAN-REMY DAVEE GUIMARAES3, RUDDY LUNA1, LUCIA ALANOCA2,4 & SAMANTA SANCHEZ1

1Instituto de Biologia Molecular y Biotecnologia, UMSA, La Paz, Bolivia 2Institut de Recherche pour le Développement, HYBAM, UMR 154 LMTG, La Paz Bolivia, e-mail: roulet@cict,fr 3Laboratorio de Traçadores, Instituto de Biofisica, UFRJ, Rio de Janeiro, Brazil 4Laboratorio de Calidad Ambiental, Instituto de Ecologia, UMSA, La Paz, Bolivia

Abstract: Mercury contamination in Amazonian rivers and lakes constitutes a significant threat to human and ecosystem health A fundamental step in its introduction to food webs and human exposure is its conversion from inorganic mercury to methyl mercury (MeHg), which is the most bioaccumulative and neurotoxic form of mercury Several studies have demonstrated that this transformation is mediated mainly by Sulfate-Re- ducing Bacteria (SRB) in aquatic environments Although links between sulfate reduction and mercury methylation have been found in Amazonian sediments and floating macrophyte roots-associated periphyton, no SRB where yet detected This study used 16s rDNA molecular probes to identify six groups of SRB (Desulfotomaculum; Desulfobulbus; Desulfobacterium; Desulfobacter; Desulfococcus Desulfonema Desulfosarcina; Desulfovibrio Desulfomicrobium) on the rizosphere of four macrophytes (Polygonum densiflorum, Hymenachne donacifolia, Ludwigia heliminthorriza and Eichhornia crassipes) from La Granja lake in Beni river (upper Madeira) floodplain, Bolivia Methylation potential (labeled 203HgCl ), microbial activ- 2 ity (3H-leucine) and organic matter, total Hg and MeHg where also determined in root- associated periphyton Water physico-chemical characteristics (redox potential, conductivity, pH and dissolved oxygen concentration) were not significantly related to SRB community composition Even more, it is impressive that five groups of these anaerobic bacteria were detected in such oxidative (+113 - +350 mV) and aerobic (152 437 mg O L-1) environment 2 SRB composition seams to be more related to macrophyte species, but with different degrees of association to their roots Desulfobulbus was significantly more abundant on Hymenachne donacifolia Desulfotomáculum was also more abundant on Hymenachne donacifolia but was also abundant on Ludwigia heliminthorriza Desulfobacter was more abundant on Hymenachne donacifolia and Polygonum desnsiflorum and appeared to be highly associated to roots because it was almost not found in samples containing only periphyton However, most groups were found more frequently in periphyton-only samples Desulfococcus Desulfonema Desulfosarcina was always found on Hymenachne donacifolia and Polygonum desnsiflorum, while Desulfovibrio Desulfomicrobium is present in all samples and Desulfobacterium was never detected Mercury methylation potentials in periphyton varied greatly between Polygonum densiflorum (275-361%) and Eichhornia crassipes (<2%) according to SRB richness These data supports the association between SRBs and methylmercury production in Amazon macrophyte rizospheres by probing the existence of a diverse SRB community

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Results about variation on SRB composition related to macrophyte species and location are also consistent with other studies where differences in sulphate reduction and mercury methylation potentials appear to be related to macrophyte specie SRB ability to survive in this highly aerobic environment could be attributed to specific metabolic pathways to tolerate oxygen or to a microfilm type organization that creates more appropriate conditions to their development

Key words: Amazon, lake, Floodplain, MeHg, SRB

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 769 Hg partitioning between dissolved and solid organic matter in mor layer of Swedish forest soils

STAFFAN AKERBLOM1, LAGE BRINGMARK1, MARKUS MEILI1 & KJELL JOHANSSON1

1Dept of Environmental Assessment, Swedish University of Agricultural Sciences, P O Box 7050, 750 07 Uppsala, Sweden, e-mail: staffan akerblom@ma slu se

Abstract: The cycling of Hg in terrestrial ecosystems is of important concern based on indications that concentrations of Hg are increasing despite declining deposition of Hg Toxicity of Hg is likely related to soil concentrations, which are determined by the balance between input and output fluxes Therefore, factors controlling the Hg turnover in forest soils need to be quantified The leaching of Hg and its association with organic matter is used in this study to describe partitioning between Hg in solid organic matter and Hg in dissolved organic phase Field studies were conducted with the aim of assessing to what extent the association of Hg to organic matter differs between dissolved and solid phases of forest soils, and between sites of high and low Hg deposition Despite differences in quality of organic matter the partitioning factor between dissolved and solid organic Hg is assumed to be comparable between different climatic and geographical regions Percolating water was collected from zero-tension lysimeters installed below the organic so called mor layer and analyzed for dissolved organic carbon (DOC) and total Hg every second week during 2003 Solid phase chemistry data was used from previous studies Two spruce forest sites were chosen, one in the climatically harsh Northern Sweden and one in Southern Sweden, where regional Hg loads are high Ratios between Hg and organic matter were calculated for dissolved and solid organic matter separately Hg found to be correlated to organic matter in both dissolved and solid phases Ratios between Hg and organic matter were similar in solution and in solids from a given site Between sites, however, the ratios differed and were higher at the site with a higher atmospheric Hg deposition during the past decades These results suggest that Hg leaching from organic soils is mostly governed by organic matter fluxes Hg content of organic matter in solutions can be deduced from Hg levels in solid organic matter Future estimates for mass balance modelling will be strongly dependent on organic matter dynamics and factors that may affect mobilisation of organic matter from organic top layers of forest soils

Key words: organic matter, forest soil, Hg-cycling

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Mercury species benthic flux measurements in coastal environments as influenced by the biological activity

DAVID AMOUROUX1, MATHILDE MONPERRUS1, DAVID POINT1, EMMANUEL TESSIER1, LAURENT CHAUVAUD2, GÉRARD THOUZEAU2, FRED JEAN2, AUDE LEYNAERT2, JACQUES CLAVIER2, JACQUES GRALL2, ERWAN AMICE2

1Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, CNRS UMR 5034, Université de Pau et des Pays de lAdour, Hélioparc, 64053 Pau, France; E-mail: david3amouroux@univ-pau3fr3 2Laboratoire des Sciences de lEnvironnement Marin, Institut Universitaire Européen de la Mer (IUEM), CNRS UMR 6539 Université de Bretagne Occidentale, Plouzané, France3

Abstract: In this paper, field experiments performed in the Bay of Brest on the French At- lantic Coast are presented as a contribution to the French PNEC program Experiments were done in shallow waters using benthic chambers to determine benthic fluxes of mercury species together with major biological activities Simultaneous determination of mercury compounds was performed by speciated isotope dilution mass spectrometry (SIDMS) allowing excellent precision and low detection limits for in situ benthic chambers experiments The results demonstrate that benthic fluxes of mercury species in such coastal environment are probably related to biological processes involved in surface sediments with significant time variability They suggest that sediment-water exchanges of mercury species are highly dynamic and driven by transient redox change at the sediment water interface

Key words: Inorganic mercury, methyl mercury, coastal environment, sediment-water interface, benthic fluxes

INTRODUCTION characterised by extensive beds of free-living red calcareous algae (maerl) Maerl beds In this paper, we present field experiments are fragile ecosystems occurring in shallow performed within the Bay of Brest coastal waters from the tropics to the arctic (Britanny), a semi-enclosed macrotidal en- They are an important habitat for a large va- vironment connected to the North Atlantic riety of marine organisms living amongst or Ocean (Oct 2002) Experiments were per- attached to its thalli, or burrowing in the un- formed in shallow waters (6-8m depth) us- derlying dead maerl/fine sediment matrix ing benthic chambers to both monitor benthic fluxes of mercury (Hg) species, such as in- Benthic Chambers Experiments: organic mercury (IHg) and monomethyl Two different stations have been investi- mercury (MMHg), and major benthic bio- gated: one located in a rather pristine area logical activity Two stations were investi- (Rozegat, M1) and one exposed to anthro- gated on a natural benthic ecosystem pogenic inputs (Kerialou, M2) For each in-

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 771 vestigated station, two series of 3 replicate experiment' Back to the lab, bulk and filtered benthic chamber incubations (65 l, 3-4 hours) samples were analyzed for mercury specia- were performed (Amouroux, 2003)' During tion (i'e', IHg and MMHg)' Mercury species each benthic chamber experiment the varia- in seawater samples were determined by tion of O , salinity, light and temperature was propylation followed by capillary GC-ICP/ 2 continuously measured using on-line multi- MS (Monperrus, 2004)' Both IHg and parameter probes (YSI)' Additionally, dis- MMHg determination was performed using crete samples were collected at the begin- species specific isotope dilution technique ning and at the end of the incubations for Hg (i'e', 199Hg2+, CH 201Hg+)' For surface sedi- 3 speciation and ancillary biogeochemical pa- ments, the top layer (0-2cm) was collected rameters (nutrients, pH, alkalinity)' For each in each core and passed on a 2mm sieve to station, sediment core samples were col- separate the fine fraction (clay and silt) from lected at the end of the incubation experi- the calcified seaweed (maerl)' Hg species ments' determinations in sediments was also performed using species specific isotope dilu- MercurySpeciation inSeawater and Sediment tion technique by ethylation followed by cap- Samples: illary GC-ICP/MS after microwave extrac- Seawater samples collected from the benthic tion of dry-freezed aliquots with concen- chambers using PP syringes were readily trated nitric acid (Rodriguez, 2003)' divided into two aliquots: the bulk fraction was directly acidified (HCl, Ultrex), and the dissolved fraction was filtered and subse- RESULTS AND DISCUSSION quently acidified' After sampling all operation were performed using clean Teflon ves- During incubation experiments, reference sel and under a portable laminar flow hood' water samples were taken outside the benthic A reference sample was also systematically chambers and did not show any significant collected out of the chambers to control for differences with incubated waters' Both fil- any contamination during the incubation ter-passing and bulk Hg species concentra-

Table 1 Hg species average concentrations in overlying waters and surface sediments in maerl beds (Bay of Brest)

RMZ-M&G 2004, 51 772 PART 2 BIOGEOCHEMISTRY tions are comparable in both investigated Firstly, measured fluxes are found much sites (Table 1) IHg is nevertheless higher in lower than previously published values, site M1 (Rozegat) compared to M2 ranging from -850 to +510 fmolm-2d-1 and - (Kerialou) For surface sediments collected 181 to +195 fmolm-2d-1, respectively for in the chambers, the first two centimeters are IHg and MMHg They are, nevertheless, sig- homogenous, and concentrations of Hg spe- nificant because of the high precision ob- cies in both sites are also similar (Table 1) tained by using the developed protocol The MMHg concentration is however two times reproducibility obtained from simultaneous higher in M2 than in M1 In addition negli- triplicate measurements with benthic cham- gible concentrations of Hg are measured in bers is satisfactory for such low concentra- the maerl calcite matrix From Hg species tions (standard deviation as error bar in Fig- measurements, it can be concluded that con- ure 1) Secondly, the significant fluxes ob- centrations in water and sediment are almost tained for Hg species exhibit high variabil- identical and that the anthropogenic influ- ity within the same site and during the same ence expected in M2 can not be depicted incubation day For both IHg and MMHg, from Hg species levels Such macrotidal en- lower effluxes are systematically obtained vironment is indeed controlled by strong during the morning (Incubation 1 I1) than water circulation all over the bay and thus during the afternoon (I2) These results are allows significant homogenization of the probably the first to illustrate such potential contaminants dynamic exchange of Hg between water and sediment on diurnal time scale In shallow Mercury Species Benthic Chamber Fluxes bay waters, sunlight and tidal-driven biologi- Figure 1 presents averaged measured benthic cal processes are indeed playing an impor- effluxes (ie, sediment to water) based on tant role for benthic ecology It is thus prob- filter-passing Hg species concentrations able that major biological processes may in turn influence Hg species benthic exchanges

Figure 1 Hg species benthic effluxes over maerl beds in the Bay of Brest Error bars correspond to the standard deviation obtained from triplicate benthic chamber incubations

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Relationship Between Benthic Ecology and was obtained (R2=0"71), suggesting a direct Mercury Exchange at the Sediment Water effect of changing respiration/production ra- Interface: tio on MMHg efflux to the water column" For Oxygen (O ) was continuously recorded dur- both species, we may thus expect that tran- 2 ing the incubation allowing an accurate sient redox changes at the sediment-water evaluation of the redox conditions within the interface induce the dissolution or precipita- chambers and benthic respiration/production tion of the organic and mineral components, ratio" First, because of the short incubation which are, in turn, able to release or trap Hg time, O was always near saturation during species" These redox changes can thus be di- 2 the experiments demonstrating that Hg spe- rectly controlled by the global benthic activ- cies efflux measurements were not influ- ity in relation to sediment deposit early di- enced by redox conditions change in the agenesis (microbial respiration) and benthic overlaying water within the chamber" Sec- primary productivity (phytobenthos)" ond, as for Hg species, O efflux shows 2 strong diurnal variation exhibiting a highly dynamic change of the benthic respiration/ CONCLUSIONS production ratio" Simultaneous measurements of CO , nutrients and Mn effluxes 2 The results obtained in this work indicate that demonstrate also that major processes in- the heterotrophic versus autotrophic benthic volved are highly variable" They are all re- characteristics are driving factors for the lated to organic matter mineralization (res- sediment-water exchanges of mercury spe- piration) and benthic primary production" cies in shallow coastal waters"

Considering these major processes, O 2 Acknowledgements effluxes can be compared to Hg species effluxes" For IHg a negative trend was ob- This work was supported by the French Na- tained between the two parameters although tional Program for Coastal Environment the correlation was not significant (R2=0"17)" (PNEC) and the MERCYMS project in the For MMHg, a significant negative correlation framework of the EU ELOISE program"

REFERENCES

AMOUROUX, D, MONPERRUS, M, POINT, D, TESSIER, E, MONPERRUS, M, TESSIER, E, AMOUROUX, D, DONARD, BAREILLE, G, DONARD, O F X, CHAUVAUD, L, O F X (2004): Simultaneous speciation of THOUZEAU, G, GRALL, J, JEAN, F, LEYNAERT, A, mercury and butyltin compounds in natural wa- CLAVIER, J, GUYONEAUD, R, DURAN, R, GONI, ter using species specific isotope dilution mass M, CAUMETTE, P (2003): Transfer of metallic spectrometry; Anal Bioanal Chem (submitted) contaminants at the sediment-water interface in RODRÍGUEZ MARTÍN-DOIMEADIOS, R C, MONPERRUS, M, coastal environments: role of the biological and KRUPP, E, AMOUROUX, D, DONARD, O F X microbial activity and diversity; J Phys IV 107, (2003): Using speciated isotope dilution with Volume I (Eds, C BOUTRON, C FERRARI), pp GC-inductively coupled plasma MS determine 41-44 and unravel the artificial formation of monomethylmercury in certified reference sediments; Anal Chem 75, pp 3202-3211 RMZ-M&G 2004, 51 774 PART 2 BIOGEOCHEMISTRY

The St Lawrence River Case Study: Linking Hg Biogeochemistry, Health and Environmental Education

M AMYOT1, C BEAUVAIS5, S CARON2, P CONSTANT 5,9, S DEGROSBOIS2, D GABROVSKA 5, 2 ,H GODMAIRE2, D LEAN3, L FISHER-ROUSSEAU2, S GARCEAU2, E GARCIA4, S GÉROME1, V G IRARD1, R GOULET4, S HAMELIN2, R HARRIS10, J HILL3, K HINDLE3, J HOLMES3, J LAROULANDIE4, M LUCOTTE2, D MERGLER2, N MILOT1, M NUGENT3, O NWOBO3, B PAGE7, M PILOTE5, D PLANAS2, L POISSANT5,2, N ROY2, L SAUVÉ2, S SICILIANO6, C VANIER2, F WANG7, H ZHANG8, J ZHANG7 [NOTE: NAMES LISTED BY ALPHABETICAL ORDER]

1 Université de Montréal 2 Université du Québec à Montréal 3 Université dOttawa 4 INRS-Eau, Terre et Environnement 5 Environnement Canada 6 University of Saskatchewan 7 University of Manitoba 8 University of Windsor 9 Institut Armand-Frappier (INRS) 10 Tetra Tech

Abstract: This case study integrates the pathways affecting Hg cycling in Lake St Pierre, a heavily-fished fluvial lake from the St Lawrence River, characterized by very large wetland areas This initiative is part of the Collaborative Mercury Research Network (COMERN) Our approach is to link fine scale critical gap studies to larger scale Hg flux studies, in an effort to assess how Hg is imported to the lake, methylated in the sediments and plants, and transferred through the food chain up to the human population Neurological studies on the population are being conducted in coordination with the biogeochemical studies Also, the community has been invited to participate in this research initiative

Key words: Case Study, Biogeochemistry, Environmental Education, Health, Fluvial wetland

INTRODUCTION UNESCO Biosphere Reserves This initiative is part of the Collaborative Mercury This case study integrates the pathways af- Research Network (COMERN) Our ap- fecting Hg cycling in Lake St Pierre, a proach is to link fine scale mecanistic stud- heavily-fished fluvial lake from the St ies to larger scale Hg flux studies, in an ef- Lawrence River, characterized by very large fort to assess how Hg is imported to the lake wetland areas and classified as one of from the atmosphere and from incoming

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 775 streams, methylated in the sediments and epi- logical (5) We found that methylmercury phytes, and transferred through the food was mainly produced in a thin layer (mer- chain up to the human population through cury methylation layer or MML) a few cen- fishing activities Neurological studies on the timeters below the sediment-water interface neighbouring populations are being con- Two-dimensional high-resolution profiling ducted in coordination with the biogeochemi- was conducted this year to uncover detailed cal studies Also, the community has been porewater chemistry (eg, Hg, MeHg, pH, invited to participate in this research initia- DOC, sulfide, and thiols) across the MML tive For instance, this research project has and to relate MeHg production to in situ Hg been integrated in the curricula of local com- speciation In addition to sulfide, the results munity colleges suggest that biogenic thiols may play a significant role in Hg speciation and methylation, as very significant peaks of biogenic RESULTS AND DISCUSSION thiols were found in the MML (6) We have also established that MeHg concentrations In recent years, we have made the following in wetland waters from different sites across advances: (1) We have established that wa- Canada were highly correlated with phospho- ter and soil components from wetland areas rus until levels where sulfide concentrations acted primarily as sources of atmospheric become significant The Lake St Pierre wet- mercury (2) Mercury evasion over these land fell on the lower end of the relation- components exhibited a diurnal pattern with ship MeHg levels were in the range 100 to maximum evasion during daytime and mini- 200 pg/L with total P from 40 to 70 µgP/L mum at night (3) We also uncovered the very This provides a warning that increased phos- active role played by wetland plants Our data phorus levels would increase the levels of suggest that reactive gaseous mercury is MeHg that in turn would likely impact down- taken up directly by plants during daytime, stream areas (7) We also used tangential flow whereas gaseous elemental mercury at the ultra-filtration to fractionate DOC by mo- air/plant interface is transferred via transpi- lecular size in a suite of 15 lakes, rivers and ration and diffusion through stomata These wetlands in order to determine natural varia- macrophytes seem to play a role in the re- tion in MeHg distribution Baie St Francois dox chemistry of the water In incubation and the Yamaska river, two of the primary experiments, we showed that Hg(II) reduc- study sites connected to Lake St Pierre, seem tion was inhibited (by oxidation or adsorp- to show large proportions of their MeHg tion) in the presence of plant tissue Epi- concentrations in the particulate and colloi- phytes growing on macrophytes near the air/ dal fractions respectively (8) At the scale of water interface were shown to be efficient the lake, the levels of SPM, dissolved Hg, methylators and, because of their palatabil- Hg in SPM and DOC measured in Baie St- ity, could play a pivotal role in Hg transfer François, the Yamaska, St-François and St- to higher trophic levels (4) Depth profiles Lawrence rivers show an important variation and incubation revealed that sediments were between sites and between seasons Globally, sites of Hg reduction under anoxic condi- for the summer months of 2003 (June to tions, and that this process was partly bio- August), the Yamaska, St-François and St-

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Lawrence rivers delivered approximately b) access to local information and experien- 17 kg of Hg per month into Lac St-Pierre" tial knowledge, c) participation of commu- (9) (130 participants) have shown that yel- nity groups to the revision of the Québecs low perch (39"1 ± 55"6 meal portions/Year) fish consumption guide and d) communitys and walleye (40"2 ± 75"5 meal portions/Year) involvement in co-constructing and diffus- are the most consumed fish in lake St-Pierre" ing information, and in raising a public de- (10) Mercury levels in yellow perch and bate" Second, the College Sorel-Tracy in- walleye from Lac St-Pierre appear relatively volvement has led to the: a) strengthening low (yellow perch: 0"08 mg/kg W"W" for a of links between university, community col- mean length at capture of 150 mm; walleye: lege and high schools for investigation and 0"22 mg/kg W"W" for a mean standard length education concerning the mercury issue, b) of 400 mm) when compared to certain lakes adoption of the COMERN project and the of the Boreal Forest" Low mercury levels in contamination issue in institutional curricu- walleye from Lake St-Pierre can be partly lum and c) development of a number of ac- explained by their relatively fast growth tions or long term projects such as mercury rates" This finding is confirmed by R" Har- monitoring in the region, follow up of the ris model" (11) Two community projects local mercury waste disposal issue and po- were developed" First, the collaborative work litical claims and d) creation of a local foun- with the community has lead to the: a) iden- dation (or organisation) dedicated to socio tification of community needs and concerns, environmental health education"

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 777 Are changes in emissions and deposition responsible for declines in biota mercury concentrations in Florida?

THOMAS ATKESON1, CURTIS D POLLMAN2, & DONALD M AXELRAD1

1Florida Department of Environmental Protection, 2600 Blair Stone Road MS 6540, Tallahassee, FL 32399-2400, USA; E-mail: thomas)atkeson@dep)state)fl)us 2TetraTech, Inc)408 University Avenue Suite 301, Gainesville, Florida, USA; E-mail cpollman@bellsouth)net

Abstract: Mercury in largemouth bass and great egrets of the Florida Everglades declined >60 % after the mid-1990s Preceding this decline were very large reductions in emissions of mercury (~93 %) from a peak level of 3,077 kg/yr in 1991 to 231 kg/yr in 2000 As south Florida is meteorologically disjunct from the continental US, atmospheric deposition of mercury in south Florida lacks a regional component, being driven by two scales of influence local (0 to 100 km) and global (> 1,000 km) In addition, the Everglades is a highly perturbed system, and alternative explanations must be considered, i e changes in hydrology, trophic state, and sulfate enrichment We have taken a weight-of-evidence approach to discriminating between the above factors Of the various hypotheses proposed, the sulfate hypothesis is the most difficult to resolve Sulfate, originating from agricultural practice in the watershed, has long been hypothesized as a critical variable in the mercury cycle in the Everglades, although the quantitative link between sulfate and mercury methylation has yet to be satisfactorily elucidated Declines in sulfate concentrations at several key locations in the Everglades where largemouth bass mercury declines have been observed do suggest that the two processes may be linked However, no changes in sulfate concentrations have been observed in lakes in north of the Everglades during the same period when the decline in largemouth bass mercury occurred We thus conclude that changing sulfate dynamics is at best a secondary determinant of biota concentrations in the Everglades Hindcast modeling of the effects of changing water column concentrations of phosphorus as an indicator of trophic state suggests that changing phosphorus dynamics does not explain the biota mercury declines; likewise, hydrologic variations also can be discounted as a important contributor Hindcast modeling does suggest that inferred changes in atmospheric deposition based on emission declines can account for the declines, but cannot robustly discriminate between the competing hypotheses of local vs global-scale question Several lines of evidence, however, do indicate that the decline in local emissions is the likely agent of change First, sediment mercury accumulation rates for different areas within the Everglades show enrichment ratios averaging 4 0 to 8 7 when 1990-1 rates were compared to pre-cultural rates (ca 1900; ROOD ET AL , 1995) These elevated flux ratios are indicative of the impact of local sources In comparison, the increase in mercury accumulation rates over approximately the same period in Lake Annie, a seepage lake located 140 km northwest of West Palm Beach (the closest source of mercury emissions) is only ca 3 2; consistent with flux enrichment ratios observed at remote sites in the Northern Hemisphere dominated by the global mercury signal Moreover, the magnitude of declines in Hg accumulation rates in Lake Annie sediments (ca 18 %) between 1990 and the present is consistent with the change in the total gaseous mercury concentrations over the Northern Atlantic (19 %) reported by SLEMR ET AL (2003) Finally, an analysis of the likely changes in relative contributions of global vs local source emission declines was conducted using changes in mercury accumulation rates, the change in both local and global emission signals, and observed changes in wet deposition to constrain the analysis These results indicate that local sources were dominant in 1990-91 (ca 58 %) but, because of the large decline in local emissions, represented only ca 10 % of the deposition signal in 2002 The attributed change in local and global scale source strengths resulted in nearly 96 % of the total change in wet plus dry deposition fluxes between 1990 and 2002 due to local emissions reductions

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Towards a hypolimnetic mass balance of Hg in a dimictic lake: Early results from the METAALICUS project#

CHRISTOPHER BABIARZ1, JAMES HURLEY2, DAV I D KRABBENHOFT3, SHAWN CHADWICK1, TARA TRINKO1, & MICHAEL TATE 3

1Environmental Chemistry & Technology Program, University of Wisconsin-Madison, USA; E-mail: babiarz@cae$wisc$edu, spchadwick@students$wisc$edu 2 Water Resources Inst$, Univ$ of Wisconsin-Madison, USA; E-mail: Hurley@wri$wisc$edu 3 Water Resources Division, USGS, Middleton, WI, USA; E-mail: dpkrabbe@usgs$gov

Abstract: Our ability to determine the fate and transport of newly deposited mercury, from that of historically deposited mercury, was recently demonstrated by the Mercury Ex- periment To Assess Atmospheric Loading In Canada and the United States (METAALICUS)% The METAALICUS project is a whole-watershed amendment study where different stable isotopes of mercury were applied to three watershed compartments totaling ~53 Hectares: the upland, the wetland, and the surface of a dimictic lake in northwestern Ontario, Canada% Results from two years of data show that new mercury is extremely particle reactive% The build up of methylmercury in the in the hypolimnion suggest ample recycling in that compartment% This observation indicates the need for a well-constrained mass balance within the hypolimnion to determine if in-lake methylation needs to be invoked to account for the build up%

Key words: atmospheric deposition, particle settling, sediment burial, fickian diffusion%

INTRODUCTION inputs of mercury, and will inform pending controls on mercury emissions that may ex- In response to considerable evidence that ceed several billion dollars to implement[2] atmospheric transport, deposition, and reemission of mercury are key processes in One of the major goals of the METAALICUS the movement of this neurotoxin throughout project is to determine the mobility of this the globe, scientists are studying the fate of new mercury through the watershed, and newly deposited mercury on a watershed in to assess the recovery time for an ecosystem northwestern Ontario, Canada[1] In the Mer- should new industrial emissions of Hg be cury Experiment to Assess Atmospheric ceased A major sink for mercury in the sys- Loading In Canada and the United States tem is expected to be the sediments of the (METAALICUS), we are able to differenti- lake where particles that scavenge mercury ate between the newly deposited and the from the water column eventually settle[3] standing pool of mercury using stable iso- However, redox conditions at the sediment tope amendments These isotopic techniques water interface, and in the overlying will provide the first direct evidence of a hypolimnetic waters during anoxia, have watershed response to changing atmospheric been shown to be sites of intense recycling

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 779 of mercury prior to burial[4] In addition to ery two weeks from early June until mid the remineralization of mercury into the dis- October The spike was introduced at dusk solved phase as particles fall, sulfur-reduc- to minimize photo reduction and evasion ing bacteria that thrive in anoxic conditions The spike solution was mixed in 20 L car- are known to convert inorganic Hg(II) into boys of lake water and slowly dispensed be- bioaccumulative methylmercury[5] low the lake surface in the wake of a trolling motor The operation took ~4 hours using Unfortunately, many of the mechanisms that two boats At the end of the spiking process control the cycling of mercury in the hy- the mercury concentration in the top 2 meters polimnion have been obscured by our inabil- of the lake had doubled from approximately ity to differentiate between mercury that is 2 to 4 ng/L Over the field season we added new to the system and that, which comes approximately 5x the annual atmospheric from the historic pool The METAALICUS deposition for the region a quantity close project not only allows such a distinction, to the annual Hg deposition on the eastern but also enables an in situ look at the net seaboard of the United States kinetics of transformations within the system In this paper we present some of the Water column profiles were collected on the first data from the METAALICUS project day preceding each spike in both the East and on the mobility of new Hg in the hypolim- West basins of Lake 658" Typical sampling nion, the importance of sedimentation, and depths were 2, 5, 7, 9, and 13 m below the the components of the hypolimnetic mass water surface" Additional samples were ob- balance tained at 5, 10, 20, 40, and 80 cm above the interface to better define important hypolimnetic processes in that region" METHODS Samples were obtained at depth using an all Teflon sampling line and weight connected A full discussion of the numerous factors that to a peristaltic pump in the boat" Samples near influence a full-scale, non-invasive, timely, the sediment water interface were collected and executable amendment study is beyond using a Close Interval Sampler (CIS; Figure the scope of this paper In general, the project goals were to select variables (target spike concentration, final lake concentrations, delivery mechanism, delivery time, and delivery matrix) such that a defendable scientific method and practical field operations could both be maintained[1] The watershed is located within the Experimental Lakes Area (ELA) of the Canadian Boreal Forest in northwestern Ontario Lake 658 is an 83 Ha dimictic lake surrounded by a 42 ha forested upland and a 2 Ha wetland on the west end The lake water spike was administered ev-

RMZ-M&G 2004, 51 780 PART 2 BIOGEOCHEMISTRY

1) placed on the sediment surface by a had an absolute detection limit of about 1 pg SCUBA diver at the beginning of the field Hg, or about 0"05 ng L-1" The minimum de- season[4]" Sediment traps were deployed at the tectable amount of MeHg was also 1 pg" sediment water interface and just below the thermocline in each basin" We use differences between upper and lower traps to assess Hg RESULTS AND DISCUSSION transport, transformation, and dissolution from particles" Traps were processed on the The hypolimnetic mass balance will be cal- day of the spike resulting in a two-week col- culated using a 1-box model (Figure 2) and lection period" Trap design followed that of the following equation: DEAN, SHAFER AND ARMSTRONG[6]" Sediments were collected via SCUBA to determine long- dM/dt = M + P - P + D + BP + IP term accumulation rates and pore-water i E H S squeezing for diffusion calculations" Where dM/dt is the change in mass with time, M is the initial mass (calculated from mea- i Total mercury concentrations were deter- sured water column profiles), P is particu- E mined using the bromine monochloride oxi- late-bound mercury from the Epilimnion dation technique followed by stannous chlo- (from sediment trap data), P is particulate H ride reduction, nitrogen purging, gold-trap bound mercury loss to the sediment water preconcentration, thermal desorption and interface (from bulk sediment core profiles), cold-vapor atomic fluorescence spectroscopy D is diffusion from the sediments (from pore S (CVAFS) detection[7]" MeHg was determined water profiles), NM is net methylation, and by distillation, aqueous phase ethylation, ni- PT is phase transfer (particulate ó filtered)" trogen purging, Carbotrap® preconcentration, The latter two terms are special cases when thermal desorption, chromatographic sepa- mass balancing MeHg or a given size frac- ration, pyrolytic conversion to Hg0, and tion (respectively) both terms drop to zero CVAFS detection[8, 9]" Analytical detection in the over-all mass balance" The equation limits (three times the s"d" of the blank) av- omits diffusion between the epilimnion and eraged 0"1 ng L-1 Hg and 0"05 ng L-1 MeHg" T the hypolimnion because thermal stratification prevents exchange" Note that during most Isotopic mercury analysis was determined using a Perkin-Elmer Elan 6000 ICP-MS that was dedicated for mercury-only analysis and was housed in a state-of-the-art mercury analytical facility operated by Dr" David Krabbenhoft at the USGS in Middleton, Wisconsin" This ICP-MS was fitted with a continuous flow injector analyzer system, and an inline gold amalgamation system, that allows for rapid sample throughput and low- level detection" The method, modeled after the pioneering work of HINTELMANN ET AL"[10],

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 781 of the year, transport of isotopic mercury from 50 % of the native MeHg concentration on the epilimnion to the hypolimnion was pri- particles by October marily through particulate matter (Figure 3a) The concentration of isotopic mercury on fall- Filtered phase Native total mercury (HgT) ing particles increased throughout the year concentrations in the water column were fairly from 0 to 0 14 ng L-1 reaching 50 % of the uniform throughout the year ranging from 1 5 native HgT on particulates In contrast, fil- to 4 ng L-1 in the filtered phase Larger con- tered phase isotopic mercury remained largely centrations were observed during the summer in the epilimnion until the thermocline broke months in the hypolimnion The isotopic down in autumn (Figure 3b) Methylation of amendment ranged from 0 to 0 8 ng L-1 in the the isotopic mercury was first noted two filtered phase At times, the isotopic amend- weeks after the initial spike and reached ment was up to 40 % of the native pool

Figure 3 202Hg as a percent of native mercury in (a) the particulate phase and (b) the filtered phase The shading scale reads in 5 % increments from 0 % (white) to 40 % (dark)

Acknowledgements Shane Olund, and John DeWilde for their help with fieldwork, analysis, and sampling The authors express their gratitude to design This work was funded by grants from Rebecca Moore, Alison Elias, Carrie Miller, EPRI, Rick Carlton project officer; the Martin Shafer, Karen Scott, Ken Sandilands, USGS; and the USEPA Kris Rolfhus, Steve Hoffmann, Mark Olson,

RMZ-M&G 2004, 51 782 PART 2 BIOGEOCHEMISTRY

REFERENCES

[1] HARRIS, R, RUDD, J W M, AMYOT, M, BABIARZ, C, [6] DEAN, K D, SHAFER, M M, ARMSTRONG, D E BEATY, K, BLANCHFIELD, P, BODALY, R A, (1993): Particle-Mediated Transport and Fate of BRANFIREUN, B, GILMOUR, C C, HEYES, A, a Hydrophobic Organic Contaminant in South- HINTLEMANN, H, HURLEY, J, KELLY, C, ern Lake Michigan: The Role of Major Water KRABBENHOFT, D, LINDBERG, S, PATERSON, M, Column Particle Species; J$ Great Lakes Res$ PODEMSKI, C, ROLFHUS, K, SANDILANDS, K, 19, pp 480-496 SCOTT, K, SOUTHWORTH, G, ST LOUIS, V (2001): [7] GILL, G A, FITZGERALD, W F (1987): Picomolar METAALICUS: A whole-ecosystem study to de- mercury measurements in seawater and other termine the relationship between atmospheric materials using stannous chloride reduction and mercury deposition and concentration in fish; two-stage gold amalgamation with gas phase Abstracts from the Sixth International Confer- detection; Mar$ Chem 20, pp 227-243 ence on Mercury as a Gobal Pollutant, [8] BLOOM, N (1989): Determination of picogram lev- Minamata, 15-19 October (M YAMAMOTO, Ed) els of methylmercury by aqueous phase pp 123 ethylation, followed by cryogenic gas chroma- [2] USEPA (1998): Mercury Report to Congress; US tography with cold vapor atomic fluorescence Government Printing Office, Washington DC detection; Can$ J$ Fish$ Aquat$ Sci$ 46, pp 1131- [3] HURLEY, J P, WATRAS, C J, BLOOM, N S (1991): 1140 Mercury cycling in a northern Wisconsin seep- [9] LIANG, L, HORVAT, M, BLOOM, N S (1994): An im- age lake: The role of particulate matter in verti- proved speciation method for mercury by GC/ cal transport; Water Air Soil Pollut$ 56, pp 543- CVAFS after aqueous phase ethylation and room 551 temperature precollection; Talanta 41, pp 371- [4] HURLEY, J P, KRABBENHOFT, D P, BABIARZ, C L, 379 ANDREN, A W (1994): Cycling of mercury [10] HINTELMANN, H, EVANS, R D (1997): Application across the sediment-water interface in seepage of stable isotopes in environmental tracer stud- lakes (Environmental Chemistry Of Lakes and ies Measurement of monomethylmercury Reservoirs); Amer Chemical Soc, Washington, (CH Hg+) by isotope dilution ICP-MS and de- 3 pp 425-449 tection of species transformation; Fres$ J$ Anal$ [5] BENOIT, J M, GILMOUR, C C, MASON, R P, HEYES, Chem$ 358, pp 378-385 A (1999): Sulfide controls on mercury speciation and bioavailability to methylating bacteria in sediment pore waters; Environ$ Sci$ Technol$ 33, pp 951-57

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 783 Mercury concentration along the last thirteen years in fish from Guanabara Bay, Brazil

AIDA P BAETA1, HELENA DO A KEHRIG1, 2, ISABEL MOREIRA1, TÉRCIA G SEIXAS1 & OLAF MALM2

1Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro, 22543-900, Rio de Janeiro, RJ, Brasil& 2Laboratório de Radioisótopos Eduardo Penna Franca, IBCCF, Universidade Federal do Rio de Janeiro, 21949-900, Rio de Janeiro, Brasil; E-mail: kehrig@biof&ufrj&br

Abstract: Guanabara Bay is one of the most important estuaries in southestern Brazilian coast for fisheries It is heavily impacted by industrial sewage and untreated domestic waste The study evaluated T-Hg concentrations in the muscle tissues of two coastal species, Micropogonias furnieri (N=64) carnivorous fish and Mugil liza (N=35) planktivorous fish collected in the following years, 1990, 1999 and 2003 Carnivorous fish showed the highest mean concentrations (1755 ±1192 µg HgKg-1 wet wt) in 1999 due to the fact that in this year all the specimens presented the highest total length and also all were adults The specimens colleted in 1990 and 2003 presented similar T-Hg (1143 ± 613 µgKg-1 wet wt and 8803 ± 772 µgKg-1 wet wt respectively) The specimens of these organisms were smaller and younger than the ones sampled in 1999 and also did not present sexual maturity The results presented a statistically significant difference (p<005) between the T-Hg in the muscle of the organisms collected in the years 1999 and 2003 The muscle of carnivorous fish always presented higher T-Hg than the ones from planktivorous fish in all sampled years Planktivorous fish presented higher mean concentrations (1770 ± 410 µg HgKg-1 wet wt) in 1999 than in the ones sampled in 2003 (483 ± 230 µg HgKg-1 wet wt) In the year 2003, all the specimens of planktivorous fish presented lower total length (290 mm 355 mm) than the ones of 1999 (370 mm 500 mm) T-Hg showed a linear increase with carnivorous fish length (L), presenting the following relationship log [T-Hg] = 24 log L -1,81 (R= 074; p<005) Probably, the main factors affecting mercury concentrations in the organisms are the age and sexual maturity effects

Key words: tropical fish, biological parameters, mercury, Brazilian estuary

INTRODUCTION in particular, heavy metals, is also related to the anaerobic conditions found in their bot- Estuaries are highly dynamic environments tom sediments (KEHRIG ET AL, 2003) but often act as efficient sinks of river-borne and marine-derived pollutants Because vari- Guanabara Bay (22°S, 43°W, 400Km2) in ous hydrodynamic features of these water Rio de Janeiro State can be considered as bodies, it can result in long residence times the most important estuaries for fisheries of material deposited there The capacity of productivity on Brazilian coast The bay is estuaries to act as a sink for pollutants and, heavily impacted by organic matter, oil and

RMZ-M&G 2004, 51 784 PART 2 BIOGEOCHEMISTRY heavy metals, including mercury, whose THgkg-1 wet wt) in 1999 due to the fact that main consequences are elevated concentra- in this year all the specimens presented the tions of toxic compounds in sediments and highest total length (350 mm - 577 mm) and changes in the pelagic and benthonic com- were adults The sexual maturity in Atlantic munities (CARREIRA ET AL, 2002) One im- croaker started at around 450 mm or 4 years portant source of mercury in this estuary is a old (VAZZOLER ET AL, 1973) chlor-alkali industry The Atlantic croaker collected in 1990 and Mercury content in aquatic biota varies 2003 presented similar T-Hg concentrations greatly among species from the same loca- (1143 ± 613 µgkg-1 wet wt and 883 ± tion Many parameters may affect the accu- 772 µgkg-1 wet wt respectively) (Fig 1) The mulation and concentration of mercury in the specimens of these marine organisms were fishs muscular system The most important smaller and younger than the ones sampled is the amount of mercury that organisms are in 1999 and did not present sexual maturity exposed through the ambient water, sediment The total length of the specimens in 1990 and food Other important parameters are: and in 2003 ranged from 190 mm to 525 mm the fish species, the species total length and and 340 mm to 430 mm respectively The weight, the age, the dietary habits, trophic results presented a statistically significant positions and sexual maturity (HUCHABEE ET difference (p << 005) between the T-Hg in the muscle of the organisms collected in the AL, 1979) years 1999 and 2003 The present study evaluated the total mercury (T-Hg) in two marine species, Mugil liza Planktivorous fish (N=35) presented higher - mullet, planktivorous benthic fish and mean concentrations (1770 ± 410 µg -1 Micropogonias furnieri - Atlantic croaker, THgKg wet wt) in 1999 than in the ones -1 carnivorous benthic fish The organisms were sampled in 2003 (483 ± 230 µg THgKg sampled in different periods: from 1999 to wet wt) (Fig 2) In the year 2003, all the specimens presented lower total length 2003 They represent some of the most abun- (290 mm 355 mm) than the ones of 1999 dant animal populations in the bay, as well (370 mm 500 mm) In this fish specie, the as those most frequently consumed by the sexual maturity started at around 400 mm local population It is important note that the muscle of car- The concentrations of T-Hg were determined nivorous fish always presented higher T-Hg by cold vapor AAS with sodium borohidrate than the ones from planktivorous fish in all as a reducing agent sampled years due to they were in different trophic levels of the food chain

RESULTS AND DISCUSSION Positive relationship was found between T-Hg concentrations in the muscle of car- T-Hg concentrations in the muscle tissue of nivorous fish and its total length, presenting the carnivorous fish (N=64) showed the high- the following relation log [T-Hg] = 24 log est mean concentrations (1755 ± 1192 µg L 181 (R = 074; p < 005)

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 785

Figure 1 The mean of T-Hg concentrations in the muscle tissue of the carnivorous fish collected in different years at Guanabara Bay

Figure 2 The mean of T-Hg concentrations in the muscle tissue of the carnivorous fish collected in different years at Guanabara Bay

CONCLUSIONS Acknowledgements

The results of this study showed the prob- The authors acknowledge the financial sup- able influence of the age, maturity sexual, port of CAPES and the masters by the assis- feeding habits and level of environmental tance during this work contamination of the estuary that were affecting mercury accumulation in the marine organisms

RMZ-M&G 2004, 51 786 PART 2 BIOGEOCHEMISTRY

REFERENCES

CARREIRA, R S, WAGENER, A L R, READMAN, J W, KEHRIG, H A, PINTO, F N, MOREIRA, I & MALM, O FILEMAN, T W, MACKO, S A & VEIGA, A (2003): Heavy Metals and Methylmercury in a (2002): Changes in the sedimentary organic car- Tropical Coastal Estuary and a Mangrove in Bra- bon pool of a fertilized tropical estuary, zil; Organic Geochemistry, Vol 34, pp 661-669 Guanabara Bay, Brazil: an elemental, isotopic VAZZOLER, A E, ZANETI, E M & KAMAKAMI, E (1973): and molecular marker approach; Marine Chem- Estudo preliminar sobre o ciclo de vida dos istry, Vol 79, 202-227 Scianidae; Programa Rio Grande do Sul II, pp HUCHABEE, J W, ELWOOD, J W & HILDEBRAND, S C 240-291, Brasil (1979) Accumulation of mercury in freshwater biota; In (NRIAGU, JO, Ed): The biogeochemistry of mercury in the environment, pp 277- 302, Elsevier, Amsterdam

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 787 Influence of solar radiation on mercury emission fluxes from soils

ENNO BAHLMANN1*, RALF EBINGHAUS2, WOLFGANG RUCK3

1Davidstrasse 3 20359 Hamburg, GERMANY; E-mail: enno%bahlmann@yahoo%de% 2 GKSS Research Centre Geesthacht, Institute for Coastal Research / Physical and Chemical Analysis, Max-Planck-Str% 1, D-21502 Geesthacht, GERMANY 3University of Lueneburg, Institute for Ecology and Environmental Chemistry, Scharnhorst-Str% 1, D-21335 Lueneburg, GERMANY

Abstract: Solar radiation may play an important role re-emission of mercury from soils We present the results from intensive laboratory studies on the influence of solar radiation on mercury emission fluxes from soils and discuss the role of solar radiation under natural conditions

Key words: air/surface exchange, solar-radiation spectral response

INTRODUCTION RESULTS AND DISCUSSION

The results of recently published mercury The Laboratory Flux Chamber System that flux studies in the field (CARPI, 1997) as well was used to carry out the experiments is de- as under laboratory conditions indicate that scribed in detail in an accompanied contri- solar radiation may be an important factor bution to this conference (BAHLMANN controlling the air/surface exchange of mer- 2004 a)% We have included 9 different soils cury over soils and that under certain condi- from background as well as from contami- tions solar radiation might increase mercury nated sites in Northern Germany covering a emissions fluxes (MEFs) several times com- Hg-concentration range from 0%05 mg/kg to pared to those obtained in the absence of 15%2 mg/kg% The speciation of mercury in solar radiation% (GUSTIN, 2002)% However the these samples is determined by humic com- mechanisms by which solar radiation affects pounds% MEFs are still poorly understood% In order to improve our understanding of these MEFs increased immediately by a factor of mechanisms we have studied the influence 3 up to 7 when the soils were radiated with of solar radiation on MEFs under controlled 320 W/m2 (no Filter) compared to those conditions in the lab over a variety of differ- fluxes obtained under dark conditions at ent soils% 20 °C% During the radiation experiments the soil surface temperature measured in a depth of 0%5 cm increased by about 4%0 °C% Calcu- lations using the temperature dependency of

RMZ-M&G 2004, 51 788 PART 2 BIOGEOCHEMISTRY the dark flux clearly show that the observed of the MEF during the radiation phases, increase of the soil surface temperature can which indicate that the MEF increase inde- only account for a minor fraction of the ob- pendent from the soil surface temperature by served increase of the MEFs (Fig% 1) even a constant amount within a soil temperature when taking changes of the atmospheric range from 10 °C to 25 °C% This results transport properties, e%g%, the introduction of reveal clear evidence for an additional light thermal convection, into account% This is also induced release of Hg° from the soil which confirmed by the temperature dependency is not related to the soil temperature%

Figure 1 calculation of the light induced offset from the temperature dependency of the dark flux

The light induced offset increased propor- Based on the decreasing rates we calculated tional to the mercury concentration in the soil a mean half life of 20 h for the light induced samples The best fitting between total mer- flux over dry soils and a mean half life time cury concentration and light induced offset of 63h for the light induced fluxes over wet was found with a linear regression curve soils When radiation was interrupted for F = 165,55c(Hg ) + 186,49, several hours and then started again the ob- -offset soil n = 13, R2 = 0,9210 served offset was higher as at the end of the Under constant conditions we observed a previous radiation phase and than decreased decrease of 04 % to 3 % per hour of the with the same rate as observed before This light induced flux Independently of the indicates, that the pool of mercury available sample the highest decrease rate appeared for light induced emission is somehow re- over dry soils (2 7% soil moisture) and low- charged Under the experimental conditions est decreasing rates were observed over wet this is only possible when mercury is trans- soils, which clearly shows that the light in- ported to the soil surface duced flux depends on the soil moisture level

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 789

Figure 2 Spectra of the solar simulation system compared to solar spectrum

Figure 3 Spectral Response of the light induced flux for different samples, relative fluxes normalized to the flux obtained without filter and 320 Wm -2

The light induced increase of MEFs is lin- sample Swb-F-1 with a mean mercury con- early correlated with the radiation intensity centration of 005 mg/kg to more than 3600 and shows a strong spectral dependency In pmol*m-2h-1 for sample OgW-Sp-1 with a order to compare the spectral dependency of mean mercury concentration of 152 mg/kg fluxes, they where normalized to the flux More than 70 % of the observed increase is obtained at 320 Wm-2 without filter for each attributed to short wave radiation below sample as shown in Fig 2 The measured 335 nm while radiation above 335 nm only fluxes ranged from 100 pmol*m-2h-1 for accounts for about 20 % to 30 % of the ob-

RMZ-M&G 2004, 51 790 PART 2 BIOGEOCHEMISTRY served increase The observed offset at wave- As the light induced flux is independent from length below 335 nm did not show any sig- the soil temperature this mechanism may also nificant spectral dependency and was more be important during winter and spring when likely correlated with the overall radiation the thermal controlled flux is restrained be- intensity We assume that the observed in- cause of low temperatures The short half life crease below 335 nm is related to a photo- of the light induced flux indicate that this chemical formation of Hg° at the soil sur- mechanism may play a minor role under face This process may be mediated by hu- natural conditions However our data indi- mic compounds, which are known for their cate that the pool of mercury available for ability to reduce mercury by a photochemi- photo reduction is probably recharged by cal mechanism (XIAO, 1995) transport of mercury either by diffusion of Hg° to the soil surface and subsequent oxidation or by the transport of soluble Hg-com- CONCLUSIONS plexes Under field conditions the deposition of mercury to the soil surface and re- Our results show that the light induced flux newing of the soil surface due to wind ero- is independent of the soil temperature and sion may provide further mechanisms to re- shows a strong spectral response in the UV- charge the pool of Hg available for photo B This reveal clear evidence for photolytical reduction The interplay between the ther- reduction of divalent mercury species at the mal controlled flux and the light induced flux soil surface has to enlightened to assess the role of the light induced flux under natural conditions

REFERENCES

CARPI, A, LINDBER, S E (1997): Sunlight mediated BAHLMANN, E, EBINGHAUS, R, RUCK, W (2004A): De- emission of elemental mercury from soil velopment and first tests of a laboratory flux amended with municipal sewage sludge; Envi- chamber system (LFMS); Presented at the ronmental Science and Technology, Vol 31, pp ICMGP in Ljubljana, Slovenia, June 27 July 2085-2091 2, 2004 GUSTIN, M S, BIESTER, H, KIM, C S (2002): Investi- XIAO, Z (1995): Air-surface exchange of mercury in gation of the light enhanced emission of mer- the environment; PhD thesis, Department of cury from naturally enriched substrates; Atmo- Inorganic Chemistry, University of Göteborg, spheric Environment, Vol 36, pp 3241-3254 Sweden

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 791 The effect of soil moisture on the emission of mercury from soils

ENNO BAHLMANN1, RALF EBINGHAUS1, WOLFGANG RUCK2

1GKSS Research Centre Geesthacht, Institute for Coastal Research / Physical and Chemical Analysis, Max-Planck-Str 1, D-21502 Geesthacht, GERMANY; E-mail: enno bahlmann@gkss 2University of Lueneburg, Institute for Ecology and Environmental Chemistry, Scharnhorst-Str 1, D-21335 Lueneburg

Abstract: We have investigated the effect of soil moisture on mercury emission fluxes (MEFs) from soils under controlled conditions with a laboratory flux chamber system Over wet soils MEFs first increase by a factor of five to ten with decreasing soil moisture, peak between 33 % and 10 % and than decrease to less than 2 % of the maximum observed flux at soil moisture levels below 1 % Our results strongly indicate that the MEFs are more likely to be controlled by the soil moisture tension rather than by the soil moisture level

Key words: air/surface exchange, soil moisture soil moisture tension

INTRODUCTION enhanced reaction between the soil components have been suggested to explain the The effect of soil moisture on mercury emis- observed effects of soil moisture* However sion fluxes (MEFs) from soils has first been till now none of the proposed mechanisms noted during an international field campaign has been improved by systematic studies* In in Reno/Nevada where a tremendous in- this contribution we will present the results crease of the mercury emission flux from of systematic studies on the effect of soil about 8 ng/m2h prior to more than 140 ng/ moisture on the emission of mercury from m²h one hour after the rain event has been soils, carried out under controlled environ- observed (LINDBERG, 1999)* Controlled ex- mental conditions with a laboratory flux periments in the field and in the lab have chamber system (BAHLMANN, 2004)* To study shown, that addition of water to dry soils lead the effect of soil moisture on MEFs the soil to an increase of the flux or may even turn a samples were watered till saturation and then soil from a sink to a source (LINDBERG, 1999) allowed to dry by evaporation during the while addition of water to a wet soil can lead measurements* The experiments were per- to a decrease of the emission flux (GILLIS, formed at a constant temperature between 25 2000)* Several explanations including physi- and and 40 °C* The soil moisture was recal- cal mechanisms such as the displacement of culated from the evaporation flux and mercury enriched soil air and the desorption checked gravimetrically in regular time of mercury adsorbed onto the soil surface as intervals* well as chemical mechanisms such as an

RMZ-M&G 2004, 51 792 PART 2 BIOGEOCHEMISTRY

RESULTS AND DISCUSSION mained on a constant level of 3!1 mol/m2h but shows a similar decline starting at a soil As a typical example figure 1 shows the ef- moisture level of 26!2 %! The decrease of the fect of the soil moisture [m/m] on the MEF evaporation flux almost parallels the decrease and the evaporation flux for a clayey soil with of the MEF but is shifted for 5!3 % towards a mean mercury concentration of 0!25 ± the dry end! At the beginning the soil tem- 0!03 mg/kg! The MEF increased from perature dropped from the temperature set 14 pmol/m2h at a soil moisture level of 86 % point of 30 °C down to 28!4 °C due to the to 76 pmol/m2h at a soil moisture level of evaporative cooling of the soil and stayed 31!7 % then turned around and declined be- steady till 27!4 % of soil moisture! Between low the detection limit (~ 2 pmol/m2h) at soil 27!4 % and 7!1 % soil moisture the tempera- moisture level of 1!8 %! The evaporation flux ture decreased to 27!8 °C and than turned exhibited different over the wet soil as it re- around and increased sharply to 29!4 °C!

Figure 1 Mercury emission flux, evaporations flux and soil surface temperature versus soil moisture for a clayey soil

Over each soil the observed change of this The almost parallel decrease of the MEF and three quantities felt into a fairly narrow range evaporation flux strongly indicates that both of soil moisture between 0!8 and 5!3 %! The are controlled by the same mechanism! Based soils can be distinguished into two groups on the assumption that the emission of mer- by the peak maximum of the MEF The first cury is primarily controlled by the interfa- group include clayey soils where the maxi- cial equilibrium of Hg° between the soil mum observed flux occurred between 30 % matrix and the soil gas, the effect of soil and 33 % soil moisture and the second group moisture can be described by film diffusion, included the sandy soils where the maxima e!g!, the diffusion of Hg° through the water occurred between 10!6 % and 13!2 %! film that encloses the soil particles and acts as a resistant (R )! The decrease of the evapo- f

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 793 ration flux is a consequence of the increas- where r is the radius of the water filled soil ing soil moisture tension (pF) (which we pores for a given pF (m) and γ is the surface could unfortunately not determine for this tension of water (10-3Nm-1)" soils) that leads to a decrease of the water vapour pressure and subsequently to a de- In contrast to the soil moisture tension which crease of the observed evaporation flux" The is proposed to effect the state of the interfacial soil moisture tension is defined as a nega- equilibrium of Hg°, the thickness of the water tive hydrostatic pressure" The decrease of the film is proposed to effect the reaction rate at vapour pressure can be derived from the gen- which Hg° is delivered into the soil gas and eral pressure dependency of the vapour pres- must therefore be limited by the diffusive trans- sure by inserting the soil water tension in this port of Hg° through the soil column" equation: p/p* = exp(-((pF) V /RT) (1) Under the experimental conditions the soil m temperature is a function of the evaporative where, V is the molar Volume (m-³mol), pF heat and the thermal conductivity of the soil" m is the soil moisture tension (Pa), R is the gas To a first approximation the constant tem- constant (8"3145 JK-1mol-1) and T is the ab- perature drop indicate a constant evapora- solute Temperature in Kelvin" As in a more tive heat flux and thus also a constant water general sense equation (1) describes the in- vapour flux" The decrease of the tempera- crease of the surface work which is neces- ture between 27"4 and 7"1 % soil moisture sary to transfer any molecule from the aque- indicate that the evaporative heat flux in- ous phase into the gas phase we suppose that creases in this interval" As the evaporation the phase equilibrium of Hg° is shifted to first remains on a constant level and then adsorbed phase with increasing soil mois- decreases in this interval the specific heat of ture tension and thus will lead to the observed evaporation increases must increase here" decrease of the MEF" Because the experiments were not conducted under equilibrium conditions the decrease of The observed increase of the MEF with de- the water vapour pressure can at least be creasing soil moisture over wet soils is not partially compensated by an increase of the only related to the increase of the air filled specific heat of evaporation, which would pore volume of the soil which controls the result in a shift of the evaporation from flux diffusivity in the soil column but also to from the theoretical expected curve towards thickness of the enclosing water film as the a higher soil moisture tension" This effect diffusion of Hg° in water is by about 4 or- could probably account for the observed dif- ders of magnitude lower than the diffusion ferences in the decrease of the MEF and the in air" Therefore the MEF should be inversely evaporation flux respectively" The turn- proportional to the thickness of the water film around of the soil surface temperature is re- which may be derived from the following lated to the sudden change of the heat con- equation (Scheffer Schachtschabel, 1998): ductivity of the soil, which occurs when the water menisci between the soil particles dis- r = 2γ*pF (3) appear (SCHEFFER & SCHACHTSCHABEL, 1998)"

RMZ-M&G 2004, 51 794 PART 2 BIOGEOCHEMISTRY

From equation (1) it follows that the appar- CONCLUSIONS ent activation energy for the emission of mercury should increase with increasing soil Our results clearly show that the soil mois- moisture tension" Theoretical calculations ture has an overall strong effect on the emis- however show, that the soil moisture tension sion of mercury from soils, which is of par- will only significant contribute to Ea when ticular interest for arid climates as the soil it exceeds 10^7 Pa and should therefore only moisture deficit under these climate condi- occur over extremely dry soils" tions can counteract the effect of high temperatures at the soil surface" The proposed Over a dry sandy soil with a mean mercury effect of the soil moisture tension provides concentration of 15"2 mg/Kg we observed for the first time an explanation for the ob- an increase of the apparent activation energy served decrease of mercury emission fluxes for the emission of mercury from about 50 over dry soils" Further on the proposed kJ/mol at 7 % soil moisture to more than 200 mechanism can explain the differences be- kJ/mol at a soil moisture level of 0"9 %" The tween sandy soils and clayey soils as the soil observed increase in dry soils was propor- moisture tension in the latter ones will gen- tional to the increase of the Ea for the evapo- erally be higher at a given soil moisture level" ration of water" This strongly reinforces the It should be highlighted the proposed mecha- hypothesis that the decrease of both quanti- nism is a pure physical mechanism which ties is controlled by the same mechanism and may also be applied to other compounds such related to the increase of the soil moisture as VOCs" tension"

REFERENCES

LINDBERG, S E, ZHANG, H, GUSTIN, M, VETTE, A, GILLIS, A A, MILLER, D R (2000): Some local ef- MARSIK, F, OWENS, J, CASIMIR, A, EBINGHAUS, fects on mercury emission and absorption at a R, EDWARDS, G, FITZGERALD, C, KEMP, J, KOCK, soil surface; The Science of the Total Environ- H H LONDON, J, MAJEWSKI, M, POISSANT, L, ment, Vol 260, pp 191-200 PILOTE, M, RASSMUSSEN, P, SCHAEDLICH, F, SCHEFFER, F (1998): Scheffer Schachtschabel, SCHNEEBERGER, D, SOMMAR, J, TURNER, R, Lehrbuch der Bodenkunde; Enke, Stuttgart% WALLSCHLÄGER, D, XIAO, Z (1999): Increase in mercury emissions from desert soils in rresponse to rainfall and irrigation; Journal of Geophysi- cal Research, Vol 104, pp 21879-21888 BAHLMANN, E, EBINGHAUS, R, RUCK, W (2004): De- velopment and first tests of a laboratory flux chamber system (LFMS); Presented at the ICMGP in Ljubljana, Slovenia, June 27 July 2, 2004

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 795 Mercury Sources and Speciation in the Waters of New York/New Jersey Harbor Estuary

PRENTISS H BALCOM1, WILLIAM F FITZGERALD1, CHAD R HAMMERSCHMIDT1, CARL H LAMBORG2, AND LARISSA J GRAHAM1

1Department of Marine Sciences, University of Connecticut, Groton, CT, USA 2 Woods Hole Oceanographic Institution, Woods Hole, MA, USA

Abstract: Mercury (Hg) contamination is ubiquitous and often severe in riverine, estuarine, and near shore systems of industrialized countries We examined the speciation of Hg in waters of NY/NJ Harbor in winter, spring, and summer seasons Scavenging by particulate matter is a major control on the partitioning, speciation, and reactivity of Hg; 90-98 % of total Hg was in the particle phase During each season, levels of total Hg in unfiltered samples were highest near the major river inflows (Newark Bay, Upper Har- bor), and were inversely related with salinity throughout the Harbor Preliminary results of this study suggest that atmospheric deposition to the watershed and subsequent runoff is the principal source of Hg to the Harbor, and that adsorption to particles is a major control on the distribution and reactivity of Hg in the water column

Key words: mercury, monomethylmercury, estuary, New York, New Jersey

INTRODUCTION of Hg The water column studies presented here were designed to complement the ob- Mercury (Hg) is not well studied in coastal jectives of a larger research project, bio- systems, and there is an urgent need for in- geochemical processes and reactions affect- creased understanding of its marine bio- ing MMHg production and its mobilization geochemical cycling Monomethylmercury from sediment in NY/NJ Harbor Estuary (MMHg) is a toxic byproduct of mercury (HAMMERSCHMIDT ET AL, 2004) (Hg) pollution in many coastal regions, and is of concern in the anthropogenically impacted (current and past) NY/NJ Harbor es- STUDY AREA AND METHODS tuarine system Near shore Hg cycling is affected by localized discharges (eg, rivers, Research cruises on the R/V Connecticut water pollution control facilities; BALCOM ET (University of Connecticut) were conducted AL, in press), sediment-water exchange of in NY/NJ Harbor (August 2002; February, modern and historic pollution May, and August 2003; February 2004) The (HAMMERSCHMIDT AND FITZGERALD, 2004; regions sampled include the Upper and HAMMERSCHMIDT ET AL, in press), and direct Lower Harbors (including Raritan Bay), and and indirect (ie, watershed leaching) inputs Newark and Jamaica Bays (Figure 1) from atmospheric transport and deposition

RMZ-M&G 2004, 51 796 PART 2 BIOGEOCHEMISTRY

During each cruise, water was sampled at solved oxygen were measured and logged with 5-10 bottom water locations (yellow dots) a sonde (YSI) throughout the Harbor; surface water was collected at one of these locations in each region of the Harbor Trace-metal clean techniques RESULTS AND DISCUSSION and equipment were used to collect water samples These included the use of an oceano- Scavenging by particulate matter is a major graphic Go-Flo bottle lined with Teflon, a non- control on the speciation of Hg in the verti- metal (Kevlar) hydrowire, a Teflon messen- cally well-mixed waters of the Harbor; ger, and Teflon sample bottles Hg speciation 90-98 % of total Hg was in the particle phase measurements included dissolved (<0 2-µm; (log K = 5 9-6 5) During each season, lev- D filtered on-board the ship) and unfiltered re- els of total Hg in unfiltered samples de- active Hg (stannous chloride reduction) and creased with distance from the major river total Hg (bromine monochloride oxidation), inflows (Hudson, Hackensack) Accord- as well as dissolved and particulate ingly, total Hg in Newark Bay and the Up- monomethylmercury (MMHg) Ancillary paper Harbor was greater than that in the Lower rameters measured included total suspended Harbor and Jamaica Bay, and total Hg was solids (TSS), dissolved organic carbon (DOC) inversely related with salinity throughout the and dissolved nutrients (nitrate/nitrite) Ver- Harbor Concentrations of total Hg and dis- tical profiles of temperature, salinity, and dissolved nitrate (nitrate enriched in surface

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 797 waters) were more variable seasonally at the CONCLUSIONS sites in Newark Bay and the Upper Harbor, consistent with fluvial inputs as a principal Preliminary results of this study suggest that source of Hg to the Harbor Similarly, atmospheric deposition to the watershed and Balcom et al (in press) have reported that subsequent runoff is the principal source of total Hg (unfiltered) is elevated in the Con- Hg to the Harbor Fitzgerald and OConnor necticut River as compared to Long Island (2001) reported that a significant portion of Sound (LIS), and that rivers serve as the riverine Hg entering NY/NJ Harbor is an- major source of Hg to the Sound thropogenic and due principally to mobilization of Hg from the watershed They indi- As indicated by particulate Hg concentra- cated that much of the Hg in the watershed tions in the Harbor, the adsorption to par- has been deposited via atmospheric pro- ticles is a major control on the distribution cesses, derived from extra- and intra-regional and reactivity of Hg in the water column Hg sources Similarly, Balcom et al (in press) species, particularly unfiltered total Hg have indicated that the majority of Hg enter- (1500 pM) and reactive Hg (240 pM) in Au- ing Long Island Sound from the Connecti- gust 2002, were elevated in Newark Bay cut River is derived from atmospheric bottom water at high suspended solids con- sources supplying Hg to the watershed centrations, which are likely due to turbu- lent mixing of surface sediments in that re- Acknowledgments gion Reactive Hg (14-40 pM) accounted for 40-50 % of total Hg (29-91 pM) in unfil- We thank Pieter Visscher, Daniel Buckley tered samples within each region in one sum- (Cornell University), and Laura Baumgartner mer survey, but reactive Hg (2-10 pM) was for their help with both laboratory and field only 5-40 % of total Hg (27-66 pM) within aspects of this project; Jani Benoit (Wheaton each region during a representative winter College), Eileen Ekstrom (Princeton Univer- survey Most of the dissolved total Hg was sity), George Waldbusser, Rachel Sytsma, reactive in both the summer (50-70 %) and Brett Branco, and Brennan Phillips for their winter (about 100 %) surveys Despite the assistance in the field; Turner Cabaniss, Cap- seasonal variability, reactive Hg (expressed tain Daniel Nelson, and crew of the R/V as a percentage of total Hg) in unfiltered Connecticut This work was supported by samples was highest in each season at the project 003/02A from the Hudson River elevated salinities in Jamaica Bay This is Foundation consistent with our findings that processes associated with estuarine mixing (e g , ion exchange, ligand competition, metal scavenging) are forming labile (reactive) Hg from riverine Hg-DOM complexes in river-seawater mixing zones (ROLFHUS ET AL , 2003; LAMBORG ET AL , 2003)

RMZ-M&G 2004, 51 798 PART 2 BIOGEOCHEMISTRY

REFERENCES

BALCOM, P H, FITZGERALD, W F, VANDAL, G M, HAMMERSCHMIDT, C R & FITZGERALD, W LAMBORG, C H, ROLFHUS, K R, LANGER, C S F (2004): Geochemical controls on the produc- & HAMMERSCHMIDT, C H (2004): Mercury tion and distribution of methylmercury in near sources and cycling in the Connecticut River and shore marine sediments; Environ Sci Technol, Long Island Sound; Mar Chem(in press) doi: 101021/es034528q FITZGERALD, W F & OCONNOR, J S (2001): Mercury LAMBORG, C H, TSENG, C-M, FITZGERALD, W F, cycling in the Hudson/Raritan Basin and NY/ BALCOM, P H & HAMMERSCHMIDT, C R (2003): NJ Harbor: Mercury flow analysis and empiri- Determination of mercury complexation char- cal constraints; New York Academy of Sciences acteristics of dissolved organic matter in natu- HAMMERSCHMIDT, C R, FITZGERALD, W F, LAMBORG, ral waters through reducible Hg titrations; C H, BALCOM, P H, VISSCHER, P T & GRA- Environ Sci & Technol 37, pp 3315-3322 HAM, L G (2004): Biogeochemical controls ROLFHUS, K R, LAMBORG, C H, FITZGERALD, W F & on the production and distribution of methylm- BALCOM, P H (2003): Evidence for enhanced ercury in sediments of Long Island Sound, New mercury reactivity in response to estuarine mix- York/New Jersey Harbor, and the adjacent con- ing; J Geophys Res-Oceans 108(C11), 3353, tinental margin; 7thInternational Conference on doi:101029/2001JC001297 Mercury as a Global Pollutant, Ljubljana, Slovenia, June 27-July 2 HAMMERSCHMIDT, C R, FITZGERALD, W F, LAMBORG, C H, BALCOM, P H & VISSCHER, P T (2004): Biogeochemistry of methylmercury in sediments of Long Island Sound Mar Chem(in press)

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 799 Redox chemistry in Minnesota streams during episodes of increased methylmercury discharge

STEVEN BALOGH, YABING NOLLET & EDWARD SWAIN

Abstract: Total mercury (THg) and methylmercury (MeHg) are flushed from watersheds during hydrological events, contaminating downstream surface waters and resident fish populations We monitored THg, MeHg, and ancillary water chemistry parameters in two streams (Cedar Creek and Trott Brook) in east central Minnesota on a weekly or semiweekly basis from April through October, 2003 The watersheds lie in the Anoka Sand Plain, a large area of sandy glacial lake and outwash deposits Wetlands and peat deposits are spread throughout the watersheds Heavy precipitation in late June resulted in discrete episodes of high concentrations (> 12 ng/L) of MeHg in both streams in early July The MeHg/THg ratio increased from 015 to 036 in Cedar Creek, and from 013 to 046 in Trott Brook during the event The high MeHg concentrations were accompanied by low dissolved oxygen concentrations and increased concentrations of the redox-sensitive elements Mn and Fe Soluble reactive phosphorus and dissolved organic carbon concentrations were also elevated, whereas sulfate concentrations were less than 1 mg/L A prolonged absence of precipitation during August and early Septem- ber brought stream levels back to baseflow values, and MeHg concentrations were reduced to less than 01 ng/L These results show that high-discharge events are the primary route of export of MeHg from these watersheds, and baseflow contributes little MeHg to downstream waters The redox water chemistry during the events sampled here suggests that MeHg in these streams is discharged from wetland areas where anoxic/anaerobic conditions prevail

Key words: methylmercury, streams, Redox chemistry

RMZ-M&G 2004, 51 800 PART 2 BIOGEOCHEMISTRY

Elevated methylmercury concentrations in flooding rivers

STEVEN BALOGH, EDWARD SWAIN & YABING NOLLET

Abstract: Previous studies have identified flooded landscapes (wetlands, impoundments, etc) as sites of elevated methylmercury (MeHg) production Here we report MeHg and total Hg (THg) concentrations and mass loadings in rivers in Minnesota during major flooding episodes in the summer of 2002 Frequent intense precipitation events throughout the summer resulted in extraordinarily wet conditions in east-central and northwestern Minnesota Streamflow remained at record-setting high levels in many rivers and streams in these regions for several weeks We observed high concentrations of MeHg (> 14 ng/L) accompanied by high MeHg/THg ratios (039 to 050) in the Roseau River in northwestern Minnesota and in the Elk and Rum Rivers in east-central Minnesota Very high MeHg mass loadings were observed in the Mississippi River just upstream of Minneapolis on July 17 (51 g MeHg/day) and July 23 (42 g MeHg/day), when MeHg concentrations at this site were 089 and 099 ng/L, respectively These rivers drain landscapes containing varying amounts of wetlands, and some of the MeHg discharged is thought to have been flushed from these wetland areas In addition, however, the flooding of vast areas of normally dry land surfaces probably also resulted in increased MeHg production, adding to the quantities of MeHg exported from these watersheds

Key words: methylmercury, Flooding, rivers

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 801 Mercury bioaccumulation and fish feeding behavior in the Rio Negro Basin

ANTONIO C BARBOSA1, JOSE G DOREA2, PEDRO S FADINI 3, GILMAR S SILVA4

1IBAMA (Brazilian Environmental Agency), Brasília; E-mail: Antonio-CarneiroBarbosa@ibamagovbr 2Faculdade de Ciências da Saúde, Universidade de Brasília, Brasília, Brazil; E-mail: dorea@rudahcombr 3Faculdade de Química, PUC, Campinas 4Instituto de Química, UNICAMP, Campinas, Brazil

Abstract: Mercury bioaccumulation in fish depends on feeding behavior Some fish species of Amazonia subjected to regular annual flooding are known to have adaptable feeding strategies The unpolluted and acidic black-waters of the Rio Negro show the highest fish-Hg concentrations in the Amazonia We used species representing standard fish classification based on trophic position to study the impact of hydrological cycles on Hg bioaccumulation Opportunity caught samples of Tucunarés (Cychla spp, carnivorous), Peixe-cachorro (Hydrolycus scomberoides, carnivorous), Traíra (Hoplias malabaricus, carnivorous), Piranha branca (Serrasalmus aff eigenamanni, carnivorous), Piranha preta (Serrasalmus rhombeus, carnivorous), Aracú (Leporinus friderici, omnivorous), Branquinha (Potamorhina latior, detritivorous), Orana preta (Hemiodus immaculatus, omnivorous), Sardinha (Triportheus elongates, omnivorous), Jaraqui escama-fina (Semaprochilodus taeniurus,detritivorous), and Pacú branco (Myleus torquatus, herbivorous) within similar weight range were studied during high and low waters of the Rio Negro Mercury in fish was determined by cold vapor atomic absorption spectrometry Ranges of Hg concentrations were higher for carnivorous and omnivorous and lowest for herbivorous species regardless of hydrological period There were distinct trends of Hg bioaccumulation as a function of fish weight (age) during high and low waters for some species (Traíra, Sardinha, Peixe-cachorro, Piranha branca, Piranha preta) but not for others (Aracú, Tucunarés, Pacú branco, Orana preta, Jaraqui escama-fina, Branquinha) In species with similar trends, the Hg bioaccumulation was higher during the flooded season for Aracú, Pacú Branco and Orana Preta and lower for Branquinha and Tucunarés Trends in fish-Hg bioaccumulation indicate that dominance of feeding strategies (primary to tertiary consumers) change among certain species as a function of annual hydrological cycles

RMZ-M&G 2004, 51 802 PART 2 BIOGEOCHEMISTRY

The use of neurochemical biomarkers to study mercury toxicity in wildlife

NIL BASU1, KATE KLENAVIC, MARY GAMBERG, MIKE O°IEN, MICHAEL KWAN, DOUGLAS EVANS, ANTON SCHEUHAMMER & HING MAN CHAN

1Department of Natural Resource Sciences, McGill University, Macdonald campus of McGill University, H9X3V9, Montreal, Canada, e-mail: niladri#basu@mail#mcgill#ca

Abstract: Piscivorous wildlife, such as mink (Mustela vison), river otter (Lutra canadensis), and ringed seal (Phoca hispida), are particularly vulnerable to mercury (Hg) toxicosis given their high trophic level and ability to effectively bioaccumulate Hg# We have demonstrated that neurochemical parameters, particularly receptor binding characteristics for the muscarinic cholinergic (mACh) and dopaminergic (D2) systems, in wildlife are novel methods to assess the effects of Hg on ecosystem health# Initial studies were completed to optimize established protocols for field-based research on wildlife# For example, multiple freeze-thaw cycles, but not storage temperatures, have an effect on receptor binding characteristics# In vitro studies conducted on brain cortex and cerebellum regions from mink, river otter, and ringed seal show that methyl Hg ( MeHg; IC50 range: 2#1-6#6 µM) can inhibit the binding of radioligands to mACh receptors, providing direct evidence that Hg can affect neurochemistry# Moreover, significant brain region - and species - specific differences in inhibition were observed# Mink and river otter were collected across Canada by trappers and levels of total Hg and MeHg were determined# There was a significant correlation between Hg (total Hg and MeHg) and mACh receptor density (r=0#546; r=0#596, respectively) and ligand affinity (r=0#413; r=0#474, respectively) in whole mink brains# A significant negative correlation was found between total Hg and D2 receptor density (r=-0#340) and ligand affinity (r=-0#346) in whole mink brains# In the otter cerebral cortex, there was a significant positive correlation between Hg (total Hg and MeHg) and mACh receptor density (r=0#720; r=0#820, respectively), but a significant negative correlation (r=-0#552; r=-610, respectively) between these parameters was obtained in the otter cerebellum# These neurochemical changes were observed at brain Hg concentrations that are lower than the lowest observ- able effects levels for these wildlife species# The physiological and ecological implications of these changes need to be addressed# In summary, these studies demonstrate that neurochemical receptor binding characteristics can be used as novel biomarkers to study the toxicological effects of Hg on wildlife#

Key words: mercury, wildlife toxicology, biomarkers, neurotoxicology, piscivorous wildlife

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 803 The antagonistic role of selenium in mercury bioassimilation by living organisms

NELSON BELZILE1, 2, YU-WEI CHEN1, JIAN TONG1, JOHN M GUNN2, 3, YVES ALARIE2, 3, GAO-JUN WU & VASU APPANNA1

1Department of Chemistry and Biochemistry 2Cooperative Freshwater Ecology Unit 3Department of Biology, Laurentian University, Sudbury, Ontario, P3E 2C6 CANADA; E-mail: nbelzile@laurentianca

Abstract: Our first results showed a clear antagonistic effect between Se and Hg in the tissues of two freshwater fish species, yellow perch and walleye This was confirmed by the low levels of Hg in tissues containing high concentrations of Se We present results showing similar trends with other aquatic species situated at lower levels of the food chain in lakes characterized by various levels of dissolved Hg and Se Higher concentrations of total Hg and methyl mercury in tissues of zooplankton, mayflies and amphipods can be directly correlated with increasing distance from Sudbury smelters and inversely correlated with Se concentrations in lake water, once again suggesting the action of an antagonistic mechanism of Se on Hg assimilation A separate study on the bacterium Pseudomonas fluorescens shows that bacteria can develop a detoxifying mechanism to eliminate an excess of Se by reducing it to an insoluble form of Se(0) and reducing Hg2+ by generating a volatile form of the metal, likely Hg(0) through the onset of some mercury reductase enzymes When the two elements are present in the culture, it appears clearly that Se is playing a detoxifying role by limiting the availability of Hg to the bacteria

Key words: mercury, selenium, antagonism, aquatic organisms

INTRODUCTION vention of oxidative damage! Some recent studies also try to relate the inhibitory effects [3, 4] Since the study conducted in 1967 by PARÍZEK of Se to specific enzymatic activities ! AND OSTÁDALOVÁ[1] who identified a protective effect of selenium on mercury toxicity, a The objective of the present work was to in- large number of studies have reported inter- vestigate the Se-Hg antagonistic effect that actions between selenium and mercury in we had already observed on perch and wall- various types of organisms including human eye[5], at other levels of the food chain in an beings! A literature review by CUVIN-ARALAR aquatic ecosystem and even on bacteria! Bio- AND FURNESS[2] presented several possible logical organisms including amphipods, mechanisms of protection including redistri- zooplankton, mayfly and yearling perch were bution of Hg in presence of Se, competition collected in lakes that are situated from for binding sites between both elements, for- 5-100 km from the metal smelters and ex- mation of a Hg-Se complex, and conversion hibit a wide range of limnological and chemi- of toxic forms to less toxic forms and pre- cal characteristics! The bacterial strain

RMZ-M&G 2004, 51 804 PART 2 BIOGEOCHEMISTRY

Pseudomonas fluorescens was obtained from RESULTS AND DISCUSSION the American Type Culture Collection and was maintained on a medium containing cit- Concentrations of total Se in lake water var- ric acid Biological samples were freeze- ied from 38 to 230 ng/L showing the increas- dried, finely ground, microwave digested in ing effect of atmospheric deposition in lakes a mixture of HNO and H O and analyzed 3 2 2 from Halfway located 100 km away from for Se by hydride generation atomic fluores- smelters to Ramsey (5 km) However, lake cence spectrometry (PSA 10055 Millenium water concentrations of total Hg remained Excalibur) and for total Hg and CH Hg+ 3 low and relatively constant (18 32 ng/L) (KOH/MeOH extraction-GC-) by cold va- in all sampled lakes Figure 1 shows the ef- por atomic fluorescence spectrometry fect of distance from smelters on the con- (Tekran 2600) The quality of digestion and centration of total Hg in tissues of amphi- analysis was controlled by using certified pod (Hyalella azteca), mayfly (Stenonema reference materials, triplicate digestion and femoratum), zooplankton and yearling perch standard spike recovery Total Se and Hg in (Perca flavescens) and illustrates the posi- lake water were determined by the same ana- tive effect of Se on Hg intake by these or- lytical techniques[5] ganisms

Figure 1 Total [Hg] in organisms as a function of distance from smelters

Halfway is ~100 km away and Ramsey is We have selected results on amphipod to il- the closest at ~ 5 km from smelters Trends lustrate the relationships between Hg concen- are similar for methyl-Hg Concentrations of trations in tissues as a function of (i) distance methyl-Hg range between 15 and 57 % of from smelters (Fig 2a), (ii) Se concentration the total depending on species in lake water (Fig 2b), (iii) Se concentration

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 805 in tissues (Fig 2c), and (iv) the Se/Hg molar This was confirmed by the low levels of Hg ratio in tissues (Fig 2d) In a previous study[5], in tissues containing high concentrations of a clear antagonistic effect was observed be- Se Similar trends are now observed in other tween total Hg and Se concentrations in tis- aquatic species at lower levels of the food sues of two freshwater fish species, yellow chain in lakes characterized by various lev- perch (R2 = 079) and walleye (R2 = 097) els of dissolved Hg and Se

Figure 2 Concentrations of total Hg in tissues of amphipods collected in different lakes expressed as a function of distance from smelters (a), of total Se conc in lake water (b), of total Se conc in the same tissues (c), and of the Hg/Se molar ratio (d)

Higher concentrations of total Hg and me- ever when total concentrations of Se are re- thyl mercury in tissues of zooplankton, may- placed by a ratio Se/Hg (Fig# 2d), correla- flies and amphipods can be directly corre- tions improved remarkably for all species, lated with increasing distance from Sudbury including those with fish species in our pre- smelters (Fig# 2a) and inversely correlated vious work# This suggests that Se is not an with Se concentrations in lake water (Fig# independent variable controlling the assimi- 2b), once again suggesting the action of an lation of Hg and that the assimilation of Hg antagonistic mechanism of Se on Hg assimi- somehow affects the assimilation of Se# lation# The correlations between total Hg and When the concentration of Se is significantly total Se in organisms (Fig# 2c) from the lower higher than that of Hg, Se plays a dominant levels of the food chain are not as clear as role in Hg assimilation processes# those that were observed in fish tissues# How- RMZ-M&G 2004, 51 806 PART 2 BIOGEOCHEMISTRY

The antagonistic effect of Se on Hg assimi- to its elemental form was affected by the lation was confirmed in a separate series of presence of Se# The reduced assimilation of experiments involving the bacterium Hg is clearly demonstrated in presence of Pseudomonas fluorescens grown in presence selenite (Fig# 3b) and the assimilation of Se of Hg or Se and both# Figure 3a shows how by P fluorescens was also inhibited by the Hg reductase activity and conversion of Hg presence of Hg in the culture (Fig# 3c)#

Figure 3 Enzymatic activity (a), concentrations of Hg (b) and Se(c) in bacteria P fluorescens exposed to mercury and selenium

CONCLUSIONS Acknowledgements

The protective effect of selenium on mercury This work was supported by the Natural Sci- assimilation was clearly demonstrated in ence and Engineering Research Council of various types of aquatic organisms at differ- Canada (COMERN), the Ontario Ministry ent levels of the food chain and in labora- of Natural Resources and Industry Canada# tory experiments involving bacteria that were grown in presence of both elements#

REFERENCES

[1] [4] PARÍZEK, J, OSTÁDALOVÁ, I (1967): The protective FARINA, M, BRANDÃO, R, LARA, F S, SOARES, F A effect of small amounts of selenite in sublimate A, SOUZA, D O, ROCHA, J B T (2003): Mecha- intoxication; Experientia 23, pp 142-143 nisms of the inhibitory effects of selenium and [2] CUVIN-ARALAR, M L A, FURNESS, R W (1991): mercury on the activity of ä-aminolevulinate Mercury and selenium interaction: A review; dehydratase from mouse liver, kidney and brain; Ecotoxicology and Environmental Safety 21, pp Toxicology Letters 139, pp 55-66 348-364 [5] CHEN, Y-W, BELZILE, N, GUNN, J M (2001): An- [3] WU, G J (2003): Selenium and mercury assimila- tagonistic effect of selenium on mercury assimi- tion and detoxification in Pseudomonas lation by fish population near Sudbury metal fluorescens MSc Thesis, Sudbury: Laurentian smelters?; Limnology and Oceanography 46, pp University 2003, 98 p 1814-1818 RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 807 The Effect of Sediment Resuspension on the Methylation and Bioaccumulation of Methylmercury into Benthic and Pelagic Organisms

CHRISTINE M BERGERON1, ROBERT P MASON2 & ELKA T PORTER3

1University of Maryland Center for Environmental Science (UMCES), Chesapeake Biological Laboratory, PO BOX 38, 20688, Solomons, USA, e-mail: bergeron@cbl-umces-edu 2University of Maryland Center for Environmental Science (UMCES), Chesapeake Biological Laboratory, PO BOX 38, 20688, Solomons, USA, e-mail: mason@cbl-umces-edu 3University of Maryland Center for Environmental Science (UMCES), Chesapeake Biological Laboratory, PO BOX 38, 20688, Solomons, USA, e-mail: porter@cbl-umces-edu

Abstract: Sediment is the most important repository for mercury (Hg) in the estuarine environment As a result, benthic organisms in contact with contaminated sediment have the opportunity to accumulate high levels of Hg, and especially methylmercury (MeHg) since sediment is the dominant site for Hg methylation In addition, resuspension provides a potential mechanism for transferring Hg and MeHg from the sediment to the pelagic food chain The objective of this study was to determine the effect of sediment resuspension on Hg cycling and the bioaccumulation of sedimentary Hg and MeHg to benthic organisms and zooplankton Tidal resuspension (4 hr-on, 2 hr-off) was simulated in mesocosm tanks that had both realistic bottom shear stress and water column turbulence Previous experiments with this system comparing resuspension to no resuspension during a one-month exposure found that resuspension enhances Hg methylation and that clams (M mercenaria) added to the tanks did not accumulate a significant amount of Hg compared to their background levels However, MeHg concentrations in zooplankton (>210 mm) were higher in the resuspension tanks The current experiments investigated the effect of differences in clam density on Hg methylation and the bioaccumulation up the food chain Clam density impacts methylation since clams initially destablize the sediments and enhance resupension All tanks were tidally resuspended and treatments of no clams vs high density clams (+/- 40 clams) were compared in July 2002, and high density vs low density (10 clams) were compared in August 2003 Sediment, water, zooplankton, and clam samples were analyzed for total Hg and MeHg, and ancillary parameters This talk will provide an overview of the results obtained and will examine the hypothesis that increasing clam density leads to higher MeHg concentrations in herbivores (clams and zooplankton) as a result of the interaction between MeHg biogeochemical cycling and system productivity

Key words: bioaccumulation, resuspension, mesocosms

RMZ-M&G 2004, 51 808 PART 2 BIOGEOCHEMISTRY

Mercury in sediments and molluscs of the southern Venice lagoon

D BERTO1, R BOSCOLO1, D FALSIROLI1, M GIANI1, S MACCHIA2, M MASSIRONI3 & V RIZZO3

1Istituto Centrale per la Ricerca scientifica e tecnologica applicata al Mare, Brondolo, 30015, Chioggia, Italy, e-mail: m giani@icram org 2Istituto Centrale per la Ricerca scientifica e tecnologica applicata al Mare, Roma, Italy 3Centro Italiano Ricerche e Studi per la Pesca, Roma, Italy

Abstract: The Venice lagoon is a 549 km2 shallow area with an average depth of 1 m and the presence of navigable channels The pollution of the lagoon shows marked geographical differences The central part has been subjected to industrial emissions, urban wastewater and shipping activities The watercourses of the drainage basin is a way of input of nutrients, pesticides and herbicides used in farming, particularly in the northern and southern lagoon The southern part is also characterised by urban waste waters (town of Chioggia, 53470 inhabitants), by dockyards and shipping and fishing activities Previous studies carried out in 80s and 90s have shown that the mercury pollution in the Venice lagoon is mainly associated to the industrial plants of Marghera in the central part of the lagoon The objective of this study was to investigate the metal pollution in the southern part of the Venice Lagoon near dockyards in order to understand if they constitute a source of contamination Here we focus on mercury distribution in sediments, in gastropod Nassarius reticulatus and in bivalves Crassostrea gigas and Mytilus gallopovincialis Sediments were sampled by Ekman grab, netted dogwhelk N Reticulatus were catched by wire basket, bivalves were collected by hand The samplings were carried out from April to September 2003 The samples were mineralized in a microwave oven by ultrapure concentrated HCl, HNO and HF mixture, for the sediments, and by concentrated HNO for the biota 3 3 Mercury was determined by cold vapour atomic absorption spectrometry (CVASS) The certified reference materials marine sediment (PACS-2, NRC, Canada) and oyster tissue (1566a, NBS,USA) were used to control accuracy of the analytical method Total mercury concentrations ranged 01-34 mg/kg dry weight in the sediments, the highest concentration were found near the dockyards The enrichment factor (EF) calculated on Hg concentration background for the Adriatic sediments (012 mg/kg dwt, GUERZONI ET AL, 1984) showed high values (10- 28) near the dockyards of Chioggia, whereas the lowest EF values (05-5) were found in the channels of the southern Venice lagoon and in the coastal marine sediments near the southern port entrance of the lagoon Eighty percent of the sampled sites showed concentrations higher than the Effect Range Median (LONG ET AL, 1995), which point out a potential risk of adverse effects on the benthic community

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 809

Mercury concentration in the gastropods fall in the range 03-13 mg/kg d wt, with highest values near harbour and dockyards and lower values in the lagoon sites and in the coastal area outside the lagoon entrance far from dockyards The mercury in netted dogwhelks was 2-3 folds more concentrated than in bivalves (Mytilus galloprovincialis and Cassostrea gigas) The sediments near the town of Chioggia showed a mercury pollution probably due to antifouling paints which were used in the past in dockyards Sediment resuspension caused by capital dredging for the construction of the new harbour could be a way of diffusion of this pollutant in the southern part of the lagoon of Venice The gastropods are predator and scavenger and therefore accumulate more mercury than the bivalves pointing out a possible contamination

REFERENCES

GUERZONI, S, FRIGNANI, M, GIORDANI, P, (1984) LONG E R, MACDONALD D D, SMITH S L, CALDER F Heavy metals in sediments from different envi- D (1995) Incidence of adverse biological ef- ronments of a northern Adriatic sea area, Italy fects within range of chemical concentration in Environ Geol Water Sci, 6: 111 - 119 marine and estuarine sediments Environmen- tal Management, 19: 81-97

RMZ-M&G 2004, 51 810 PART 2 BIOGEOCHEMISTRY

Do Mercury Records in Ombrotrophic Peat Bogs Solely Reflect Atmospheric Deposition?

*H BIESTER1, A MARTINEZ-CORTIZAS2, R KILIAN3, C FRANZEN1

1 Institute of Environmental Geochemistry, University of Heidelberg, INF 236, 69120 Heidelberg, Germany; *E-mail: hbiester@ugc(uni-heidelberg(de 2 Department of Soil Science and Agricultural Chemistry, Faculty of Biology, University of Santiago, E-15782 Santiago de Compostela, Spain 3 Dept( of Earth Sciences (FB VI), University of Trier, 54286 Trier, Germany

Abstract: Historical mercury accumulation and present day Hg deposition rates were investigated in three ombrotrophic peat bogs and a crater lake located in the Magellanic Moor- lands, Chile To evaluate the influence of peat decomposition processes on Hg records in peat, carbon/nitrogen ratios were determined as a measure for the degree of peat degradation Our results indicate that Hg concentrations in peat are strongly influenced by peat diagenesis, and increase during peat decomposition as a result of mass loss (carbon loss) Thus, Hg concentrations in peat do not necessarily reflect atmospheric Hg deposition Mercury accumulation rates derived from peat profiles were also influenced by peat decomposition, because differences in mass accumulation rates during peat evolution are not compensated by linear changes in density, peat accumulation or Hg concentrations We suggest normalizing Hg accumulation rates to carbon accumulation rates to achieve comparability of Hg accumulation rates derived from differently altered peat sections Normalisation to carbon accumulation rates reduces Hg accumulation rates in low degraded peat sections in the upper peat layers by factors of more than two Carbon normalized Hg accumulation rates were then comparable to values derived from lake sediments and atmospheric Hg deposition measurements

Key words: mercury, peat bogs, peat decomposition, mass loss

INTRODUCTION pend strongly on physical properties such as density or accumulation rates of the peat and Ombrotrophic peat bogs have been widely on time-dependent biogeochemical alteration used to evaluate long-term records of atmo- processes Formation of peat is a complex spheric mercury (Hg) deposition One of the process accompanied by an intense mass loss major aims of these investigations is the es- (> 90 %), which decrease exponentially with timation of the increase of atmospheric Hg increasing depth of the peat profile Thus, fluxes during the industrial age compared to accumulation rates or concentrations of an pre-industrial fluxes Differences in Hg con- element in different core sections of a peat centrations or accumulation rates between core are only comparable when normalized bog sites are generally assumed to reflect to all chemo-physical changes which affect varying atmospheric fluxes Metal concen- concentration or on accumulation rates of an trations or accumulation rates, however, de- element during peat evolution Up to now,

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 811 influences of peat humification on metal actions in peat bogs do strongly depend on cumulation rates are assumed to be compen- changes in the intensity of peat decomposi- sated linearily by appropriate changes in peat tion, which are mainly controlled by the wa- density or in metal concentrations ter level in the mire, and do not necessarily reflect atmospheric deposition From this it In this study, Hg concentrations and accumu- becomes evident that changes in atmospheric lation rates in peat profiles from three pris- Hg deposition could be only estimated from tine ombrotrophic bogs (GC1, S 52°47443/ net Hg accumulation rates determined in W 72°56616, Sky1 S 52°30668/ dated peat sections The GC1 peat core (Fig W 72°07505, Pbr2, S 53°38281/ 1C) is the only core where Hg accumulation W 70°58029), and one sediment core from rates during the past 100 years could be de- a deep crater lake, all located in the Magel- termined Here, Hg concentrations increase lanic Moorlands, Chile (52 °S), were com- by a factor of about 3, whereas Hg accumu- pared The effect of peat decomposition on lation rates in the same section increase by a Hg records was evaluated by comparing Hg mean factor of 5 (max 18) from about concentrations to carbon/nitrogen (C/N) ra- 34 µg/m2/yr in pre-industrial times to a mean tios in peat and Hg accumulation rates to the of 172 µg/m2/yr (max ~ 60 µg/m2/yr) in the extent of mass loss To estimate to which industrial period However, the increase in Hg extent Hg accumulation rates determined in concentrations in the atmosphere in the same geochemical archives (peat bogs, lake sedi- period is estimated to a factor of 2 - 3 only, ments) correspond to recent Hg deposition compared to pre-industrial times (Mason et rates, we measured Hg concentration in rain- al 1994) In the PBR2 and the SKY1 cores water and determined precipitation rates at we found an increase in Hg accumulation the three bog sites Calculated recent wet Hg rates in the past ~ 2000 years of a factor of 2, deposition rates were then compared to Hg which could not be explained by natural varia- accumulation rates determined in peat bogs tion of atmospheric Hg deposition and lake sediments Being a major parameter in the calculation of metal accumulation rates mass accumulation RESULTS AND DISCUSSION seems to be one of the factors to explain changes in Hg accumulation Comparison of Figure 1 A, B, C shows opposite trends for carbon and Hg accumulation rates in the bogs C/N ratios and Hg concentrations in all peat indicate that low degraded peat sections tend cores, which indicate that Hg concentrations to overestimate Hg accumulation rates when increase with increasing peat humification compared to higher degraded sections, which (low C/N-ratios) and vice versa Mercury have lost considerable amounts of mass It concentrations were found to increase drasti- has been proposed in previous studies cally above tephra layers in oligotrophic Sph- (BIESTER ET AL, 2003) that non-linearity of agnum bogs as a result of intense mass loss parameters used to calculate mass accumula- due to high peat mineralisation induced by tion is the main reason for this overestima- high nutrient supply from the tephras tion We assume that peat accumulation in the (Fig 1A) Accordingly, mercury concentra- catotelm does not follow gravitational com-

RMZ-M&G 2004, 51 812 PART 2 BIOGEOCHEMISTRY

Figure 1 Peat chronology, Hg concentrations and peat C/N ratios derived from three ombrotrophic peat bogs (Pbr2 (A), Sky1 (B), and GC1, and a crater lake (D) located in the Magel- lanic Moorlands, Chile'

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 813 paction, because in fact the solid material is MLCFs is based on the differences in car- floating in the bog water due to its low den- bon accumulation rates between low de- sity and can therefore not increase linear graded peat sections and a reference section for highly decomposed peat in the catotelm To compare Hg accumulation rates in low (BIESTER ET AL, 2003) (Table 1) After degraded peat section with those in old and normalisation the increase in Hg accumula- highly decomposed peat we suggest normal- tion during the past ~ 100 years is similar to izing Hg accumulation rates to mass (car- what was found in sediments of the crater bon) accumulation rates Normalisation of lake, where Hg accumulation rates increase Hg accumulation rates to rates of carbon ac- by a factor of ~ 3 from 14 µg/m2/yr (peat cumulation by a mass loss correction factor 37 µg/m2/yr) to ~ 5µg/m2/yr (peat 17 µg/ (MLCF) reduces Hg accumulation rates in m2/yr) Similar values were found for recent low degraded peat in the upper peat sections wet Hg deposition rates which amount to ~ by factors of more than two Calculation of 3 µg/m2/yr at the GC1 site

Table 1 Mercury and carbon accumulation rates, and density in patagonian peat cores (PBR2, SKY1, GC1) and mass loss (MLCF) corrected (corr') Hg accumulation rates'

CONCLUSIONS and mass accumulation It is suggested to normalise Hg accumulation rates for mass Mercury concentrations in peat bogs can be accumulation in differently decomposed peat strongly influenced by peat decomposition sections to gain comparability processes Variations of Hg concentrations in peat do therefore not necessarily reflect Acknowledgement variation of external Hg fluxes Mercury accumulation rates derived from differently This project was funded by the Deutsche decomposed peat sections are not directly Forschungsgemeinschaft (DFG: BI 734/1-1 comparable due to differences in mass loss and KI 456/6-2)

RMZ-M&G 2004, 51 814 PART 2 BIOGEOCHEMISTRY

REFERENCES

BIESTER, H, MARTINEZ-CORTIZAS, A, BIRKENSTOCK, S, KILIAN, R (2003): Historic Mercury Records in Peat Bogs The Role of Peat Decomposition, and Mass Losses; Env Sci Tech 3, 32-39 MASON, R P, FITZGERALD, W F, MOREL, F M M (1994): The biogeochemical cycling of elemental mercury: anthropogenic influences; Geochim Cosmochim Acta 58, 3191-3198

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 815 The effect of chronic sulphur deposition on the seasonal variation of peat pore water methylmercury and the vertical distribution of sulphur reducing bacteria in a boreal mire

KEVIN BISHOP1, INGER BERGMAN2, QIANG TUX3, WOLFGANG FRECH3, AND MATS NILSSON2

1Department of Environmental Assessment, Swedish University of Agricultural Sciences, Sweden; E-mail: kevin bishop@ma slu se 2Department of Forest Ecology, Swedish University of Agricultural Sciences, Sweden; E-mail: mats b nilsson@sek slu se 3Department of Analytical Chemistry, University of Umeå, Sweden

Abstract: We investigate the hypothesis that long-term sulphate (SO 2-) deposition has in- 4 creased bioaccumulation of methylmercury (MeHg+) in remote lakes that receive significant amounts of runoff from peatlands This was done by determining the effect of long-term SO 2- deposition on the temporal variation in peat pore water methylmercury 4 (MeHg+) concentrations in a boreal, low sedge mire The seasonal mean of the pore water MeHg+ concentrations from the HighS plots (1 3±0 08 ng/L,SE; n=44) was significantly (p=0 000) higher than the mean MeHg+ concentration in the LowS plots (0 6±0 02 ng/L,SE; n=44) From these results, we believe that peatlands impacted by SO 2- deposition can be a significant source of MeHg to the downstream aquatic system 4

Key words: mercury, methylmercury, mires, sulfur-reducing bacteria, acid deposition

INTRODUCTION real catchments is complex and involves numerous biogeochemical and physical controls, Historically, human activities have caused most of which are still unknown Therefore, large emissions of mercury to the atmosphere it is important to elucidate the impact of these This has contributed to widespread mercury control factors on MeHg+ production in these pollution and increased concentrations in the environments biota eg fish The deposition of mercury in the boreal region is relatively low (IVERFELDT, Boreal wetlands have been identified as a 1991), but the concentrations of mercury in potentially important source of MeHg+ to fish are higher than in other regions with simi- lakes (ST LOUIS ET AL, 1994; BISHOP ET AL, lar or even higher deposition rates (LINDQVIST 1995; HURLEY ET AL, 1995; KRABBENHOFT ET ET AL, 1991) One key to the difference be- AL, 1995) Factors affecting the significance tween Hg deposition and the high degree of of wetland sources can be the proportion of bioaccumulation is one particular species of mires (ST LOUIS ET AL, 1994; BISHOP ET AL, Hg, methylmercury (MeHg+) that is most 1995; HURLEY ET AL, 1995; KRABBENHOFT ET prone to bioaccumulation (GILMOUR AND AL, 1995; BRANFIREUN ET AL, 1996) and ri- HENRY, 1991) The cycling of MeHg+ in bo- parian zones (BISHOP ET AL, 1995; DRISCOLL

RMZ-M&G 2004, 51 816 PART 2 BIOGEOCHEMISTRY

ET AL, 1998) within the catchments Another MeHg+ at one point in time is not sufficient possible factor in the catchment production to prove a persistent effect of MeHg+ is SO 2- deposition, which stimu- 4 lates the production of MeHg+ (BRANFIREUN Other factors of major importance for the ET AL, 1999, 2000; HEYES ET AL 2000) regulation of SO 2- reduction (and hence any 4 sustained effect of SO 2-) are the occurrence 4 The importance of sulphate-reducing bacte- of competing e--acceptors eg oxygen which ria (SRB) for methylation of mercury is well- is mainly determined by the prevalence of documented (COMPEAU AND BARTHA 1985; saturated conditions (REGNELL, 1994), tem- GILMOUR ET AL, 1992; KING ET AL, 1999) perature (KING ET AL, 1999), and availabil- The possibility that SO 2- in acid-rain has ity of easily degradable carbon for the sul- 4 enhanced in-lake methylation was suggested phate-reducing bacteria (BODALY ET AL, 1984; by Gilmour and colleagues (GILMOUR AND KING ET AL, 1999) All of these factors vary HENRY, 1991; GILMOUR ET AL, 1992) Some in boreal peatlands during the snow-free pe- recent findings have also indicated that the riod To investigate the importance of these availability of SO 2- for SRB is a major fac- factors for the persistence and magnitude of 4 tor regulating the concentration of MeHg+ the acid-rain effect, we studied the temporal in mire pore water (BRANFIREUN ET AL, 1999, variation in peat pore-water MeHg+ in re- 2000) BRANFIREUN ET AL (1999) suggested sponse to ambient (ca 3 kg S ha-1 yr-1) and SO 2- reduction in the anoxic zone of mires enhanced (20 kg S ha-1 yr-1) long-term SO 2- 4 4 and riparian wetlands as the functional ex- deposition in a low sedge mire in northern planation for the increased concentrations of Sweden during one snow-free period Our MeHg+ in runoff from boreal wetlands In main hypothesis is that elevated pore-water that study addition of SO 2-, corresponding MeHg+ is maintained by an increased pool 4 to 28 kg SO 2- ha-1, to a boreal peatland in- of sulphur (due to enhanced deposition), 4 creased the pore-water concentrations of which can be recycled at the mire surface MeHg+ from 2 to 4 ng/L within 24 hours through reduction of SO 2- (to eg HS-) and 4 The MeHg+ concentrations, however, re- subsequent re-oxidation of reduced sulphur turned to ambient levels after 5 days Long- species to SO 2- Since we are interested in 4 term increases in S deposition (20 kg/ha/yr) ascertaining the effect of this process on were recently found to elevate peat pore MeHg+ loading to lakes and their biota, we water MeHg+ measured on one occasion, five have sampled the uppermost ten centimetres weeks after the most recent experimental below the water table, regardless of the wa- SO 2- amendment had been made The eleva- ter table depth relative to the mire surface 4 tion in MeHg+ concentrations was measured This is the water most likely to compose the relative to peat pore water subjected to an runoff from wetlands to lakes in the region ambient deposition of 3 kg/ha/yr in a boreal, low sedge mire (BRANFIREUN ET AL, 2000) Such a long-term effect would greatly in- RESULTS crease the potential significance of sulphur deposition for MeHg+-loading to the aquatic In this paper we investigate the hypothesis ecosystem But an observation of elevated that long-term sulphate (SO 2-) deposition has 4

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 817 increased bioaccumulation of methylmer- nounced in the HighS plots The pore water cury (MeHg+) in remote lakes that receive MeHg+ concentration was not correlated to significant amounts of runoff from peatlands either total Hg, DOC concentrations or pH This was done by determining the effect of The pore water MeHg+ concentration was long-term SO 2- deposition on the temporal also not correlated to either MeHg+ or S in 4 variation in peat pore water methylmercury the solid peat (MeHg+) concentrations in a boreal, low sedge mire throughout the snow-free portion of 1999 The experimental additions of SO 2- 4 DISCUSSION AND CONCLUSION started in 1995 We sampled four plots (4 m2), two receiving ambient levels of sulphur From these results, we believe that peatlands (3 kg ha-1 yr-1) (LowS) from precipitation and impacted by SO 2- deposition can be a sig- 4 two plots receiving 20 kg ha-1 yr-1 (HighS) nificant source of MeHg to the downstream applied on five occasions during the snow aquatic system This would mean that in- free period Pore water was sampled every creased deposition of SO 2- in acid rain has 4 week between May 26th and October 20th in contributed to the modern increase in the 1999, 0-10 cm beneath the groundwater MeHg burdens of remote lakes hydrologi- level Pore water was also sampled at 4 dif- cally connected to peatlands This would help ferent depths down to 40 cm beneath the explain why the catchment yields of MeHg groundwater level on 3 different occasions from small boreal catchments are not well We analysed pore water for MeHg+, mercury correlated to the atmospheric input of Hg (Hg ), SO 2-, pH, and dissolved organic car- tot 4 (LEE ET AL , 1998) According to our hypoth- bon (DOC) On one occasion the solid peat esis, the large catchment MeHg yields would was analyzed for its content of MeHg+, Hg tot result from the stimulation of Hg methyla- and S The seasonal mean of the pore wa- tion by SO 2- in acid rain, rather than directly tot 4 ter MeHg+ concentrations from the HighS from the Hg deposition itself or as a conse- plots (1 3±0 08 ng/L,SE; n=44) was signifi- quence of surface water acidification cantly (p=0 000) higher than the mean MeHg+ concentration in the LowS plots The cycling of MeHg+ in catchments is com- (0 6±0 02 ng/L,SE; n=44) The temporal plex, and involves numerous biogeochemi- variation in pore water MeHg+ concentra- cal and physical controls, most of which are tions was larger in the HighS plots compared still unknown The findings presented here to the LowS plots, with an amplitude of > 2 are not likely to be applicable to all ng/L in the HighS plots compared to 0 5 ng/ catchments, but if they are applicable to high- L in the LowS plots The concentrations of latitude catchments containing peatlands or MeHg+ in the HighS plots were positively other areas of anoxic organic sediments, then correlated (r2=0 21; p=0 001) to the ambient they represent an important link in our un- groundwater level, with the lowest concen- derstanding of catchment-scale Hg cycling trations of MeHg+ during the period with with implications for Hg uptake by fish that lowest groundwater level The concentra- extend across the boreal and sub-boreal tions of MeHg+ decreased with depth in all zones of North America, Europe and Asia four plots, but the decline was more pro-

RMZ-M&G 2004, 51 818 PART 2 BIOGEOCHEMISTRY

REFERENCES

BISHOP, K, LEE, Y-H, PETTERSSON, C AND ALLARD, B HEYES, A, MOORE, T R, RUDD, J W M AND DUGOUA, (1995): Terrestrial sources of MeHg+ in surface J J (2000): Methyl mercury in pristine and im- waters: The importance of the riparian zone on pounded boreal peatlands, experimental Lakes the Svartberget catchment; Water, Air, and Soil Area, Ontario; Canadian Journal Of Fisheries Pollution 80, 435-444 and Aquatic Sciences 57, 2211-2222 BRANFIREUN, B A, HEYES, A AND ROULET, N T (1996): HURLEY, J P, BENOIT, J M, BABIARZ, C H, SHAFER, The hydrology and methylmercury dynamics of M M, ANDREN, A W, SULLIVAN, J R, a Precambrian shield headwater peatland; Wa- HAMMOND, R AND WEBB, D A (1995): Influ- ter Resources Research 32, 1785-1794 ences of watershed characteristics on mercury BRANFIREUN, B A, ROULET, N T, KELLY, C A AND levels in Wisconsin rivers; Environmental Sci- RUDD, W M (1999): In situ sulphate stimula- ence and Technology 29, 1867-1875 tion of mercury methylation in a boreal peatland: IVERFELDT, A (1991): Occurrence and turnover of at- Toward a link between acid rain and MeHg+ mospheric mercury over the Nordic countries; contamination in remote environments; Global Water, Air and Soil Pollution 56, 251-265 Biogeochemical Cycles 13, 743-750 KING, J K, SAUNDERS, F M, LEE, R F AND JAHNKE, R BRANFIREUN, B A, BISHOP, K, ROULET, N, GRANBERG, A (1999): Coupling mercury methylation rates G AND NILSSON, M (2000): Mercury cycling in to sulfate reduction rates in marine sediments; the boreal forest zone: the effect of acid rain Environmental Toxicology and Chemistry 18, constituents on peatland pore water methylm- 1362-1369 ercury concentrations; Geophysical Research KRABBENHOFT, D P, BENOIT, J M, BABIARZ, C L, Letters 28, 1227-1230 HURLEY, J P AND ANDREN, A W (1995): Mer- COMPEAU, G C AND BARTHA, R (1985): Sulfate-re- cury cycling in the Allequash Creek watershed, ducing bacteria: principal methylators of mer- northern Wisconsin Water; Air and Soil Pollu- cury in anoxic estuarine sediment; Applied and tion 80, 425-433 Environmental Microbiology 50, 498-502 LINDQVIST, O, JOHANSSON, K, AASTRUP, M, ANDERSSON, DRISCOLL, C T, BLETTE, V, YAN, C, SCHOFIELD, C L, A, BRINGMARK, L, HOVENIUS, G, HÅKANSON, L, MUNSON, R AND HOLSAPPLE, J (1995): The role IVERFELT, Å, MEILI, M AND TIMM, B (1991): of dissolved organic carbon in the chemistry and Mercury in the Swedish environment-recent re- bioavailability of mercury in remote Adirondack search on causes, consequences and corrective lakes; Water, Air, and Soil Pollution 80, 499-508 methods; Water, Air and Soil Pollution 55, 1-261 DRISCOLL, C T, HOLSAPPLE, J, SCHOFIELD, C L AND REGNELL, O (1994): The effect of pH and dissolved MUNSON, R (1998): The chemistry and trans- oxygen levels on methylation and partitioning port of mercury in a small wetland in the of mercury in freshwater model systems; Envi- Adirondack region of New York, USA; Bio- ronmental Pollution 84, 7-13 geochemistry 40, 137-146 ST LOUIS, V L, RUDD, J W M, KELLY, C A, BEATY, GILMOUR, C C AND HENRY, E A (1991): Mercury me- K G, BLOOM, N S AND FLET, R J (1994): Im- thylation in aquatic systems affected by acid portance of wetlands as sources of methyl mer- deposition; Environmental Pollution 71, 131-169 cury to boreal forest ecosystems; Canadian GILMOUR, C C, HENRY, E A AND MITCHELL, R (1992): Journal of Fishery and Aquatic Sciences 51, Sulfate stimulation of mercury methylation in 1065-1076 freshwater sediments; Environmental Science and Technology 26, 2281-2287

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 819 Cycling of methylmercury and mercury in a boreal catchment: Input-Output budget and Hg soil stores

KEVIN BISHOP AND YING-HUA LEE

1Department of Environmental Assessment, Swedish University of Agricultural Sciences, Sweden; E-mail: kevin bishop@ma slu se 2Swedish Environmental Research Institute, Sweden

Abstract: This paper will present the input/output data of Hg/MeHg and the results of a soil Hg/MeHg survey in a rural catchment with riparian wetlands in northern Sweden The results will provide an understanding of the transferring /transformation and cycling of MeHg/Hg in the forest ecosystem and of the role of current atmospheric Hg/MeHg sources for the output by runoff

Key words: mercury, methylmercury, biogeochemical cycles, soil storage

INTRODUCTION Hg/MeHg and the results of a soil Hg/MeHg survey in a rural catchment with riparian The widespread atmospheric deposition of wetlands in northern Sweden$ The total at- mercury (Hg) and methylmercury (MeHg) mospheric input will be estimated as the sum on the terrestrial ecosystem has built up a of Hg/MeHg in wet deposition and litterfall$ large Hg store in the soil$ The soil pools of The results will provide an understanding of Hg/MeHg are the potential source of Hg ac- the transferring /transformation and cycling cumulated in the freshwater food chain$ The of MeHg/Hg in the forest ecosystem and of fraction of the soil Hg/MeHg store leaving the role of current atmospheric Hg/MeHg the catchment depends mainly on the inter- sources for the output by runoff$ action of atmospheric deposition, climate and soils as integrated by hydrological transport$ The catchment characteristics, climate, and RESULTS AND DISCUSSION hydrology have been identified as the important factors influencing the output of The observation of the main streams output Hg/MeHg$ However, the role of the contem- data (monthly and episodic) over a decade porary level of atmospheric deposition of reveals similar trends between different years Hg/MeHg as opposed to the soils stores in in the dynamic output patterns of MeHg and determining the Hg/MeHg output from soil Hg-tot in relation to water flow and seasonal to surface water is not completely resolved, change$ The balance of input/output data and especially the direct influence of atmo- shows that about 20 % of total MeHg input spheric wet deposition on the Hg/MeHg$ This (0$46 g kin4 yr) and 7 % of total Hg input paper will present the input/output data of (24 g km4 yr) were transported out of the

RMZ-M&G 2004, 51 820 PART 2 BIOGEOCHEMISTRY soil by runoff, The atmospheric input by MeHg of atmospheric origin from soil to soil litterfall accounts for about 85 % of total in- water and methylation of inorganic Hg in put to the forest floor The survey of the soil soil/soil water, especially in the riparian wet- Hg/MeHg pool shows that the concentrations land and the mire, are the main cause of the of total Hg (100 to 200 ng/g DW) and MeHg mobilization of the accumulated past depo- (1 to 2 ng/g DW) in the soil mor of the ri- sition and of the increase of the portion of parian peat soil and of the podzol soil have MeHg in total Hg in soil/soil water and even- the same level as in the litterfall Compared tually in runoff water to the MeHg level in soil mor, there was a great increase (2 to 5 times) in the MeHg concentration in the riparian peat soil hori- CONCLUSIONS zon under the mor layer There was an extreme decrease in the concentration in the This study suggests that the processes trans- top layer of the mineral soil for both the ri- ferring MeHg of atmospheric origin from soil parian peat soil and the podzol soil Very high to soil water and methylation of inorganic MeHg concentrations were found in the Hg in soil/soil water, especially in the ripar- streambank sphagnum mosses (2 to 20 ng/g, ian wetland and the mire, are the main cause DW) and in the mire at 0 to 20 cm depth of the mobilization of the accumulated past (5 to 10 ng/g, DW) These results support deposition and of the increase of the portion our findings with respect to the soil solution of MeHg in total Hg in soil/soil water and at different layers from several soil profiles eventually in runoff water This suggests that the processes transferring

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 821 The importance of the Dissolved Organic Carbon in the Mercury Cycle in the Negro River Basin - Amazon, Brazil

MÁRCIA CRISTINA BISINOTI1, PEDRO SÉRGIO FADINI2 AND WILSON F JARDIM1

1Universidade Estadual de Campinas, UNICAMP Caixa Postal 6154, 13084-971, Campinas, São Paulo, Brazil; E-mail: mbisinoti@hotmailcom 2Pontifícia Universitária Católica de Campinas, PUC-Campinas, Rodovia D Pedro I, km 136, 13012-970, Campinas, São Paulo, Brazil

Abstract: Light driven mechanisms of hydrogen peroxide (H O ) production and the role of 2 2 this compound in the redox chemistry of mercury are well accepted Dissolved organic carbon (DOC) also plays an important role on the aquatic chemistry of mercury since it acts as both the precursor and scavenger of H O , and as a possible reducing agent of 2 2 mercuric ions The lability (or age) of the DOC has become a key parameter when investigating the redox barrier formed at the sunlit surface of water bodies, thus controlling evasive/invasive mercury fluxes The lability of fresh DOC extracted from topsoil was evaluated by spiking both black and white waters with 6,000 to 7,300 nmol/L of hydrogen peroxide and following its rate of destruction Most water samples showed a balance between consumption/generation of H O when illuminated However, when 2 2 black waters were fortified with labile DOC (up to 24 mg C/L), a pseudo first order kinetics of consumption of H O was observed with t 1/2 = 4 min, whereas for white 2 2 waters this value was around 4 times higher (t 1/2 = 16 min) The importance of these findings is discussed to establish new parameters to assess the lability of organic carbon in rivers and lakes and the importance of better understanding of the mercury cycle in the Amazon

Key words: hydrogen peroxide, mercury cycle, redox lability, organic matter, surface waters

involves the generation of H O % The decom- INTRODUCTION 2 2 position of H O in natural waters generally 2 2 Located in the northern part of the Brazilian causes the production of hydroxyl radicals, Amazon, the Negro River basin shows a pre- which contribute to the oxidation of Dis- dominance of black acidic water bodies, with solved Gaseous Mercury (DGM)% Then, the up to 20 mg C/L and pH as low ranging from quantification of hydrogen peroxide in 4%5 down to 3%8% The area is characterized aquatic bodies is of major importance in un- by two seasons: the dry season (August to derstanding the mercury biogeochemical February) and the rainy season (March to cycle in natural waters[1, 2]% July)% In a study performed by FADINI[3] in the Ne- Hydrogen peroxide formation in natural gro River Basin, Amazon, the predominance waters is related to photochemical oxidation of two major redox mechanisms was ob- of dissolved organic matter since the latter served to explain the aquatic chemistry of

RMZ-M&G 2004, 51 822 PART 2 BIOGEOCHEMISTRY mercury in black waters, with the oxidative between 6,000 and 7,300 nmol/L to evalu- one conducted mainly by hydrogen perox- ate the consumption rate of this compound% ide, whereas the reduction of mercury ions was associated to naturally occurring organic DOC was measured using a Total Organic substances% Competition of these two mecha- Carbon Analyzer Model TOC-5000 nisms could be explained by the lability of (SHIMADZU)% Hydrogen peroxide was deter- this organic matter present in the water col- mined using the DPD method in a Spectro- umn% The author further considered that this photometer (Micronal, B-382 model) with a labile organic matter was being pumped into 10 cm quartz cell[4]% the aquatic system in the rainy periods% Dur- ing the dry season, the labile compounds are exhausted by both biotic and abiotic mecha- RESULTS AND DISCUSSION nisms, and the water column remains rich in recalcitrant Dissolved Organic Carbon The lability of organic matter of natural wa- (DOC)% ter in the Negro River Basin depends on rainy and dry season% From February to July rain To further investigate this hypothesis, the is the most responsible for leaching fresh present work evaluated the H O consump- 2 2 organic matter in the soil to the water bod- tion in both black and white water samples ies% SILVA[5] has observed that black waters from this basin% Experiments were performed can show by two mechanisms the control Hg in situ, in the dry season, using samples in cycling% In the first one, the reduction of in- natura and samples fortified with fresh DOC organic mercury occurs by H O (photoin- 2 2 extracted from forest topsoils that become duced reduction), and in the second the oxi- flooded during the wet season% dation of Hg0 occurs by H O (photoinduced 2 2 oxidation)% Thus, one may expect that during the rainy period, with the input of labile EXPERIMENTAL organic substance, hydrogen peroxide would be consumed by this substance, and the or- Water samples of Iara Lake (black water, ganic matter would act as reducing agent% original DOC = 8%2 mg/L) and Branco River During the dry season, recalcitrant organic (white water, original DOC = 5%4 mg/L) re- matter present in these aquatic bodies are no ceived a spike of fresh DOC, reaching longer able to act as a H O scavenger, thus 2 2 24%0 mg C/L (Iara Lake) and 36%2 mg C/L leaving this compound to act as a major oxi- (Branco River)% A water-soluble organic car- dant of mercury species% bon fraction from the top of flooded soils was extracted using a 10 % (w/v) suspen- Hydrogen peroxide photoconsumption was sion of soil/natural water left in contact for evaluated in both white and black water 20 days% After this contact time, the suspen- samples from the Negro river basin, and sion was filtered using a 0%45 µm GFC fil- compared to controls stored in the dark% La- ter% After that, water samples in natura and bility is defined here as the consumption re- samples fortified with organic matter were action rate of hydrogen peroxide by the or- spiked with H O at concentrations varying ganic matter% Experiments were carried out 2 2

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 823 using different natural waters (samples col- Figure 1 shows that in natura samples lected in January, dry season), as well as in (Fig 1a) do not show a marked decrease in these same samples fortified with fresh or- hydrogen peroxide concentration as a func- ganic matter from topsoil tion of time, showing a steady-state situation between production and consumption of In both experiments, with black and white H O When these samples were fortified 2 2 waters, the consumption rate of hydrogen with organic matter (Fig 1b) a first-order peroxide was investigated in the dark as well kinetic mechanism for the consumption of as in samples exposed to the solar light It H O was established For white water 2 2 can be observed (Figures 1a, 1b, 2a and 2b) sample (Fig 2) the same behavior was ob- that light has little effect on the consump- served for both in natura (Fig 2a) and forti- tion of H O fied water (Fig 2b) 2 2

Figure 1 Hydrogen peroxide consumption as a function of time in the Iara Lake (black water) Sample in natura (a) with DOC = 82 mgC/L compared to fortified sample (b) showing a DOC = 240 mgC/L In the legend D is used for samples kept in the dark, and S for samples exposed to light

Figure 2 Hydrogen peroxide consumption as a function of time in the Branco River (white water) a) Natural water (DOC = 54 mg C/L) and b) water after enriched with organic substance (DOC = 362 mg C/L) In the legend D is used for samples kept in the dark, and S for samples exposed to light

RMZ-M&G 2004, 51 824 PART 2 BIOGEOCHEMISTRY

On the other hand, in both samples, enrich- CONCLUSIONS ment with organic matter led to the establishment of first-order kinetic mechanisms In this work has been demonstrated that hy- for the consumption of the spiked H O , with 2 2 drogen peroxide can be pointed as indicator half life times (t1/2) of 04 and 16 minutes of lability of organic matter in the water col- for black and white waters, respectively$ umn in the Negro River Basin, Amazon$ These results show that the kinetic consump- When water sample spiked with H O tion of H O is a potential indicator of or- 2 2 2 2 showed a balance between consumption and ganic matter lability$ In this way, naturally generation of this compound, it may be an occurring hydrogen peroxide can oxidize indication that recalcitrant (old) organic mat- labile organic matter and/or DGM when re- ter is predominant$ On the other hand, first- calcitrant organic matter is predominant in order mechanisms of H O consumption in- 2 2 the water body$ During flooded times, with dicate the presence of new (labile) organic input of labile organic matter, a competition matter that will act as a mercury oxidizing between DOC and H O occurs and the re- 2 2 agent, inhibiting evasive fluxes from the sult can be retention of the mercury in the aqueous layer to the atmosphere$ water column due to a redox layer formed by H O at the illuminated water surface 2 2 Acknowledgements

This work was partially funded by FAPESP (grants 02/03395-1 and 00/13517-1)$

REFERENCES

[1] ZEPP, R G, BRAUM, A M, HOIGNÉ, J, LEENHEER, J [3] FADINI, P S (1999): Comportamento do ciclo A (1987): Photoproduction of hydrated elec- biogeoquímico do mercúrio na Bacia do rio Ne- trons from natural organic solutes in aquatic gro (AM); PhD Thesis, Campinas: Universidade environments; Environmental Science & Tech- Estadual de Campinas 2001, 98 p nology 21, pp 485-490 [4] BADER, H, SIURZENEGGER, V, HOIGNÉ, J (1988): Pho- [2] LIAO, C-H, GUROL, M D (1995): Chemical Oxida- tometric-method for the determination of low tion by photolytic decomposition of hydrogen- concentrations of hydrogen-peroxide by the per- peroxide; Environmental Science & Technology oxidase catalyzed oxidation of N, N-Diethyl-P- 29, pp 3007-3014 Phenylenediamine (DPD); Water Research 22, pp 1109-1115 [5] SILVA, G S (2004): Dinâmica Biogeoquímica do Mercúrio na Bacia do Rio Negro Amazônia e seus fluxos na interface água-atmosfera; PhD Thesis, Campinas: Universidade Estadual de Campinas 2004, 115 p

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 825 Mercury speciation with emphasis in the organic species in the Negro River Basin - Amazon, Brazil

MÁRCIA CRISTINA BISINOTI* AND WILSON F JARDIM

Universidade Estadual de Campinas, UNICAMP Caixa Postal 6154, 13084-971, Campinas, São Paulo, Brazil; *E-mail: mbisinoti@hotmailcom

Abstract: To further elucidate Hg cycling, this study was focused on the Hg speciation, including the photodegradation of methylmercury Average values obtained using Cold Vapor Atomic Fluorescence Spectrometry (CVAFS) for Total-Hg and Organic-Hg were 10 and 15 ng/L respectively for black waters (n=20), whereas for white waters these values were 4 and 02 ng/L (n=12) Field experiments of methylmercury degradation using PET bottles with water samples spiked with 50 ng/L of methylmercury and exposed to 6 h of solar light (32 mW/cm2 at 365 nm) showed that the destruction of methylmercury follows the order black waters>white waters>distilled water During solar exposure, methylmercury losses in black water accounted for almost 60 % of the total spike, at an approximate rate of 5 ng/Lh According to the results obtained, it has been estimated that organic mercury accounts for up to 15 % of the total burden of mercury in black waters, and to nearly 5 % in white waters at the Negro River watershed

Key words: organic mercury, photodegradation, black and white water, speciation of mercury

INTRODUCTION mining activities in this area are virtually nonexistent[3] In this watershed (690,000 It is well known that the ecotoxicity of mer- km2) there is a predominance of black wa- cury cannot be explained by the total con- ters, with low pH (< 45), low particulates centration of the metal alone Among the (5 mg/L) and high levels of organic carbon numerous metal species found naturally, the (DOC values of 1020 mg/L), in contrast to most toxic one is by far the methylmercury white water bodies, with pH values in the (MeHg) MeHg can be produced in the range of 55-68 and low levels of DOC aquatic environments through both biotic and (2-6 mg/L) abiotic processes, it is dependent on seasonal variations[1], and easily accumulates in the Despite the fact that in the last decade many aquatic food chain due to its affinity for papers dealing with mercury contamination sulfidryl groups[2] in the Amazon area were published[4, 5], very little is known on the mercury cycle in this Mercury contamination in the Negro River environment, specially on the rate of methy- Basin (Amazon) has been associated mainly lation/demethylation in tropical waters In to mercury leaching from soil, since gold this context, the main objective of this work

RMZ-M&G 2004, 51 826 PART 2 BIOGEOCHEMISTRY was to evaluate the concentration of Organic- pH = 4 2 and TOC =15 mg/L) and white Hg in the waters of the Negro River Basin, water samples (Branco river, pH=6 8 and as well as to investigate the behavior of TOC=3 5 mg/L) Ultrapure water (milliQ, MeHg in the presence of solar light TOC < 1 0 mg/L) was used as reference in all experiments Water samples were spiked EXPERIMENTAL with 50 ng/L of MeHg (SpectraPure), and the 600 mL PET bottles containing the con- Determination of Organic-Hg in waters: taminated waters were exposed to solar light The procedure proposed by BLOOM[6], was and, kept incubated at the water surface for modified according to the following: to an up to 6 h Dark control were incubated in the aliquot of 100 mL of the sample it was added same way At every two hours, bottles were 5 mL of a KCl saturated solution in HCl 10 removed from the water and monitored for % (v/v), followed by the extraction with 40 (DGM), and Organic-Hg mL of dichloro methane for 10 h using an orbital shaker at 150 rpm The organic layer was transferred to a flask containing 100 mL RESULTS AND DISCUSSION of deionized water, purged with N for 1 hour 2 to remove all the solvent, leaving the ex- Speciation of mercury tracted MeHg in deionized water To this solution, it was added 10 mL of a 002 mol Total Hg represents the sum of all dissolve L-1 BrCl and allowed to oxidize the organic and particulate Hg species in the water mercury species for 30 min After this time samples, whereas the concentration of Or- interval, it was added 400 µL of a 30 % (w/ ganic-Hg represents all possible methylated v) hydroxylamine chloride and the mercury Hg species Major results obtained in both was measured by CVAFS (Brooks Rand) excursions (January/2002 and January/2003) after the reduction using a 10 % (w/v) stan- indicate detectable amounts of organic mer- nous chloride in 10 % (v/v) HCl solution cury in both white and black waters, with values oscillating between 2 6 % and Sampling locations: Water samples from 14 8 % of the total mercury for black wa- Negro River Basin, Amazon, were collected ters For white water, organic mercury con- in January 2002 and January 2003 Surface tent was 3 8 % (Table 1) As pointed out by water samples were taken at seven sampling FADINI AND JARDIM[3], concentration of total points: Iara Lake, Unini River, Jualperi River, mercury is higher in black waters when com- Jaú River, and Caurés River (black waters), pared to the ones observed in the Branco Branco River (white waters) and Araçá Lake River Also, the percentage of organic mer- (a mixture of black and white waters) cury showed its highest value (14 8 %) in a lake with black waters (Iara Lake) Photodegradation of MeHg and formation of Dissolved Gaseous Mercury (DGM): Total mercury concentrations obtained for In situ experiments were performed only water samples from the Negro river are during the excursion of January 2003 using higher than the ones obtained by other au- both black water samples (Iara lake, thors not only in the Amazon (Tapajós, fil-

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 827

Table 1 Concentration (ng/L) of different mercury species in water from Negro River Basin compared to some selected water bodies worldwide

tered water sample), but also for other water average rate of 5 ng/L"h, followed by the bodies in the world, except in the Sacramento Branco river (~ 2"8 ng/L"h) and finally MilliQ River Basin (Gold mining area)" The values water (~2"5 ng/L"h)" MeHg was not de- of Organic-Hg ranged from 0"03 to stroyed in the dark in either sample" In this 0"40 ng/L in this work" These values are context, the results indicate the light-depen- lower than the ones normally found in fresh- dence mechanism of organic mercury deg- waters worldwide" radation in both aquatic bodies" SELLERS ET AL"[10] also demonstrated that in natural wa- Photodegradation of MeHg and ters occur photodegradation of MeHg" formation of DGM Dissolved Gaseous Mercury (DGM) is an op- Organic mercury destruction mediated by erational parameter defined as all volatile solar light is shown in Figure 1" According aqueous mercury species prone to amalgam- to the results, higher rates of destruction were ation in gold, such as Hg0, HgCl , CH HgCl 2 3 obtained for black waters (Iara Lake), at an and CH HgCH [11]" According to FITZGERALD 3 3

Figure 1 MeHg degradation in black and white water from Negro River Basin (a)" DGM formation in black and white water from Negro River Basin (b)" In the legend D is used for samples kept in the dark, and S for samples exposed to solar radiation"

RMZ-M&G 2004, 51 828 PART 2 BIOGEOCHEMISTRY

AND MASON[12], elemental mercury (Hg0) is the reductive pathway prevails, thus generating most important contributor to the DGM, ac- more DGM than the oxidative mechanism counting for 95 to 100 % of this stock in the occurred in black waters" atmosphere" In this particular case, in a sample spiked with MeHg, the formation of DGM indicates the destruction of the organic spe- CONCLUSIONS cies generating Hg0" Comparing the DGM formation mediated by light for the two types of In this work has been demonstrated that in waters (Figure 2), it is observed higher values the Negro River Basin the Organic-Hg con- for the Branco river when compared to the Iara centration is generally higher in black wa- lake, during the 6h exposure to a solar light ters than the ones observed white waters" intensity that remained nearly constant around Waters from both types of aquatic bodies 2"4 mW"cm-2 measured at 365 nm" spiked with MeHg and exposed to solar light suffered photodegradation, a light-depen- The apparent controversy results shown in dence mechanism that can reach values of Figure 1 and 2 concerning higher destruc- 5 ng L-1 h-1" tion rates of MeHg in sunlit black waters compared to lower production of DGM when Acknowledgements compared to white waters can be explained by postulating different mechanisms of This work was supported by the FAPESP MeHg destruction, where in white waters a (grants 02/03395-1 and 00/13517-1)"

REFERENCES

[1] [4] REGNELL, O, EWALD, G, LORD, E (1997): Factors GUIMARÃES, J R D, FOSTIER, A H, FORTI, M C, controlling temporal variation in methyl mer- MELFI, J Á, KEHRIG, H, MAURO, J B N, MALM, cury levels in sediment and water in a season- O, KRUG, J F (1999): Mercury in human and ally stratified lake; Limnology Oceanografic 42, environmental samples from two lakes in pp 1784-1795 Amapá, Brazilian Amazon: natural background [2] KANNAN, K, SMITH J R, LEE, R L, WINDOW, H L, and antropogenic contamination; Ambio 28, pp HEITMULLER, P T, MACAULEY, J M, SUMMERS, 296-301 J K (1998): Distribution of total mercury and [5] BARBOSA, A C, DE SOUZA, J, DOREA, J G, JARDIM, methylmercury in water, sediment, adn fish from W F, FADINI, P S (2003): Mercury South Florida Estuaries; Archieves Environment biomagnification in a tropical black water, Rio Contamination Toxicology 34, pp 109-118 Negro, Brazil; Archieves Environment Contami- [3] FADINI, P S, JARDIM, W F (2001): Is the Negro river nation Toxicology 45, pp 235-246 basin (Amazon) impacted by naturally occuring [6] BLOOM, N S (1989): Determination of picogram mercury?; Science Total Environmental 275, levels of methylmercury by aqueous phase pp71-82 ethylation, followed by Cryogenic Gas Chro- matography with Cold Vapor Atomic Fluores- cence Detection; Canadian Journal Fish Aquatic Science 46, pp 1120-1131

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 829

[7] ROULET, M, LUCOTTE, M, GUIMARÃES, J R D, [10] SELLERS, P, KELLY, C A, RUDD, J W M, RHEAULT, I (2000): Methylmercury in water, MACHUTCHIN, A R (1996): Photodegradation of seston, and epiphyton of na Amazon river and methylmercury in lakes; Nature 380, pp 694- its floodplain, Tapajós River, Brazil; Science of 697 the Total Environment 261, pp 43-59 [11] SCHROEDER, W H (1994): Amospheric mercury 8] MASON, R P, ROLFHUS, K R, FITZGERALD, W F measurements at a rural site in southern (1998): Mercury in the North Atlantic; Marine Ontário, Canadá; Watras: Lewis Publishers: Chemistry 61, pp 37-53 Boca Raton 1994, 281 p [9] DOMAGALSKI, J (2001): Mercury and methylmercury [12] FITZGERALD, W F, MASON, R P (1996): The global in water and sediment of Sacramento River Ba- mercury cycle: oceanic and anthropogenic as- sin, Califórnia; Applied Geochemistry 16, pects; Kluwer Academic Publishers, Nether- pp1677-1691 lands 1996, 85 p

RMZ-M&G 2004, 51 830 PART 2 BIOGEOCHEMISTRY

Forest Fire Effects on Mercury Concentrations in a Rocky Mountain Forest Ecosystem

ABIR BISWAS1, BJORN KLAUE1, GERALD J KEELER2, JOEL D BLUM1

1Department of Geological Sciences, University of Michigan, 425 E University Ave , Ann Arbor, Michigan 48109, USA 2Air Quality Laboratory, University of Michigan, 109 South Observatory, Ann Arbor, Michigan 48109, USA

Abstract: The impact of forest fires on pools of major elements including carbon, calcium, and sulfur has been extensively studied but effects of fire on potentially toxic trace metals are not as well understood We examined the effects of three recent Wyoming, USA, wildfires of varying burn intensities on mercury (Hg) concentrations in soils and vegetation in forest ecosystems Paired watershed studies were conducted using burned and unburned watersheds of similar vegetation type and age, climate, and geology A wide range of mercury concentrations was found in unburned watershed soil profiles, suggesting variations in mercury accumulation associated with vegetation type and topography Burned watershed soil profiles had variably lower Hg concentrations than unburned watershed profiles, suggesting burn intensity-dependent Hg volatilization by wildfires Our results demonstrate that while a significant amount of Hg is released by wildfires, estimations of Hg release must consider variations in burn intensity and pre- fire mercury accumulation

Key words: forest, fire, combustion, soil

INTRODUCTION food chain, decreasing reproductive success in some predatory birds and negatively af- Mercury is a potentially harmful trace metal fecting the health of predators including the that is important to investigate due to its se- Florida panther (FACEMIRE ET AL, 1995) rious health effects, which include neurological damage in humans (MAHAFFEY, 1999) It Though the major pools of mercury are known, is regulated in US drinking water (US EPA, the size of each pool and the flux between pools 1974) and has been targeted for national remains uncertain Recent studies in South emissions controls Natural and anthropo- Africa and Washington state, USA suggest that genic sources contribute equally to atmo- fires may contribute more to the annual natu- spheric mercury which is a global pollutant ral Hg flux from terrestrial ecosystems to the due to the atmospheric residence time of ~1 atmosphere than previously realized (BRUNKE year of its dominant elemental form (Hg0) ET AL, 2001; FRIEDLI ET AL, 2003), (FRIEDLI ET (SCHROEDER AND MUNTHE, 1998) Upon depo- AL, 2003) Due to its gaseous phase, mercury sition, Hg can be methylated to methylmer- is easily volatilized by fire (FRIEDLI ET AL, 2001) cury, a form that can bioaccumulate up the and lost to the atmosphere RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 831

FIRE EVENTS AND EXPERIMENTAL METHODS

This study focuses on three recent fires that occurred in northwestern Wyoming near Jackson, WY Watersheds affected by the August 2000 Granite Creek Fire (GCF) and the July-August 2001 Green Knoll Fire (GKF) were sampled during the 2002 and 2003 summers The East Table Fire (ETF) occurred during the summer of 2003 and was Figure 1 Sampling area marked sampled less than one week later For each by star in Wyoming, USA burned watershed, a nearby unburned watershed of similar age, climate, vegetation, Mercury enters forest ecosystems via wet and and bedrock geology was sampled as a con- dry atmospheric deposition, and to a lesser trol The burned/unburned forest pairs were extent, assimilation via stomatal uptake Par- on average ~160 years old with similar over- ticulate Hg tends to adsorb to foliar surfaces, story composition, predominantly lodgepole eventually entering the soil profile either by pine and Douglas fir Meadow areas and as- foliar washing during precipitation events or pen stands were also sampled, though this during litterfall and subsequent litter decom- land-cover generally accounted for <10 % position (ERICKSEN ET AL, 2003) During a of the total watershed area in each case Du- forests lifetime there is a net accumulation plicate soil cores were collected from coni- of mercury in forest soils; soil Hg is often fer, aspen, and meadow plots during sum- associated with organic matter (GRIGAL, mer 2003 at random locations across each 2003; SCHWESIG AND MATZNER, 2001) Previ- watershed, including a variety of elevations ous work has indicated that the bulk of the Ambient atmospheric mercury concentra- Hg stored in forests is likely in the soil rather tions in this region are similar to, but slightly than associated with the vegetation which higher on average, than other rural areas in only accounts for approximately 10 % of the the US with typical concentrations of vapor total Hg stored (GRIGAL, 2003) Topography phase mercury < 5 ng/m3 and particulate and leaf surface area are the two major con- phase mercury in the range 1-15 pg/m3 trols in the capture and accumulation of particulate and gaseous phase Hg from the at- Soil and vegetation samples were analyzed mosphere As the bulk of forest Hg resides for mercury using a thermal analysis in the soil column, burn intensity, which re- coldvapor isotope dilution inductively flects heating through the soil column, may coupled plasma mass spectrometry (ICP be the most important determinant of the MS) method Samples were placed in quartz percentage of stored mercury being released crucibles and heated along a 25 0C to 750 0C during a fire linear gradient at a rate of ~ 10C/s (LAURETTA ET AL, 2001) Online quantification of the

RMZ-M&G 2004, 51 832 PART 2 BIOGEOCHEMISTRY

Hg released from the samples was achieved aspen areas because of the difference in fuel by a known, constant flow of an enriched availability Of the 3 burned areas sampled, 200Hg and 201Hg spike through the furnace, visual observations, including tree trunk burn which was generated by a coldvapor system height, percentage of crown burned, and depth The amount of natural Hg released from the of burning through the soil profile, indicate samples was evaluated by isotope dilution moderate to high burn intensity at the GKF, for every 3s interval and a wider range from very low to moderate burn intensities at ETF and GCF

RESULTS

More than 300 soil samples from 3 pairs of burned/unburned watersheds, at 6 depths through the soil column, were analyzed All samples were prepared and analyzed using the same techniques Moisture content and percent organic carbon was also determined for all samples

There were large standard deviations in the surficial soils as a result of heterogeneity in Hg accumulation in conifer-dominated plots High-resolution (1-2 cm) soil analysis through the profile indicates that Hg concentrations were elevated at the surface (compared to the bottom of the core) and increased with depth in the organic layer (down to ~6cm) Mercury concentrations decreased with depth through the mineral soil There was a significant difference in Hg concentrations between burned and unburned surficial soils at each area, though not deeper in the soil profile Normalized to soil density, which increases from 04 to 14, Hg concentrations are similar throughout the profile Soil profiles collected at aspen and meadow sites had similar Hg trends but lower concentrations as these samples were collected in clearings with little vegetation

Coniferous areas with more litter and duff were more intensely burned than meadow and

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 833

Thermal analyses of the soils indicated that range of burn intensities indicate that a fire the onset of Hg release was typically 180 0C of this magnitude would release ~ 01 Mg of and the peak of Hg release was approxi- Hg from the soil On average, 42 million mately 320 0C This is consistent with the acres are burned yearly in the US, suggest- theory that the Hg in these soils was a form ing that wildfires, depending on burn inten- of Hg2+ associated with organic matter, likely sity, may release 60 - 110 Mg annual Hg flux humic acids in soils (BIESTER ET AL, 2002) into the atmosphere, a substantial amount Thermal speciation of different Hg com- compared to the estimated US anthropogenic plexes was not observed, suggesting that all flux of 144 Mg of the stored Hg was in this form Heating experiments investigating temperatures effects on Hg release from soils suggest that CONCLUSIONS the temperature a soil was subjected to was as important as the duration of time the tem- This study demonstrates that while a signifi- perature was held Heating the sample for cant amount of Hg is released by wildfires, 1hr at 180 0C released little Hg, while hold- estimations of Hg release must consider varia- ing the sample at 320 0C for 4 hrs resulted in tions in burn intensity and pre-fire mercury complete Hg release Heating 180 0C for accumulation Past fire suppression practices 4 hrs and 320 0C for 1 hr resulted in incom- in the US have caused a buildup of flammable plete release materials, which combined with the legacy of pollution in the 20th century, suggests that Focusing on the Green Knoll Fire, which contemporary fire regimes may result in burned 4470 acres, the Hg concentrations in greater mercury release than historic fire re- the unburned soil column decreased from an gimes This study reinforces the importance average of 158 ppb near the surface to 38 of wildfires to the global mercury cycle and ppb at 10-15 cm Moderate fire intensity re- indicates that forests in the Rocky Mountain sulted in only ~ 85 % of the organic soil ho- region may contain large reservoirs of Hg that rizon mercury being volatilized Extrapola- can be released during fires, adding to the tions from our soil core data, considering a global budget of mercury emissions

REFERENCES

BIESTER, H, MULLER, G & SCHOLER, HF (2002): Bind- ERICKSEN, JA ET AL (2003): Accumulation of atmo- ing and mobility of mercury in soils contami- spheric mercury in forest foliage Atmos nated by emissions from chlor-alkali plants Sci Environ; Vol 37, No 12, pp 1613-1622 Total Environ; Vol 284, No 1-3, pp 191-203 FACEMIRE, CF, GROSS, TS & GUILLETTE, LJ (1995): BRUNKE, EG, LABUSCHAGNE, C & SLEMR, F (2001): Reproductive impairment in the florida panther Gaseous mercury emissions from a fire in the - nature or nurture Environ Health Persp; Vol Cape Peninsula, South Africa, during January 103, Suppl, No, pp 79-86 2000 Geophys Res Lett; Vol 28, No 8, pp FRIEDLI, HR, RADKE, LF & LU, JY (2001): Mercury 1483-1486 in smoke from biomass fires Geophys Res Lett; Vol 28, No 17, pp 3223-3226

RMZ-M&G 2004, 51 834 PART 2 BIOGEOCHEMISTRY

FRIEDLI, HR, RADKE, LF, PRESCOTT, R, HOBBS, PV MAHAFFEY, KR (1999): Methylmercury: A new look & SINHA, P (2003): Mercury emissions from the at the risks Public Health Reports; Vol 114, August 2001 wildfires in Washington State and No 5, pp 397-415 an agricultural waste fire in Oregon and atmo- SCHROEDER, WH & MUNTHE, J (1998): Atmospheric spheric mercury budget estimates Global mercury - An overview Atmos Environ; Vol Biogeochem Cycles; Vol 17, No 2, pp 32, No 5, pp 809-822 GRIGAL, DF (2003): Mercury sequestration in forests SCHWESIG, D & MATZNER, E (2001): Dynamics of and peatlands: A review J Environ Qual; Vol mercury and methylmercury in forest floor and 32, No 2, pp 393-405 runoff of a forested watershed in Central Eu- LAURETTA, DS, KLAUE, B, BLUM, JD & BUSECK, PR rope Biogeochemistry; Vol 53, No 2, pp 181- (2001): Mercury abundances and isotopic com- 200 positions in the Murchison (CM) and Allende US EPA, (1974): Safe drinking water act http:// (CV) carbonaceous chondrites Geochim wwwepagov/safewater/sdwa/sdwahtml Cosmochim Acta; Vol 65, No 16, pp 2807- 2818

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 835 Growth rates and the bioaccumulation of mercury by a predatory fish: whole-lake experimental approaches

PAUL BLANCHFIELD1, MIKE PATERSON1, HOLGER HINTELMANN2 AND REED HARRIS3

1Freshwater Institute, Fisheries & Oceans Canada, Winnipeg, Canada; E-mail: BlanchfieldP@dfo-mpo%gc%ca 2Department of Chemistry, Trent University, Peterborough, Canada 3Tetra Tech Inc%, Oakville, Canada

Abstract: We examined the relationship between growth rates and mercury accumulation by predatory fish through whole-lake fish transfer experiments and stable mercury isotope techniques The first study involved the transfer of growth-stunted populations of northern pike (Esox lucius) from their native lake into lakes with no predatory fish Pike mercury concentrations decreased in proportion to increases in growth Overall, we did not observe significant changes in pike body burdens of mercury In a separate study we examined individual growth rates and mercury levels of pike from a lake receiving increased loadings of inorganic mercury Preliminary findings from this study suggest a positive relationship between growth rate and changes in THg concentrations Together these whole-lake experiments present some contrasting results, suggesting that the extent to which growth influences mercury levels is variable and system-dependent

Key words: growth dilution, body burden, biopsy, stable mercury isotope

INTRODUCTION We examined the role that growth plays in the bioaccumulation of mercury by a top- Mercury is by far the most common contami- predator, the northern pike (Esox lucius), in nant responsible for fish consumption advi- two different ways First, we conducted sories across North America Of most con- whole-lake transfers of growth-stunted pike cern are predatory fish since these species to lakes without predatory fish and monitored are generally sought after for consumption, changes in pike Hg levels In the spring of and because these species tend to have the 1993, pike were moved from their native lake greatest levels of mercury due to the to two lakes at the Experimental Lakes Area bioaccumulation and biomagnification of in northwestern Ontario[2] Lake 110 is natu- this compound through the food web The rally oligotrophic, while Lake 227 is rate at which fish grow is one factor influ- eutrophic due to the addition of phosphorus encing mercury accumulation fish with that began in 1968 The differences in trophic higher growth rates have lower levels of status of these lakes resulted in a different mercury compared to slow-growing conspe- amount of prey base for introduced pike that cifics[1] This finding is of interest, because influenced their growth rates we also know that the largest and oldest fish tend to have the greatest concentrations of In the second study, we examined growth mercury in their tissues rates and mercury levels of pike from a lake RMZ-M&G 2004, 51 836 PART 2 BIOGEOCHEMISTRY receiving increased loadings of inorganic creased densities of minnows and changes mercury METAALICUS (Mercury Experi- in planktonic productivity and community ment To Assess Atmospheric Loading In composition[4] Before the addition of pike, Canada and the US) is a whole-ecosystem concentrations of Hg were approximately experiment in which mercury loading to a 30-50 % lower in cyprinids and zooplank- headwater lake (Lake 658) and its watershed ton from eutrophic Lake 227 than from olig- has been increased by 3-4 fold annually since otrophic Lake 110 Pike stocked into each 2001 Mercury is being added in the form of lake grew rapidly and their Hg concentra- a stable Hg isotope (202Hg) that allows for tions decreased markedly Within three the quantification of newly deposited mer- months of introduction, the mean biomass cury separately from background mercury of individual pike doubled and mean con- As part of this study, we first developed centrations of mercury in pike were reduced methods to accurately and reliably measure to 30-70 % of initial levels (Table 1) De- fish muscle Hg concentrations from small creases in Hg concentrations were greatest samples (<100 mg) harvested with biopsy in eutrophic Lake 227, where pike grew most tools from anaesthetized fish with little or rapidly and fed on minnows with lower con- no mortality[3] This study focused on the re- centrations of mercury Comparison of the lationship between mercury levels and results with predictions of bioenergetic mod- growth rates of individual fish over time els suggested that changes in mercury concentrations in pike were primarily the result of growth dilution Our results indicate that RESULTS AND DISCUSSION trophic conditions can strongly affect Hg concentrations in fish and other biota The Whole-lake transfer studies between-lake differences in Hg concentrations were at least partly determined by dif- The introduction of pike initiated several ferences in growth rates and growth dilution changes in food web structure including de- of Hg

Table 1 Changes in northern pike weight, mercury concentration and body burden, three months after transfer to eutrophic Lake227 and oligotrophic Lake110

Stable isotope study tive growth increased body mass, on average, by 8 % annually, although annual in- The northern pike of Lake 658 are a stunted creases up to 33 % were observed Prelimi- population, often exhibiting negative or mini- nary findings from this study suggest a posi- mal annual increases in body mass Roughly tive relationship between growth rate and half of the recaptured pike showed annual total mercury concentrations, and an even losses in body mass Pike that showed posi- stronger positive relationship between

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 837 growth and the accumulation of newly-de- dent! Diet may also play a key role in these posited isotopic mercury contrasting findings, as observed in a previous study[1]! We are presently using bio-energetic modeling to further explore these CONCLUSIONS findings!

Together these whole-lake experiments Acknowledgements present some contrasting results, suggesting that the extent to which growth influences This work was supported in part by Fisher- mercury levels is variable and system-depen- ies and Oceans Canada and EPRI, U!S!A!

REFERENCES

[1] ESSINGTON, T E AND HOUSER, J N (2003): The ef- [3] BAKER, R F, BLANCHFIELD, P J, PATERSON, M J, fect of whole-lake nutrient enrichment on mer- FLETT, R J AND WESSON, L (2004): Evaluation cury concentration in age-1 yellow perch; Trans- of non-destructive biopsy methods for the analy- actions of the American Fisheries Society 132, sis of mercury in fish tissue; Transactions of the pp 57-68 American Fisheries Society (in press) [2] KIDD, K A, PATERSON, M J, HESSLEIN, R H, MUIR, [4] ELSER, J J, STERNER, R W, GALFORD, A E, D C G AND HECKY, R E (1999): Effects of CHRZANOWSKI, T H, FINDLAY, D L, MILLS, K northern pike (Esox lucius) additions on pollut- H, PATERSON, M J, STAINTON, M P, AND ant accumulation and food web structure, as SCHINDLER, D W (2000): Pelagic C:N:P stoichi- determine by d13C and d15N, in a eutrophic and ometry in a eutrophied lake: responses to a oligotrophic lake; Canadian Journal of Fisher- whole-lake food-web manipulation; Ecosystems ies and Aquatic Sciences 56, pp 2193-2202 3, pp 293-307

RMZ-M&G 2004, 51 838 PART 2 BIOGEOCHEMISTRY

The movement of newly deposited mercury through an aquatic food web

PAUL BLANCHFIELD1, MIKE PATERSON1, CHERYL PODEMSKI1, AND HOLGER HINTELMANN2

1Freshwater Institute, Fisheries & Oceans Canada, Winnipeg, Canada; E-mail: BlanchfieldP@dfo-mpo&gc&ca 2Department of Chemistry, Trent University, Peterborough, Canada&

Abstract: Through whole-ecosystem additions of stable mercury isotopes to a lake and its watershed, we are examining the link between increased atmospheric mercury deposition and Hg concentrations in fish and their associated food web (METAALICUS project)) Here we focus on the timing and magnitude of newly-deposited isotopic Hg (spike Hg) to the lake surface after two year of addition) Newly-deposited spike Hg was readily methylated and quickly incorporated into the aquatic food web) Spike mercury was present in zooplankton, benthic invertebrates and forage fish within 3, 4 and 8 weeks, respectively, after mercury additions) Two years after addition, spike Hg accounted for a significant proportion of the total Hg concentration in biota (25 %) and is continuing to increase in a linear fashion for all fish species) These findings suggest that fish Hg levels will respond to changes in Hg deposition to aquatic systems although old Hg stored in lake sediments will continue to contribute to fish Hg levels after reductions in atmospheric Hg emissions)

Key words: whole-ecosystem mercury addition, METAALICUS, stable mercury isotope, atmospheric mercury deposition, food web

INTRODUCTION concentrations when there is a change in atmospheric mercury deposition? Contamination of fish with methylmercury (MeHg) is commonplace across North METAALICUS (Mercury Experiment To America and has largely been attributed to Assess Atmospheric Loading In Canada and atmospheric deposition from anthropogenic the US) is a whole-ecosystem experiment in sources Health concerns related to the hu- which mercury loading to a headwater lake man consumption of mercury-contaminated and its watershed has been increased by a fish have incited proposals to reduce indus- factor of 3-4x annually for three years (2001- trial emissions of Hg to the atmosphere, yet 2003) A different stable isotope of mercury the link between wet deposition of inorganic has been added to each of the upland, wet- mercury and MeHg concentrations in fish land and lake portions of the Lake 658 wa- remains poorly defined This talk will de- tershed at the Experimental Lakes Area scribe research that uses newly available (Ontario, Canada) This study is the first techniques to directly investigate the follow- whole-ecosystem addition of stable Hg iso- ing question: What happens to fish mercury topes anywhere and allows for an assessment

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 839 of the relative contributions of new and flavacens) had spike mercury present in mea- old mercury to overall levels of mercury surable amounts within two months since the The addition of a stable Hg isotope allowed start of isotopic Hg additions, while it took us to trace the food-web bioaccumulation of another month for the spike mercury to show the experimentally-added Hg (spike Hg), up in other forage fish species# Spike mer- separate from the background Hg present in cury was detectable in all fish species ex- Lake 658 (ambient Hg)[1] The present talk cept northern pike (Esox lucius) by the fall will focus on the spike mercury added di- of the first year (~120 days after first addi- rectly to the lake surface Wet deposition tion), including other large-bodied fish such rates at the ELA are ~71 µg Hg/m2/yr[2] and, as white sucker (Catostomus commersoni) in total, we added roughly three times this and lake whitefish (Coregonus amount (~23 µg Hg/m2) in nine fortnightly cluepaformis)# additions of 202Hg (as HgCl ) to the lake sur- 2 face by boat Magnitude of Response

Because fish obtain most of their mercury The proportion of spike Hg tended to be con- via their diet, here we focus on mercury lev- sistent among all trophic levels, from zoop- els in fish and their prey In the present study, lankton through to prey fish, within the first we assessed MeHg levels in zooplankton and year# Spike mercury increased in biota an- benthic invertebrates and THg levels in prey nually, initially making a small contribution fish monthly in Lake 658 and a reference lake to overall mercury levels (4 %) by the end of (Lake 240) We also measured Hg levels in 2001, but after the 2 years of addition, ac- large fish species using biopsy methodol- counting for one-quarter of the mercury in ogy[3] Our specific objective was to deter- fish# The accumulation of spike mercury mine the magnitude and timing of the re- appears to be tightly linked to water concen- sponse of newly-deposited spike mercury on trations of spike mercury for zooplankton MeHg concentrations in fish and their asso- species, but for benthic invertebrates, spike ciated food web Hg concentrations better reflect sediment concentrations# Concentrations of spike mercury in forage fish species appear interme- RESULTS AND DISCUSSION diate to zooplankton and benthic levels# The concentration of spike mercury has contin- Timing of Response ued to increase in a linear fashion for all fish species since the start of this study# Spike mercury applied to the surface of Lake 658 started to appear as MeHg in zooplankton within weeks after the first addition# CONCLUSIONS Similarly, spike mercury was present in benthic invertebrates one month after the The use of stable isotopes of mercury has been initial additions to Lake 658# A short time essential to partitioning the accumulation of later, spike mercury was detected in the fish newly-deposited mercury from the pool of community# Age 1+ yellow perch (Perca mercury already present in the system# In

RMZ-M&G 2004, 51 840 PART 2 BIOGEOCHEMISTRY summary, newly-deposited spike mercury mercury levels in biota could respond readily accounts for a significant portion of the mer- to reduced atmospheric emissions cury in all biota within two years Although our data are preliminary, they suggest that Acknowledgements

This work was supported by Fisheries and Oceans Canada, NSERC and EPRI, U S A

REFERENCES

[1] HINTELMANN, H, HARRIS, R, HEYES, A, HURLEY, J [3] BAKER, R F, BLANCHFIELD, P J, PATERSON, M J, P, KELLY, C A, KRABBENHOFT, D P, LINDBERG, FLETT, R J AND WESSON, L (2004): Evaluation S, RUDD, J W M, SCOTT, K J AND STLOUIS, V of non-destructive biopsy methods for the analy- L (2002): Reactivity and mobility of new and sis of mercury in fish tissue; Transactions of the old mercury deposition in a boreal forest eco- American Fisheries Society (in press) system during the first year of the METAALICUS study; Environ Sci Technol 36, 5034-5040 [2] ST LOUIS, V L, RUDD, J W M, KELLY, C A, HALL, B D, ROLFHUS, K R, SCOTT, K J, LINDBERG, S E, AND DONG, W (2001): Importance of the forest canopy to fluxes of methyl mercury and total mercury to boreal ecosystems; Environ Sci Technol 35, pp 3089-3098

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 841 Mercury Speciation and Transport in the Canals of Venice

NICOLAS S BLOOM1 AND LIGIA M MORETTO2

1Frontier Geosciences, 414 Pontius North Seattle, WA 98109 USA; E-mail: nicolasb@nickslab%org 2Universita CaFoscari, S% Marta, 2137 Venezia 30123, Italy; E-mail: moretto@unive%it

Abstract: Hg speciation and suspended matter were measured seasonally in seven canals of Venice, as well as three canals in the Marghera industrial zone between 2000 and 2003 All samples were collected and processed using ultra-clean sampling and analyzed using cold vapour atomic fluorescence spectrometry (CVAFS) techniques We found that the most elevated Hg levels in the entire Venice Lagoon were in the urban canals of Venice, rather than the industrial zone, probably as a result of infiltration of raw domestic sewage from the ancient infrastructure Hg in the canals was found to be strongly and inversely proportional to the tidal height, which supports the notion that the city of Venice is a net source of Hg to the Lagoon, as a result of tidal pumping

Key Words: Mercury, Methyl Mercury, Speciation, Venice, Canals

INTRODUCTION lated inner city canals, to bigger collector channels, and finally to the Canale Most of the sewage in the city of Venice is Grande and out into the open Lagoon not treated, but rather percolates out through (Figure 1) The industrial zone canals, by porous septic tanks below sea level (PAVONI contrast, are wider and deeper to permit the ET AL, 1990) Following microbiological de- passage of large ships Samples were col- composition, the liquid containing nutrients lected and filtered (04 µ) using established and trace metals diffuse into the waters of ultra-clean techniques (MORETTO ET AL, the city canals Since sewage is typically elevated in Hg due to the use of dental amalgams and the consumption of seafood, we hypothesized that the canal system could become contaminated with Hg, which would then become a source to the Lagoon during tidal flushing To test this hypothesis, samples were collected in seven urban and three industrial canals, over the range of the tidal cycle, in both summer and winter The urban canals were chosen to represent the tortuous flow of water from the small, relatively iso-

RMZ-M&G 2004, 51 842 PART 2 BIOGEOCHEMISTRY

2003), and analyzed for total Hg using BrCl nals mean (3°) is made up from measure- oxidation, SnCl reduction and dual gold ments in three smaller canals: Canale SS 2 amalgamation prior to CVAFS detection Apostoli, Rio Tentor, and Rio Marin; while (BLOOM AND FITZGERALD, 1988; BLOOM AND the mean for the smallest canals (4°) was CRECELIUS, 1983) CH Hg was determined taken from samples in Rio dei Frari and Rio 3 with aqueous ethylation, purging onto dei Miracoli The mean for the Marghera Carbotrap, and then isothermal GC- industrial zone canals was made up prima- CVAFS detection (LIANG ET AL, 1994) rily of the two major shipping canals as well as a smaller dead-end supply canal The value shown for the average Lagoon water is RESULTS AND DISCUSSION from all samples collected in the Bacino San Marco, an open water area several hundred Data presented in this paper are grouped into meters from the city The value for back- means based upon the relative size and de- ground water is the average for all results gree of isolation of the canals We adopted a collected at the Lido port during inflowing designation by degrees as follows: the larg- tide Although the lowest in the Lagoon, these est (Canale Giudecca) was designated as pri- are known to be an order of magnitude higher mary (1°), and the second largest, the Canale than truly clean Adriatic Sea water (BLOOM Grande, as secondary (2°) The tertiary ca- ET AL, 2004)

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 843

The mean concentrations for Hg and CH Hg during the summer, as a result of both lower 3 in the Venice canals are an order of magni- flushing and warmer temperatures tude higher than the open Lagoon average, (Figure 3)& In this study, the 3° and 4° canals and two orders higher than water entering were sampled at both high and low tide at the Lagoon from the Adriatic Sea (Figure 2)& the end of winter (March, 2003) and the end The 2° and 3° canals appear to harbor the of summer (August, 2002)& Although the data highest concentrations, with a dramatic de- are limited, the percentage of CH Hg was, if 3 crease toward open water, and a weaker de- anything, slightly higher in the coldest pe- cline in the 4° canals& We speculate that this riod, suggesting that the canals, themselves, latter observation is due to the quiescence of are not a major source of Hg methylation& these inner canals, which allows greater par- More likely, CH Hg observed comes in con- 3 ticulate settling& This is supported by the cert with the Hg, from the same raw sewage pattern in TSS for these sites& Even though source& The percentage of CH Hg seen in 3 the Marghera industrial zone has the legacy of huge Hg discharges from chlor-alkali plants and other industries (BLOOM ET AL&, 2004), today, Hg levels in its canals are considerably lower than those found in most urban canals& This is a measure of both the extensive efforts employed in cleaning up industrial discharges during the 1980s, as well as probably much higher tidal flushing rates of these large, deep canals&

We examined the potential for the inner canal system to become a CH Hg incubator 3

RMZ-M&G 2004, 51 844 PART 2 BIOGEOCHEMISTRY

these waters (0&4 % of total) is similar to the CONCLUSIONS percentage seen in the discharges from the aeration tanks of domestic sewage treatment Hg and CH Hg are elevated within the ur- 3 plants (GLIMORE AND BLOOM, 1995)& ban canals of Venice, both in comparison to the waters of the Venice Lagoon, and even The biggest factor determining the observed with respect to the canals of the Marghera Hg concentrations in the canals appears to industrial zone& Hg appears to be highest be the tidal cycle (Figure 4)& In every canal deeper within the maze of canals, where tidal investigated, the concentrations of both Hg flushing is diminished& Hg and CH Hg are and CH Hg were highest at low tide, and low- 3 3 inversely proportional to tide height, indi- est at high tide, with the difference being cating that the urban canals are a net source greatest in the mid-size canals (2° and 3°) of Hg, which is supplied to the Lagoon by and tapering off at either end of the size tidal pumping& The absolute concentration range& These minimum-maximum findings of Hg in the canals is somewhat higher dur- in six canals corroborate the detailed tidal ing summer compared to winter, perhaps re- cycle Hg relationship reported earlier for the flecting a greater degree of tourist-related Canale SS Apostoli (BLOOM ET AL&, 2004), sewage inflow& The percentage of Hg in the which showed that the change in Hg con- methylated form, on the other hand, was rela- centration during the tidal cycle is smoothly tively constant at about 0&4 % of the total related to the tidal stage& during both warm and cold periods& This suggests that the inner canal system is not a strong methylation incubator during summer, and that CH Hg may be due to direct 3 seepage into the canals&

REFERENCES

BLOOM, N S, MORETTO, L M, SCOPECCE, P AND UGO, LIANG, L, BLOOM, N S, AND HORVAT, M (1994): Clin P (2004): Mar Chem (in press) Chem Vol 40/4, pp 602-607 BLOOM, N S AND FITZGERALD, W F (1988): Anal Chim PAVONI, B, SFRISO, A, DONAZZOLO AND ORIO, A (1990): Acta 208, pp 151-161 Sci Tot Environ 96, pp 235-252 BLOOM, N S AND CRECELIUS, E A (1983): Mar Chem MORETTO, L, BLOOM, N, SCOPECE, P AND UGO, P 14, pp 49-59 (2003): J Phys IV Fra Vol 107, pp 887890 GILMORE, C AND BLOOM, N S (1995): Water Air Soil Pollut 80, p 799

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 845 A Core Profile for Hg and other Metals at Ai Pili (Venice Lagoon)

NICOLAS S BLOOM1, LIGIA M MORETTO2 AND PAOLO SCOPECE2

1Frontier Geosciences, 414 Pontius North Seattle, WA 98109 USA; E-mail: nicolasb@nickslab$org 2Universita CaFoscari, Santa Marta, 2137 Venice (30123) Italy; E-mail: moretto@unive$it

Abstract: A sediment core profile collected in a polluted inlet of the Venice Lagoon was analyzed for 22 trace metals, 210Pb, 137Cs and CH Hg in the solid phase and 10 trace 3 metals plus CH Hg in the pore water! The profile indicated most metals showing a maxi- 3 mum in concentration at approximately 15 cm depth, corresponding to a time 50-75 years ago, during the rapid development of the Marghera industrial area located on the western shore of the Lagoon! The metals showing the greatest contamination levels were Zn, Hg, Cd, Co and Cu, which showed enrichment factors ranging from approximately 50 to 5 times background!

Key Words: Sediment, Metals, Mercury, Venice Lagoon

INTRODUCTION ous phase ethylation, and GC-CVAFS detection (BLOOM ET AL , 1997) An aliquot of the Two sediment cores were collected from Ai remaining sediment was digested in a Teflon bomb with a mixture of HNO + HF + HCl, Pili, a contaminated inlet on the western 3 and then analyzed for Hg using SnCl reduc- shore of the Venice Lagoon, adjacent to the 2 Marghera Industrial zone (BLOOM ET AL , tion and dual-amalgamation CVAFS (BLOOM 2004) The first core, from which most of AND CRECELIUS, 1983; BLOOM AND FITZGERALD, the metals data were collected, was taken on 1988) The digest was then twice taken to dryness with added HNO , to drive off fluo- October 21, 2002 The second core, collected 3 on June 22, 2003, was used for radiological ride, and analyzed for most metals using dating, and was also analyzed for Hg as a ICP/MS As and Se were analyzed using cross check Based on the change in sedi- HG-AFS, and Ag by ZGFAAS to avoid in- ment color, it appeared as though the upper terferences common to ICP/MS The second 3-4 cm of the sediment was oxidized (brown, core was counted for 210Pb and 137Cs using Fe(OH) , compared to the black (FeS) sedi- gamma ray spectrometry by Battelle North- 3 ments below) The cores were rapidly ex- west (SEQUIM, USA) Although the sedimen- truded in the field, with 10 grams immedi- tation rates are low, and the area is subject to ately taken from the center of each section anthropogenic, wind-driven, and biological and placed into a 20 mL glass vial and fro- mixing, we were able to use 137Cs and 210Pb zen at -20 oC The samples remained frozen dating to estimate the sedimentation rate at until aliquoting for CH Hg analysis, which between 0 2 ± 0 1 cm yr-1 For comparison, 3 was performed by solvent extraction, aque- an average sediment for the northern La-

RMZ-M&G 2004, 51 846 PART 2 BIOGEOCHEMISTRY goon was prepared by homogenizing one years covered by these cores, all of the an- gram each from 29 surface sediment samples thropogenic trace metals showed profound we had earlier collected from 9 dispersed sub-surface maxima (Figure 1) The depth sites Porewater was collected in 10 cm depth of the peak for most of the trace metals (Cu, intervals at Ai Pili in October of 2002 using Zn, Cd, Tl, Pb, As, Se, Sn, Sb) was about 15 an in situ diffusion cell described by and UGO cm, or approximately 75 years ago This cor- ET AL (1999) responds to the early development and rapid industrialization of the Marghera Industrial zone immediately before and during World RESULTS AND DISCUSSION War II Ag showed a maximum at 9 cm, while for Co it was located at 21 cm The peak for Means and summary statistics for the whole Hg, 3-12 µg g-1 depending upon which core core are presented for 22 metals and CH Hg is used (Figure 2) was seen at 3 cm, although 3 in Table 1 The values are arranged in order concentrations were highly elevated over the of decreasing relative standard deviation entire length of the core This profile sug- (RSD) of the elements within the profile gests a peak Hg input to the lagoon only While crustal metals (Fe, Na, Mg, Ca, Al, 15 years ago, which is after the expected Cr, Ni, Zr and 6 others not shown) revealed maximum releases (1950s1980s) of Hg little change in concentration over the ≈ 150 from the Hg-cell chlor-alkali plants in

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 847

elevated levels were observed from 020 cm, followed by a rapid drop to 002 ng g-1 This trend differs from that observed at other shallow marine sites (BLOOM, ET AL, 2004), where maximum CH Hg is at the top, with a de- 3 crease to near zero over less than 10 cm The differences in CH Hg profile may result from 3 the much thicker oxic layer, which could serve to force the locus of methylation activity deeper into the sediments

At the same time as the first core collection, a pore water profile was collected about 1 meter away Analysis of the pore water for some of the same metals as in the sediments allowed the calculation of a series of distribution coefficients (Table 2) for the 0-10 cm sediment layer (the pore water sampler was only capable of 10 cm resolution) Although K s are ambiguous because the aqueous and d solid phase metal speciation is unknown, they do provide an operationally defined ranking of the net affinity of the metals for the solid phase in this system Hg was found to have the highest K of all the metals, while d

Marghera (BLOOM ET AL, 2003) Because the peak at 3 cm was greatly attenuated in the second core, taken only 8 months later, we suspect it may have been the result of a more recent, short-term discharge to the Ai Pili inlet itself, rather than a long-term Lagoon- wide phenomenon A maximum for CH Hg 3 (24 ng g-1) was found at 4-6 cm, although

RMZ-M&G 2004, 51 848 PART 2 BIOGEOCHEMISTRY

CH Hg was three orders of magnitude less ground concentrations (deep sediment cores) 3 strongly bound This suggests that CH Hg is are available for most metals in the Lagoon 3 readily released from the sediments to the sediments, making accurate assessment of water column during the tidal pumping that the degree of contamination rather difficult occurs as the sediments are submerged and Sediment-water distribution coefficients cal- re-emerge each day culated from pore-water collected at the same site showed that inorganic Hg is the most strongly bound of all of the metals studied, while CH Hg is approximately 3 orders of CONCLUSIONS 3 magnitude more soluble This suggests the possibility that as CH Hg is produced in the Sediments in shallow waters of the western 3 part of the Venice Lagoon are highly con- sediments by microbial activity, it is readily taminated with respect to several important flushed from the sediment to the overlying toxic metals, particularly Hg, Cd, Ag, Cu, water during the daily cycle of tidal inunda- and Tl Unfortunately, no high quality back- tion and re-emergence

REFERENCES

BLOOM, N S, MORETTO, L M AND UGO, P (2004): PAVONI, B, DONAZZOLO, R, MARCOMINI, A, DEGOBBIS, Limnol Oceanogr, Vol 49, pp 367-375 D, AND ORIO, A A (1987): Mar Pollut Bull, BLOOM, N S, COLEMAN, J A AND BARBER, L (1997): Vol 18, pp 18-24 Fres Anal Chem 358, pp 371-377 UGO, P, BERTOLIN, A AND MORETTO, L M (1999): In- BLOOM, N S AND FITZGERALD, W F (1988): Anal tern J Environ Anal Chem 73, pp 129-143 Chim Acta 208, pp 151-161 BLOOM, N S AND CRECELIUS, E A (1983): Mar Chem, Vol 14, pp 49-59

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 849 Assessing the bio-availability of dissolved Hg(II) employing genetically engineered Escherichia coli

RALPH BONA & HOLGER HINTELMANN

Watershed Ecosystems Program, Trent University, 1600 West Bank Drive, Peterborough# Ontario, Canada, K9J 7B8; E-mail: ralphbona@trentu#ca and hhintelmann@trentu#ca# Tel# No: 001-748-1011 ext# 7759#

Abstract: Two genetically engineered strains of E coli, expressing the mercury-binding cytosolic protein, and hence used as model organisms in studying mercury bioavailability, can accumulate almost 50 % of Hg(II) in solutions containing ambient levels of the cation" Furthermore, the distribution of accumulated Hg between cytosol and the rest of the cell is such that the amount bound in the former reduces with increasing Hg concentration in solution"

Keywords: E coli, glutathione sulfur transferase (GST), metallothionein (MT), bioavailability"

INTRODUCTION metallothionein (MT), which due to its high cysteine amino acid content (about 20 %) It is now generally acknowledged that am- strongly binds and hyper-accumulates ionic bient methylmercury formation in aquatic Hg The same amino acid residues, though, ecosystems cannot be precisely extrapolated render the protein unstable as molecules of from methylation rates obtained in spiking the latter can dimerise or be oxidized via experiments using total mercury concentra- SH linkage The proteins are therefore fused tions alone This is because not all species to glutathione sulfur transferase (GST) in the of mercury are bioavailable for methylation engineered cells for their expression and sta- (GUTNECHT, 1981) underscoring the need to bilization The M3T strain also has the mer develop a tool for assessing the specific avail- operon genes, merP and merT encoding the ability of different species of inorganic mer- periplasmic and cytosolic mercury transport cury In this project we attempt to quantify proteins respectively, and these enable ac- the bioavailable fractions of some species of tive and specific uptake of Hg In prelimi- dissolved mercury, often encountered in nary laboratory experiments, we have con- freshwater systems, under controlled labo- firmed with the aid of sodium dodecyl sul- ratory conditions Two strains of E coli (M4 fate poly-acryl amide gel electrophoresis and M3T), genetically engineered at Cornell (SDS-PAGE), the ability of the bacteria to University in the USA (CHEN AND WILSON, express the protein, MT They were also ob- 1997) to accumulate significant amount of served, by ICP-MS measurements of the Hg are being employed in these experiments 200Hg stable isotope, to accumulate signifi- Both strains (Bioaccumulator) can express cant amount of inorganic Hg from solutions the low molecular weight, cytosolic protein containing as low as 10ng/l of mercury

RMZ-M&G 2004, 51 850 PART 2 BIOGEOCHEMISTRY

Our main objectives were to determine the to the containing glass vessel The remain- fraction of mercury internalized by the bac- ing half pellet was lysed with 750 µl of teria (a direct measure of bioavailability); and B-PER The commercial reagent is a non- the role of the mercury transport proteins ionic preparation in 20 mM Tris HCl, pH 75 encoded by the mer operon genes in the M3T buffer (PIERCE, 2003), and hence may not strain (but also expressed by bacteria inhab- chemically interact with or alter the status iting Hg contaminated lakes) on Hg uptake or location of the mercuric cation The lysate, essentially cytosolic, was then digested and analyzed for Hg METHODS AND RESULTS

In all experiments, cultures of the two strains were grown overnight in LB broth at 37°C to an optical density measurement at 600 nm of 09, corresponding to a cell density of about 109 cells/ml They were then induced with 1mM of the lac-operon inducer, isopro- Lanes 1 and 2: The non-induced M3T and M4 strains, respectively pyl-b-D-thiogalactopyranoside (IPTG), for Lanes 3 and 4: The induced M3T and M4 strains, re- 4 hours The cells were harvested by cen- spectively trifugation at 3500 rpm for 15 minutes, and Lane 5: Blank washed twice with 67 mM phosphate buffer Lane 6: See-BlueM Pre-stained marker A fraction of this was lysed with 300 µl of Figure 1 Electrophoretic gel showing MT-GST fu- the proprietary bacterial protein extraction sion protein at ~31 kDa reagent (B-PERM), which has been demonstrated to be more effective, gentle and con- The stable isotope accumulation experiments venient than the traditional mechanical meth- revealed that 40 to 50 % of Hg present in the ods of lysis, such as sonication (PIERCE, solution was internalized by the M4 and M3T 2003) The GST-MT fusion protein was iso- strains respectively, regardless of the initial lated and purified by affinity chromatogra- Hg concentration" Such level of uptake is phy using a GST ® Bind kit, and character- expected in bacteria endowed with Hg trans- ized by SDS-PAGE, with an expected mo- port and storage proteins described by lecular weight of ~31 kDa as shown in Fig- HUDSON ET AL" (1994) as important in facili- ure 1 The remaining cells were exposed to tated uptake of the cation" Facilitated uptake two solutions containing 10 and 50ng/l 200Hg is now claimed to be potentially more im- stable isotope in phosphate buffer for 1 hour portant than passive diffusion as a mecha- followed by washing and centrifugation The nism of Hg accumulation (KELLY ET AL, supernatant and 50 % of the pellet were di- 2003)" The amount of Hg accumulated was gested and analyzed for the isotope by ICP- higher in the M3T than the M4 (Kruskal- MS Mass balance calculations revealed that Wallis ANOVA, p<0"05, df=1, Figure 2), the sum of the Hg levels in supernatant and again supporting claims by HUDSON ET AL" pellet was equal to the amount of initial spike, (1994)" It was also observed that a slightly and that there was no significant loss of Hg higher fraction (70 %) of the Hg associated

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 851 with the cell is cytosol-bound at lower Hg sub-lethal levels, as both strains lack the concentration of 10 ng/l, but this dropped to merA gene that encodes the NADPH depen- about 60 % at 50 ng/l initial concentration dent flavoprotein, mercuric reductase respon- for both strains" This decline could be attrib- sible for conferring mercury resistance to utable to the bacteria developing mechanisms bacteria (CHEN AND WILSON, 1997; HOBMAN to maintain the amount of Hg internalized at AND BROWN, 1996)*

(a) (b)

Figure 2 The amount of 200Hg isotope internalized by the two strains of E coli at an initial concentration of 10ng/l (a), Kruskal-Wallis p>005, df=1; and 50ng/l (b) Kruskal-Wallis p<005, df=1

REFERENCES

CHEN, S AND WILSON, D B (1997): Genetic engineer- HUDSON, R J, GHERINI, S A, WATRAS, C J, AND ing of bacteria and their potential for Hg2+ PORCELLA, D B (1994): Modelling the bio- bioremediation; Biodegradation 8, pp 97-103 geochemical cycle of mercury in lakes: The GUTKNECHT, J (1981): Inorganic mercury (Hg2+) trans- mercury cycling model (MCM) and its applica- port through lipid bilayer membranes; J Mem- tion to the MTL study lakes In Mercury Pollu- brane Biology 61(61) tion Integration and synthesis (WATRAS, C J HOBMAN, J AND BROWN, N (1996): Overexpression of AND HUCKABEE, J W, Eds), Lewis publishers, merT, the mercuric ion transport protein of pp 473-523 transposon Tn501, and genetic selection of Hg KELLY, C A, RUUD, J W M AND HOLOKA, M H hypersensitivity mutations; Mol Gen Genet (2003): Effect of pH on mercury uptake by an 250, pp 129-134 aquatic bacterium: Implications for Hg cycling; Environ Sci Technology 37, pp 2941-2946 Pierce PoppersTM Cell lysis solution (2003): http://wwwpiercenetcom/poppers/nonanimated/bper/ indexhtml (04/04/2004)

RMZ-M&G 2004, 51 852 PART 2 BIOGEOCHEMISTRY

Laboratory Simulation of Site Specific Conditions and Methyl Mercury Formation in Aquatic Systems

JEAN-CLAUDE, J BONZONGO

Department of Environmental Engineering Sciences, PO Box 116450, University of Florida, Gainesville, FL 32611-6450, USA (bonzongo@ufledu)

Abstract: In this study, the potential of different land use types to impact the methylation of ambient sedimentary inorganic mercury (Hg) was investigated Laboratory experiments were conducted using freshwater sediments, and the effects of selected human-imposed conditions on aquatic systems tested Unlike most previous Hg methylation and methyl- Hg (MeHg) demethylation studies, which are based on measurements of potential transformation rates of added inorganic Hg2+ or CH HgX, in this work, changes in the specia- 3 tion of Hg already present in the sample was tracked down after the addition of selected common pollutants (eg acid, sulfate, nitrate, phosphate, organic matter added as yeast, or different combinations of the above), to simulate the impact of different land use types Their potential to accelerate MeHg production was then evaluated In addition to confirming some anticipated trends, such as the now well-established effect of sulfate and pH on Hg biotransformation and MeHg production, the study points out the importance of organic matter and nutrient additions on Hg transformations Obtained results suggest that land use practices should merit consideration as a potential means of reducing mercury contamination in aquatic biota, and ultimately in humans

Key words: watershed, land use, methylation of ambient Hg

INTRODUCTION bodies via direct atmospheric deposition and The contamination of aquatic biota by mer- runoff One way to successfully reduce me- cury (Hg) remains a serious environmental thyl-Hg contamination and exposure could problem, and this, despite preventive and come from the combination of (1) implemen- remedial measures such as the reduction of tation of the above-mentioned measures and human exposure to Hg by issuance of safe (2) the development of appropriate land man- consumption levels and policy measures agement practices that limit methyl-Hg pro- aimed at reducing anthropogenic emissions duction from inorganic Hg already present Anticipated results from the current Hg pol- in soil/sediments lution curbing efforts could, however, be delayed by MeHg inputs from land-use in- In this study, an evaluation of the potential duced methylation of inorganic Hg already of land-use derived pollutants to interfere accumulated in sediment, as the latter be- with the cycling of Hg and favor the produc- haves as a sink for Hg collecting in water tion of MeHg from inorganic Hg already present in sediments is examined

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 853

RESULTS AND DISCUSSION Potential effect of sulfate additionFor sulfate impact (eg from mining wastes), sulfate (as Na SO ) was added to sediment slur- Materials and methodsTo investigate the 2 4 potential impact of land use derived-pollut- ries to produce a series of final concentra- ants on ambient sedimentary Hg, laboratory tions ranging from zero to of 600 µM above experiments were conducted using sediment the background level collected from the pristine Sipsey River in the Mobile-Alabama River Basin The Potential effect of nutrient additionTo composition of the wet-sieved sediments study the potential impact of agricultural run- (1mm mesh, and representing 63 % of the offs and municipal discharges on Hg speciation, we focused on phosphate (P-PO 3-), as bulk sediment), used in slurry preparation 4 was 8031ng/g for total-Hg, MeHg level was the latter is the limiting nutrient in most below analytical detection limits, the organic aquatic systems In natural aquatic systems, matter content (determined by LOI) was an increase in P-concentrations brings about 574 % and the water content, 875 % Sedi- ecological changes that interfere either di- ment slurries were prepared in acid pre- rectly or indirectly with the cycling of Hg cleaned BOD-bottles using deionized water The initial sediments contained 049 µM of water extractable P-PO 3- The initial N-NO - in 1:1 (m/v) ratio And to simulate pollutant 4 3 inputs from different land use types, high concentration in sediments was not determined, but N-NO - was added to slurries to purity chemicals (ACS reagent grade) were 3 used and added to slurries as follows produce in all slurries, a final concentration of 2mM above levels already present in Potential effect of organic matter addition samples An increasing trend in the P:N ra- To simulate the input of organic carbon (eg tio was then obtained by maintaining a fixed concentration of N-NO - and progressively autochthonous and allochthonous) into sedi- 3 increasing the levels of P-PO 3- added ments, organic matter as yeast, containing 4 04ng as total-Hg per g and MeHg level below analytical detection limits, was used as All incubations were run in parallel with source of easily biodegradable organic car- control, non-spiked sediment slurries, and bon The organic matter content of tested sedi- MeHg production in controls subtracted from ments was 574 % (determined by LOI), and those obtained from spiked slurries Also, yeast was added to slurries to produce a range molybdate and BESA was used to assess the of organic matter concentration from 02 to contribution of SRB and methane produc- 1g (above background level) per 10ml slurry ing bacteria (MPB) in MeHg formation Be- fore incubation, both slurries and the Potential effect of pHThe effect on in situ headspace of bottles containing slurries were change in pH was simulated by the use of flushed with high purity nitrogen Bottles either 01N HCl (eg acid mine drainage) or were then hermetically capped and incubated 01N NaOH (eg alkaline effluents, or sim- at 20 0C for 5 days Each treatment was run ply a pH rebound from acidic conditions) to in triplicate, and no Hg was added to the slur- adjust the pH to values spanning the range ries For sediment characterization, total-Hg of 5 to 8, from the initial value of ~739 was determined after acid digestion (with

RMZ-M&G 2004, 51 854 PART 2 BIOGEOCHEMISTRY

HNO /H SO mixture) of an aliquot of the kaline alcohol digestion of a pre-weighed 3 2 4 slurry in acid-cleaned volumetric flask slurry aliquot in an acid-cleaned screw capped with acid-cleaned marbles Samples capped Teflon vial and heating at ~75 0C, were brought to a refluxing boil on a hot plate followed by ethylation of an aliquot of buff- until the solution became clear After cool- ered digestate, Tenax trapping, GC-separa- ing and dilution with Nanopureâ water, Hg tion, decomposition, and detection by CV- was determined by the SnCl reduction tech- AFS In addition to reagent blanks and liq- 2 nique with detection by cold vapor atomic uid standard solutions run during analysis, a fluorescence spectrometry (CV-AFS) MeHg standard reference material, IAEA-480 and was determined using a method adapted from samples spiked with known amounts of Hg Bloom (1989) The method involves an al- were analyzed with samples

Figure 1 Effect of pollutants on speciation of ambient sedimentary Hg

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 855

ResultsOverall, all treatments resulted in lation with a peak %MeHg around sulfate changes in Hg speciation, in that, at the end concentration of 400 ìM& Similar to the pH of the 5 day-incubation period, sediments effect, %MeHg in these conditions are far with initial MeHg below analytical detection lower as compared to those produced in the limits produced detectable levels of MeHg optimum region of organic matter addition& (see Figure 1)& Effects of phosphate(Fig& 1d) Only a few Effects of organic matter(Fig& 1a)& The studies have reported so far on field or labo- addition of different levels of yeast to sedi- ratory data relating nutrients and/or particu- ment slurries led to a bell-shaped curve, with late organic carbon to rates of MeHg forma- an optimum region around the concentrations tion& These experimental data tend to indicate of 0&4 to 0&6 g of yeast/10 ml of slurry& One that P-addition could affect Hg transforma- possible explanation for the decreasing tions in low P- level sediments, as a limiting %MeHg with increasing organic matter con- nutrient for microbial growth& Its direct im- tent of the slurry could be the reduced pact on Hg transformation is likely to be neg- bioavailabilty of Hg, which has a strong af- ligible in systems that are not P-limited& How- finity for organic matter& Mercury has very ever, nutrients could likely impact Hg trans- high stability constants with organic ligands formation via primary production and subse- and can form stable bonds to carbon& It is quent increase in decaying organic matter that worth to note that slurries that received no could produce an effect similar to the one re- yeast addition had detectable MeHg levels ported for yeast addition& at the end of the incubation period, with levels quite similar to those observed in samples Finally, the use of specific inhibitors of SRB containing 1g of yeast& This is probably a and MPB shows that these microbial groups simple temperature change driven MeHg contribute a great deal of MeHg produced in production (incubation conducted at 20 0C)& the slurries& However, the observed inhibition of MeHg production in BESA-treated Effects of pH(Fig& 1b) Similar to the ef- slurries was either equal or more pronounced fect of organic matter addition, changes in than in molybdate-treated slurries, especially pH show an optimum region of MeHg pro- in the optimum region& These results suggest duction/accumulation centered around a pH that for the sediment under consideration, of 6&5& Above pH 6&5, the percentage of pro- MPB play a significant role in MeHg produced MeHg decreases rather steadily with duction as well& increasing pH& Overall, much less Hg is transformed to MeHg (maximum of ~25 %), as compared to the optimum transformation CONCLUSIONS observed in the presence of organic matter& These results suggest that the introduction Effects of sulfate(Fig& 1c) Similar to the into aquatic systems of pollutants other than quasi bell-shaped curve produced by Hg could promote the methylation of inor- Gilmour and Henry (1991), the addition of ganic Hg already present in sediments& The sulfate promotes MeHg production/ accumu- importance of such transformations would

RMZ-M&G 2004, 51 856 PART 2 BIOGEOCHEMISTRY probably vary with sediment characteristics Acknowledgements and the type and concentration of pollutants Overall, organic matter and nutrients seem This work was supported partly by US-EPA, to have the most pronounced effect on Hg Grant # R827168-01-0, and support from speciation Accordingly, one should expect Occidental Chemical and UF Foundation contrasting MeHg levels in a river or aquatic system with sections polluted by, say, acid mine drainage, nutrients, and organic carbon

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 857 Grain size partitioning of mercury in sediments of the middle Odra river (Germany/Poland)

LEONARD BOSZKE1, ARTUR KOWALSKI2 & JERZY SIEPAK2

1Collegium Polonicum, A Mickiewicz University, S³ubice, Poland; E-mail: boszke@euv-frankfurt-ode 2Faculty of Chemistry, A Mickiewicz University, Poznañ, Poland; E-mail: zawig@amuedupl

Abstract: The aim of this study is to determine the distribution of mercury in different grain size fractions of surface sediments from the middle course of the Odra river Mercury concentrations were determined in bulk sediments of different grain size fractions using the cold vapor atomic fluorescence spectrometry method The total mercury concentration in bulk sediments varied from 0051 to 131 mg/kg dry weight The concentration of total mercury was determined in the grain size fractions < 02, 02 05, 05 10, 10 20 and > 20 mm to be (in mg/kg dw): 0118 299, 0033 099, 0034 117, 0035 197 and 0017 365, respectively Gradual decrease in the mercury concentration with increasing grain size from fine to coarse fraction has been observed only for sediments taken from the riverbed Although, no similar gradual decrease in the mercury concentrations has been observed for sediments from the river-banks, finer sediments (< 02 mm) still tend to show higher concentrations of mercury

Key words: Odra river, bottom sediment, grain size, fractionation, mercury

INTRODUCTION The texture of river bottoms can have different character Most often they are sandy, made The Odra river is one of the five longest riv- of particles size 01-1 mm, in lower courses ers in Europe and transports and collects a muddy with a dominant fraction of the par- large number of substances from natural and ticle size 0001-01 mm Sometimes the char- anthropogenic sources$ The Odra River Ba- acter of the bottom is mixed or changing along sin has a catchment area of 118$861 km2$ The the river course even over short distances basin is situated in the industrialised and Near the banks, as a result of increased fric- highly populated centre of Europe, shared tion, the water flow velocity decreases and by Poland, Czech Republic and Germany, the sediments contain more clay or organic respectively 89 %, 6 % and 5 % of catch- components than in the center of the river- ment area$ The upper part of the Odra catch- bed The kind of mineral components deter- ment is dominated by mines of coal, copper, mines the compactness and particle-size dis- lead, zinc and sulphur as well as heavy in- tribution of the bottom sediments The par- dustry$ The middle part and the underflow ticle-size distribution decides about the inten- are under heavy load of agriculture and com- sity of capturing and bonding of substances munal waste waters from Eisenhütten- dissolved in water on the surface of the solid stadt, Frankfurt/Oder, S³ubice, Kostrzyñ particles of the suspension and bottom sedi- (SZYJKOWSKI, 1995; IOP 2002)$ ments (STARMACH ET AL, 1976) RMZ-M&G 2004, 51 858 PART 2 BIOGEOCHEMISTRY

The aim of this study was to recognise a dis- area Bottom sediments were collected at 7 tribution of mercury among different particle sites in the middle course of the Odra River size fractions and to investigate potential in 2002 (Figure 1) Sediments from German sources of mercury pollution in the middle (A) and Polish (C) banks, and from the course of the Odra River and its drainage middle part of riverbed (B) were collected

Figure 1 Map of the study area

RESULTS AND DISCUSSION although some differences in the mean concentrations of mercury were found except The study revealed significant differences in the fraction < 02 mm, the mean concentra- degree of mercury pollution between the tion of mercury was higher in the samples grain size fractions of surface sediments ex- collected at the German bank, lower from amined (Table 1) The mean concentrations the Polish bank and the lowest from the cen- of mercury in the granulometric fractions tral river bed For the fraction < 02 mm, the < 02, 02 05, 05 10, 10 20 and mean concentrations of mercury in the > 20 mm were as follows (mg/kg): samples from the Polish (088±112 mg/kg) 083±081 (0118 299), 023±024 (0033 and German (086±066 mg/kg) banks were 099), 021±027 (0034 117), 040±055 close The concentration of mercury in the (0035 197) and 048±086 (0017 365) samples collected from the central riverbed The variance analysis (ANOVA) did not was lower (057±046 mg/kg) The concen- show statistically significant differences trations of mercury in the other fractions: (p > 005) in the mean concentration of mer- 02-05 mm, 05-10 mm, 10-20 mm and cury in the cross-section profile of the sedi- >2 mm were the highest from the sediments ments from the Odra river section studied, collected from the German bank: (mg/kg):

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 859

Table 1 Concentrations of mercury in bulk sediments and in different grain size fractions of bottom sediments of the middle Odra river (mg/kg dry weight)

033±033, 039±040, 071±064, 091±125, in the mean concentration of mercury in lower in the samples from the Polish bank: coarser fractions can be a result of the in- 022±023, 015±010, 037±057, 041±043, flow of this element from anthropogenic and the lowest from the samples collected sources eg mining Many authors have in- from the central riverbed: 011±008, dicated that greater particles of the sediment 008±005, 008±005, 005±002 can reside for a longer time at the same site, often in shallow places of rivers and streams No gradual decrease in the mean concentra- so in aerobic conditions, and thus can better tion of mercury with increasing grain size document the anthropogenic inflow of heavy has been established, contrary to what could metals to bottom sediments (SALOMONS AND be expected from literature The finer frac- FÖRSTNER, 1984) Coarser particles can have tion of bottom sediments tends to accumu- longer time for development of mercury ab- late greater amount of mercury, and thus sorbing coatings on their surface eg an or- lower concentrations of mercury were ex- ganic layer or/and a layer of manganese and pected in greater size fractions In general, iron hydroxides, than finer particles It seems higher concentration of mercury in the finer that in the bottom sediments over the Odra fractions is related to greater surface area of river section studied an important role is this fraction and hence a greater number of played by organic matter It cannot be ex- mercury bonding sites, and to the presence cluded that mercury is accumulated in the of detrital minerals being products of rock Odra river sediments by influence other fac- weathering Detrital material is the washed tors, eg the presence of CaCO to a greater 3 out fraction of colloidal character, which in- degree than by organic matter and manga- dicates its enhanced sorption properties nese and iron hydroxides, because a strong (SALOMONS & FÖRSTNER, 1984) An increase positive correlation (r=099) has been found RMZ-M&G 2004, 51 860 PART 2 BIOGEOCHEMISTRY between the concentrations of mercury and fraction has been observed only for sedi- CaCO in river bottom sediments ments taken from the riverbed Although, no 3 (JOHANNESSON ET AL, 2003) Moreover, ac- gradual decrease in mercury concentrations cumulation of mercury in particular from fine to coarse fractions has been ob- granulometric fractions of the Odra river served for sediments from riverbanks, finer bottom sediments can be affected by the spe- sediments (< 02 mm) still tend to show ciation of mercury It has been established higher concentrations of mercury The higher that in bottom sediments polluted with mer- concentrations of mercury in the finer- cury, HgS has been accumulated in the coarse grained sediments are due to the increase in grained fractions in 80 % on average, while the surface area and surface properties of clay the other mercury species have been accu- minerals The long residence time to accumulated by the fine grained fraction (in 55 mulate coatings and associated mercury and % on average) (BIESTER ET AL, 2000) the presence of coarse fractions of industrial and communal wastes is possibly responsible for the high content of mercury in the coarse CONCLUSIONS size fraction at riverbanks

The concentrations of mercury in different Acknowledgements grain size fractions of the Odra river sediments are significantly affected by the grain This work was supported by the Polish Com- size distribution Gradual decrease in the mittee for Scientific Research (KBN) under mercury concentration from fine to coarse grant No 3 T09D 079 26

REFERENCES

BIESTER, H, GOSAR, M & COVELLI, S (2000): Mer- SALOMONS, W & FÖRSTNER, U (1984): Metals in cury speciation in sediments affected by dumped Hydrocycle; Springer Verlag, Berlin, Heidelberg, mining residues in drainage area of the Idrija 349 p mercury mine, Slovenia; Environ Sci Technol STARMACH, K, WRÓBEL, S & PASTERNAK, K (1976): 34, 3330-3336 Hydrobiologia, Limnologia; PWN, Warszawa, IOP International Odra Project (2002): Results of 620 p (in Polish) International Odra Project; (A-K MEYER, Ed), SZYJKOWSKI, A (1995): Zasoby wodne dorzecza Odry Hamburg, 127 p i stopieñ ich zanieczyszczenia; In (JANKOWSKI, JOHANNESSON, L T, STEVENS, R L & ERIKSSON, K W & WIERKOSZ, K, Eds) Korytarz ekologiczny (2003): The influence of an urban stream on doliny Odry stan, funkcjonowanie, zagro¿enia, sediment geochemistry in Göteborg Harbour, Warszawa, 45-66 (in Polish) Sweden; Env Geol 43, 434-444

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 861 Distribution of mercury in surface waters, bottom sediments and soils from Poznañ city (Wielkopolska District, Poland)

LEONARD BOSZKE1, ARTUR KOWALSKI2 & JERZY SIEPAK2

1Collegium Polonicum, A Mickiewicz University, S³ubice, Poland; E-mail: boszke@euv-frankfurt-ode 2Faculty of Chemistry, A Mickiewicz University, Poznañ, Poland; E-mail: zawig@amuedupl

Abstract: Total mercury concentrations have been determined in surface water and bottom sediments (ponds, lakes, streams and rivers) as well as in soil samples collected in 2003 from Poznañ city! The total mercury concentration in the surface water was 19!2 ± 7!8 ng/L (range 8!7-39!5)! In bottom sediments collected at the same as water, the total mercury concentration was 81!9 ± 48!8 ng/g dry weight (29!0-210)! The average total mercury concentration in the soil from urban areas was 146 ± 130 ng/g dry weight (17-746)!

Key words: mercury pollution, surface water, bottom sediment, soil, Poznañ city, Poland!

INTRODUCTION tamination in urban area are hazardous waste and sewage sludge (KABATA-PENDIAS & The total mass of mercury emitted to the at- PENDIAS, 1999) mosphere from industrial sources in Poland has been estimated on 40 tons per year The aim of this study was to determine a dis- (MNISZEK, 1996) The main source emission tribution of mercury in surface waters, bot- of mercury to the atmosphere is combustion tom sediments and soils from Poznañ City of fuels As a consequence of this processes The concentration of total mercury was de- about 26 tons of mercury are emitted to the termined in 22 samples of urban bulk water atmosphere per year Processes of combus- (ponds, lakes, streams and rivers) and bot- tion of hard coal and lignite are responsible tom sediment samples from the same sites for the release of 44 % and 18 3 % of the Moreover, mercury was determined in total mercury emitted to the atmosphere 61 samples of urban soil (0-10 cm) Mercury Other sources of mercury such as cement was determined using the cold vapor atomic production process and used up fluorescent fluorescence spectrometry method (CV- lamps release 16 6 % and 6 4 %, respectively AFS) The soil samples were analysed after (MNISZEK, 1996) The main sources of mer- wet digestion with concentrated nitric acid cury in urban areas are combustion facili- in a whole glass apparatus consisting of ties, including coal-fired power plants, mu- round bottom flask partial condenser and a nicipal solid waste incineration and hospital water cooler incineration Other sources of mercury con-

RMZ-M&G 2004, 51 862 PART 2 BIOGEOCHEMISTRY

RESULTS AND DISCUSSION bottom sediments from the water reservoirs in Poznañ city are relatively higher than in The total mercury concentration in the surface the bottom sediments from sites relatively water was 192 ± 78 ng/L (range distant from the urbanized and industrialized 87-395) A relatively high average concentra- areas The samples of bottom sediments from tion was noted in the water from the Warta river streams, lakes, rivers and channels contained 249 ± 56 ng/L, while lower ones in the stream mercury in the concentrations: 12 ng/g, 224 ± 121 ng/L and pond water 11-50 ng/g, 21-70 ng/g and 16-44 ng/g, re- 204 ± 65 ng/L Relatively the lowest average spectively (FALANDYSZ ET AL , 1996a) The concentration of mercury was noted for the wa- bottom sediments from various sites in Po- ter collected from lakes 146 ± 53 ng/L land collected from sites located very close to or within the urbanised and industrialised In the bottom sediments from the same sites areas showed much higher mercury concen- where samples of water were collected, the trations: up to 490 ng/g in ponds and streams, total mercury concentration was 81 9 ± up to 690 ng/g in rivers, and up to 1800 ng/g 48 8 ng/g dry weight (29 0-210) A relatively in channels (FALANDYSZ ET AL , 1996a) high concentration was noted in ponds 116 ± 66 ng/g, while lower ones in the lake The average total mercury concentration in water 77 6 ± 52 0 ng/g, in the Warta river soil from Poznañ city was 146 ± 130 ng/g dry - 76 5 ± 32 7 ng/g and in the stream 68 8 ± weight (range 17-746) Spatial distribution of 43 9 ng/g The concentrations of mercury in mercury in the soil is presented in Figure 1

Figure 1 Spatial distribution of mercury in soil from Poznañ city

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 863

The mean concentration of mercury in the undisturbed soil from the park or along the soil samples from farmlands under direct roadside an average mercury concentration effect of anthropopressure was 130 ng/ g dry was 120 ± 150 ng/g, 460 ± 610 ng/g and 140 mass (range 2!3-450)! The concentration of ± 160 ng/g, respectively (LINDE ET AL!, 2001)! mercury in urban soils from parks and lawns was 160 ng/g (4!7-930) and different samples of barren soil contained 430 ng Hg/g (9!9- CONCLUSIONS 4800) on average! The forest soils contained, on average, 95 ng Hg/g (38-250), and differ- The results of the study have shown that mer- ent soil samples from agricultural areas con- cury distribution in the samples of water and tained 61 ng/g (7!3-250) (FALANDYSZ ET AL!, bottom sediments, collected from various sites 1996b)! The concentration of mercury in the in Poznañ is relatively uniform! In contrast to soils from the other urban agglomerations in the above, the concentration of mercury in the Poland varied from 1080 ng/g in Warszawa, soil samples varies in a relatively large range! 1140 ng/g in Wroc³aw, 1380 ng/g in Kraków The soil samples from the city centre con- and from cities in Upper Silesia was up to tained higher mercury concentration! 4010 ng/g (LIS & PIASECZNA, 1995)! For example, the average concentration of mercury Acknowledgements in the soils from Stockholm (Sweden) was 590 ± 1160 ng/g! The soil samples collected This work was supported by the Polish Com- from the city centre showed higher mercury mittee for Scientific Research (KBN) under concentration - average 860 ± 960 ng/g! In grant No 3 T09D 079 26!

REFERENCES

FALANDYSZ, J, KAWANO, M, DANISIEWICZ, D, LINDE, M, BENGTSSON, H & ÖBORN, I (2001): Con- STEPNOWSKI, P, BOSZKE, L & GO£ÊBIOWSKI, M centration and pools of heavy metals in urban (1996a): Total mercury in freshwater and soils in Stockholm, Sweden; Water Air Soil nearshore sediment from various sites in Poland; Pollut 1, 83-101 Bromat Chem Toksykol 29, 183-186 (in Pol- LIS, J & PIASECZNA, A (1995): Geochemiczy Atlas ish with English abstract) Polski Pañstwowy Instytut Geologiczny FALANDYSZ, J, KAWANO, M, DANISIEWICZ, D, CHWIR, Warszawa (in Polish) A, BOSZKE, L, GO£ÊBIOWSKI, M & BORY£O, A MNISZEK, W (1996): Emission of mercury to the at- (1996b): Investigation on the occurence of mer- mosphere from industrial sources in Poland; cury in soils in Poland; Bromat Chem Toksykol Environ Monit Assess 41, 291-299 29, 177-181 (in Polish with English abstract) KABATA-PENDIAS, A & PENDIAS, H (1999): Biogeochemia pierwiastków ladowych; Wydawnictwo Naukowe PWN, Warszawa (in Polish)

RMZ-M&G 2004, 51 864 PART 2 BIOGEOCHEMISTRY

Historical of Mercury in Serrasalmus Sp of Samuel Hydroelectric Reservoir, Ro Amazon

DB BRASIL1, RC OLIVEIRA1, R ALMEIDA1, EL NASCIMENTO1, R MIYAI1, WR B ASTOS 1 & EG SILVEIRA

1Environmental Biochemistry Laboratory, Federal University of Rondônia UNIR BR-364, Km 9,5 Porto Velho/RO, e-mail: labmerc@unir,br, 2Electrics Central of North of Brazil S/A, R, Major Amarantes, 513, Arigolândia-RO, e-mail: robertomiyai@eln,gov,br,

Abstract: The Samuel reservoir it formed in 1989 with dam of the Jamari River, that stays between km 55 and the km 130 of BR-364 that league Porto Velho at Cuiabá) For being a new lake, it finds with larger carnivorous frequency species like; piranhas, tucunarés, trairás, fishes dogs, among others) Doesnt have aluvionar auriferous registration in Jamari basin, since this mineral exploration process is what contributes direct or indirectly for mercury make available for the environment) However, in the Madeira River there were metal intense releases Hg for the environment, since this is used in the gold amalgamation process) Mercury release, mostly of between 1970 to 1980 in the auriferous exploration, so much directly in the river, how much way vaporization in re-burning process, being these vapors transported for long distances) For their characteristic lentic and in vegetable decomposition process, the reservoirs have the capacity of benefiting methylation phenomenon of mercury promoted for microorganisms and will easily be incorporated by biota aquatic) The generous Serrasalmus sp (piranha) was selected for the referring work for owning piscívorous alimentary habit, occupying the trophic higher- level of the food chain, and to be an endemic species in the reservoir) The specimens were going collected with assist of armed wait chains in the lake, was soon after going accomplished of measure the size followed by retreat slice of the copies dorsal part) And, behind previous digestion samples with acid and oxidizer reagents, it followed the concentration reading of total mercury by cold vapor generation coupled atomic absorption spectrophotometer (FIMS-400)) Samples of Serrasalmus sp) it has been collected since 1991) The concentration average results and interval band of Hg in the Serrasalmus sp) they were: 1991: 0)360 + 0)205mg/kg (0)148 0)905mg/kg); 1994: 0)974 + 0)497 mg/kg (0)735 1)219mg/kg); 1996: 0)749 + 0)343mg/kg (0)191 1)479mg/kg); 1997: 0)887 + 0)373mg/kg (0)241 2)168mg/kg); 1998: 0)548 + 0)512 mg/kg (0)241 2)168mg/kg); 1999: 0)397 + 0)253mg/kg (0)533 0)706mg/kg); 2001: 1)117 + 0)590 mg/kg (0)445 1)759mg/kg)) Except for years average 1991 and 1999, Hg concentration in Serrasalmus sp) it overtakes the maximum value recommended by the World Health Organization (WHO) for fish consumption (0)500mg/kg); and in year of 2001, it observed mercury concentration average in Serrasalmus sp)) It concludes that there wasnt until the concentrations referred metal stabilization in the Samuel reservoir)

Key words: Amazon, fishes, reservoir

Financial Support: PNOPg/CNPq; CAPES/RENOR; UNIR e RIOMAR)

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 865 Mercury in Ictiofauna of Samuel Hydroelectric Reservoir, Amazon Brazil

DANIELE BRAGA BRASIL1; RONALDO ALMEIDA1; ELISABETE LOURDES NASCIMENTO1; RONALDO CAVALCANTE OLIVEIRA1; ROBERTO KEYDI MIYAI2; WANDERLEY RODRIGUES BASTOS1 & ENE GLÓRIA DA SILVEIRA1

1Environmental Biochemistry Laboratory, Federal University of Rondônia UNIR, BR 364, Km 9,5, Porto Velho/RO; E-mail: [email protected]. 2Electrics Central of North of Brazil S/A, R. Major Amarantes, 513, Arigolândia-RO; E-mail: [email protected].

Abstract: The Jamari river basin doesnt own historically gold mining occurrences, however mercury high level on the reservoir area have been observed through ictiofauna The formatted Samuel lake reservoir with 560 km2 of area flooded in 1989 Hg regional origin found in the lake is enough argued by the scientific community, because natural sources as the chemical, geological and vegetable biomass burning would be big contribution The specimens were going collected with armed wait chains in the lake, was soon after going accomplished biological measure And, after previous digestion acid of the samples it followed concentration reading of total mercury by cold vapor generation coupled atomic absorption spectrophotometer (FIMS-400) It found the next average and respective values standard deviations, besides minimum and maximum values in the generous: Serrasalmus sp (n=99) 0614+0045 µgg-1 (0144 - 2190 µgg-1); Hoplias malabaricus (n=40) 0403+0024 µgg-1 (0102 - 1005 µgg-1); Cicla sp (n=39) 0405+0020 µgg-1 (0102 - 1098 µgg-1) and, Hydrolicus scombroides (n=40) 0866+0045 µgg-1 (0260 - 2506 µgg-1) Demonstrating that the generous Serrasalmus sp and cicla sp they overtake the maximum value recommended by the World Health Organization (WHO) for fish consumption of 0500 µgg-1 Recommending a more intense study in the area regarding one mercury made available for ictiofauna

Key words: mercury, Amazon, reservoir, fishes

INTRODUCTION Among the potentials factors that can influence the mercury bioaccumulation in aquatic In the lakes, rivers of forests and marshy ar- ecosystems they include environmental fac- eas the Hg can change in methyl-Hg for the tors: as pH, dissolved organic carbon (DOC) intense microbial activity of these areas and temperature; ecological factors as produc- slightly acid The methyl-Hg concentration tivity and tropic chain and physiologic factors, in the sediments, water and fish can be in- as the different degrees of mercury assimila- fluenced by the interface sediment/water for tion for the organisms (WASTRAS ET AL, 1998) the simple fact of a larger microbiological activity (ALVES ET AL, 1993) The fish can be used as a good indicator in monitoring programs of the impacts caused by

RMZ-M&G 2004, 51 866 PART 2 BIOGEOCHEMISTRY activities of gold mining, since they are samples and vegetable biomass burning would be big easy to obtain directly of the local fishermen contribution whose analysis doesnt present difficulty Be- sides allowing direct evaluation of risks the The fish were collected in the reservoir of health it publishes (FOSTIER ET AL, 1997) the Samuel Hydroelectric among the years of 1994 and 1997 In laboratory the samples were identified, the biometrical was accom- MATERIALS AND METHODS plished, and left a small bracket of fabric of the number area of the fish, that was main- The formatted Lake by Samuel reservoir, in tained frozen until the moment of the Hg the Jamari river with 560 km2 of area flooded determination occurred in 1989, still it today suffers the organic decomposition goes submerged A muscle bracket was then submitted a woods influence in 130 km length and widths chemical digestion process with acid re- that vary of 1 to the 20 km and the depth agents and oxidizers, second methodology average of 7 meters (Figure 1) The original proposed by BASTOS ET AL (1998) It goes Hg regional found in the lake is enough ar- Hg determination was realized by atomic gued by the scientific community, because absorption spectrophotometer coupled cold natural sources as the chemical, geological vapor generation (FIMS-400 Perkin-Elmer)

Figure 1 Location of the study area

RESULTS AND DISCUSSION geners possess carnivorous alimentary habit, these representatives were chosen due to the The table 1 presents the Hg values found in fact of the same ones belong to the top of the fishes geners selected for this study, as aquatic alimentary chains and in several well as the n samples, standard deviation and works they have if shown great bio- minimum and maximum values All of the monitoring RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 867

Table 1 Average Hg concentration with their respective standard deviation, as well as you minimum and maximum values in the studied fishes

The largest mercury values were found for the alimentary habit% This figure showed rela- the geners of Serrasalmus sp (piranha) and tively high Hg concentration for the fish for the species Hydrolicus scombroides (fish- planctivorous (0%469 µg%g-1), since for the fact dog), whose values crossed the certain maxi- of the plankton to be located in the base of mum limit for WHO (0%500 µg%g-1)% In spite aquatic alimentary chain, they dont present of the specimens of the two other geners in high Hg concentrations in muscle% study also present alimentary habit preferentially carnivorous, these didnt cross the Already the average Hg concentration found value recommended by WHO% for the carnivorous fish crossed recommended by WHO% Differently of the fish of The Figure 2 presents the average Hg values habit alimentary herbivores and detritivorous found in also collected in reservoir among that presented low mercury% This explained the same period (1994-1997) in relation to due to alimentary habit%

Figure 2 Average Hg values in relation to the preferential alimentary habit in the ictiofauna the Jamari river

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CONCLUSIONS tends the deposits in the bottom sediment, favorable for the process methylation This The Jamari River basin where is sited Samuel way the mercury in organic form enters in reservoir doesnt possess occurrences of gold the aquatic alimentary chain tending the mining, however the existent mining in the bioaccumulation and biomagnification, pre- area can cause impacts on the area of it in- senting their largest values in the organism fluences of the reservoir, through the atmo- chain tops, as presented in the present work spheric mercury It cannot also discard the hypothesis of which the soils of the area are Acknowledgements polluted for sources and/or anthropogenic sources Through the lixiviation process and This work was supported by the UNIR, flood of the characteristic soils in the rainy PNOPG/CNPq No 55 0882/01-4, RIOMAR period can cart rich mercury particles directly Foundation and SEBRAE-RO for the water column That in the reservoir

REFERENCES

ALVES, S L R ET AL (1993): Mercúrio em áreas de FOSTIER, A H, GUIMAR ES, J R D, FOSTIER , M C, garimpo de Ouro; Série Vigilância, N° 12, MELFI, A J, VELOSO, S, FERREIRA, J R, MATTOS, Estado do México: Metepec D P & KRUG, F J ( 1997): Comparação entre BASTOS, W R, MALM, O, PFEIFFER, W & CLEARY, D os sedimentos de fundo e ictiofauna carnívora, (1998): Establishment and analytical quality utilizados como indicadores no monitoramento control of laboratories for Hg determination in dos níveis de mercúrio em lagos do Estado do biological and geological samples in the Ama- Amapá (Região Amazônica); Revista Brasileira zon, Brazil Technical Review; Ciência e de Ecologia 1, pp 72-75 Cultura Journal of the Brazilian Association for WASTRAS, C J & BLOOM, N S (1998): Bioacumulação the advance of Science, Vol 50(4) p 255 of mercury im pelagic freshwater food webs; The Sciencie of the Total Environment 219, pp 183- 208

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 869 Trends in Mercury Accumulation in Lake Sediments across the Upper Midwest, USA

PATRICK L BREZONIK AND RICK J SCHUMAKER1

Department of Civil Engineering, University of Minnesota, Minneapolis, MN 55455 USA; email: brezo001@umn(edu( 1Current address: University of Idaho, P(O( Box 443018, Moscow, ID 83844

Abstract: Statistically significant west-east trends of increasing surficial Hg concentrations and enrichment factors (EF) were found in sediments from 20 lakes across a 600 km transect in the Upper Midwest region of the United States" Location along the transect explained 21 % of the variability in maximum surficial concentrations and 15 % of the variability in sediment EF; there was no west-east trend in Hg concentrations for pre- industrial sediments" The average Hg enrichment factor in the eastern subregion was ~1"0 greater than in the western subregion (an increase of ~50 %)" Hg enrichment in the sediments decreased on average by ~25 % in the last 40 years, but the regional nature of enrichment has remained relatively constant" The results support the conclusion that atmospheric Hg deposition in this region is influenced by both continental or hemi- spheric-scale transport and regional-scale transport"

Key words: sediments, lakes, mercury accumulation, enrichment factors

INTRODUCTION are expanding to decrease Hg emissions However, if deposition is dominated by glo- Mercury (Hg) contamination in remote lakes bal-scale transport, local-regional efforts to is attributed to atmospheric deposition[1] control emissions may have little influence Paleolimnological studies[2] indicate that Hg on regional pollution; if deposition is domi- accumulation rates in the Upper Midwest nated by regional-local transport, the efforts increased by ~35 since pre-industrial times should be more effective This study ex- A geographic pattern in Hg deposition in the amined the importance of various scales of U S was reported[3] in 1992, with higher Hg Hg transport Using Hg concentrations and in soils of eastern zones of a transect from enrichment factors in lake sediments along NW Minnesota to eastern Michigan Com- a W-E gradient of sulfate deposition in the parison of Hg accumulation in lake sedi- Upper Midwest, Lakes, we found a trend in ments from Alaska and Minnesota sug- sediment Hg and from this made inferences gested[4] that ~40 % of Hg deposition in the about regional patterns in Hg deposition Midwest may have a regional anthro-pogenic origin; N-S gradients in atmospheric Hg deposition also were found in Minnesota[5] METHODS However, regional patterns of Hg in lake sediments are not always found[6] Because Our study included 20 lakes in a forested area of concerns about Hg health impacts, efforts along a 630 km gradient of wet sulfate depo-

RMZ-M&G 2004, 51 870 PART 2 BIOGEOCHEMISTRY sition from eastern Minnesota to Upper (60-80 cm) date back to ca the 17th century Michigan (in sulfate deposition zones 3-5[3]) Hg enrichment in the Upper Midwest began Selected lakes vary in latitude by < 100 km in the mid- to late 19th century Lakes were selected using data from the East- ern Lakes Survey[7] To minimize watershed Hg analyses were done on wet sediment influences and ranges of lake/watershed samples [12] Wet and dry weight and loss on characteristics correlated with sediment ignition were determined separately to mea- [Hg][8], we targeted seepage lakes with small sure water, organic, and carbonate contents watersheds and low development We chose Sediments were digested by published pro- small lakes (< 31 ha, z < 11 m) with simple cedures and analyzed by CVAAS Appropri- m morphometry and watershed/lake area ratios ate procedures were used to ensure data reli- (WA/LA) < 59 Selected lakes had low color ability[12] Calibration standards were diluted and DOC because humic matter affects Hg from a certified standard Results for NIST export from watersheds and may increase Hg estuarine sediment (63 +12 ng Hg/g) were retention in water Low pH and low ANC within the stated limits (59 +12 ng Hg/g; are associated with high Hg in sediments[8]; n = 22); precision (mean RSD) based on du- thus, we avoided lakes with pH < 50 or plicate analyses of 10 % of samples was 7 % > 80 and ANC < 0 µeq/L or > 1000 µeq/L at ~83 ng Hg/g (n = 11) and 14 % at ~50 ng Hg/g (n = 30) We computed enrichment fac- We collected one core in the deepest area of tors, EFs, as ([Hg] - [Hg] )/[Hg] , where s b b each lake with a piston corer Cores were [Hg] and [Hg] are concentrations in surficial s b accepted if there were no signs of disturbance and background sediments; EF = 10 indi- at the sediment-water interface To assess the cates that [Hg] = 2[Hg] We calculated en- s b reliability of single cores, duplicate cores richment factors (EF ) normalized to the om were collected from 9 lakes If the lake bot- OM of sediments: EF = ([Hg] /OM - om m s tom was uniform, the second core was col- [Hg] /OM )/ [Hg] /OM Surficial (EF ) and b b b b 0-2 lected nearby If the lake had other deep ar- maximum near-surface (EF ) enrichment m eas, we collected the additional core there factors were calculated from [Hg] in the Cores were extruded within 48 h and refrig- 0-2 cm segments and the maximum [Hg] in erated at 4 °C until analysis The top 8 cm of the top 8 cm, respectively Background [Hg] cores were segmented into 2-cm intervals to was determined by excluding minimum and represent recent deposition; alternating maximum values in the 60-80 cm segments 2- and 5-cm segments were collected from and averaging the remaining values except the 60-80 cm stratum for background condi- in one lake, where [Hg] decreased with depth tions We selected these strata based on 210Pb in these segments In this case only the deep- analysis of sediments in studies on similar est segment was used lakes, which yielded linear sedimentation rates of ~1-3 mm/yr[9] We assumed a rate of Most variables were linearized by log or 2 mm/yr to estimate age in samples, based square root transformations for correlations on averages for lakes in the region[10,11] Seg- to examine relationships between lake chem- ments in the top 8 cm represent Hg depos- istry and watershed characteristics, lake loca- ited in the last 40-50 years, and bottom strata tion, and sediment Hg variables Distance east

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 871

(DE) on the transect and pH were not trans- of most interest, [Hg] and EF , were not sig- m m formed Relationships with DE were used to nificantly correlated with WA/LA, but higher [Hg] and EF were associated with lakes of detect trends in Hg variables and factors that m m lower color and DOC and higher SO 2- Back- influence sediment [Hg] across the region 4 ANOVA was used to determine differences ground [Hg] was significantly correlated only in sediment [Hg] among the three zones of with DOC, but DOC was not correlated with DE Lake [SO 2-] was correlated with [Hg] sulfate deposition in the area Because the 4 m variance in some variables was greater in zone and DE The latter reflects the gradient of wet 5 than in other zones, these measures were sulfate deposition across the Upper Mid- log transformed before analysis west[13] SORENSEN ET AL [8] found a correlation between wet SO 2- deposition and surface 4 [Hg] but not with bedrock geology RESULTS AND DISCUSSION Background and surficial Hg concentrations plotted by DE (Fig 1a) show that [Hg] in- All cores were from depositional areas, gen- m erally at > 80 % of z Sediments were floc- creases eastward (r = 0 46, p = 0 01), but m [Hg] does not Location along the transect culent (average water content > 91 % in all b explains ~20 % of the variability in [Hg] but one lake) and highly organic (mostly m The trend in [Hg] was similar but had a 40-70 % OM) Near-surface sediments in all 0-2 cores were enriched in Hg compared with pre- lower significance (p = 0 07) A similar rela- [14] industrial strata Average near-surface [Hg] tionship was found in Sweden We also m = 180 ng/g [dw]; range = 89-315 ng/g Aver- found a significant W-E trend (p < 0 05) of increasing EF (Figure 1b); location ex- age background [Hg] = 49 ng/g [dw]; range m b = 23-76 ng/g EF ranged from 1 to 8 8, with plained 16 % of the regional variability in m EF Hg enrichment was not correlated with a median EF of 2 8 Our concentrations and m m EF results are within ranges found by others OM in surficial sediment In fact, no mea- in this region; e g , other studies in the region sure of Hg in sediment was significantly correlated with OM or OM , but the relation- reported EF usually between 1 and 4, but s b ship of EF to DE (r = 0 42, p = 0 03) was sometimes as high as 10 om similar to other EF measures Our study was Our selection of lakes was successful in that within wet sulfate deposition zones 3-5 of most variables thought to influence [Hg] in the region used to detect Hg trends in forest [3] sediments were not significantly correlated soils Unfortunately, our study design did with lake location (DE) or measures of Hg in not provide sufficient lakes to detect a sig- sediment Lake depth and area, watershed nificant difference in EF between zones; data size, ANC, DOC, pH, OM , OM , and [Hg] from at least 10 lakes in each zone would be s b b did not change significantly across the region needed to detect a significant difference of [12] Hg levels in sediment were not correlated with 1 0 in EF at p < 0 1; for details see None- theless, the median EF in zone 5 was higher morphometry variables, but a few variables m other than sediment Hg measures were cor- than the values for zones 3 and 4, and the median EF in zone 5 was ~1 5 times higher related with DE WA/LA and [SO 2-] increased 0-2 4 with DE, and color decreased The variables than that in zones 3 and 4 These results are consistent with the soil results[3]

RMZ-M&G 2004, 51 872 PART 2 BIOGEOCHEMISTRY

Figure 1 Trends in (a [left]) [Hg] (squares), [Hg] (diamonds), and [Hg] (triangles) mer- 0-2 m b cury concentrations and (b [right]) EF and EF enrichment factors for sediments of 20 lakes 0-2 m across a ~600 km transect from east-central Minnesota to eastern Upper Michigan, USA)

Our EF values suggest that Hg enrichment W-E increase in sediment [Hg] supplies only has decreased by ~25 % in the last 40 years a minimum estimate of the regional contri- A consistent difference of 08 in EF between bution at the east end of the transect The [Hg] and [Hg] across zones 3-5 suggests increase in [Hg] amounts to 40 % of total 0-2 m m that Hg deposition and delivery to lakes has [Hg] at the east end; the increase in [Hg] m 0-2 decreased consistently across the region amounts to ~30 % of total [Hg] at the east 0-2 Recent decreases in atmospheric deposition end It cannot be assumed that all Hg at the the Upper Midwest are thought to reflect re- west end is from global-scale transport; thus, gional efforts to lower Hg emissions from regional sources likely contribute more than various anthropogenic sources[4] The consis- 30-40% of the sediment Hg in eastern Up- tent increase of 11 in both EF and EF per Michigan As noted earlier, ENGSTROM 0-2 m between Zones 4 and 5 implies that the re- AND SWAIN [4] estimated that regional anthro- gional pattern of Hg enrichment has re- pogenic sources accounted for ~40 % of the mained similar despite the change in the level Hg loading to rural Minnesota lakes and of enrichment natural/ anthropogenic global-scale sources accounted for 60 % Thus, as little as 35-40 Our results provide evidence for a regional % of the Hg deposition to lakes in eastern signal in Hg deposition in the Upper Mid- Upper Michigan may be from global-scale west, but it is difficult to infer how much transport The balance is from regional sediment Hg is from regional sources The sources, including eastern North America variance explained by DE (15-20 %) under- These crude estimates support the argument estimates regional contributions because that controlling Hg emissions at regional and there is no basis to expect that the regional national scales will have positive effects on signal should be linear along the transect The Hg deposition to lakes in the Upper Midwest

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 873

REFERENCES

[1] FITZGERALD, W F, ENGSTROM, D R, MASON, R P, [8] SORENSEN, J, GLASS, G, SCHMIDT, K, HUBER, J, RAPP, NATER, E A (1998): The case for atmospheric JR, G (1990): Airborne mercury deposition and mercury contamination in remote areas; Environ watershed characteristics in relation to mercury Sci Technol 32, pp 1-7 concentrations in water, sediments, plankton, [2] SWAIN, E B, ENGSTROM, D R, BRIGHAM, M E, and fish of eighty northern Minnesota lakes; HENNING, T A, BREZONIK, P L (1992): Increas- Environ Sci Technol 24, pp 1716-1727 ing rates of atmospheric mercury deposition in [9] ENGSTROM, D, ET AL (1994): Atmospheric mercury midcontinental North America; Science 257, pp deposition to lakes and watersheds: a quan-titative 784-786 reconstruction from multiple sediment cores; In [3] NATER, E A, GRIGAL, D F (1992): Regional trends in (BAKER, L, Ed) Environmental chemistry of lakes mercury distribution across the Great Lakes states, and reservoirs, Adv Chem Ser 237, Amer north central USA; Nature 358, pp 139-141 Chem Soc, Washington DC, pp 33-66 [4] ENGSTROM, D R, SWAIN, E B (1997): Recent de- [10] HENNING, T (1989): Historical and areal deposi- clines in atmospheric mercury deposition in the tion of mercury in NE Minnesota and Northern Upper Midwest; Environ Sci Technol 31, pp Wisconsin lakes; MS Thesis, Univ of Minne- 960-967 sota, Minneapolis [5] GLASS, G E, SORENSEN, J A (1999): Six-year trend [11] BRIGHAM, M (1992): Accumulation of mercury in (1990-1995) of wet mercury deposition in the Minnesota, Alaska, and Wisconsin lakes; MS Upper Midwest, USA; Environ Sci Technol 33, thesis, Univ of Minnesota, Minneapolis pp 3303-3312 [12] SCHUMAKER, R (1997): Regional trend in mercury [6] LUCOTTE, M, MUCCI, A, HILLAIRE-MARCEL, C, enrichment of lakes located across the upper PICHET, P, GRONDIN, A (1995): Anthropogenic Midwest; MS thesis, Univ of Minnesota, Min- mer-cury enrichment in remote lakes of north- neapolis ern Quebec (Canada); Water Air Soil Poll 80, [13] EILERS, J, BRAKKE, D, LANDERS, D (1988): Chemi- pp 467-476 cal and physical characteristics of lakes in the [7] KANCIRUK, P, EILERS, J, MCCORD, R, LANDERS, D, Upper Midwest, United States; Environ Sci BRAKKE, D, LINTHURST, R (1986): Characteris- Technol 22, pp 164-172 tics of lakes in the eastern United States Vol III: [14] JOHANSSON, K (1985): Mercury in sediment in Data compendium of site characteristics and Swedish forest lakes; Verh Internat Verein chemical variables EPA/600/4-86/007c, US Limnol 22, pp 2359-2363 Environ Prot Agency, Washington, DC, 439 p

RMZ-M&G 2004, 51 874 PART 2 BIOGEOCHEMISTRY

Assessing biomagnification of mercury in food webs using stable isotopes: A global perspective

LINDA CAMPBELL, MARLENE EVANS, ROBERT HECKY, KAREN KIDD, LYLE LOCKHART, DEREK MUIR, SARAH GEWURTZ, MIRIAM DIAMOND & GARY STERN

Abstract: For the past decade, stable isotopes of nitrogen and carbon have been used as an effective tool to assess food web structure in freshwater and marine ecosystems globally Stable nitrogen isotope ratio (delta-15 N) have been used as a trophic position indicator, while stable carbon isotope ratios (delta-13 C) have been used to assess carbon sources to biota The ability of mercury (Hg), particularly methylmercury (MeHg) to biomagnify through food webs is well known As such, biomagnification factors (BMF) can be obtained for an ecosystem using the slope of the regression of Hg concentrations values in biota from an ecosystem against their trophic position, as indicated by delta-15 N values The importance of BMF to Hg burdens in food webs can be compared with other factors such as food chain length, latitude and lake trophic status Databases for lakes ranging over a wide size and trophic gradient in tropical, temperate and Arctic latitudes have been assembled over the last 10 years The lakes are located in the North- west Territories, western and central Canada, northeastern USA, and in eastern Africa In addition, a review of other mercury biomagnification studies that incorporated stable isotope analyses in other sub-Arctic, temperate and tropical regions is included This provides an opportunity to compare mercury biomagnification and trophodynamics across latitudes, lake sizes and climate regimes Regression slopes of log Hg vs delta 15-N were found to range from 016 to 029 across systems Food chain length, as estimated from lower trophic species to top trophic predators (piscivorus fish), were calculated, and it was found that the tropical African lakes had the widest range of food chain lengths while the temperate and northern lakes had a narrower range of food chain lengths Despite similar biomagnification factors and longer food chain lengths in many African lakes, THg concentrations in top trophic predators are lower than those in North American lakes This suggests that the bioavailability of Hg may be different in tropical and temperate lakes

Key words: Biomagnification, Latitude, Food webs

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 875 Atmospheric deposition and fate of mercury in high-altitude watersheds of the Rocky Mountains

DONALD CAMPBELL

Abstract: Despite the potential for cold high-altitude ecosystems to act as sinks in the global mercury cycle, atmospheric deposition and fate of mercury have not been measured extensively at mountain sites in the Western United States At Buffalo Pass in northwestern Colorado (the highest site in the national Mercury Deposition Network at 3234 m elevation), mercury in wet deposition is around 8 mg/m2, comparable to many sites in the upper Midwestern United States where fish consumption advisories are widespread because of elevated levels of mercury from atmospheric deposition Similar levels of mercury deposition have been measured about 90 km east of Buffalo Pass at Loch Vale in Rocky Mountain National Park (RMNP) Concentrations of total mercury in headwater streams in RMNP averaged 1-4 ng/L during spring and summer of 2001-2003 Higher concentrations were observed during snowmelt and rainfall events Dissolved mercury was generally greater than particulate mercury in these clear mountain streams Mercury and dissolved organic carbon peaked as soils were flushed during early snowmelt and rainy summer periods Methyl mercury concentrations measured in the streams were generally near or less than 004 ng/L during summer, but concentrations of methyl mercury in excess of 05 ng/L were measured in the hypolimnion water of snow-covered lakes, suggesting that winter conditions may be important in controlling methylation and bioaccumulation of mercury Overall, mercury retention in these alpine/subalpine ecosystems generally exceeded 80 %; however, the mercury exported in streamflow may still be sufficient to contribute substantially to mercury loading in downstream lakes and reservoirs

Key words: deposition, Lakes, streams, Rocky Mountains

RMZ-M&G 2004, 51 876 PART 2 BIOGEOCHEMISTRY

Mercury partition in contaminated sediments from Tagus estuary

JOÃO CANÁRIO, MIGUEL CAETANO, CARLOS VALE & JOÃO LAVRADO

National Institute for Agronomy and Fisheries Research - IPIMAR, Av# Brasilia, 1449-006 Lisbon, Portugal; E-mail: jcanario@ipimar#pt

Abstract: Surface sediments and sediment cores were collected in three different areas of the Tagus Estuary Sediments were sliced in 05-cm layers and pore water extracted Mercury, Fe and Mn were determined in the solids Sulphur was determined in HCl and Cr(II) extractions Total and reactive mercury, chlorinity, S2-, SO 2- and total Fe and Mn 4 were measured in pore waters Mercury concentrations in surface sediments showed higher values in sediments near chlor-alkali and inoperative industrial plants Mercury levels in sediments from a natural park, away from local sources, were one order of magnitude below Highly reducing conditions were found closer to chlor-alkali industry near the sediment-water interface and lower levels of reactive and total dissolved mercury indicate that Hg is retained inside that sediment Suboxic conditions found in the other sites suggest that Hg may diffuse from sediment to the water column

Key words: Mercury, sediments, sulphur, Tagus Estuary

INTRODUCTION A total of 50 samples of surface sediments (first 5-cm layer) were colleted in these two Sediment chemistry influences the partition- areas Three sediment cores of 30-cm long ing and the post-deposition remobilisation of were collected in the proximity of the two metals In several cases the vertical profiles sources and far from the emissions in the of total mercury have been related to the his- Tagus Natural Park Cores were sliced in 1-2 cm layers under N atmosphere and pore torical evolution of mercury contamination 2 in the area (GOBEIL AND COSSA, 1993; PEREIRA water extracted by centrifugation ET AL, 1998) Although the availability of mercury in contaminated sediments is of great Mercury, Fe and Mn were determined in the concern, due to the toxicity of its organic solid fraction as total concentration and ex- forms (COVELLI ET AL, 1999), only a few stud- tractable HCl (AVS) through CV-AAS and ies have approached the diagenesis and mo- FAAS Sulphur was determined in AVS and bility of mercury in coastal contaminated sedi- pyrite fractions by polarography (DPCSV) ments (GOBEIL AND COSSA, 1993; GAGNON ET (LUTHER ET AL, 1991; HENNEKE ET AL, 1991) Total mercury (Hg ; 1 h exposure to 1000W AL, 1997) The Tagus estuary has been con- T UV lamp) and reactive mercury (Hg ) were taminated by mercury from a chloralkali in- R dustry in the north margin, and unoperative measured in the pore waters by CV-AFS industrial plant in the south margin (MUCCI ET AL, 1995) Pore water chlorinity,

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 877

S2-, SO 2-, Fe and Mn were analysed respec- highly reducing conditions at site A were con- 4 tively by an argentometric method, DPCSV, firmed by AVS (197 µmol g-1) and pyrite turbidimetry and FAAS# (341 µmol g-1), while at stations B and C maximum values were 11 (AVS) and 6#6 (pyrite) µmol g-1# In the cores A and B, Hg con- RESULTS AND DISCUSSION centrations were higher below the surface reflecting emissions occurred in the past, Mercury concentrations in surface sediments as commonly observed in hotspot areas reflect the local sources: values near the chlor- (Figure 1)# alkali industry (st# A; max# 47 nmol g-1) and the unoperative industrial plant (st# B; max# Although the highest concentrations were 13 nmol g-1) were one order of magnitude found near the active source, extreme above concentrations in the other stations sulphidric conditions may also contribute to -1 2- higher sequestration in the solids# Both Hg (2#2-5#4 nmol g )# Vertical profiles of S , Fe R and Hg concentrations in pore waters from and Mn in pore waters from st# A showed T suboxic conditions in the first centimetre layer st# A were one order of magnitude below the and then changed abruptly with the depth to values found in pore waters from stations B highly reducing conditions (max [S2-] = and C (Figure 2)# These differences reinforce 422 µM)# In stations B and C the suboxic lay- the hypothesis of Hg precipitation as sulphide ers were thicker (4 cm) and less anoxic in forms at st# A# deeper sediments (max [S2-] = 0#06 µM)# The

Figure 1 Vertical profiles of mercury concentrations (nmol g-1) in sediment cores collected at sites A, B and C in the Tagus Estuary

CONCLUSIONS with highly sulphidric environments, as observed in station A, more mercury is precipi- Results evidenced that mercury concentra- tated as sulphide forms and less quantity is tion in pore waters of contaminated sedi- in pore waters# Consequently, availability of ments is highly influenced by the presence mercury to organisms living in the sediment of sulphide# If contamination is associated and diffusion to water column is minimized#

RMZ-M&G 2004, 51 878 PART 2 BIOGEOCHEMISTRY

Figure 2 Vertical profiles of reactive (Hg ) and total (Hg ) dissolved mercury concentra- R T tions (pM) in sediment cores collected at sites A, B and C in the Tagus Estuary

Acknowledgements

This work was funded by the Portuguese Ministry of Science and Higher Education through the restructuring program MACAC, MLEM12/2000$

REFERENCES

COVELLI, S, FAGANELI, J, HORVAT, M & BRAMBATI, A LUTHER, G W, FERDELMAN, T G, KOSTKA, J E, (1999): Pore water distribution and benthic flux TSAMAKIS, E J & CHURCH, T M (1991): Tem- measurements of mercury and methylmercury poral and spatial variability of reduced sulphur in the Gulf of Trieste; Estuarine Coastal Shelf species (FeS, S O 2-) and porewater parameters 2 3 Science 48, pp 415-428 in salt marsh sediment; Biogeochemetry 14, pp GAGNON, C, PELLETIER, E & MUCCI, A (1997): 57-88 Behaviour of anthropogenic mercury in coastal MUCCI, A, LACOTTE, M, MONTGOMERY, S, PLOURDE, marine sediments; Marine Chemistry 59, pp Y, PICHET, P & TRA, N (1995): Mercury 159-176 remobilization from flooded soils in a hydro- GOBEIL, C & COSSA, D (1993): Mercury in sediments electric reservoir of Northern Quebec La and sediment pore water in the Laurentian Grande-2: Results of a soil resuspension experi- Trough; Canadian Journal of Fisheries and ment; Canadian Journal of Fisheries and Aquatic Science 50, pp 1794-1800 Aquatic Science 52, pp 2507-2517 HENNEKE, E, LUTHER, G W & DE LANGE, G J (1991): PEREIRA, M E, DUARTE, A C, MILLWARD, G E, ABREU, Determination of inorganic sulphur speciation S, VALE, C (1998): An estimation of industrial with polarographic techniques: Some prelimi- mercury stored in sediments of a confined area nary results from recent hypersaline anoxic en- of the lagoon of Aveiro (Portugal); Water Sci- vironments; Marine Geology 100, pp 115-123 ence and Technology 36, pp 125-130

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 879 Total and organic mercury in muscle tissues of the blue shark (Prionace glauca L1758) from Northeast Atlantic

1 2 1 2 JOÃO CANÁRIO , VASCO BRANCO , CARLOS VALE & CARLOS REIS

1 National Institute for Agronomy and Fisheries Research - IPIMAR, Av Brasilia, 1449-006 Lisbon, Portugal, Email: jcanario@ipimarpt 2 Dept of Animal Biology, Faculty of Sciences, University of Lisbon, Campo Grande, Ed C2, 1749-016 Lisbon, Portugal

Abstract: The blue shark is among the most common species of pelagic sharks Contami- nants in sharks are expected in high concentrations since they are top predators, long- lived and slow growth species This work presents levels of mercury in the muscular tissue of blue sharks caught east of the Azores and south of Canaries, and examines variations with the shark length, sex and fishing location No relationship was found between mercury concentration and sex In both surveyed areas, total and organic mercury concentrations increased with shark length, but the percentage of organic mercury was higher in sharks from the Azores This difference is in line with higher organic mercury in food items collected from stomachs of sharks caught in Azores waters

Key words: Organic mercury, Blue shark, Total mercury, Northeast Atlantic

INTRODUCTION formed in order to determined the relative importance of each prey group to the shark Blue shark is one of the most common spe- diet, and some prey items were frozen for cies of great pelagic sharks being the main later mercury analysis In laboratory, muscle by-catch of the Portuguese longline fleet tar- tissues and prey remains were freeze dried and samples were analysed for total (Hg ) geting swordfish (SANTOS ET AL, 2002) T and organic mercury (Hg ) Total mercury Sharks tend to bioacumulate high levels of org contaminants, since they are top predators was measured by atomic absorption spec- and generally are long-lived and slow growth trometry in a mercury analyser LECO AMA- species (HUETER ET AL, 1995) 254 Organic mercury was extracted from samples with concentrate HBr followed by Fifty individuals were captured in oceanic extraction into toluene and back-extraction waters of northeast Atlantic Twenty-three with cysteine solution (SCERBO AND sharks were caught east of the Azores and BARGHIGIANI, 1998) Mercury in cysteine solutions was measured as it was for Hg the remaining south of Canary Islands (Fig- T ure 1) Muscle tissues samples were taken from each individual and were immediately International certified standards (dogfish frozen Fork length was measured for each muscle tissue DORM-1 and DORM-2 shark and sex and maturity state were veri- (NRCC Canada) were used to control the fied Stomach contents analyses were per- accuracy of our procedure Statistical analy-

RMZ-M&G 2004, 51 880 PART 2 BIOGEOCHEMISTRY

sis was performed using the non-parametric RESULTS AND DISCUSSION Mann-Whitney test (U), in order to detect differences in Hg and Hg concentrations T org Total mercury concentrations in sharks cap- between locations, sexes and maturity state tured in Canary Islands varied between 111 Spearman coefficient (r ) was determined to -1 s and 127-µg g and in those captured in verify the correlation between Hg and Hg -1 T org Azores ranged from 111 to 830 µg g levels and shark length For all statistical tests (Figure 2) Ranges of organic mercury con- the significance level was α= 005 centrations were 043-846 µg g-1 and 105-700 µg g-1 in Canaries and Azores, respectively No significant differences were found between sexes for Hg (U=206; T p>005) and Hg (U=203; p>005) concen- org trations At both locations there is a tendency for total and organic mercury to increase with the shark length (r ≈ 060, p< 005) s

Total mercury concentrations showed no significant differences (U=258; p= 040) between the two capture sites although for organic mercury highly significant (U=166; p=00077) differences were noted, with organic mercury concentrations in individuals from Azores being generally higher than Figure 1 Sampling locations (A from in those from Canaries In fact, Hg Azores; B Canaries) and sharks org fork length (FL) measure

Figure 2 Variation of total mercury (Hg ) concentrations (µg g-1) and [Hg ]/[Hg ] ratios T org T (%) with fork length in muscle tissues of blue sharks captured in Azores and in Canaries

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 881 accounted in Azores individuals to 90 % of CONCLUSIONS the total Hg, while in those captured in Ca- nary Islands is around 60 % (Figure 2)' The results obtained in this survey suggest that differences on the proportion of Hg in org Identification of food remains showed that, blue sharks reflect different accumulation of in both locations cephalopods were the most Hg through the food web' Further investi- org common preys in blue sharks stomachs, be- gation should be made in order to understand ing crustaceans a minor component' The the mechanism of organic mercury produc- analysis of Hg and Hg in the food remains T org tion and bioaccumulation in the food webs is in line with the results found in muscle of the top predators presenting high accu- tissues of blue sharks: 90 % of Hg is Hg T org mulation' in food remains of individuals caught in Azores waters, while this proportion is 60- Acknowledgments 70 % in Canaries This work was supported by the Portuguese Ministry of Science and Higher Education through the restructuring program MACAC, MLEM 12/2000'

REFERENCES

HUETER, R E, FONG, W G, HENDERSON, G, FRENCH, M SANTOS, M N, GARCIA, A, PEREIRA, J G (2002): His- F AND MANIRE, C A (1995): Methylmercury con- torical review of the by-catch from the Portu- centration in shark muscle by species, size and guese surface long-line swordfish fishery: ob- distribution of sharks in Florida coastal waters; servations on the blue shark (Prionace glauca) Water, Air and Soil Pollution 80, pp 893-899 and short-fin mako (Isurus oxyrinchus); ICCAT, MACHADO, P B, FIGUEIREDO, I (2000): Tubarões e raias collective volumes of scientific papers 54 (4), Recursos de importância crescente; IPIMAR pp 1333-1340 report, divulgação nº 11 SCERBO, R, BARGHIGIANI, C (1998): Organic mercury determination in fish samples using an automatic mercury analyser; Environmental Technology% 19, pp 339-342

RMZ-M&G 2004, 51 882 PART 2 BIOGEOCHEMISTRY

Effect of solar radiation on mercury mobility in intertidal sediments

JOÃO CANÁRIO & CARLOS VALE

National Institute for Agronomy and Fisheries Research - IPIMAR, Av! Brasilia, 1449-006 Lisbon, Portugal; E-mail: jcanario@ipimar!pt

Abstract: Anoxic sediments from two areas of the Tagus estuary were homogenised and distributed by two sets of 36 uncapped Petri dishes The samples were placed on the intertidal sediments and exposed to direct solar radiation and kept in dark (control) for 6-8 hours The decrease rates of acid volatile sulphides (abrupt in the first 3 hours) and of pyrite (linear) were the same in sediments under light and dark conditions The total Hg concentrations were relatively constant in sediments kept in dark, but decreased from 176 to 765 nmol g-1 and from 345 to 135 nmol g-1 in the experiments I and II, respectively, in those exposed to solar radiation during the period of higher UV radiation Similar evolutions were found in non-reactive Hg in pore waters (300 to 259 nM and 0725 to 0105 nM) On the contrary, reactive Hg was higher in pore waters of the sediments exposed to solar radiation and increased with the time, 424 to 845 pM and 53 to 193 pM These results indicate that most mercury released in pore waters was photochemically reduced in a short period of time and escaped rapidly to the atmosphere In the estuary, the transfer of Hg0 from intertidal sediments to the atmosphere is probably enhanced by during episodes of strong bottom resuspension and bioturbation

Key words: mercury, solar radiation, intertidal sediments

INTRODUCTION on the alterations of mercury concentrations in solids and pore waters The field experi- Topmost layers of coastal sediments are fre- ments were performed during the atmo- quently resuspended by waves and tidal cur- spheric exposure of intertidal sediments at rents and, at low-tide, subsurface anoxic sedi- two areas of the Tagus estuary with contrast- ments may be temporarily exposed to the at- ing degree of contamination mosphere During these periods the sediment chemistry tends to change due to exposure to solar radiation and air, in particular, ele- RESULTS AND DISCUSSION ments that are redox sensitive and those that have a high vapour pressure like mercury Subsurface anoxic sediments were collected Moreover, dredging operations in harbours in two sites of the Tagus estuary with differ- and navigational channels cause exposure of ent degree of Hg contamination In each site anoxic sediments to the atmosphere This collected sediments were homogenised and communication reports the effect of expos- aliquots were distributed by 36 uncapped ing anoxic sediments to the atmosphere, un- Petri dishes The thickness of each sediment- der direct solar radiation and dark conditions, set was 05-cm The dishes were placed on

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 883 intertidal sediments at two conditions: AVS concentrations in the sediment samples 18 dishes in dark (covered with a black box), decreased abruptly in the first three hours, and and 18 dishes exposed to direct solar radia- the gradients were independent of the light tion! The field experiment, run for 6-8 hours conditions (experiment I: 650 to 45 µmol g-1; during the tidal period, was air-exposed! Air Experiment II: 2!36 to 0!09 µmol g-1)! At both and sediment temperature as well as total UV experiments pyrite concentration decreased radiation intensity were measured during linearly with the time (r2 better than 0!91, these experiments! Two samples were taken p<0!05)! The decreases of AVS and pyrite in each hour and analysed for (i) total Hg and the sediments indicate rapid oxidation inde- Fe (CV-AAS and FAAS); (ii) Hg and Fe ex- pendent of the light conditions (Figure 1)! tracted by HCl (1M) and hydroxylammo- During the experiments, mercury concentra- nium (0!04 M); (iii) acid volatile sulphide tions in sediments kept in dark were relatively (AVS) and pyrite by polarography! Pore wa- constant, but decreased considerably in those ters were also separated by centrifugation exposed to solar radiation! This contrasting from the solids and analysed for reactive pattern was observed in the two experiments, (Hg ) and non-reactive (Hg ) dissolved in spite of the differences in initial Hg con- R NR mercury by CV-FAS! centrations (Figure 1)!

Figure 1 Evolutions of acid volatile sulphides (AVS), pyrite (mmol g-1) and total mercury concentrations (nmol g-1) in sediments under light and dark conditions in Experiment I

During the first 3 hours of Experiment I, Hg Hg concentrations in the same conditions NR decreased abruptly from 17!6 to 10!0 nmol g-1, decreased from 3!00 to 2!59 nM in Experiment and then to 7!65 nmol g-1! A more gradual de- I and from 0!725 to 0!105 nM in Experiment II crease was observed in Experiment II: from (Figure 2)! 3!45 to 1!35 nmol g-1 during 8 hours! A similar time-course evolution was also observed for These field experiments, which simulate pro- both Hg and Hg ! In the two experiments Hg cesses occurring in intertidal sediments when R NR R concentrations were higher in pore waters ex- temporarily exposed to the atmosphere posed to solar radiation than in dark! Moreover, around low tide, evidence the release of Hg Hg under light conditions increased with the principally due to the effect of solar radia- R time (424-845 pM and 53-196 pM in Experi- tion! Under dark conditions only a slight in- ments I and II, respectively)! On the contrary, crease was measured in reactive Hg in pore

RMZ-M&G 2004, 51 884 PART 2 BIOGEOCHEMISTRY

Figure 2 Evolutions of reactive Hg - (pM) and non-reactive Hg - (nM) dissolved R NR mercury concentrations in sediments under light and dark conditions in Experiment I waters, probably due to oxidation of ations mean that most mercury released from sulphides When sediments remain exposed solids to pore waters should have been pho- to solar radiation, total Hg concentrations tochemically reduced in short periods of time decreased more than 50 %, the non-reactive and escaped rapidly to the atmosphere In Hg forms in pore waters 75-90 %, and reac- fact, several mercury species such as com- tive Hg increased drastically plexes with OH-, HS-, Cl- and organic ligands can absorb the highly energetic UV of the The substantial decrease of Hg in sediments solar spectrum (FUJITA ET AL, 1973; coincided with the period of higher UV ra- STROMBERG ET AL, 1991; NRIAGU, 1994), and diation around 14:00h (GMT) Since radia- consequently be reduced in its excited state tion had no effect on the pyrite oxidation, According to NRIAGU (1994) photolysis rate other processes should induce additional is rather fast, occurring in order of seconds mercury released to pore waters, probably to hours This finding supports the rapid re- the oxidation of particulate organic matter lease of Hg from sediments observed in the by UV radiation The direct photoreduction experiments Apparently, reactive mercury from the solid sediments should not be ex- (Hg ) in pore waters corresponds to an in- R cluded, since HgS can be photochemically termediate step reduced and semiconductor compounds (eg, metal oxides) can promote Hg photoreduction in providing charge carriers and valence CONCLUSIONS band holes (NRIAGU, 1994) The increases of reactive mercury in pore waters at the end These results suggest the rapid release of Hg of the experiments I and II, under light con- from the solids, presumably associated with ditions, (029 and 005 pmol g-1, respectively) organic matter, and the destruction of Hg- can be considered negligible in comparison complexes in pore waters due to the effect to the decrease in solids (10,000 and 2,100 of direct solar radiation Since increases in pmol g-1, respectively) The unbalanced situ- reactive forms do not balance decreases in

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 885 solids and in non-reactive forms, volatile Hg ACKNOWLEDGEMENTS are probably formed and evaded to the atmosphere This work was funded by the Portuguese Ministry of Science and Higher Education through the restructuring program MACAC, MLEM12/2000

REFERENCES

FUJITA, S, HORRI, H, TANIGUCHI, S (1973): Pulse pho- STROMBERG, D, STROMBERG, A, WAHLGREN, U (1991): tolysis of mercuric ion in aqueous solutions; Relative quantum calculations on some mercury Journal of Physical Chemistry 77, pp 2868- sulfide molecules; Water, Air and Soil Pollution 2871 56, pp 681-695 NRIAGU, J O (1994): Mechanistic steps in the photoreduction of mercury in natural waters; The Science of the Total Environment 154, pp 1-8

RMZ-M&G 2004, 51 886 PART 2 BIOGEOCHEMISTRY

Mercury in marine sediments and mussels from Taranto Gulf (Ionian Sea, Southern Italy)

N CARDELLICCHIO, C ANNICCHIARICO, A DI LEO, S GIANDOMENICO

CNR Institute for Coastal Marine Environment, Section of Taranto, Via Roma 3, I-74100 Taranto (Italy); E-mail: card@istta-le-cnr-it

Abstract: Total mercury (Hg) was determined in coastal marine sediments and in mussels (Mytilus galloprovincialis) collected from Taranto Gulf (Mar Piccolo and Mar Grande), Ionian Sea, South Italy Total mercury concentrations in sediments ranged from 002 to 1155 µg g-1 dry weight In Mar Piccolo, mercury levels were higher than those reported for sediments of he other areas in the Mediterranean sea Mercury concentrations in mussels are correlated with the sediment contamination The evaluation of quality indexes TEL and PEL shows that the 78 % of stations in Mar Piccolo exceeds the individual PELs

Key words: mercury, sediments, mussels, Taranto Gulf

INTRODUCTION culation of water Taranto seas are a noteworthy economic resource, being the site of Sediments are known to act as a sink for intensive mussel farming Hg monitoring in mercury introduced to the sea by river run- sediments and mussels of this area results to off, wastewater and atmospheric depositions be very important for studying the transfer Benthic organisms are, therefore, expected of the metal from abiotic phase to biotic to be exposed to increased mercury content phase The aim of this work was to study Several species, including mussels, have both the mercury distribution in sediments been used as indicator of the exposure, based and the accumulation in mussels (Mytilus on the assumption that mercury contents in galloprovincialis) The analytical results soft tissue of mussels are related to mercury were compared with the published results for concentration in the corresponding environ- other coastal areas of the Mediterranean Sea ment Taranto Seas, Mar Piccolo and Mar Sediment quality indexes such as TEL Grande (Ionian Sea, Southern Italy), repre- (Threshold Effect Level) and PEL (Probable sent a marine ecosystem example whose bio- Effect Level) have been determined to as- logical balances have been modified step by sess the contamination level of sediments and step, in relation to the anthropic development in general the quality of studied environment and, in particular, to the big industry settlement Mar Piccolo is a semi-enclosed basin Sediments samples were collected at 33 sta- subject to pollution phenomena, due to both tions located in the harbour area of Taranto, a large industry settlement and to its pecu- while mussels were collected at 7 stations liar morphology, which causes a scarce cir- located in the mussel culture areas of Mar

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 887

Figure 1 Sampling sites in Gulf of Taranto (GT), Mar Grande (MG) and Mar Piccolo (MP), Taranto, Italy

Piccolo and Mar Grande influenced by ur- from the Community Bureau of Reference ban and industrial wastes (Fig 1) For Hg (Commission of the European Community) determination, 02 g of dry sediment was Recovery of mercury for sediment was at digested with 9 ml of concentrated nitric acid least 94 % while for mussel tissue was at and 3 ml of concentrated fluoridric acid in a least 88 % closed teflon vessel using a microwave oven After mineralization, digests were diluted to 50 mL with ultra-pure water and stored in a RESULTS AND DISCUSSION polyethylene bottles until analysis Mercury concentrations in sediments are re- Mussels samples (with the bissus removed, ported in Table 1 4 to 5 cm long, commercial size) were analyzed in pools of 30 specimens Soft tissue The results show that mercury concentrations of mussels was separated from shells and found in the sediments of Mar Piccolo were homogenized About 1 g (wet weight) of higher than those found in Mar Grande and homogenized sample was mineralized with in Gulf of Taranto In fact, concentrations of 10 ml of concentrated HNO using a micro- 3 mercury in sediments collected in Mar Pic- wave oven After mineralization, digests colo ranged from 003 to 1155 µg g-1 dry were diluted to 50 mL with ultra-pure water weight The results show that the contami- and stored in a polyethylene bottles until nation of sediments in two inlets of Mar Pic- analysis colo were different In fact, mercury concentration in sediments collected in the first in- Total mercury was determined by cold let (station MP1-MP5) ranged from 204 to vapour atomic absorption spectrometry 1155 µg g-1 dry wt, while mercury concen- Sediment and mussel samples were analyzed trations in the sediments of the second inlets in triplicate The accuracy of the methods (stations MP6-MP9) ranged from 003 to were evaluated by analyzing two certified 210 µg g-1 dry wt Mercury levels in the Mar reference materials: CRM 277 (Estuarine Piccolo were higher than the one reported sediment) and CRM 278R (Mussel tissue) for sediments in the Tyrrhenian Sea, Adriatic

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Table 1 Mercury concentrations (mean ± SD) in sediments of the Mar Grande (MG), Gulf of Taranto (GT) and Mar Piccolo (MP)

Sea (except for the Trieste Gulf) and it were based on the large datasets of effects and no- of the same order of magnitude than the one effects arranged in ascending order of chemi- for the Grado Lagoon (Tab 2) cal concentration The TEL is defined as the geometric mean of the 15th percentile con- The retrospective evaluations of chemical centration of the set of effects and the 50th residues the biological significance in sedi- percentile concentration of the no-effects ments is fraught with difficulties, if there are dataset Similarly, the PEL is the geometric no contemporary biological measurements mean of the 50th percentile of the effects data However, a variety of attempts has been and the 85th percentile of the no-effects data made to set numerical sediment quality The TEL/PEL analysis showed that the guidelines (SQGs) In particular, the Thresh- 78 % of stations in the Mar Piccolo and old Effect Level (TEL)/Probable Effect Level 38 % of the stations in the Mar Grande ex- (PEL) weight-of-evidence approach, adopted ceed the individual PELs (TEL value for by MACDONALD (1996), seems to have pro- Hg = 013 µg g-1 dw and PEL value for duced guideline values which are protective Hg = 07 µg g-1 dw) Therefore, sediments against the majority of negative effects on in Mar Piccolo should contain acutely toxic the organisms The TEL/PEL method is concentrations of mercury

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 889

Mercury distributions in soft tissue of mus- urbanization of the Ionian Sea shore and sels are shown in Fig 2 Hg concentrations greater industrial activity of the eastern coast ranged from 004 to 010 µg g-1 wet weight in Taranto This area, in fact, includes ILVA, Mercury levels of in mussels collected in the a steel production plant, and Agip, an oil re- first inlet of Mar Piccolo (stations MP01- finery, which are the most significant indus- MP04) were higher than those reported for trial settlements of the Ionian Sea area The other Italian locations (GIORDANO, 1991; presence of these industries yields a huge RENON, 1991) with intensive harbour activ- amount of particulate, which is released di- ity, such as La Spezia (004 µg g-1 ww), rectly into the atmosphere as smoke, as well Piombino (003 µg g-1 ww) and Naples as a great mass of waste This waste, together (003 µg g-1 ww) with wastewaters from the various processes and treatment installations, is disposed of in a sea area adjacent to Mar Grande More- over, the higher level of contamination in the first inlet could be due to a concentration effect by the ILVA water-scooping machine, which is located along the west coast of the first inlet In fact, it sucks about 150,000 m3/ h of water from the Mar Piccolo to the met- allurgic center for blast furnace cooling and Figure 2 Distribution of mercury it generates an equalizing water stream from (µg g-1 ww) in soft tissue of mus- Mar Grande As Mar Grande area is the seat sels from Mar Piccolo (MP) and of important harbour and industrial activi- Mar Grande (MG) ties, the equalizing water stream might be responsible for a contamination of the first inlet of the Mar Piccolo Secondly, into the CONCLUSIONS first inlet there are more possible sources of mercury due to navy yard activities These Mercury concentrations found in sediments results suggest that continuous monitoring and mussels in the Mar Piccolo basin are of mercury in these areas is recommended, indicative of a polluted environment It is because the effects of the mercury on the believed that the sources of this pollution are environment, and subsequently on man, anthropogenic influences, such as a higher could be significative

REFERENCES

BALDI, F, BARGAGLI, R (1984): Mercury pollution in COVELLI, S, FAGANELI, J, HORVAT, M BRAMBATI, A marine sediments near a chlor-alkali plant: dis- (2001): Mercury contamination of coastal sedi- tribution and availability of the metal; The Sci- ments as the result of long-term cinnabar min- ence of the Total Environmental 39, pp 5-26 ing activity (Gulf of Trieste, northern Adriatic BRAMBATI, A (1997): Metalli pesanti nelle lagune di sea); Applied Geochemistry 16, pp 541-558 Marano e Grado; Ed Regione Friuli-Venezia Giulia, Trieste, p 175

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FERRARA, R, MASERTI, B (1992): Mercury concentra- MACDONALD, D D, CARR, R S, CALDER, F D, LONG, tion in the water, particulate matter, plankton E R AND INGERSOLL, C G (1996): Development and sediment of the Adriatic sea; Marine Chem- and evaluation of sediment quality guidelines istry 38, pp 237-249 for Florida coastal waters; Ecotoxicology 5, pp GIORDANO, R P, ARATA, L, CIARELLI, S, RINALDI, M, 253-278 GIANI, A M, CICERO, AND COSTANTINI, S (1991): RENON, P AND MALANDRA, R (1991): Metalli Heavy metals in mussels and fish from Italian dinteresse ispettivo Cd, Hg, Pb, in specie di coastal waters; Marine Pollution Bulletin 22, pp molluschi eduli lamellibranchi nellAdriatico; 10-14 Il Pesce 3, pp 73-85

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 891 Mercury Accumulation in Organs of Striped Dolphins from the Mediterranean Sea, Southern Italy

NICOLA CARDELLICCHIO, ALBA DECATALDO, ANTONELLA DI LEO

CNR Institute for Coastal Marine Environment, Section of Taranto, via Roma 3, I-74100 Taranto (Italy)

Abstract: Mercury was determined in the liver and in the kidney collected from 24 striped dolphins (Stenella coeruleoalba) stranded along the southern coasts of Apulia, Italy, during the years 1987 and 1991# Liver samples were also analysed for methyl mercury and selenium content# Mercury concentrations ranged from 0#8 to 463 µg g 1 wet wt in the liver and from < 0#05 to 41#7 µg g 1 wet wt in the kidney respectively# The liver is the accumulation organ for mercury: in this organ a strong positive correlation between inorganic mercury concentration and selenium was found, confirming results of other authors# The role of selenium in detoxification process of methyl mercury has been discussed# The results show that mercury levels in dolphins stranded on the south-eastern coasts of Italy are generally lower than those found in dolphins from the northwestern Mediterranean coasts# Mercury concentrations related to geographic variations and pollution of the Mediterranean marine environment have been discussed#

Key words: Mercury, Selenium, Dolphins, Pollution, Mediterranean#

INTRODUCTION liver and in the kidney collected from 24 striped dolphins (Stenella coeruleoalba) Mercury is a well-known and persistent ma- stranded along the southern coasts of Italy rine pollutant that is capable of being during the years 1987 and 1991 (Figure 1) biomagnified in the tissues of higher-order carnivores Due to their relatively long life and their position at the last link of trophic networks, marine mammals are good indicators for the long term monitoring of mercury accumulation in the marine environment

Dolphins stranded along the coasts are nowa- days a noteworthy source of information about physiology and biology of these organisms: for this reason, various monitoring researches on stranded animals both in the anatomo-pathological and in chemical-toxicological field have been carried out[1-3] In Figure 1 Coastal area in the Medi- terranean sea where dolphins were this work, mercury was determined in the found#

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After collection, samples were transferred to homogenized liver samples were digested PTFE-containers and frozen at -20°C Be- with 10 ml of HNO (4 h at 160 °C): sele- 3 fore the analysis, samples were homog- nium was then determined by graphite fur- enized For total mercury determination, nace atomic absorption spectrometry samples were digested under pressure with a 10 ml of a H SO -HNO mixture (1:1) for 2 4 3 4 h at 160 °C Mercury concentration was RESULTS AND DISCUSSION determined by cold vapor atomic absorption spectrometry Liver samples were also ana- Total mercury concentrations in the liver and lyzed for methyl mercury content Methyl in the kidney of dolphins are shown in Fig- mercury was determined by high-pressure ure 2 It is evident that the liver is the accu- liquid chromatography coupled with cold mulation organ for mercury Generally, the vapor atomic absorption spectrometry values of total mercury increase with length (HPLC-CV-AAS) after an acid hydrolysis of dolphins, and therefore with age; for the step at room temperature proposed by relationship between age and total length of PALMISANO[4] For selenium determination, dolphins, see André[5]

Figure 2 Total mercury in the liver and in the kidney of dolphins analysed

Figure 3 Comparison between total Hg and Se in the liver of dolphins

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 893

The total body load of mercury increases the MeHg percentage was higher and throughout the dolphins life: in the very fast- Se/Hg ratio was in the range 1#1 13#3# inorg growing of the young dolphins, mercury con- In these specimens the MeHg demethylation centration increases little with age, because has probably not been activated yet# Such of growth dilution; when growth slows, the observations led to the hypothesis that the continuous intake of alimentary mercury in- final compound of MeHg demethylation creases the mercury levels in tissue# Besides, could be HgSe, and, therefore, the detoxifi- the size of the prey and the quantities of food cation process of mercury in the dolphin liver ingested increase in proportion to the growth could be due to formation of tiemannite of the dolphins, so that trophic supplies of (HgSe)# Tiemannite is the mercury com- the metal increase progressively# The data pound with a very low solubility constant; it shown in Figure 3 indicate that in the liver is not destroyed by the proteolitic enzymes# the increase of Hg concentration is associ- Thus it may represent a terminal compound ated with the increase of Se levels# of the mercury detoxification process, which occurs in the liver# Marine food is a good It has been proposed that at high concentra- source for selenium# Se is an essential factor tions of methyl mercury the liver accumu- of a mammalian enzyme, gluthatione peroxi- lates Se, which is somehow involved in the dase, controlling intracellular H O levels in 2 2 detoxification process[6]# In this work, we mitochondria and in cytoplasm# Nevertheless, have calculated the fraction of inorganic selenium in excess is a toxic agent: it is a pow- mercury by difference between total mercury erful metal-binding agent, with chemical prop- and methyl mercury (Hg = Hg erties similar to sulfur# Selenium is known to INORG tot MeHg); the molar ratio values Se/Hg are form insoluble complexes with mercury# The INORG reported in Figure 4# remarkable tolerance of marine mammals to heavy metals is well known# WAGEMANN AND MUIR[7] proposed the limit of tolerance for Hg For adult specimens (length ≥ 168 cm, speci- in mammalian hepatic tissue to be within the mens 7 - 24), the average value of this ratio range 100 400 µg g-1 wet wt; Hg concentra- was approximately 1# In the young dolphins tions in our specimens fall within this range#

Figure 4 Comparison between Se/Hg and total Hg in the liver of dolphins analysed INORG RMZ-M&G 2004, 51 894 PART 2 BIOGEOCHEMISTRY

It has been reported that marine mammals CONCLUSIONS can concentrate mercury from fish and shellfish, and, at the same time, be able to toler- In marine mammals, the liver is the accumu- ate it with no apparent symptoms of poison- lation organ for mercury# High levels of the ing# This tolerance could be indicative of metal were found particularly in the liver of detoxification processes, based on the capa- adult dolphins# However, these levels were bility of these organisms to store contami- below the limit of tolerance for Hg in mam- nants in a non-toxic physico-chemical form# malian hepatic tissue# For adult specimens, One of the means of detoxification is through inorganic Hg was strongly correlated with Se the binding of metals to metallothioneins# In concentration (p < 0#001): the equimolar marine mammals, this has been demonstrated Se/Hg is in agreement with the hypoth- INORG for metals such as Cd, Zn, Cu# The results of esis of a very insoluble compound formation our previous researches[8] show that (tiemannite), which leads to the immobiliza- metallothioneins are not involved in the tion of mercury in the liver# Generally, no dif- mechanism of mercury detoxification# There- ference in mercury levels could be detected fore, another detoxification process is in- between the two periods of stranding of the volved, which is probably the immobiliza- animals# The results of the present work, com- tion of mercury in the liver as tiemannite# pared to those available in literature, show that mercury levels in dolphins stranded on the south-eastern coasts of Italy are generally lower than those found in dolphins from the French Mediterranean coast[9-10] and from the northern Mediterranean coast of Italy (Ligurian Sea)[11]#

REFERENCES

[1] CARDELLICCHIO, N (1995): Persistent contaminants [4] PALMISANO, F, CARDELLICCHIO, N, ZAMBONIN, P G in dolphins: an indication of chemical pollution (1993): Speciation and simultaneous determi- in the Mediterranean sea; Water Sci Technol nation of mercury species in dolphin liver by 32, pp 331-340 liquid chromatography with on-line cold vapor [2] CARDELLICCHIO, N, GIANDOMENICO, S, RAGONE, P, atomic absorption spectrometry; Fresenius J DI LEO, A (2000): Tissue distribution of metals Anal Chem 346, pp 648-52 in striped dolphins (Stenella coeruleoalba) from [5] ANDRÉ, J M, RIBEYRE, F, BOUDOU, A (1990): Mer- the Apulian coasts, Southern Italy; Mar Environ cury contamination levels and distribution in tis- Res 49, pp 55-66 sues and organs of Delphinids (Stenella [3] CARDELLICCHIO, N, DECATALDO, A, DI LEO, A, attenuata) from the eastern tropical Pacific in MISINO, A (2002): Accumulation and tissue dis- relation to biological and ecological factors; Mar tribution of mercury and selenium in striped Environ Res 30, pp 43-72 dolphins (Stenella coreuleoalba) from the Medi- [6] PALMISANO, F, CARDELLICCHIO, N, ZAMBONIN, P G terranean Sea; Environ Pollut 116, pp 265-271 (1995): Speciation of mercury in dolphin liver A two-stage mechanism for the demethylation accumulation process and role of selenium; Mar Environ Res 40, pp 109-121

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[7] WAGEMANN, R, MUIR, D C G (1984): Concentra- [10] AUGIER, H, PARK, W K, RONNEAU, C (1993): Mer- tions of heavy metals and organochlorines in cury contamination of the striped dolphin marine mammals of northern waters: overview Stenella coeruleoalba Meyen from French and evaluation; Can Tech Rep Fish Aqu Sci Mediterranean coasts; Mar Pollut Bull 26(6), 1279, 97 p pp 306-311 [8] DECATALDO, A, DI LEO, A, GIANDOMENICO, S, [11] CAPELLI, R, DRAVA, G, DE PELLEGRINI, R, MINGANTI, CARDELLICCHIO, N (2004): Association of met- V, POGGI, R (2000): Study of trace elements in als (mercury, cadmium and zinc) with organs and tissues of striped dolphins (Stenella metallothionein-like-proteins in storage organs coeruleoalba) found dead along the Ligurian of stranded dolphins from the Mediterranean Sea coasts (Italy); Adv Environ Res 4, pp 31-43 (Southern Italy); J Environ Monit 6(4), pp 361-367 [9] ANDRÉ, J, BOUDOU, A, RIBEYRE, F, BERNHARD, M (1991) : Comparative study of mercury accumulation in dolphins (Stenella coeruleoalba) from French Atlantic and Mediterranean coasts; Sci Total Environ 104, pp 191-209

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Mercury Exposure to Peregrine Falcons Nesting on Power Plant Stacks

RICHARD CARLTON

Abstract: In 1989, Peregrine Falcons (Falco peregrinus), which at that time were listed as an endangered species in the United States, began utilizing artificial nest boxes placed high on stacks at coal-fired power plants in the upper Midwest% Mae, the first Peregrine to produce young on a power plant stack, fledged two chicks in 1990% Since then the power plant Peregrine nesting program has grown rapidly so that Peregrines fledged from power plant sites now comprise over 30 % of the Midwest population% Compared to nests on buildings, cliffs, and bridges, power plant nests have the highest rates of nest productivity and chick-to-fledgling survival% Peregrine Falcons currently nest at power plants in Minnesota, Iowa, Wisconsin, Kentucky, Kansas, Michigan, Indiana, and Ohio% Coal-fired power plant boilers are known point sources of atmospheric mercury emissions% Therefore, even though there was no a priori indication of metal toxicity based on behavioral data, it was decided that Peregrines nesting at coal-fired plants should be investigated to determine their risk for developing heavy metal toxicity over time% This study tracked concentrations of mercury, selenium, chromium, nickel, and arsenic in power plant-nesting Peregrines over a three-year period, yielding a profile of each sites contaminant levels, and providing a baseline against which the contaminant levels of future Peregrines can be measured% Peregrine Falcons nesting at coal-fired plants had higher blood methylmercury concentrations than did Peregrines nesting at nuclear power plants or in urban locations% How- ever, Peregrines at coal-fired plants did not accumulate heavy metals at levels hazardous to their physical or reproductive health% Adult Peregrines showed a stronger correlation between plant output of Hg(II) and blood methylmercury concentrations than did chicks, suggesting that adults would make better bio-sentinels% Peregrine adults and chicks at coal-fired plants also accumulated selenium and chromium, but not at harmful levels% Urban nesting falcons had the highest levels of arsenic, while nickel exposure was apparently insignificant for all groups% Based on our results, Peregrine Falcons at coal- fired power plant sites do not appear to be at risk for significantly increased exposure to heavy metals when compared with falcons nesting at nuclear plants or in urban areas% Furthermore, on average, Peregrines migrating through the Midwest from other latitudes had higher metals levels than did resident Peregrines%

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 897 The effect of trees (Poplar nigra) on soil mercury flux

ANTHONY CARPI1, UMME HAIDERMOTA1, PHU NGUYEN2, AND MICHAEL SMALLIGAN2

1Department of Sciences, John Jay College, The City University of New York, 445 West 59th Street, NY, NY, 10019, USA 2Department of Forestry, Michigan State University; Corresponding authors E-mail: acarpi@jjay2cuny2edu

Abstract: Soils have long been recognized as a significant source of mercury reemission; however, it is only recently that the role of trees on soil mercury fluxes has been examined in detail We used a modified dynamic flux chamber to examine the effects of trees (Populus x canadensis Moench NE-367) on soil mercury emissions Separate chambers were constructed around the tree soil system and the foliage area to allow mercury emissions to be quantified independently in these compartments A third chamber was constructed around a separate, identical soil system that was not planted with P canadensis to serve as a control Soil and foliar mercury fluxes were examined before and after the addition of dissolved mercury salts to the soil At the conclusion of the study, poplars were harvested and sampled for mercury transport Mercury emissions in the tree canopy chamber were not dependent on soil mercury addition and appeared to cycle between emission and deposition in day and night, respectively Tissue sampling confirmed this finding by showing that soil mercury accumulated in the roots but was not transported through the tree system Trees did, however, increase the emission of mercury from the soil system and this effect was independent of solar radiation levels

Key words: Hg, processes, poplar, plant

INTRODUCTION be associated with atmospheric deposition as opposed to root accumulation (ERICKSEN Despite decades of research and regulatory ET AL, 2003) Tree canopies themselves ex- efforts focused on mercury contamination, hibit a bi-directional flux of mercury, with the metal remains a significant environmen- emissions processes predominating on av- tal threat Recent estimates suggest that erage (LINDBERG ET AL, 1979; LINDBERG reemission process may account for up to 40 ET AL, 1998) % of the global mercury cycle While soil mercury processes have been well studied, We examined the role of newly planted trees the role of trees on this pathway is less un- on mercury flux To do this, two soil derstood Plants grown in mercury contami- mesocosms were constructed in our labora- nated soil have higher concentrations of the tory using 005 m3 of soil (0219 m2 surface metal than those grown in mercury-free me- area) The first mesocosm (System 1) was dium, and this difference appears to be most used as a soil-only control System 2 was significant in the root systems (SIEGEL & planted with four trees (Populus x canadensis SIEGEL, 1988) The majority of mercury in Moench NE-367) placed approximately the above-ground portion of trees appears to 25 cm apart Each soil system was enclosed

RMZ-M&G 2004, 51 898 PART 2 BIOGEOCHEMISTRY within a modified dynamic mercury flux were continually monitored during this pro- chamber (KIM & LINDBERG, 1995), and the cess# On day 77 all four trees were harvested collective canopy of the four trees was con- by cutting the stem at the soil surface and the tained within a third dynamic flux chamber three systems were monitored for 8 additional (System 3)# Flux measurements were taken days# At the end of the trial, tree roots were every 10 minutes using two Tekran 2537A separated from the soil mixture and all tree Mercury Vapor Analyzers# The two tekrans tissues were analyzed for mercury using a were calibrated daily using their internal per- Lumex RA-915+ Mercury Analyzer# meation source and were normalized to each other# Soil temperature, moisture and solar radiation were monitored concurrently to RESULTS AND DISCUSSION flux measurements# Mercury flux from both soil chambers ex- The systems were monitored for 13 days be- hibited a diel pattern that was correlated with fore the addition of mercury# Starting on day solar radiation and soil temperature as has 13 and continuing until day 59, each soil sys- been reported previously (CARPI & LINDBERG, tem was watered by adding four measure- 1997)# To compare mercury fluxes between ments of 250 ml of a 600 ppb mercury solu- systems, we examined the mean daily Hg tion (prepared using NIST SRM 3133) at the flux, the maximum daily flux and the sum base of each tree (or its equivalent in of daily Hg fluxes for the two soil chambers# System 1) at a depth of 3 cm# Both systems During the first 10 days of measurement,

Figure 1 Daily Mean Hg Flux for System 1 (no trees) and System 2 (w/trees)

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 899 prior to the addition of mercury spiked irri- than system 1 due to shading by the tree gation water, no significant difference be- canopy and canopy flux chamber! Shortly tween system 1 and system 2 was noted for after day 59, when the sub-surface mercury any of these variables! On day 10, a soil irrigations concluded, the difference in flux moisture probe was added to system 1 which between the two soil chambers returned to disturbed the soil and as a result this system zero! A summary of these results showing showed increased mercury emissions for sev- the daily mean Hg flux is shown in Figure 1! eral days following this disturbance! On day 14, mercury-spiked irrigations began on both No significant change in mercury flux from systems! Shortly after this time and lasting the foliar canopy (system 3) was seen after through day 59 when mercury-spiked irri- mercury-spiked irrigations began (Figure 2)! gations ceased, system 2, the system planted System 3 exhibited net emissions during the with hybrid poplars, showed significantly daytime which were nearly equivalent to elevated fluxes of mercury as compared to deposition levels seen at night! system 1! This difference was noted for all three variables compared (mean, maximum Tissue analyses correlated with these findings! and sum flux) and was significant at the 95% No significant differences were found in stem level using both analysis of variance and χ2 or leaf mercury between poplars grown in test statistics! This difference was indepen- mercury-irrigated soil versus control trees dent of incident solar radiation as, on aver- grown in mercury-free medium! Significantly age, system 2 received 30% less radiation elevated levels of mercury were found in root tissue of mercury-irrigated trees!

Figure 2 Daily Mean Hg Flux for System 3 (foliar canopy)

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CONCLUSIONS & Miller, 2000) Elevated emissions may also be due to the affect of the tree roots on the Soil mercury emissions from a system planted soil chemistry; however this hypothesis re- with hybrid poplars averaged 28% higher than quires further investigation No net flux was a control system without trees These results observed from the foliage system This result were confirmed by a second set of experi- confirms previous findings that translocation ments in our laboratory While the mechanism and transpiration of soil mercury in trees is of flux induction is unclear, two possibilities negligible (LINDBERG ET AL, 1979; ERICKSEN exist First, increased emissions may be due ET AL, 2003) to soil moisture differences between the two chambers However, since system 2 had con- Acknowledgements sistently lower soil moisture levels due to transpiration by the trees, this mechanism would This work was supported by the Michigan be contrary to previous findings on the role Department of Environmental Quality of soil moisture on soil mercury flux (Gillis Funding for equipment was also provided by a US Education Department Title V grant

REFERENCES

CARPI, A & LINDBERG, S E (1997): The Sunlight LINDBERG, S E, HANSON, P J, MEYERS, T P & KIM, Mediated Emission of Elemental Mercury from K H (1998): Air/surface exchange of mercury Soil Amended with Municipal Sewage Sludge; vapor over forests-the need for a reassessment Environmental Science and Technology, Vol 31, of continental biogenic emissions; Atmospheric no 7, pp 2085-2091 Environment, Vol 32, pp 895-908 ERICKSEN, J A, GUSTIN, M S, SCHORRAN, D E, LINDBERG, S E, JACKSON, D R, HUCKABEE, J W, JOHNSON, D W, LINDBERG, S E & COLEMAN, J JANZEN, S A, LEVIN, M J & LUND, J R (1979): S (2003): Accumulation of atmospheric mer- Atmospheric emissions and plant uptake of cury in forest foliage; Atmospheric Environment, mercury from agricultural soils near the Vol 37, pp 1613-1622 Almadén mercury mine; Journal of Environmen- GILLIS, A A & MILLER, D R (2000): Some local en- tal Quality, Vol 8, pp 572-578 vironmental effects on mercury emission and Siegel, S M & Siegel, B Z (1988): Temperature de- absorption at a soil surface; Sci of the Total terminants of plant-soil-air mercury relation- Environ, Vol 260, pp 191-200 ships; Water, Air and Soil Pollution, Vol 40, pp KIM, K-H & LINDBERG, S E (1995): Design and ini- 443-448 tial tests of a dynamic enclosure chamber for measurements of vapor-phase mercury fluxes over soils; Wat Air and Soil Pollut, Vol 80, pp 1059-1068

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 901 Integration of the influence of environmental and biological parameters on Hg concentration in fish from lakes of the Canadian Shield using Geographical Information System (GIS) tool

JEAN CARREAU1, MARC LUCOTTE1, ROMAN TEISSERENC1 & CAROLINE DUFOUR1

1University of Québec at Montréal, 201 Président Kennedy, h2x 3y7, Montréal, Canada, e-mail: carreau%jean@uqam%ca

Abstract: Within the COMERN (Collaborative Mercury Research Network), we found a strong inverse relation between growth rate of walleye (Stizostedion vitreun) and mercury concentration in fish tissue in lakes of the Canadian Shield$ However, this relation was not observed in all lakes$ For example, there is a lake of 1800 ha situated at 300 km in the north of Montreal City that is divided in two sections by a sill$ In this lake, Hg concentration in walleye significantly varied between the two different sections$ These variations may be explained by the differences in the watershed characteristics between these two sections$ The section in which we found the highest concentration of mercury in walleye has a larger area perturbed by logging (27 % vs$ 16 %)$ Anterior studies, in Canada and elsewhere in the world, demonstrated the importance of the watershed perturbations on mercury concentrations found in plankton and fishes$ We con- duct a two steps complementary approach to link fish mercury concentration with the lakes environmental characteristics and with fish biology$ First of all, we use molecular biomarkers, which characterize intensity and nature of the organic matter exchanges between the watershed and the lake$ These biomarkers also inform us of the degradability potential of organic matter and also on the methylation potential of the inorganic mercury, Secondly, to link the results from the biomarkers study and the watershed characteristics, we undertook the development of a Geographical Information System (GIS)$ This GIS not only provide us information on watershed perturbations, but also offer a complete portrait of the watershed physiography (slope %, vegetation type, % of wet area, soil type)$ Actually, we are able to link average mercury concentration in fish with certain biomarkers characteristics and to specific vegetation cover of the watershed, as bogs, hardwood and coniferous forests$

Key words: Geographical Information System (GIS), watershed influence, molecular biomarkers

RMZ-M&G 2004, 51 902 PART 2 BIOGEOCHEMISTRY

In situ kinetics of mercury bioaccumulation in Mytilus galloprovincialis estimated by transplantation experiments

STELLIO CASAS1, DANIEL COSSA2, JEAN-LOUIS GONZALEZ1, CEDRIC BACHER3, BRUNO ANDRAL1

1Institut français de recherche pour lexploitation durable de la mer (Ifremer), BP 330, F"83507 La Seyne-sur-mer, France" E-mail: Stellio"Casas@ifremer"fr 2Institut français de recherche pour lexploitation durable de la mer (Ifremer), BP 21105, F"44311 Nantes cedex 03, France 3Institut français de recherche pour lexploitation durable de la mer (Ifremer), BP 70, F"29280 Plouzané, France

Abstract: Monitoring coastal contamination by trace metals pollution using mollusks bivalves as quantitative bioindicators is widely performed in many international biomonitoring programs For this purpose, studying mercury dynamic in marine mussels is a reliable tool In situ experiments on uptake and elimination kinetics were conducted in three Mediterranean sites, chosen on the basis of their contamination levels Mussels were transplanted from a clean area to a highly contaminated one and then transferred back to a clean site This approach makes it possible to define bioaccumulation factors and uptake and elimination rates consistently with the real environmental conditions

Keywords: Bioindicator, Mytilus galloprovincialis, bioaccumulation, heavy metals, transplantation

INTRODUCTION the monitored sites (eg, RIGET ET AL, 1997) The data collected from the active monitor- Mussels (Mytilus spp) are used as quantita- ing are however dependent on animal equili- tive bioindicators of metal contamination in bration time with the ambient levels of the coastal waters throughout the world The chemicals concerned The resulting common term for this monitoring technique bioaccumulation is also influenced by envi- is Mussel Watch (eg, GOLDBERG, 1975) ronmental factors and biological processes The traditional approach (or passive ap- For example, as proxies for growth rate, the proach) for a Mussel Watch program is to variation of the soft tissue weight has been collect and analyze indigenous populations shown to produce significant changes in from designated sites However, the natural metal concentrations in the tissues during the variability of trace metals in tissue is a ma- starvation or spawning period and this must jor concern for temporal and geographical be provided for in the monitoring system trend interpretations of the data (COSSA, 1989) Active monitoring approaches have The present experiments address the ques- been proposed to partially overcome these tion of the exposure period required for the problems They consist in using mussels equilibration for both uptake and depuration transplanted from a reference population to situations in the case of mercury in the mus-

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 903 sel, Mytilus galloprovincialis Many com- characterized by an initially rapid period fol- parative studies of food and environmental lowed by a slower one (Figure 1A) The contamination have been achieved in short kinetics looked like an asymptotic curve term laboratory experiments, using tracer reaching a pseudo-equilibrium During the technique labeling algae and seawater to es- 6-month exposure, the rate of uptake was timate the metal kinetics with mollusks steady except between 9 and 16 December (BORCHARDT, 1983; FOWLER, 1982; LEE ET AL , 2002, which was the period in which there 1998; RODITI AND FISHER, 1999; ROESIJADI ET was a visibly abrupt loss of weight in the AL , 1984) The significant differences in the mussel soft tissue due to spawning (Figure results observed in these studies emphasize 1B) A pseudo-equilibrium was attained after the need for caution when predicting the in 110 days at a mercury concentration of situ bioaccumulation factors (BF) of metals 0 5 mg kg-1 During the 3-month experiment, Our experiments have been designed to ex- the pseudo-equilibrium (0 42 mg kg-1) was plore the mercury kinetics in situ within reached somewhat rapidly after 60 days These M galloprovincialis, with the simultaneous two mercury accumulation curves are similar measurements of the metal concentrations in and attain a saturation plateau at the same time water and suspended particles, and measure- At the end of the experiments, observations ments of the mussel biometrics They make were made pertaining to amounts of mercury it possible to simultaneously observe both of 1 57 and 1 64 µg per mussel for the 3 and the metal accumulation and physiological 6-month experiments respectively change within the mollusk In the uncontaminated Bages lagoon, the ki- M galloprovincialis used in the experiments netics of mercury concentration in soft-tis- were from a pristine mussel farm (Les sue were flat and devoid of any significant Aresquiers, Gulf of Lions, Northwestern Medi- accumulation (Figure 1) The mercury con- terranean Sea) with a dissolved mercury concentration in soft tissue at the end of the ex- centration in water of around 0 35 ng L-1 They periments was about 5 times lower compared have been transplanted for 6 months in Laza- to the contaminated site at Lazaret Bay A ret Bay where a permanent mercury contami- perturbation of kinetics was observed in each nation exists (the dissolved mercury concen- location, around the 17/12/02, during a sub- tration in water amounts to 2 2 ng L-1) This stantial loss of soft weight corresponding to contamination period was followed by a the spawning period 3-month depuration period in Port-Cros Island The same transplantation was performed in the The decontamination kinetics of mercury in Bages lagoon, where mercury contamination soft-tissue of mussels transplanted from is low (dissolved mercury is 0 5 ng L-1) Lazaret Bay to Port-Cros was significant and comprised a decrease of 23 % after 103 days (Figure 1A) Consistently with the absence RESULTS AND DISCUSSION of mercury contamination in the Bages lagoon, no mercury change in the mussel soft- The uptake of mercury in mussels transplanted tissue could be observed after the transplan- in Lazaret Bay showed an accumulation curve tation of mussels from Bages to Port-Cros

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Bioaccumulation is the result of interaction and the major forcing variable was the con- between physiological factors (growth, re- tamination level of the environment production, storage, etc), chemical factors (uptake, excretion, accumulation, etc) and Growth and reproduction are the two major environmental factors (temperature, salinity, biological factors influencing the bioconcen- etc) These factors influence the tration process On the one hand, the spawn- bioaccumulation process in time and space, ing of mussel, which corresponds to a sig- and thus are forcing variables In kinetic nificant loss of weight (up to 40 % of the term, these factors interact on each other in soft tissue mass here), coupled to the accu- relation to time, to the characteristics of the mulation process, causes an abrupt increase sites and to the magnitude of the contamina- of mercury concentration in tissue On the tion During the accumulation process in the other hand, the growth counteracts the mer- contaminated site, the uptake attained a maxi- cury accumulation and its increase seemingly mum rate at the beginning of the experiment dilutes the mercury content of the animals

Figure 1 Mussel transplantation experiments (a) Mercury concentrations in the mussel dry soft tissue, (b) Dry mass of the soft tissue per mussel

Our results show that mercury uptake did not solved mercury concentration in the water), linearly proceed over time in mussels, con- calculated during the experiments increase trary to many studies in other bivalves Mus- with time (Table 1) The highest values of sels may require a long period of exposure the BF have to be taken into account with a to reach equilibrium with ambient metals steady state assumption The BF calculated Therefore, the bioconcentration factor (BF: for the decontamination experiments are in- mercury concentration in the mussel soft tis- dicative of non-equilibrium situations sue on a wet weight basis divided by the dis-

Table 1 Variations of the bioconcentration factor (BF) for different sites and kinetics

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 905

Bioaccumulation can also be predicted on the basis of the measurements of the rate constants of uptake and elimination A simple bioaccumulation model made up of one input via water, impact of weight changes and of one output via faeces can be calculated:

with C : Hg concentration in soft-tissue of mussels (µgg-1); C : Hg concentration in mussel water water (µgl-1); P: Soft-tissue weight (g); r : uptake rate (lg-1d-1); r : elimination rate (d-1) da ad

Table 2 Uptake and decontamination rates for mercury in Mytilus spp BF: bioconcentration factor at pseudo- equilibrium; r : uptake rate; r : elimination rate da ad

Values of uptake and elimination rates cal- REFERENCES culated here are similar to lower values found in lab-studies (Table 2) Uptake rates may BORCHARDT, T (1983): Influence of food quantity on the be overestimated in lab-studies, due to the kinetics of cadmium uptake and loss via food and short time of the experiments (15-30 days) seawater; Mytilus edulis, Mar Biol 76, pp 67-76 COSSA, D (1989): A Review of the Use of Mytilus Spp and without reaching a pseudo-equilibrium as Quantitative Indicators of Cadmium and Thus, only the first rapid period of uptake is Mercury Contamination in Coastal Waters; observed Oceanol Acta 12, pp 417-432 Fowler, S W (1982): Biological transfer and transport processes; In: Pollutant transfer and transport in the sea (G KULLENBERG, Ed), CRC press CONCLUSIONS Boca Raton, pp 2-65 GOLDBERG, E D (1975): The Mussel Watch; Mar This kinetic approach provides an under- Pollut Bull 6, pp 111-113 LEE, B G, WALLACE, W G AND LUOMA, S N (1998): standing of metal bioaccumulation and a Uptake and loss kinetics of Cd, Cr and Zn in the validation of the use of mussel transplanta- bivalves Potamocorbula amurensis and tion for mercury monitoring purposes The Macoma balthica: effects of size and salinity; parameters determined here will be used in Mar Ecol Prog Ser 175, pp 177-189 a biokinetic model coupling mussel growth RIGET, F, JOHANSEN, P, AND ASMUND, G (1997): Up- take and release of lead and zinc by blue mus- and mercury uptake and excretion, which is sels (Mytilus edulis) Experience from transplan- the next step in our research By combining tation experiments in greeland; Mar Pollut Bull environmental and biological data, the model 34, pp 805-815 could constitute an optimized biomonitoring RODITI, H A AND FISHER, N S (1999): Rates and routes of trace element uptake in zebra mussels; tool, which can be applied to various coastal Limnol Oceanogr 44, pp 1730-1749 environments ROESIJADI, G, YOUNG, J S, DRUM, A S, AND GURTISEN, J M (1984): Behaviour of trace metals in Mytilus edulis during a reciprocal transplant field experiment; Mar Ecol Prog Ser 18, pp 155-170 RMZ-M&G 2004, 51 906 PART 2 BIOGEOCHEMISTRY

Biochemical and Hematological Parameters in Amazonian Fish from Aquatic Systems Affected by Gold Mining

ZULEICA C CASTILHOS1, LUIS C PEREIRA DA SILVA2, NADIA ALMOSNY2, SAULO RODRIGUES-FILHO1, ANA PAULA RODRIGUES1, 4, ROBERTO C VILLAS-BÔAS1 MARCELLO M VEIGA3, CHRISTIAN BEINHOFF3

1 CETEM, Centre for Mineral Technology, Av Ipê, 900, 21941-590, Rio de Janeiro, Brazil, zcastilhos@cetemgovbr; 2 Fluminense Federal University, School of Veterinary, Niterói, Brazil; 3 UNIDO, United Nation Industrial Development Organization, Vienna International Centre, PO Box 300, A-1400, Vienna, Austria; 4 Fluminense Federal University, Department of Geochemistry, Niterói, Brazil

Abstract: The main objective of this work is to assess biochemical and hematological parameters in Amazonian fish from aquatic systems influenced by gold mining areas These parameters could be used as effect biomarkers in ecological risk assessment Fish sampling was conducted in August 2003, at two study areas: at São Chico and at Creporizinho mining sites or garimpo areas A total of 42 fish specimens of 2 species (Carás and Traíras) were collected: 27 specimens in S o Chico (18 Carás and 9 Traíras) and 15 specimens in Creporizinho (11 Carás and 4 Traíras) It was investigated the mercury muscle levels and some biochemical and hematological parameters in blood of fish from several sites in São Chico and in Creporizinho Traíras and Carás from São Chico (7 71±6 20 µg/g, n=9; 2 61±1 02 µg/g, n=18, respectively) showed higher Hg levels than from Creporizinho (0 72±4 30 µg/g, n=4; 0 42±0 26 µg/g, n=11 respectively), but similar length and/or weight between areas Traíras from Creporizinho showed higher globular volume and erythrocytes number than Traíras from São Chico Carás from Creporinho showed higher globular volume and mean globular volume than those from São Chico Mercury levels and globular volume showed significant negative correlation for both species (Traíras: -0 82; p<0 005 n=11; Carás: -0 37; p<0 05 n=29) These results suggest that mercury levels may cause decrease in number of erythrocytes, which are smaller than normal ones, characteristics of regenerative anemia

Keywords: Amazonian fish, mercury, gold mining

INTRODUCTION water chemistry and other variables could be important Physiological biomarkers may Whereas potential human health effects from identify effects at a tissue/organ before they Hg exposure have received considerable at- are apparent at a clinical/pathological level tention, relatively few studies have explored Biological markers, or biomarkers, are ob- effects of realistic environmental Hg concen- servable properties of an organism that trations on fish or have attempted to use wild indicate biochemical components, structure, fish collected from polluted site where or function and that can be measured bio- interactions among factors including diet, logically

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 907

The main objective of this approach is to and 4 Traíras)! It was investigated the mer- assess biochemical and hematological pa- cury muscle levels and some biochemical rameters in Amazonian fish from aquatic (amino-alanina transferase-ALT; amino- systems influenced by gold mining areas! spartate transferase-AST; creatina kinase and Both the level of Hg in tissue and the hema- creatinine), and hematological parameters tological and biochemical responses were (hematocrit, hemoglobin, erythrocytes and measured in each specimen! The results of total leukocyte count; trombocytes-leuko- total Hg in fish muscles and fish blood and cytes) in blood of fish from several sites in biochemical parameters were used as effects São Chico and in Creporizinho! After fish biomarkers in ecological risk assessment! caught, still alive, the blood was drawn by caudal puncture with an EDTA containing syringe! The total blood was kept in RESULTS AND DISCUSSION Eppendorf tubes and hematological exams were performed! In the field, the manual Some studies have been shown that MeHg methods for counting erythrocytes were per- has affinity for red blood cells (WHO, 1990)! formed as the same time as the total leuko- So, hematology might be an important diag- cyte count! Smears, two slides per individual, nostic test related to Hg exposure! It is pos- were prepared from fresh and without anti- sible to classify and evaluate fish anemias coagulant substances blood, air dried, fixed and this can be particularly important in fish, in methanol, and stained with Giemsas solu- since clinical signs of anemia are often tion! The hematocrit (or globular volume) was masked until quite late in the pathogenesis performed by microhematocrit method! The of the disease (STOSKOPF, 1993)! In fishs concentration of medium globular hemoglo- erythrocytes, about 90 % of the Hg is in the bin (CHGM) was obtained by the formula: organic form (OLSON, 1973), as the same ra- CHGM = Hemoglobin x100/Hematocrit! The tio presented in muscles! Additionally, ex- results are shown in Tables 1 and 2! perimental Hg poisoning in fish showed marked hematological anomalies (GILL, It should be noted that by macroscopic clinic 1985)! However, in order to evaluate the observation of fish specimens, they did not contaminants adverse effects on ichthyo- show any significant alteration, except in fauna and other wildlife, one should estab- Traíras from A2, which showed very high lish the normal or reference values, overall number of muscles parasites in all fish to Amazonian species (ALMOSNY, 2001), sampled! It has been suggested that wild since the information is limited! population in equilibrium with its environment shows close to 30 % of organisms with Fish sampling was conducted in August 2003, visible number of parasites, while in stressed at two study areas: at São Chico and at population, a higher number of parasites are Creporizinho mining sites or garimpo ar- to be found in higher percentage of organ- eas! A total of 42 fish specimens of 2 species isms, as observed in Traíras from A2! (Carás and Traíras) were collected: 27 specimens in São Chico (18 Carás and 9 Traíras) Traíras and Carás from São Chico showed and 15 specimens in Creporizinho (11 Carás higher Hg levels than from Creporizinho, but

RMZ-M&G 2004, 51 908 PART 2 BIOGEOCHEMISTRY similar length and/or weight between areas! On the other hand, hematological parameters All biochemical parameters measured in the showed significant differences between spe- present work did not show any difference cies from distinct areas! Traíras from between sites! These data maybe resulted due Creporizinho showed higher globular volume to low number of specimens with biochemi- and erythrocytes number than Traíras from São cal parameters measured, available to com- Chico! Carás from Creporinho showed higher pare between areas, which did not permit globular volume and mean globular volume perform the correlation analysis! In addition, than those from São Chico! Mercury levels and those biochemical parameters could not be globular volume showed significant negative sensible as mercury biomarkers! However, correlation for both species (Traíras: -0!82; the data are important because they can be p<0!005 n=11; Carás: -0!37; p<0!05 n=29)! used as biochemical reference values for These results suggest that mercury levels may Amazonian fish, considering as rare data! cause decrease the number of erythrocytes, which are smaller than normal ones, characteristics of regenerative anemia!

Table 1 Total mercury in muscles, biochemical and hematological parameters of Traíras from Garimpo´s area

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 909

Table 2 Total mercury in muscles, biochemical and hematological parameters of Carás from Garimpo´s area

CONCLUSIONS gest that fish hematological parameters are appropriate effects biomarkers in ecological The results of the present work suggest that risk assessment due to mercury exposure, but mercury levels may cause decrease in num- those effects seem to be specie-specific In ber of erythrocytes, which are smaller than addition, despite of biochemical parameters normal ones, characteristics of regenerative measured in the present work have not shown anemia Previous works showed that Hg cause any difference is fish species collected in dis- decrease in number erythrocytes, but they tinct sites, suggesting that they may not be were bigger than the control group, interpreted sensible as mercury biomarkers, it should be as a non-regenerative anemia in Cichla sp taken into account the low number of deter- from Amazonian aquatic ecosystems minations and the need of further investiga- (CASTILHOS, 2004) As a result, one could sug- tion in different fish species

REFERENCES

ALMOSNY, NRP & SANTOS, L (2001): Laboratory sup- OLSON, K R, BERGMAN, HL & FROMM, PO (1973): port in wild animal medicine In: Fowler, M and Uptake of methyl mercury chloride and mercu- Cubas, Z (eds) Biology, Medicine and Surgery ric chloride by trout: A study of uptake path- of South American Wild Animals Iowa State ways into the whole animal and uptake by eryth- University Press, Iowa pp500-505 rocytes in vitro J! Fish Resear! Board Canada; CASTILHOS, ZC, ALMOSNY, N, SOUTO, PS, PEREIRA DA Vol 30, pp 1293-1299 SILVA, LCC, LINDE, AR, BIDONE, ED (2004): STOSKOPF, MK (1993): Fish Medicine Philadelphia: Bioassessment of Ecological Risk of Amazonian WB Saunders Company Ichthyofauna to Mercury Bulletin of Environ- WHO (1990): Environmental Health Criteria 101: mental Contamination and Toxicology; Vol 72, Methylmercury Geneva, World Health Organi- No 4, pp 671-679 zation GILL, TS & PANT, J (1985): Mercury-induced blood anomalies in the freshwater teleost Barbus conchonius Ham Water, Air and Soil Pollut; Vol 24, pp165-171 RMZ-M&G 2004, 51 910 PART 2 BIOGEOCHEMISTRY

197Hg(II) radiotracer determination of methylmercury production potential rates in sediments of Lake Escondido, Argentine Patagonia

SOLEDAD PÉREZ CATÁN1, SERGIO RIBEIRO GUEVARA1, MARK MARVIN-DIPASQUALE2, MARÍA ARRIBÉRE1, & ISAAC MARCOS COHEN3

1Laboratorio de Análisis por Activación Neutrónica, Centro Atómico Bariloche, 8400 Bariloche, Argentina; E-mail: ribeiro@cab)cnea)gov)ar 2U) S) Geological Survey, 345 Middlefield Rd) / MS 480, Menlo Park, CA 94025, USA; E-mail: mmarvin@usgs)gov 3Facultad Regional Buenos Aires, Universidad Tecnológica Nacional, Argentina)

Abstract: The variation in seasonal Hg(II)-methylation rates in Lake Escondido sediments was assessed using 197Hg as a radiotracer Sediment was collected from the near shore (littoral) rooted macrophyte zone (4 m water depth), and from the non-vegetated profundal lake center (8 m water depth) Experiments consisted of amending triplicate samples with 197Hg(II) and incubating for 4 to 48 hours In addition, samples in which microbial activity was inhibited by flash freezing immediately after inoculation were assayed as controls The Hg-methylation potential rates for the two sites exhibited contrasting seasonal trends, with peak rates for the littoral site occurred during spring-summer, whereas the highest rates for lake-center were during autumn-winter The recovery of 197Hg in non-incubated control samples from both sites was up to 15X higher in autumn-winter (May to September) compared to spring-summer (December to February) It is unclear if these seasonal differences in the controls reflect abiotic Me197Hg production or the carry-over of organic-bound non-methylated 197Hg(II) in the extraction The results suggest that the seasonal and spatial differences in how mercury is cycled may be strongly influenced by carbon dynamics within this small mountain lake

Key words: Lake Escondido, radiotracer 197Hg, sediments, Hg methylation, Argentina

INTRODUCTION community composition, and MeHg degradation processes The integrated impact of The microbial methylation of mercury (Hg) these variables on Hg(II)-methylation can be occurs naturally in anoxic sediments of assessed by measuring potential rates of aquatic systems The resulting methylmer- benthic MeHg production in laboratory ex- cury (MeHg) is a biological neurotoxin, periments using radio-labeled Hg(II) com- which is readily bioaccumulated in aquatic pounds (GILMOUR AND RIEDEL, 1995; MARVIN- food webs Net Hg(II) methylation rates vary DIPASQUALE ET AL, 2003) or stable isotope widely, both among and within ecosystems, enrichments (Hintelmann and Evans, 1997) as they are influenced by many factors in- The most frequently used radioisotope in cluding: temperature, sediment and overly- Hg(II)-methylation studies is gamma-emit- ing water geochemical conditions, bacterial ting 203Hg However, when adequate nuclear RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 911 facilities are available for its production, the under anoxic conditions in a nitrogen gamma-emitting 197Hg (ground state) can be atmosphere! also successfully employed (RIBEIRO GUEVARA ET AL!, 2004)! Sediment temperature, as well as bottom and surface water dissolved oxygen, specific Lake Escondido is located on the east side conductance, and temperature were mea- of the patagonian Andes (41°2S, 71°4W), sured in the field at both sampling sites! Sedi- in the Nahuel Huapi National Park, at 764 m ment pH was measured in the laboratory! The above sea level! It has a total area of dry sediment organic matter content was as- 0!08 km2, and a maximum depth of 8 m! The sessed as weight loss by loss on ignition dominant vegetation in the watershed is a (LOI) (550 °C for 8 hours)! mixed forest of coihue (Nothofagus dombeyii), ciprés (Austrocedrus chilensis) The 197Hg (II) tracer was produced by irradia- and ñire (Nothofagus antartica)! The littoral tion of 20 to 30 mg of commercial HgCl in 2 zone of the lake is dominated by the macro- an irradiation facility at the RA-6 research phytes Schoenoplectus californicus, and reactor (Bariloche, Argentina) (RIBEIRO Potamogeton linguatus! Nitella sp! colonized GUEVARA ET AL!, 2004)! The crystalline deeper areas but always at low densities! 197HgCl was dissolved in 3!2 % HNO after 2 3 Lake Escondido is a warm, monomictic wa- the irradiation! Working solutions were pre- ter body (during hard winters its surface can pared by dilution with low-Hg, ASTM Grade freeze, behaving as dimictic)! The Secchi 1 water! Total Hg concentrations of the work- disc is visible at the maximum depth, al- ing solutions were determined by CVAFS! though during spring and summer visibility Hg(II)-methylation experiments consisted of decreases to 7 m! Chlorophyll α concentra- amending triplicate sediment samples tion is typically low; 0!5 and 1!8 mg!m-3 were (3!0 ± 0!1 g each) per site and incubating for measured in winter and summer 1988, re- different time periods (4 to 48 h) at room tem- spectively (DÍAZ AND PEDROZO, 1993)! perature! Total Hg amendments ranged from 0!05 to 0!1 µg!g-1 wet sediment, which was below the in-situ total Hg concentrations METHODS (0!1 to 0!5 µg!g-1 wet weight)! Following incubation, methyl-197Hg (Me197Hg) was ex- The seasonal variation of Hg(II)-methylation tracted from sediment using toluene, which was then dried using anhydrous Na SO rates in fresh surface sediment (0-6 cm) of 2 4 Lake Escondido was assessed using radio- (MARVIN-DIPASQUALE ET AL!, 2003)! The 197Hg active 197Hg(II)! Sediment was collected us- tracer was measured in 10 mL samples of the ing a gravity corer from two lake sampling resulting toluene extract using high-purity sites: the near shore (littoral) macrophyte germanium detectors (HPGe), both planar and zone (about 4 m depth), and the non-veg- coaxial! The measured emissions associated etated lake center (at maximum lake depth; with 197Hg decay were reported elsewhere about 8 m)! Samples were collected in plas- (RIBEIRO GUEVARA ET AL!, 2004)! Samples in tic vessels with minimum contact with air, which microbial activity was inhibited by and they were processed in the laboratory flash freezing just after inoculation (non-in-

RMZ-M&G 2004, 51 912 PART 2 BIOGEOCHEMISTRY cubated controls) were also assayed Any were highest from March thru September 197Hg measured in the toluene-extracted phase (autumn thru winter)! Figure 1 shows the of these controls was subtracted from the seasonal trends of methylation potential rates 197Hg similarly extracted from live incubated calculated for 24 h incubations! Methylation samples to obtain biotic Hg-methylation po- incubation time-course data (not shown) ex- tentials To examine whether radioactivity hibited a non-linear behavior, with a sharp measured in non-incubated controls reflected increase in rates after about 30 hrs! of incu- the carry-over of non-methylated 197Hg(II) or bation, for both sampling sites! The highest abiotic Me197Hg production, a more extensive Hg(II)-methylation potential rates were extraction procedure was also used in three (0!0295 ± 0!0051) %!g wet sed-1h-1 at lake out of six experiments This involved follow- center in May experiment, and ing our standard one-step toluene extraction (0!0155 ± 0!0021) %!g wet sed-1h-1 at the lit- with an extraction into an aqueous toral site in December, calculated for 40 hr thiosulphate solution, then re-extracting back incubations! These values were similar to into toluene (GILMOUR AND RIEDEL, 1995) This those for a Salicornia (pickleweed) domi- procedure should potentially eliminate any nated marsh site (0!0194 ± 0!0092 %!g wet non-methylated 197Hg(II) from the second sed-1h-1), and much higher than a trio of open toluene extraction water non-vegetated estuarine sediment sites (< 0!0004 %!g wet sed-1h-1) from San Pablo Bay (California, USA), measured using RESULTS AND DISCUSSION 203Hg(II) under similar experimental conditions (MARVIN-DIPASQUALE ET AL!, 2003)! An The methylation potential rate for the two increase in the activity of Hg-methylating sites exhibited contrasting seasonal trends; sulfate reducing bacteria, stimulated by the peak rates for the littoral site were during increase of organic matter loading and in- September thru February (spring thru sum- creasing temperature during spring-summer, mer), whereas rates at the lake-center site may explain the seasonal pattern observed

Table 1 Characteristics of Lake Escondido sediments and water

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 913 for the littoral site This conclusion is sup- There was a strong seasonal change in the ported by the presence of sulfide (noted by amount of radioactivity measured in the non- smell) at this site during December Organic incubated controls, with up to 15X higher matter inputs to sediments correspond mostly recovery in winter compared to summer (for to macrophyte dead leaves and allochthonous single-step extractions) There was a 32 % contributions, with much higher organic con- to 70 % lower recovery of 197Hg in control tents (as % LOI) in the littoral zone than in samples subject to the more extensive thio- the profundal lake center (Table 1) The lower sulfate re-extraction procedure While the sediment pH observed during the May thru differences between these two methods may September period may have increased the suggest the potential for abiotic MeHg for- availability of Hg(II) to methylating bacte- mation (as measured in the thiosulfate re- ria, which could potentially account for the extracted controls), we cannot rule out the higher rates at the lake-center site during this possibility that non-reacted 197Hg(II) bound same period to dissolved organic matter was carried over through both extraction procedures

Figure 1 Seasonal variation of MeHg production rate of sediment sampled from Lake Escondido littoral zone and lake center (24 h incubation time) MeHg recovery of killed control samples was subtracted to obtain net methylation potentials

REFERENCES

DÍAZ, M M AND PEDROZO, F L (1993): Seasonal suc- GILMOUR, C C AND RIEDEL, G S (1995): Measure- cession of phytoplankton in a small Andean ment of Hg methylation in sediments using high patagonian lake (Rep Argentina) and some con- specific activity 203Hg and ambient incubation; siderations about the PEG model; Arch Water, Air, and Soil Pollution 80, pp 747-756 Hydrobiol 127, pp 167-184

RMZ-M&G 2004, 51 914 PART 2 BIOGEOCHEMISTRY

HINTELMANN, H AND EVANS, R D (1997): Application RIBEIRO GUEVARA, S, JEREB, V, ARRIBERE, M, PÉREZ of stable isotopes in environmental tracer stud- CATÁN, S, HORVAT, M (2004): The production ies - Measurement of monomethylmercury and use of 197Hgg radiotracer to study mercury (CH Hg+) by isotope dilution ICP-MS and de- transformation processes in environmental ma- 3 tection of species transformation; Fresenius trices This conference Journal of Analytical Chemistry, Vol 358, No 3, pp 378-385 MARVIN-DIPASQUALE, M C, AGEE, J J, BOUSE, R M, JAFFE, B E (2003) Microbial cycling of mercury in contaminated pelagic and wetland sediment of San Pablo Bay, California; Environmen- tal Geology Vol 43, pp 260-267

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 915 Abiotic Methylation of Mercury in the Aquatic Environment

VALBONA CELO1, SUSANNAH L SCOTT2, & DAVID R S LEAN3

Departments of Chemistry1 and Biology3, University of Ottawa, 150 Louis Pasteur, P O Box 450, Station A, Ottawa, ON, Canada, K1N 6N5, Valbona Celo@ec gc ca 2Department of Chemical Engineering, University of California, Santa Barbara, CA 93106-5080 USA, sscott@engineering ucsb edu

Abstract: In order to assess the contributions of abiotic pathways for mercury methylation in the water column and conditions under which their contributions may be important, we have studied aqueous phase reactions of mercury in two oxidation states, ie, Hg(II) and Hg(0), with some of the potential methyl donors known to be present in the environment These include methyl iodide, methyltin compounds and a simple model for methylcobalamin: the methylcobaloxime, MeCo(dmg) (H O) We report the kinetics of 2 2 the methylation reactions and the yield of methylmercury as a function of environmental conditions such as pH, temperature, ionic strength and chloride concentration Me- thyl iodide reacts slowly with Hg(0) to give MeHgI in low yield, via an oxidative addition mechanism The presence of Hg(II) causes the hydrolysis of MeI, yielding MeOH and HgI as final products, without mercury methylation Transmethylation reactions of 2 methyltin(IV) complexes and MeCo(dmg) H O yield methylmercury quantitatively 2 2 Reactions of methyltin(IV) complexes proceed only in basic, saline medium The reaction with MeCo(dmg) H O proceeds faster in acidic medium but is completely inhibited 2 2 by chloride

Key words: abiotic methylation, methylmercury, mechanism, kinetics, rate constants

INTRODUCTION aquatic environment by two pathways: microbial metabolism (biotic processes) and The main sources of methylmercury in the chemical methylation (abiotic processes) aquatic environment are considered to be at- Although it is widely accepted that biotic mospheric deposition and terrestrial runoff, processes account for most, if not all, envi- especially from wetlands The relatively high ronmental mercury methylation, a number levels of methylmercury found in sediments, of highly respected investigators have re- biota and water suggest that other sources of cently provided evidence of abiotic mercury methylmercury need to be identified Inter- methylation[1-3] However, the relative impor- nal processes, ie, natural methylation of in- tance of abiotic methylation of mercury is organic mercury in the water column and not known The objective of this work was sediments, must contribute significantly to to determine the mechanisms of these reac- the overall methylmercury burden In prin- tions and to evaluate the conditions under ciple, methylmercury can be formed in the which abiotic pathways may be important

RMZ-M&G 2004, 51 916 PART 2 BIOGEOCHEMISTRY

RESULTS AND DISCUSSION

Reaction of Hg(II) with methyl(aqua)bis(dimethylglyoximato)Co(III)

MeCo(dmg) (H O) has been used to model the chemistry of methylcobalamin[4] When a 2 2 solution containing 012 mM MeCo(dmg) H O and 20 mM Hg2+ at pH 15 (HNO or 2 2 (aq) 3 HClO ) was allowed to react at 211 °C for 30 min, the yield of methylmercury was (0107 4 ± 0005) mM, or (89 ± 4)% Methyl transfer from cobalt to mercury was deemed to be quantitative, eq 1:

MeCo(dmg) H O + Hg(II) + H O → Co(dmg) (H O) + + MeHg+ (1) 2 2 2 2 2 2

The reaction between excess Hg(II) and dence of k is consistent with the change in obs MeCo(dmg) (H O), monitored as the loss of activity of the Hg2+ ion# 2 2 absorbance due to the latter at 440 nm, is first- order in both reactants, Figure 1a# The appar- When similar experiments were conducted in the ent second-order rate constant depends strongly presence of Cl- (0#01 1#0 M), the decay of the on pH, Figure 1b# The pH effect is ascribed to methylcobaloxime absorbance was negligible reversible protonation of a coordinated and the methylmercury product was undetect- dimethylglyoximato ligand, to give the unre- able# Thus chloro complexes of mercury are un- active complex MeCo(dmg)(dmgH)(H O)+# reactive towards MeCo(dmg) H O# We conclude 2 2 2 The rate constant is also a function of ionic that methylcobalt(III) complexes are possible strength, Figure 1c# The ionic strength depen- methylators of Hg(II) only in freshwater#

Figure 1 (a) Bleaching of the absorbance due to 015 mM MeCo(dmg) (H O) by 10 mM 2 2 Hg(II) at pH 15, µ = 0030 M (HNO ) The solid line is the single exponential curve fit The 3 inset shows the [Hg(II)] dependence of the pseudo-first-order rate constants (b) pH dependence of the pseudo-first-order rate constants at µ = 10 M (NaClO ) (c) Ionic strength 4 dependence (HNO /NaClO ) of the pseudo-first-order rate constants at pH 15 All experi- 3 4 ments were conducted at 211 °C

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 917

Reactions of Hg(II) with methyltin compounds

Reactions of Hg(II) with excess mono-, di- or trimethyltin(IV) produced methylmercury in 75 % to 85 % yield, eq 2:

Me SnX + Hg(II) + H O → Me SnX + MeHgX (2) n 4-n 2 n-1 3-n

The kinetics are first-order in tin and Hg(II)/ The apparent second-order rate constants are highly dependent on pH, due to transformation of the unreactive methyltin cations to reactive hydroxide complexes/ The rate constants also vary with the concentration of chloride/ In the case of Me SnOH, the form of the chloride dependence is consistent with the reactive 3 mercury species being HgCl -/ The transition state requires a second chloride associated 3 with the tin reagent/ These results show that methyltin(IV) complexes are most likely to contribute to abiotic mercury methylation in seawater/

Reaction of Hg(II) with methyl iodide

When excess methyl iodide is added to an aqueous acidic solution of Hg(II), methanol is formed, according to the stoichiometry shown in eq 3:

Hg2+ + 2 MeI + H O → HgI + 2 MeOH + 2 H+ (3) 2 2

This reaction corresponds to hydrolysis of methyl iodide assisted by the electrophilic Hg2+ ion/ HgI was detected by its UV spectrum (λ = 265 nm)/ Methylmercury iodide was also 2 max detected in trace amounts, ca/ 0/003 %, however this yield is insignificantly different from the artifact methylmercury formed during analysis/ Methyl iodide is therefore not a potential methylator of oxidized mercury/ This result is not unexpected, since methylation of metals by methyl iodide typically occurs by oxidative addition to the reduced form of the metal/

Reaction of Hg(0) with methyl iodide

A saturated aqueous solution of Hg(0) at neutral pH was shaken overnight with 2/0 mM MeI at room temperature in a dark bottle wrapped with aluminum foil/ The next day, the solution was found to contain (2/4 ± 0/9) nM methylmercury (average of ten replicates)/ The yield based on [Hg(0)] is 1/1%/ Although low, this yield is similar to that found for sulfate-reducing bacteria/ The mechanism is presumably oxidative addition, eq 4:

Hg(0) + MeI → MeHgI (4)

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The kinetics of methylmercury formation could be as high as 0 2 pg L-1 year-1 Further were measured by withdrawing and analyz- work under natural conditions is essential ing aliquots from reaction mixtures saturated with Hg(0) and spiked with methyl iodide The reaction is pseudo-first-order in [Hg(0)] CONCLUSIONS and the pseudo-first-order rate constants depend linearly on [MeI] The second-order rate This study demonstrates the possibility of constant is k = 0 020 M-1 s-1, or 3 3 x 10-23 cm3 abiotic pathways for mercury methylation in molecules-1 s-1 at neutral pH and room tem- the aquatic environment The yield of meth- perature A larger value, 8 0 x 10-21 cm3 mol- ylmercury formed and the rate of methyla- ecules-1 s-1, was reported previously,[5] how- tion depend on environmental factors such ever, it was measured in the presence of a as pH, temperature, and the presence of 700 W/m2 solar flux The rate of the reaction complexing agents, such as chloride is known to be accelerated by radiation [6] Re- cent work has shown[7] that when solar radia- Acknowledgements tion reaches surface waters, elemental mercury is formed and reaches a pseudo-steady This work was funded by a Strategic Grant from state within about 2 hours at about 200 pg L-1 the National Science and Engineering Research In the presence of MeI at a concentration of Council (Canada) and COMERN (Collabora- ca 200 pg g-1, methylmercury production tive Mercury Research Network), Canada

REFERENCES

[1] WEBER, J H (1993): Review of possible paths for [5] HALL, B, BLOOM, N S, MUNTHE, J (1995): An experi- abiotic methylation of mercury in the aquatic mental study of two potential methylation agents environment; Chemosphere 26, pp 2063-2077 of mercury in the atmosphere: CH I and DMS; 3 [2] EBINGHAUS, R, WILKEN, R D (1993): Transforma- Water, Air and Soil Pollut 80, pp 337-341 tions of mercury species in the presence of Elbe [6] CRAIG, P J (1986): Organometallic Compounds in river bacteria; Appl Organomet Chem 7, pp the Environment; Longman: London 127-135 [7] ODRISCOLL, N J, LEAN, D R S, LOSETO, L, [3] FALTER, R, WILKEN, R D (1998): Isotope experi- CARIGNAN, R, SICILIANO, S D (2004): Effect of ments for the determination of the abiotic mer- Dissolved Organic Carbon on the Photoproduc- cury methylation potential of a River Rhine sedi- tion of Dissolved Gaseous Mercury in Lakes: ment; Vom Wasser 90, pp 217-231 Potential Impacts of Forestry; Environ Sci [4] RANDACCIO, L, FURLAN, M, GEREMIA, S, SLOUF, M, Technol Web Release Date: 27-Mar-2004 SRNOVA, I, TOFFOLI, D (2000): Similiarities and differences between cobalamins and cobaloximes Accurate structural determination of methylcobalamin and of LiCl- and KCl-containing cyanocobalamins by synchroton radiation; Inorg Chem 39, pp 3403-3413

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 919

Rates and Mechanisms of Mercury Methylation by Methyltin Compounds in the Aquatic Environment

VALBONA CELO1, SUSANNAH L SCOTT2, & DAVID R S LEAN3

Departments of Chemistry1 and Biology3, University of Ottawa, 150 Louis Pasteur, P"O" Box 450, Station A, Ottawa, ON, Canada, K1N 6N5, Valbona"Celo@ec"gc"ca 2Department of Chemical Engineering, University of California, Santa Barbara, CA 93106-5080 USA, sscott@engineering"ucsb"edu

Abstract: Methyltin complexes may cause methylation of inorganic mercury in the aquatic environment The objective of this work was to measure the yields and rates of these reactions and to investigate their dependence on metal speciation Methylmercury is the quantitative product of the reactions of the Hg(II) with mono-, di- and trimethyltin(IV) Neutral or anionic methyltin hydroxide and/or carbonate complexes are more reactive than cationic aqua complexes, limiting transmethylation to alkaline media Reactivity follows the unexpected order trimethyltin < dimethyltin < monomethyltin Analysis of the chloride dependence shows that HgCl - is the reactive mercury species, thus making 3 mercury most susceptible to transmethylation in seawater

Key words: methylmercury, methyltin, kinetics, marine chemistry

INTRODUCTION adequately account for speciation reported unexpected reactivity trends[2-4] Some of the Methyltin(IV) compounds present in natu- discrepancies are resolved in this work, via ral waters and sediments are formed mainly assessment of speciation of the pH- and chlo- by environmental methylation The highest ride-dependent speciation of each reactant water concentrations have been observed for monomethyltin (up to 1200 ng Sn L-1 in seawater and up to 680 ng Sn L-1 in fresh wa- RESULTS AND DISCUSSION ter), followed by dimethyltin (up to 500 ng Sn L-1 in sea water and up to 260 ng Sn L-1 in Stoichiometry A reaction mixture contain- fresh water) and trimethyltin (up to 20 ng ing 020 mM trimethyltin and 0020 mM Sn L-1 in seawater and not more than 8 ng HgCl 2- at pH 100 and [Cl-] = 10 M was 4 Sn L-1 in freshwater)[1] Methyltin compounds allowed to react for 2 hours at 40 0C, then are considered to be potential methylators of analyzed for methylmercury The yield was inorganic mercury Speciation, both of (0015 ± 0002) mM MeHgCl (average of methyltins and of mercury, is expected to be 3 experiments), or (75 ± 9) % In similar re- of great importance in determining the rates actions with 020 mM dimethyltin or of transmethylation under environmental monomethyltin, yields of methylmercury conditions Earlier studies which did not were (82 ± 5) % and (80 ± 7) %, respec-

RMZ-M&G 2004, 51 920 PART 2 BIOGEOCHEMISTRY tively, after 1 hour at 20 0C Methyl transfer from tin to mercury is therefore quantitative in a basic, chloride-containing medium, eq 1:

Me Sn(IV) + Hg(II) + Cl- → Me Sn(IV) + MeHgCl (1) n n-1

Kinetics of methyl transfer In 10 M KCl at ponential, Figure 1b, characteristic of a pH 100, Hg(II) exists predominantly as pseudo-first-order reaction The pseudo-first- HgCl 2-, which absorbs in the UV with λ = order rate constants k depend linearly on the 4 max obs 232 nm When an aerobic solution of 0020 concentration of trimethyltin(IV), Figure 1c mM HgCl 2- was mixed with 020 mM 4 trimethyltin, the absorbance at 232 nm de- The rate constant k depend strongly on pH, obs creased, Figure 1a The kinetic profile is ex- Figure 2a

Figure 1 (a) Evolution of the UV spectrum of 0020 mM HgCl 2- upon addition of 020 4 (aq) mM Me Sn(IV) at pH 100 and 448°C in the presence of 10 M Cl- (b) Kinetic profile of the 3 reaction at 232 nm The solid line is the single exponential fit to the experimental data (c) Determination of the apparent second-order rate constant

Figure 2 Acid dependence of the pseudo-first-order rate constants k for the reactions of obs 0020 mM Hg(II) with (a) 20 mM Me Sn(IV) at 448°C; the solid lines is the curve fit to eq 3 4; (b) 050 mM Me Sn(IV) at 3010C; and (c) 050 mM MeSn(IV) at 302 0C, in 10 M KCl 2

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 921

The variation in k is presumed to arise from equilibria involving trimethyltin(IV) in basic, obs chloride medium, eq 2-3%[5]

Me Sn(OH ) + + Cl- → Me SnCl + 2 H OK = 0%25 (2) 3 2 2 3 2 Cl Me Sn(OH ) + → Me SnOH + H+ + H OK = 4%93 x 10-7 (3) 3 2 2 3 2 TMT

The experimental data were to fit to eq 4, with k and K as independent parameters% TMT TMT k = k K / ([H+] + K + [H+] [Cl-] K ) (4) obs TMT TMT TMT Cl

The pH dependence clearly shows that the trimethyltin(IV) species which reacts with Hg(II) is Me SnOH% The second-order rate constant k also changes dramatically with chloride 3 TMT concentration in the range 0%01-0%1 M, at constant ionic strength (1%0 M), Figure 3a% The chloride dependence shows that the reactive mercury species are HgCl and HgCl -, and that 2 3 the transition state involves chloride association with Me SnOH, eq 5-7, where K and K 3 3 4 are the sequential formation constants for HgCl - and HgCl 2-, respectively% 3 4

HgCl + Me SnOH + Cl- → MeHgCl + Me Sn(OH)Cl + Cl- k (5) 2 3 2 HgCl2 HgCl - + Me SnOH + Cl- → MeHgCl + Me Sn(OH)Cl + 2 Cl- k (6) 3 3 2 HgCl3- k = (α [Me Sn(IV)] )(k [Cl-]+k K [Cl-]2)/(1+K [Cl-]+K K [Cl-]2) (7) obs Me3SnOH 3 total HgCl2 HgCl3- 3 3 3 4

Chloride assistance of electrophilic transalkylation has previously been discussed in terms of a 4-center transition state, Figure 3c%[6]

Figure 3 (a) Chloride dependence of k for the reaction of Hg(II) with 25 mM Me Sn(IV) TMT 3 at pH 75, 448°C and 10 M ionic strength (KCl/NaClO ) The solid line is the curve fit to eq 4 7 (b) Speciation of Hg(II) in chloride medium (c) Proposed transition state for transmethylation

RMZ-M&G 2004, 51 922 PART 2 BIOGEOCHEMISTRY

Similar kinetic behavior was observed for yield significant amounts of MeHgCl Rate reactions of Hg(II) with Me Sn(IV) and constants increase with pH and chloride con- 2 MeSn(IV) In each case, the pH dependence centration due to changes in speciation of the of the apparent second-order rate constant reacting complexes Hydroxo and/or indicates that a hydroxo species is the active carbonato complexes of the methyltins react methylating agent, Figure 2b,c The fitted faster than the aqua complexes HgCl - is the 3 values of K and K identify the reac- most reactive chloro complex of mercury At DMT MMT tive tin species as Me Sn(OH) - and pH 10, monomethyltin is the most reactive 2 3 MeSn(CO )(OH) 2-[5] tin compound, however, relative reactivities 3 3 vary with pH

CONCLUSION Acknowledgement

Reactions of methyltin compounds with This work was supported by a Strategic Grant mercuric ions in the marine environment may from the Natural Sciences and Engineering Research Council of Canada

REFERENCES

[1] HAMASAKI, T; NAGASE, H; YOSHIOKA, Y; SATO, T [4] CERRATI, G; BERNHARD, M; WEBER, J H (1992): (1995): Formation, distribution and Model reactions for abiotic mercury methyla- ecotoxicology of methylmetals of tin, mercury tion: Kinetics of methylation of mercury(II) by and arsenic in the environment Crit Rev mono-, di-, and trimethyltin in seawater Appl Environ Sci Technol 25, pp 45-91 Organomet Chem 6, pp 587-595 [2] JEWETT, K L; BRINCKMAN, F E; BELLAMA, J M [5] FOTI, C; GIANGUZZA, A; PIAZZESE, D; TRIFILETTI, G (1978): Influence of environmental parameters (2000): Inorganic speciation of organotin(IV) on transmethylation between aquated metal cations in natural waters with particular refer- ions, ACS Symp Ser 82, pp 158-187 ence to seawater Chemical Speciation and [3] HOWELL, G N; OCONOR, M J; BOND, A M; Bioavailability 12, pp 41-52 HUDSON, H A; HANNA, P J; STROTHER, S [6] KASHIN, A N; BELETSKAYA, I P; REUTOV, O A (1986): Methylmercury generation in seawater (1979): Reactivity of organotin compounds by transmethylation reactions of organolead and XVII Mechanism of the reaction of RSn(CH ) 3 3 -tin compounds with inorganic mercury as moni- with mercuric chloride in the presence of chlo- tored by multinuclear magnetic resonance and ride ion Russian Journal of Organic Chemistry electrochemical techniques Aust J Chem 39, 15, pp 600-603 pp 1166-1175

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 923 Speciation Controls on the Fate and Transport of Mercury and Methylmercury across Biogeochemical Gradients

SHAWN CHADWICK, CHRIS BABIARZ1, JAMES HURLEY2 & DAVID ARMSTRONG3

1Environmental Chemistry and Technology Program, University of Wisconsin - Madison, 660 N# Park St#, 53706, Madison, WI, USA, e-mail: babiarz@cae#wisc#edu 2Aquatic Sciences Center, 268 Goodnight Hall1975 Willow Dr, 53706, Madison, WI, USA, e-mail: hurley@aqua#wisc#edu 3Environmental Chemistry and Technology Program, University of Wisconsin - Madison, 660 N# Park St#, 53706, Madison, WI, USA, e-mail: armstrong@engr#wisc#edu

Abstract: As part of the Mercury Experiment to Assess Atmospheric Loading in Canada and the United States (METAALICUS), the biogeochemical cycling of mercury (Hg) and methylmercury (MeHg) is being investigated to better understand the relationship between atmospheric loading and bioaccumulation' Lake 658, an 8-hectacre first-order boreal lake, was dosed bi-monthly with stable 202Hg during the summers of 2001-2003 at a loading 4-5 times the normal annual wet deposition (4-5 ug/m2/year)' Preliminary results from deployed sedimentation traps indicated that both inorganic 202Hg and 202MeHg were being delivered to the sediment-water interface by settling particulate matter and that the newly-deposited Hg and MeHg was being actively recycled in the hypolimnion' The hypolimnetic cycling of Hg and MeHg is hypothesized to be controlled by organic and inorganic aqueous phase speciation (e'g' sulfide, S-containing DOM) and solid-phase partitioning' However, the relative role of iron/manganese oxides, DOM, and sulfide species in controlling the fate and transport of Hg and MeHg in the hypolimnion is poorly understood' Selective resins (e'g' DEAE, Chelex-100) were used to better understand the changes in speciation of Hg and MeHg across critical biogeochemical gradients (e'g' oxic/anoxic, sulfate/sulfide)' The use of selective resins and intensive sampling at characterized biogeochemical gradients allows a better understanding of the role of specific ligands controlling the fate and transport of Hg and MeHg near the sediment-water interface'

Key words: speciation, Transport, fate

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Development and application of WARMF to track mercury species in river basins from atmospheric deposition to fish tissue

CARL W CHEN1, JOEL W HERR2, ROBERT A GOLDSTEIN3, AND KEITH HANSON4

1 Systech Engineering, Inc, USA; E-mail: carl@systechengineeringcom 2Systech Engineering, Inc, USA; E-mail: joel@systechengineeringcom 3Electric Power Research Institute, USA; E-mail: rogoldst@epricom 4Minnesota Power Company, USA; E-mail: khanson@mnpowercom

Abstract: A GIS based watershed model (WARMF) was enhanced to track mercury species from atmospheric deposition through watershed compartments to fish tissue! It was applied to St! Louis River, Nemadji River, and North Coast Rivers of Minnesota that drain to Lake Superior! Preliminary results show that WARMF simulated hydrology and concentrations of mercury species in various river sections comparable to the observed data! Predicted fish tissue concentrations of methylmercury were in the range of scat- tered data! The new atmospheric deposition and legacy mercury accumulated in soil contribute nonpoint source mercury to rivers and lakes! Reduction of atmospheric deposition and soil erosion may lower mercury concentrations in rivers and in fish tissue, very slowly!

Keywords: watershed model, atmospheric deposition, legacy mercury, hydrology, biogeochemistry, aquatic, terrestrial, fish tissue mercury

INTRODUCTION sota Predicted stream flows and concentrations of Hg (II) and total Hg match the ob- Mercury in fishes caught in many river ba- served for several river segments Simulated sins of Minnesota exceeds the criteria for fish tissue mercury was within the range of human consumption WARMF, which is an the observed Functional test suggested that existing GIS based watershed model, was legacy mercury in soil is a function land uses enhanced with algorithms to track Hg(0), Reducing sediment erosion can decrease the MeHg, and Hg(II) from atmospheric deposi- nonpoint source loads of mercury to surface tion through watershed compartments to fish water When the atmospheric deposition of tissue Photo demethylation and evasion in mercury is reduced by 30%, the model pre- terrestrial soil and transport of mercury spe- dicts a very slow response in the nonpoint cies with total suspended sediment and dis- source loads to Nemadji River solved organic carbon are considered Me- thylation and demethylation occurring in the sediment and water column of wetlands and RESULTS AND DISCUSSIONS lakes are simulated The model was applied to St Louis River Basin, Nemadji River Ba- The 16,660 square kilometers of drainage sin, and North Coast River Basin of Minne- area were delineated into land catchments,

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 925 river segments, and lakes (Figure 1) Land The weekly precipitation chemistry data catchments have land use distribution on were provided by seven NADP/NTN sta- surface and four soil layers below it Lakes tions The weekly mercury deposition data are divided into water layers These water- were derived from three NADP/MDN sta- shed compartments form a network to route tions The point source loads from some flow and water quality For each compart- 50 point source dischargers were compiled ment, water balance, heat budget, and mass from Minnesota Point Source Database balance, which includes the sink and source Their mercury concentrations were estimated terms for chemical transformations are per- from limited measurements formed with a daily time step to predict the transport and fate of various water quality For comparison to model results, observed constituents flows were compiled from six USGS gage stations Observed water quality data were compiled from 40 stations Only limited number of stations have Hg(II) and total mercury data Mercury fish tissue data were obtained from Minnesota Pollution Control Agency

Figure 2 compares the simulated and observed flows and total mercury for Knife River and Nemadji River The model follows the seasonal trend and magnitude of the observed values Figure 1 Delineated land catchments, river segments, and lakes of the watershed Figure 3 shows the mercury loadings from various sub-regions of the watershed The Many land catchments have flat slope to be- bar charts show that mercury was derived come upland wetlands Many river segments mostly from the nonpoint source loads The become lowland wetlands due to beaver ac- model tracked the source of mercury to land tivities ArcView shape files of Land use uses Barren lands have the highest mercury and soil data were imported to WARMF For output per unit area due to high erosion initial condition, the legacy mercury concen- Coniferous forest lands have higher yield trations, contained in watershed soil (includ- relative to deciduous forest lands due to high ing landfills) and surface sediments of riv- leaf area index Forest soils adsorb mercury ers, wetlands, and lakes, were estimated from from atmospheric deposition The model literature shows that increasing vegetative cover or building buffer strips reduce soil loss and The model is driven by meteorology, precipi- mercury output Conversion of forest lands tation chemistry, dry deposition and point to residential and commercial development source data The daily meteorology data increase the mercury output due to the lack were provided by 25 meteorology stations of soil to retain the atmospheric mercury

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Figure 2 Comparisons of simulated and observed flow and total mercury

Figure 3 Mercury loading from various sub-regions

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 927

The model provides flux output, which de- further model calibration is needed before a picts inflow, outflow and chemical transfor- final conclusion can be made One should mation in catchments, rivers, and lakes It also keep in mind that responses depend on can be used to evaluate the watershed re- many watershed-specific characteristics; sponses to changes Nemadji River basin hence, one must be wary of broad generali- receives 32,000 mg/d of wet deposition and zations from the study of a limited number 45,000 mg/d of dry deposition of mercury of similar watersheds If the atmospheric deposition is reduced 30 %, the nonpoint load of mercury to the Acknowledgement river will decrease only slightly from 6,300 mg/d to 6,260 mg/d over an eleven The work was supported by the Electric years period due to the continued release of Power Research Institute, Minnesota Power legacy mercury from soil Company, and Western Lake Superior Sani- tary District A stakeholder group was funded by US EPA to participate in the public in- CONCLUSION volvement for the development of total maximum daily load of mercury for St Louis WARMF has been developed to follow the River Basin, Nemadji River Basin, and North transport and fate of mercury throughout the Coast River Basins The model formulations watershed system Preliminary model results have been peer reviewed by a panel of ex- appear to have matched the observed data perts, chaired by Professor Charles Driscoll reasonably Preliminary results indicate a of Syracuse University Revisions of the slow system response to the reduction of at- model are being made to incorporate the sug- mospheric deposition of mercury However, gestions made by the review panel

RMZ-M&G 2004, 51 928 PART 2 BIOGEOCHEMISTRY

Mercury contamination in the food web from a warm temperate coastal lagoon possible impacts on the population

P C OELHO1, E POLICARPO, ME PEREIRA1, MA PARDAL2 & A DUARTE1

1Chemistry Department, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; E-mail: jcoelho@dq(ua(pt 2IMAR-Institute of Marine Research, University of Coimbra, 3004-517 Coimbra, Portugal(

Abstract: The aim of the work was to assess the accumulation of mercury through different trophic levels in three sites subject to different contamination levels and to evaluate the influence of sediment, water and suspended particulate matter mercury concentrations in the accumulation process Scrobicularia plana was found to be the most sensitive specie to mercury contamination, probably due to feeding tactics Carcinus maenas presented small differential tissue accumulation N diversicolor was found to be the least responsive specie to mercury contamination Though all results fall bellow maximum metal levels permitted for human consumption, this work shows that mercury concentrations in the tissues of macroinvertebrates from the most contaminated areas of a Por- tuguese coastal lagoon (Ria de Aveiro) must be considered preoccupant, and monitoring of these levels should be considered

Key words: Bioaccumulation; Trophic levels; Ria de Aveiro coastal lagoon

INTRODUCTION

It has long been recognised that heavy metals in the marine environment are ecologically preoccupant, through high persistence and toxicity at trace levels Heavy metal contamination problems in estuarine and marine ecosystems have arisen mainly as a result of anthropogenic influence, and sediments act as a sink for metals Sediment resuspension and bioturbation may remobilise these particles, increasing its bioavailability (LAPORTE ET AL, 1997; HYLANDER, 2000) By bioaccumulation and bioamplification processes along the food web, metal concentrations in estuarine organisms can represent severe risks to public health For the past 50 years, the Ria de Aveiro, a coastal lagoon in the Western coast of Portugal (Figure 1) was

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 929 subject to continuous mercury discharges RESULTS AND DISCUSSION originating from a chloro-alkali industry, which created a contamination gradient in Mercury concentrations in sediments, SPM the lagoon ecosystem (PEREIRA ET AL , 1998) and waters (filtrated through 0 45 µm) at the three sampling sites are presented in Table 1 The main aim of this work was to assess the Total mercury concentrations in sediments accumulation of mercury through various were high in Laranjo site and similar low con- trophic levels of the food web in three sites centrations were found in the other two sites located at different distances from the mer- Mercury in SPM also showed mercury con- cury contamination source (Mira, Coroa and centrations with the same pattern of the sedi- Laranjo, Fig 1) and to evaluate the influence ment Water mercury concentrations were of sediment, water and suspended particu- very low at the three studied sites (Table 1) late matter (SPM) mercury concentrations Economically important macroinvertebrate Individual (N=10-12) and composite samples species were selected (Nereis diversicolor, (number of organisms of at least 15) of Nereis used as fish bate, Scrobicularia plana and diversicolor and Scrobicularia plana were Carcinus maenas consumed directly by the analysed to test for composite sample valid- local population), to verify if mercury accu- ity, and Carcinus maenas (composite, c a 15 mulation at this trophic levels can represent individuals with 3 5 cm average size) a risk to the population samples were divided in three different

Table 1 Sediment (µg g-1), water (ng L-1) and SPM (µg g-1) mercury concentrations at the three sampling sites

Figure 2 Mercury concentrations (µg g-1, wwt) (error bars represent the standard deviation) in individual and composite samples of Scrobicularia and Nereis at the three sampling sites

RMZ-M&G 2004, 51 930 PART 2 BIOGEOCHEMISTRY subsamples (muscle, guilds and hepatopan- metal source The levels of mercury were creas), to account for differential tissue ac- also higher in Mira than in Coroa, despite cumulation Total mercury concentrations in the contrary relation with the distance to Nereis diversicolor and Scrobicularia plana mercury source C maenas and N are presented in Figures 2 and 3 shows metal diversicolor were both less contaminated concentrations in the different tissues of the than S plana, which can possibly be ex- Carcinus maenas plained by different feeding tactics and contaminated sediment exposure The somewhat S plana had the highest mercury levels, with surprising results in Mira site are probably a maximum of 037 µg g-1 wwt in individual related with the hydrodynamics of the sys- samples and 033 µg g-1 wwt in the compos- tem, which is responsible for the transport ite sample from Laranjo site (Figure 2) The of fine metal-rich particles that will be con- Mira site, despite the higher distance from sumed by invertebrates At the studied sys- the contamination source, showed higher tem, the water currents are the major respon- mercury concentrations than Coroa site N sible for the transport of particles towards diversicolor was the specie less responsive the sea, away from the Coroa site area, and to mercury contamination, with low mercury this can probably explain the differences in concentrations in all samples In C maenas organisms mercury levels between sites with tissues, the higher mercury levels were found similar sediment contamination in the guilds at the site located nearby the

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 931

CONCLUSIONS tem, through transport of fine metal-rich suspended particles towards the sea Scrobicularia plana was found to be the most sensitive specie to mercury contamination Though all results fall bellow maximum Feeding tactics and sediment exposure may metal levels permitted for human consump- be the driving forces controlling these results tion, this work showed that mercury concen- Carcinus maenas presented differential tis- trations in the tissues of macroinvertebrates sue accumulation, with highest mercury lev- from the most contaminated areas of the Ria els found in guild tissue at the most contami- de Aveiro system must be considered nated site, consistent with findings by other preoccupant, and monitoring of these levels author (LAPORTE ET AL, 1997) N diversicolor should be considered was the least responsive species to mercury contamination Hydrodynamics should play Acknowledgements an important role concerning invertebrate mercury contamination in the studied sys- This work was supported by a PhD grant to P Coelho from a Research Unit of the Uni- versity of Aveiro CESAM

REFERENCES

PEREIRA, M E, DUARTE, A C, MILLWARD, G E, VALE, HYLANDER, L D (2001): Global mercury pollution and its C & ABREU, S N (1998): Tidal export of par- expected decrease after mercury trade ban; Water, ticulate mercury from the most contaminated Air and Soil Pollution, Vol 125, pp 331-344 area of Aveiros Lagoon, Portugal; The Science of the Total Environment, Vol 213, pp 157-163 LAPORTE, J M, TRUCHOT, J P, RIBEYRE, F & BOUDOU, A (1997): Combined effects of water pH and salinity on the bioaccumulation of inorganic Mercury and Methylmercury in the shore crab Carcinus maenas Marine Pollution bulletin; Vol 34, pp 880-893

RMZ-M&G 2004, 51 932 PART 2 BIOGEOCHEMISTRY

Mercury Methylation and Bacterial Activity in Tropical Freshwater Phytoplankton

SÉRGIO A. COELHO-SOUZA & JEAN R. D. GUIMARÃES

Laboratório de Traçadores, Instituto de Biofísica Carlos Chagas Filho , UFRJ, Rio de Janeiro, Brasil; E-mail: [email protected] and [email protected]

Abstract: The aim of this study was to evaluate mercury methylation potentials and bacterial activity in phytoplankton from the oligotrophic reservoir of Ribeirão das Lajes and the hypereutrophic mesohaline Jacarepaguá lagoon. At the reservoir, sampling was done in summer by 10 minutes trawls with 25 µm nets at the center of the reservoir. Bottom sediment was also sampled at 4 locals of the reservoir. At the lagoon phytoplankton samples were taken manually during a cyanobacteria bloom, in autumn and winter. Mercury methylation, bacterial and sulfate-reducing (SR) activity were measured by 203 2+ 3 35 2- incubation with Hg , H-Leucine and SO4 respectively. All incubations were done in triplicate and with a killed control. At Ribeirão das Lajes reservoir Me203Hg formation was higher in sediment (up to 5 %) than in phytoplankton (up to 2 %) contrasting with bacterial activity measurements observed (2,5 and 15 x 10-5 mM of incorporated leucine/ g d.w./h, respectively). At Jacarépaguá lagoon, methylation was undetectable and bacterial activity was highest (4500 x 10-7 mM of incorporated leucine/g d.w. /h) with 1000nM leucine. Bacterial activity was higher in light than in dark condition and, like SR activity (20-25 %), was elevated after 48 hours of pre-incubation (90 x 10-5 nM of incorporated leucine/gdw/h). In unshaken M. aeruginosa samples Hg methylation was measurable in the floating cell mat but not in the bottom water fraction. Even low methylation potencials by phytoplankton associated bacteria are relevant for Hg bioaccumulation due to the expected high bioavailability of MeHg produced directly in the water column.

Key words: methylation, phytoplankton, bacterial activity, sulfate-reduction

INTRODUCTION Cyanobacteria cultures are able to methylate Besides sulfate-reducing bacteria, a variety Hg (COELHO-SOUZA, 2000). of others microorganisms are able to methylate Hg, including aerobic bacteria, fungi and The samples were obtained at two different seaweeds. Hg methylation in the water col- places in Rio de Janeiro state. The Ribeirão umn is usually low in aquatic tropical sys- das Lajes Reservoir supplies electric energy tems (GUIMARÃES ET AL., 1998). Mercury and potable water to some districts of Rio de methylation in phytoplankton has not been Janeiro city. The sampling occurred in sum- studied yet, despite the evidence that marine mer (December/2001) by trawling 25 µm phy- 0 cyanobacteria produce Hg as a way of mer- toplankton nets at the center of the reservoir cury detoxification. An association of bacte- during ten minutes. Bottom sediments were ria with cyanobacteria mucilage is common, also sampled at four different locals of the including sulfate-reducing bacteria.

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 933 reservoir. The other studied area, the and kept under constant shaking (80 rpm). hypereutrophic mesohaline Jacarepaguá la- The experiments were done in triplicate and goon, receives industrial and domestic efflu- sulfate-reduction activity was estimated as 35 2- ents and presents frequent toxic cyanobacteria the percentage of total added SO4 recov- blooms. The samples were taken in autumn ered as 35S-. (april/2002) and winter (june/2002).

Methylmercury formation in phytoplankton RESULTS AND DISCUSSION and bottom sediments was assayed with the radiochemical technique described by Though bacterial activity was detected from FURUTANI & RUDD (1980) and modified by 50 nM, no saturation was reached up to GUIMARÃES ET AL. (1995). Briefly, 20 mL 1.000 nM leucine, which was the leucine samples of phytoplankton were incubated concentration used in all experiments. In 203 203 during 1 to 4 days with HgCl2 in light and Ribeirão das Lajes reservoir Me Hg forma- dark conditions. Incubations were done in tion was higher in the top layer of bottom triplicate and a killed control. 203MeHg was sediment than in natural phytoplankton (Fig- acid-leached, extracted in toluene and quan- ure 1a), though bacterial activity was signifi- tified by liquid scintillation. All incubations cantly (p≤0.05) higher in natural phytoplank- were done in the laboratory and started ton samples (Figure 1b). Despite the rela- within 6 hours after sampling. Net mercury tively low values of Me203Hg formation by methylation was expressed as the proportion phytoplankton, it is important to stress that of Me203Hg formed from the total 203Hg added this microorganisms are found in water col- for incubation. umn resulting in a higher bioavailability of this toxic compound if compared to MeHg The 3H-Leucine uptake essay (SMITH & AZAM produced in sediments. There was no signifi- ET AL. 1992) was adapted to phytoplankton cant difference (p≤0.05) in bacterial activity samples. Firstly, a pre-incubation was done among the sediments from the studied sites by shaking bottles with 20 mL of natural of the reservoir. The site 2 presents a lower phytoplankton (equivalent to ~0.02 g.d.w.) sulfate-reduction activity and is characterized for 1 to 2 days under light or dark condi- by a lower percentage of fine particulate tions. Three drops of this phytoplankton were matter and lower MeHg concentrations. Con- added to vials containing 5mL of distilled trasting with the Ribeirão das Lajes reser- water filtered in 0.22 µm membranes. voir, in the impacted environment of Jacarepaguá lagoon Me203Hg formation was Sulfate-reduction was measured in Ribeirão not detected although higher bacterial activ- das Lajes sediments as described by ULRICH ity was found in this site. The phytoplank- ET AL. (1997) and adapted to natural phy- ton from Jacarepaguá lagoon is basically toplankton population of Jacarepaguá la- made of cyanobacteria, specially Microcystis goon. The samples were maintained under a aeruginosa (COELHO-SOUZA, 2003), while in constant N2 flux. Bottles containing 20 mL Ribeirão das Lajes reservoir phytoplankton of natural phytoplankton were incubated presents a much higher diversity. during 6 and 48 hours in the light or dark

RMZ-M&G 2004, 51 934 PART 2 BIOGEOCHEMISTRY

Bacterial activity associated to Microcystis To verify the relationship between cyano- aeruginosa was higher under light, suggest- bacteria and the bacteria in its mucilage, bac- ing a relationship between cyanobacteria terial production was measured in separate photosynthesis and bacterial activity (Figure portions: the top culture layer (concentrated 2a). Heterotrophic activity was higher val- natural phytoplankton cells) presented higher ues after 48 hours of pre-incubation, the same 3H-leucine incorporation rates, followed by incubation period as used in methylation es- the underlying layer of dissolving cells, while says. Additionally, sulfate-reduction tended no detectable heterotrophic activity was ob- to be higher in 48 than in 6 hour incubations served in unfiltered water sampled from the but was inhibited by light, possibly due to bottom of the culture (Figure 3).

O2 production by cyanobacteria photosynthesis (Figure 2b).

Figure 1. Mercury methylation (A) and leucine uptake (B) in samples from Lajes reservoir.

Figure 2. Time course and light conditions in leucine uptake (A) and sulfate-reduction % (B) in phytoplankton samples from Jacarepaguá lagoon.

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 935

Figure 3. Leucine uptake by different portions of a cyanobacteria culture from Jacarepaguá lagoon.

CONCLUSIONS potencials in phytoplankton is relevant and warrants further study as MeHg produced in Studies about methylmercury production, the water column itself is expected to have bacterial activity and sulfate-reduction asso- higher bioavailability. However, the available ciated to phytoplankton mucilage are scarce. methods for measuring heterotrophic activ- The aim of this work was to measure these ity and sulfate-reduction activity in phy- parameters and verify any correlation between toplankton still require some development. them with samples from distinct tropical freshwater systems. No correlation between Acknowledgements the parameters was observed with the small number of samples and experiments done This work was supported by CNPq, IAEA here, but the finding of low net methylation and CRDI, Canada.

REFERENCES

COELHO-SOUZA, S A (2000): Potencial de metilação GUIMARÃES, J. R. D., MEILI, M., MALM, O. & BRITO, E. de mercúrio em perifiton associado às raízes de M. S. (1998): Hg methylation in sediments and macrófitas aquáticas e em fitoplâncton; BSc floating meadows of a tropical lake in Pantanal Monography/UERJ, Rio de Janeiro, 37 p (in floodplain, Brazil; Science of Total Environment, Portuguese) Vol. 213, pp. 165-175. COELHO-SOUZA, S. A. (2003): Formação de SMITH, D. C. & AZAM, F. (1992): A simple, economical metilmercúrio, atividade bacteriana, e sulfato- method for measuring bacteria protein synthesis redução em raízes de macrófitas aquáticas (rio rates in seawater using 3H-Leucine; Marine Mi- Tapajós-PA) e fitoplâncton. Master thesis/UFRJ, crobial Food Webs, Vol. 6, No. 2, pp. 107-114. 73 p. (In Portuguese). ULRICH, G. A., KRUMHOLZ, L. R., SUFLITA, J. M. (1997): FURUTANI, A. & RUDD, J. W. M. (1980): Measurement A rapid and simple method for estimating sul- of mercury methylation in lake water and sedi- fate reduction activity and quantifying inorganic ment samples; Applied Environmental Microbi- sulfides; Applied and Environmental Microbi- ology, Vol. 40, pp. 770-776. ology, Vol. 63, No. 4, pp. 1627-1630. GUIMARÃES, J. R. D., MALM, O. & PFEIFFER, W. C. (1995): A simplified radiochemical technique for measurement of net mercury methylation rates in aquatic systems near goldmining areas, Amazon, Brazil; Science of Total Environment, Vol. 213, pp.165-175. RMZ-M&G 2004, 51 936 PART 2 BIOGEOCHEMISTRY

Distribution and chemical availability of mercury in sediments of the San Francisco Bay Estuary

CHRISTOPHER H CONAWAY1, E J KERIN1 & AR FLEGAL1

1WIGS Laboratory, Department of Environmental Toxicology, University of California at Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA

Abstract: San Francisco Bay estuary is contaminated by mercury from historic mining activities, as well as from more contemporary sources, throughout its watershed The mines at New Almaden, which was the largest mercury mining district in North America left behind a legacy of contaminated sediment Much of that mercury was used in hydraulic mining to extract gold in the Sierra Nevadas and resulted in billions of cubic meters of mercury contaminated sediment, much of which was subsequently deposited in San Francisco Bay from the Sacramento and San Joaquin Rivers Because of the need to assess the bioavailability of mercury in different sediment pools, and also due to the great range of mercury concentrations observed, we evaluated the use of a sequential extraction method in resolving the relative geochemical mobility of mercury in the sediments of this system Sediment samples were collected from the San Francisco Bay area and tributaries, as well as from background Pacific coastal streams in both urban and undeveloped areas to compare with the San Francisco Bay samples Sequential extractions were performed using the method of BLOOM ET AL[1] The differing natures of several sediment types are captured in the results of this study In the northern reach of the estuary, where contamination is largely hydraulic mining sediment, the majority of the mercury is found in the 12N HNO extractable fraction, 3 whereas in the southern reach, where contamination is from weathering of mercury sulfide deposits and mining wastes from New Almaden, there is an increasing relative abundance of mercury in the aqua regia extractable fraction These differences indicate both differing sediment sources in these areas and the effects of chemical weathering and physical processes on mercury speciation in this system Using sequential extraction techniques, it is possible to evaluate not only concentrations, but also relative chemical availability of mercury in sediments of the highly contaminated San Francisco Bay estuary This picture of the spatial and geochemical distribution of mercury is the first step in a more detailed investigation of chemical mobility and bioavailability in this system

Key words: sediment, sequential extraction, San Francisco Bay

[1] BLOOM, N S; PREUS, E; KATON, J; HILTNER, M Anal Chim Acta 2003, 479, 233-248

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 937 Mercury distribution in the water column at the shelf edge of the Celtic Sea, North Atlantic

1 2 3 DANIEL COSSA , MARIE-HÉLÈNE COTTÉ-KRIEF AND ROBERT P MASON

1Institut français de recherche pour lexploitation durable de la mer (Ifremer), BP 21105, F$44311 Nantes cedex 03, France 2Institut de biogéochimie marine, Ecole Normale Supérieure, F$92120 Montrouge, France 3Chesapeake Biological Laboratory, University of Maryland, Solomons, MD20688 USA

Abstract: Eight vertical total mercury profiles at the shelf edge of the Celtic Sea (western European continental margin) were performed in January 1994 and June 1995! Total mercury concentrations ranged from 0!3 to 9!4 pM! The low concentrations encountered in the shelf water (< 1!5 pM) prelude any significant influence of continental waters in this area! Mean mercury concentrations were close to 2 pM in the Lower Deep Water (LDW), in the Labrador Sea Water (LSW) and in the Mediterranean Intermediate Water (MIW)! Between LDW and LSW, the Iceland-Scotland Overflow Water (SOW) exhibited higher concentrations (2!8 ± 0!4 pM)! The upper part of the North East Atlantic Central Water (NEADW) and lower part of the North Atlantic Deep Water (NEACW) were characterized by marked peaks of concentration, which are interpreted in term of atmospheric influence and particle regeneration!

Keywords: mercury, continental margin, shelf break, Celtic Sea, Atlantic Ocean!

INTRODUCTION sented here are a part of the OMEX project (Ocean Margin Exchange, a MAST Program Although most trace elements concentrations from the European Union, Wollast and Chou, in coastal and shelf waters do not appear to 2001), which explored the water column of differ widely from the open ocean waters, the Celtic Sea in the Eastern North Atlantic various studies have shown local enrich- Ocean during a winter and a summer cruise ments in the margin surface waters In coastal in January 1994 and June 1995 respectively waters and enclosed seas, COSSA ET AL (1994) and COQUERY AND COSSA (1995) showed mercury enrichments in near-shore waters We RESULTS AND DISCUSSION constructed a tentative mass balance calculation for mercury at the ocean margins, In the upper 200 meters, total mercury con- which concluded that the ocean may contrib- centrations (HgT) ranged from 029 to ute to the mercury load of the coastal waters 937 pM with the extreme values in the up- (COSSA ET AL, 1996) However, data to sup- per 200 m Subsurface peak concentrations port these assertions were scarce, especially were found with the highest concentrations mercury distribution profiles in the water occurring during the summer cruise These column near the shelf edge The results pre- maxima are attributed to regeneration pro-

RMZ-M&G 2004, 51 938 PART 2 BIOGEOCHEMISTRY cesses below the seasonal thermocline Concentrations around or below 2 pM were Within the first 50 m strong variations were found below 2000 m regardless of season observed: between 060 and 250 pM in sum- (Fig 1) This concentration level is in good mer and 090 and 359 pM in winter The agreement with those (only total mercury highly variable concentrations in surface data were taken into account) published pre- samples were attributed to the net effect of viously by MASON ET AL (1995 and 1998) deposition and evasion for the North Atlantic deep waters, south of Iceland, and also by earlier measurements The low mercury concentrations in coastal by Gill and Fitzgerald (1987) at the slope in waters were consistent with measurements the northwest Atlantic The Lower Deep made in the English Channel (COSSA AND Water (LDW, bottom water below 4000 m) FILEMAN, 1991), and confirm that coastal wa- concentrations were typically 196 ± 023 pM ter mercury enrichment is only a concern for (mean ± standard deviation, n=5) and the the near-shore zone (e g , COSSA ET AL , 1996; Labrador Sea Water (LSW, identified by low COSSA ET GOBEIL, 2000) Mercury, supplied salinity and high dissolved oxygen) concen- from continental waters through estuaries, is trations were 197 ± 063 pM (n=5) In be- rapidly scavenged by coastal sediments and/ tween, the Iceland-Scotland Overflow Wa- or evolved to the atmosphere after reduction ter (ISOW, identified by a small salinity peak (COSSA AND GOBEIL, 2000; ROLFHUS AND at 2600 m) mercury concentrations were sta- FITZGERALD, 2001; LAURIER ET AL , 2003) tistically higher, with a mean of 276 ±

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 939

035 pM (n=3) The upper part of the North in the open NorthEast Atlantic The concen- East Atlantic Deep Waters (NEADW) and trations at the surface are not enriched com- the lower part of the North East Atlantic pared to the nearby open ocean Moreover, Central Waters (NEACW), ie, the 600 to the lowest concentrations were encountered 700 m layers corresponding to salinity mini- in the shelf water Continental influence from mum, were characterized by marked peaks rivers does not reach this area probably due of mercury (Fig 1) These three mercury to sedimentation and atmospheric recycling enriched water masses originate from sink- occurring in estuaries and other nearshore ing of surface waters, previously in contact areas with the atmosphere Mean mercury concentration in the Mediterranean Intermediate The vertical profiles confirm that the deep Water (MIW) was 204 ± 084 pM (n=8) Atlantic waters have mercury levels around between 900 and 1100 m From HORVAT ET or below 2 pM The profiles pattern suggest AL (2003) measurements low concentrations the existence of an atmospheric signature: (< 2 pM) are characteristic of the deep west- parts of NEACW and NADW, which con- ern Mediterranean waters sist of water masses previously in contact with the atmosphere, have high mercury concentrations The processes of biological up- CONCLUSIONS take, remineralization and photoreduction reasonably explain the high variability of the Mercury concentrations near the shelf edge surface and sub-surface waters of the Celtic Sea are quite similar to profiles

REFERENCES

COQUERY, M, COSSA, D (1995): Mercury Speciation Cossa D, Sanjuan, J, Noël, J, 1994 Mercury Trans- in Surface Waters of the North Sea; Neth J Sea port in the Waters of the Strait of Dover Mar Res 34, 245-257 Poll Bull 28, 385-3894 COSSA, D, GOBEIL, C (2000): Mercury Speciation in COSSA, D, FILEMAN, C (1991): Mercury concentrations the Lower St Lawrence Estuary; Can J Fish in surface waters of the English Channel: A co- Aquat Sci 57, 138-147 operative study; Mar Pollut Bull 22, 197-200 COSSA, D, MARTIN, J-M, TAKAYANAGI, K, SANJUAN, HORVAT, M, KOTNIK, J, FAJON, V, ZVONARIC, T AND J (1997): The Distribution and Cycling of Mer- PIRRONE, N (2003): Speciation of mercury in cury in the Western Mediterranean; Deep Sea surface and deep-sea waters in the Mediterra- Res II 44, 721-740 nean Sea; Atmos Environ 37, S93-108 COSSA, D, COQUERY, M, GOBEIL, C, MARTIN, J-M LAURIER, F J G, COSSA, D, GONZALEZ, J-L, BREVIERE, (1996): Mercury Fluxes at the Ocean Margins E, SARAZIN, G (2003): Mercury transformations 229-247; In Regional and Global Cycles of and exchanges in a high turbidity estuary: the Mercury: Sources, Fluxes, and Mass Balances role of organic matter and amorphous (W BAEYENS, R EBINGHAUS AND O VASILIEV, oxyhydroxides; Geochim Cosmochim Acta 67, Editors) Kluwer Academic Publishers, 3329-3345 Dordrecht, The Netherlands

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MASON, R P, ROLFHUS, K R, FITZGERALD, W F (1998): ROLFHUS, K R, FITZGERALD, W F (2001): The eva- Mercury in the North Atlantic; Mar Chem 61, sion and spatial/temporal distribution of mer- 37-53 cury species in Long Island Sound, CT-NY; MASON, R P, ROLFHUS, K R, FITZGERALD, W F (1995): Geochim Cosmochim Acta 65, 407-418 Methylated and elemental mercury in the sur- WOLLAST, R, CHOU, L (2001): Ocean Margin Exchange face and deep ocean waters of the North Atlan- in the Northern Gulf of Biscay: OMEX I An in- tic; Water Air Soil Pollut 80, 665-677 troduction; Deep Sea Res II 48, 2971-2978

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 941 Behaviour of Hg species in the Isonzo river mouth (northern Adriatic sea)

STEFANO COVELLI1, RAFFAELLA PIANI1, JO E KOTNIK2, MILENA HORVAT2, JADRAN FAGANELI3, MARTINA LOGAR2, DARIJA GIBIÈAR2, ALESSANDRO ACQUAVITA4, ANTONIO BRAMBATI1

1Dept of Geol, Environ & Mar Sciences, Trieste, Italy; E-mail: covelli@univtriesteit 2Joef Stefan Institute, Ljubljana, Slovenia; E-mail: jozekotnik@ijssi 3National Institute of Biology, Marine Biological Station, Piran, Slovenia; E-mail: jadranfaganeli@uni-ljsi 4Laboratory of Marine Biology, Trieste, Italy; E-mail: acquavit@univtriesteit

Abstract: The interaction between mercury species and physico-chemical parameters in the estuarine zone of Isonzo river in different seasonal conditions were investigated Par- ticulate Hg and MeHg are well correlated to medium-coarse silty suspended sediment and organic matter Desorption of Hg from particles in the brackish layer was observed Due to the presence of a salt wedge, the lower river course seems to be a trap of Hg carried by fluvial waters MeHg normally decreases approaching the sea but the local increase in the inner zone of the salt wedge could be related to methylation processes in the bottom water layer

Key words: mercury, methylmercury, suspended matter, biogeochemical cycling, deltaic system

INTRODUCTION material seaward to the prodelta zone Mer- cury (Hg) contaminated freshwater inputs of The Isonzo river (Fig1) is affected by long the Isonzo river have affected the Gulf of periods of low-medium discharges and short peaks of intense riverine flow, associated with high suspended sediment load, following heavy rainfalls Most of the year, the highly stratified water column and related hypopycnal flux prevail in the dynamic regime within the lower reach of the distribu- tary mouth (Fig 2) The Isonzo river mouth may be defined as a microtidal, low energy and fine-grained deltaic system[1] This type of circulation, and the consequent buoyancy- dominated depositional pattern, is interrupted during extreme river floods The salt wedge is pushed out of the river mouth and the outflow spreads as a plume above the underlying marine water, transporting fine riverborne Figure 1 Sampling stations along the Isonzo river

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Figure 2 Representation of water stratification in the Figure 3 Relationship between particulate Hg and lower course of the Isonzo river (eg February 2002) MeHg and grain-size of suspended matter

Trieste and the northern Adriatic sea since systematic measurements of physico-chemi- nearly 500 years as a result of excavation of cal (salinity, temperature, turbidity, dissolved cinnabar rich deposits in the Idrija mining O ) and compositional (Hg species, POC, 2 district in western Slovenia PON, SPM, grain-size) parameters along the water column were investigated at nine sam- Although several recent studies have de- pling stations (Fig1) Sampling was con- scribed some aspects of mercury bio- ducted along the main axis of the river chan- geochemistry in the Idrija-Isonzo river sys- nel moving upstream, during neap tide contem[2], in the coastal waters[3] and sediments[4] ditions, in freshwater and saltwater layers of the Gulf of Trieste, little is known about and at variable depths (brackish waters), ac- mercury behaviour in the lower course river cording to the salinity profiles In May, field system The results of a study on the effects operations were performed after one day of of physical and biogeochemical factors on heavy rains As a consequence, a small plume the distribution of mercury species within the of suspended sediments formed in the river estuarine zone of the river mouth in dif- and it was intercepted while sampling was ferent seasonal conditions are herein pre- still in progress Analytical methods used in sented Three field samplings were con- this study are reported in previous papers on ducted during low (Aug 2002) and medium Hg research in the Gulf of Trieste[1, 3] river discharges (Feb and May 2002), and

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RESULTS AND DISCUSSION SPM, PHg is positively correlated to the medium-coarse silty fraction (mostly Total Hg (THg) concentrations in freshwa- 16-32 µm), no matter the type of water and ters increased from February (avg! sampling (Fig! 3)! Dissolved mercury (DHg) 18!2 ng/l) to August (avg! 25!7 ng/l)! How- values appear quite uniform along the water ever, the highest contents were found in the column (avg! ranging from 5!44 to bottom saltwaters in late spring (63!5 ng/l) 8!66 ng/l) except in May, where a sharp in- and summer (31!3 ng/l)! Most of the mer- crease from fresh (avg! 1!78 ng/l) to cury transported by the fluvial course is in saltwaters (avg! 31!7) is observed! In terms particulate form (PHg avg! between 51 and of percentage of THg, the thin mixing layer 87 % of THg)! PHg concentrations in fresh always shows higher value of DHg (avg! and saltwaters are normally higher than the 39-54 %) in comparison with surface and brackish intermediate layer, especially in bottom waters probably due to Hg desorp- May (avg! 18!0 and 37!1 ng/l, respectively), tion from suspended matter! Reactive Hg and August (avg! 25!4 and 28!5 ng/l, respec- (RHg) concentrations in water samples are tively) indicating that at intermediate salini- usually lower than 1 ng/l! As percentage of ties a removal process is operative! In bot- THg, RHg is always slightly higher in the tom saltwaters PHg increases toward the brackish waters (avg! 3!8-14!0 %) in com- river mouth! Saltwaters entering with tidal parison with the other two layers! Positive fluxes and higher turbulence causing correlation between RHg and DHg in Au- resuspension at lower depth of the mouth gust suggests that part of dissolved Hg is may explain this downstream gradient! Look- reactive and potentially involved in bio- ing at the relationships with grain-size of geochemical trans-formations! Estuarine

Figure 4 Particulate and dissolved Hg and MeHg along the lower course of the river

RMZ-M&G 2004, 51 944 PART 2 BIOGEOCHEMISTRY waters show high dissolved gaseous mercury ger association to SPM in comparison with (DGHg) values (avg 068-115 ng/l) in win- brackish (104-105) and saltwaters (105) The ter, whereas low values are observed in lower Kd for MeHg (104) in all waters indi- spring and summer (avg 009-031 ng/l) cates a weaker binding of organic Hg on particulate matter Particulate methylmercury (PMeHg) shows the highest values in February (avg 3082- 4175 pg/l) in comparison with May (1179- CONCLUSIONS 2640 pg/l) and August (957-2288 pg/l) It can be noted a decrease of PMeHg from the PHg and PMeHg are mainly carried in me- upper estuary to the river mouth in all sam- dium-coarse silty particles by freshwaters pling periods PMeHg concentration increases Brackish waters show the lowest contents of as SPM shows higher amounts in the 16-32 PHg due to removal processes, whereas the µm fraction in freshwaters, whereas a nega- lowest values of PMeHg were encountered tive relationship is shown for saltwaters in saltwater Seawater enters with tidal fluxes (Fig3) A good positive correlation was found at the bottom, carrying particles with high between POC and PMeHg in water samples PHg but as the salt wedge tip is approached, except for freshwaters in August, which were the coarse fraction may accumulate at the negatively correlated PMeHg was normally river bottom and SPM becomes enriched by < 1% of PHg although higher percentages (up the finest fraction The higher DHg/THg ra- to 25%) were found in the brackish layer in tio found in the thin mixing layer may indi- February and August This evidence could be cate desorption of Hg from particles At the related to phytoplankton component in these salt wedge tip where dissolved oxygen con- two seasons This was confirmed by micro- centrations are low, methylation processes scopic analyses and grain-size spectra of may possibly act in the bottom water col- SPM The dissolved MeHg (DMeHg) shows umn The lower course of the river seems to decreasing concentrations through the water act as a trap, at least for MeHg, and no rel- column from the surface to the bottom Fresh- evant supply of Hg to the sea during normal water concentrations of DMeHg were high flow conditions can be estimated Resuspen- in August (200-250; max 1350 pg/l) and in sion due to turbulence at the river mouth and February (150-200 pg/l) decreasing down- flocculation of small suspended particles stream (Fig4) It appears that, in summer, the determine enrichment of coarser particles biological activity and low riverine flow play and PHg in the salt wedge within the river an important role in MeHg availability in flu- channel Only during very high river floods vial waters In May, the surface waters gen- occurring in autumn, a relevant amount of erally show low DMeHg values (10-15 pg/l), Hg prevalently bound to suspended sedi- although higher values are found in those ments is carried into the Gulf of Trieste samples of the upper river course affected by Eventually, the river plume diverted by ENE the suspended sediment plume wind-driven surficial currents can be an important way of Hg dispersion and export from The distribution coefficient (Kd l kg-1) of Hg the Gulf to the northern Adriatic sea and the in the freshwaters is 105-106 showing a stron- adjacent lagoon system

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 945

REFERENCES

[1] COVELLI, S, PIANI, R, FAGANELI, J, BRAMBATI, A [3] FAGANELI, J, HORVAT, M, COVELLI, S, FAJON, V, (2004): Circulation and suspended matter dis- LOGAR, M, LIPEJ, L, CERMELJ, B (2003): Mer- tribution in a microtidal deltaic system: the cury and methylmercury in the Gulf of Trieste Isonzo river mouth (northern Adriatic Sea) Sedi- (northern Adriatic sea); The Science of the Total ment Transport in European Estuarine Environ- Environment 304, 315-326 ments, (CIAVOLA, P, COLLINS, M B AND CORBAU [4] COVELLI, S, FAGANELI, J, HORVAT, M, BRAMBATI, A C, Eds) Journal of Coastal Research, Special (2001): Mercury contamination of coastal sedi- Issue n°41, in press ments as the result of a long-term cinnabar min- [2] HINES, M E, HORVAT, M, FAGANELI, J, BONZONGO, ing activity (Gulf of Trieste, Northern Adriatic J-C J, BARKAY, T, MAJOR, E B, SCOTT, K J, sea); Applied Geochemistry 16, 541-558 BAILEY, E A, WARWICK J J, LYONS, W B (2000): Mercury biogeochemistry in the Idrija river, Slovenia, from above the mine into the Gulf of Trieste; Environmental Research Sec- tion A, 83, 129-139

RMZ-M&G 2004, 51 946 PART 2 BIOGEOCHEMISTRY

Transfer of mercury in the food webs of Lake St-Pierre

FABIEN CREMONA1, DOLORS PLANAS1 & MARC LUCOTTE1

1GEOTOP-UQAM-McGill and COMERN, Universite du Quebec a Montreal, CP 8888 Suc Centre Ville Montreal, Qc H3C 3P8 Canada; E-mail: cremonafabien@courrieruqamca

Abstract For human populations, the main way of contamination by mercury (Hg) is through the consumption of fish In Quebec (Canada), annually, there are 1387 tons of freshwater fish caught each year by professional fishermen, more than half of the catches are from Lake St-Pierre, a widening of the St-Lawrence River Despite the fact that this lake receives high inputs of Hg their fish have much lower concentrations than in Cana- dian boreal lakes for the same species and standardized fish length The classical Hg path, sediment, deep benthos or zooplankton could not explain the low fishs Hg concentrations in Lake St-Pierre Our working hypothesis to explain the observed differences is based on littoral trophic approach Indeed, we think that the uniqueness of Lake St-Pierre is the dominance of the littoral zone which has very complex trophic web and can bear several trophic bottlenecks This means that in the littoral zone, many organisms, mainly invertebrates occupying high trophic levels are not equally consumed by fish The preliminary results of our study seems to indicate that the inedible macroinvertabres had the highest THg concentrations

Key words: mercury, trophic web, macroinvertebrates, bottleneck

INTRODUCTION civorous fish species (Stizostedion vitreum) Hg concentrations were significantly different within the same lake regardless of iden- For a given THg input in aquatic ecosystems, tical growth rates; these differences were fish Hg accumulation could be very differ- related to the sample location in the lake ent between them There are currently two Others factors should also be taken in ac- hypotheses to explain these differences The count in order to better explain Hg dispari- first hypothesis is related to fish growth rate, ties in fish For example, higher organic which is positively related to temperature matter concentration or extended anaerobic Thus, when the growth rate is fast fish present conditions favor Hg methylation and thus lower Hg concentrations for a given length counterbalance this biodilution in eutrophic (VERTA, 1990; STAFFORD AND HAINES, 2001) conditions (JACKSON, 1993) None of these The other hypothesis is that the productivity explanations considered trophic interactions of the system determines the amount of that are critical when one is interested in con- Hg accumulated in the fish Higher primary taminants transfer and biomagnifications production in eutrophic lakes causes Our hypothesis is that not all the Hg avail- biodilution of Hg (JERLENOV ET AL , 1975) able is transferred to top predators because Yet, in a recent study Simoneau et al (un- some organisms are trophic bottlenecks published data); have found that for a pis- Invertebrate organisms like Heteropterans

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 947 and some Coleopterans are voracious RESULTS AND DISCUSSION macroinvertebrates that are scarcely eaten by fish since they produce chemical defenses The macroinvertebrates communities against predators (RHODES, 1994)" This sampled in Lake St"Pierre presented some means that the high Hg concentrations of spatial heterogeneity in the community com- inedible organisms would not be transferred position" Considering the relative taxa abun- to fish, which must eat at lower trophic lev- dance, the Gastropods (Prosobranchia and els and hence they accumulate less Hg con- Pulmonata) dominated in three stations centrations" Another point that we would (ADF, GIR, MAS) when the Heteropterans considered in this research is the potential dominated in the fourth station (BSF)" How- dichotomy in Lake St"-Pierre between me- ever, when the relative biomass is consid- thylation sites, sediment and macrophyte- ered Gastropods (dry weight minus weight epithyte complex in meadows" The study is of shell) were only dominant in two of the carried on at different sites in Lake St-Pierre: three stations (ADF and MAS), and Amphi- Baie St-François (BSF) and Anse du Fort pods (Gammarus sp") had the highest biom- (ADF) located on the south shore and, the ass in the third station (GIR)" Heteropterans Girodeau Island (GIR) and Maskinonge continued to be the dominant taxa in BSF (MAS) on the north shore" The wide distri- when we considered biomass" bution of the four stations permits us to cover the spatial heterogeneity of the lake"

Figure 1 Mean total Hg (THg) concentrations in invertebrate and vertebrate taxa (Alevin) in Lake St-Pierre

RMZ-M&G 2004, 51 948 PART 2 BIOGEOCHEMISTRY

The THg preliminary analysis showed that invertebrates that are considered as bottle- predators (black) have the highest THg con- necks in trophic webs had the highest Hg centrations while grazers (white) have the concentration of all sampled taxa in our study lowest Omnivorous and detritivorous func- ecosystem This implies that benthivorous tional groups (grey) have intermediate val- fish must eat at the lower trophic levels, ues Among predators, trophic bottleneck which are much less contaminated with Hg taxa (Belostomatidae, Corixidae, Gyrinidae, such as Gastropods and Amphipods Thus, Neoplea sp, Notonectidae) had higher THg our hypothesis could explain, at least partly, than the other macroinvertebrates predators the low Hg values found in fish of Lake (Hirudinae, Hydracarina, Hydrophilidae (l), St-Pierre Zygoptera) or fish larvae (Alevin) (Fig 1) Acknowledgements

CONCLUSIONS This work was supported by the NSERC- funded Collaborative Mercury Research Our hypothesis seems to be confirmed by Network of Canada (COMERN) these preliminary results Inedible macro-

REFERENCES

JACKSON, T A (1993): Effects of environmental fac- STAFFORD, C P & HAINES, T (2001): Mercury con- tors and primary production on the distribution tamination and growth rate in two piscivore and methylation of mercury in a chain of highly populations; Environ Toxicol Chem 20(9), eutrophic riverine lakes; Water Poll Res J 2099-2101 Canada 28(1), 177-216 VERTA, M (1990): Changes in fish mercury concen- JERLENOV, A, LANDNER, L & LARSSON, T (1975): Swed- trations in an intensively fished lake; Can J ish perspectives on mercury pollution; Res J Fish Aquat Sci 47, 1888-1897 Water Pollut Control Fed 47, 810-822 RHODES (1994): A review of predator avoidance defenses by aquatic insects through the use of chemical substances; Colorado State University Fort Collins, Colorado 80523

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 949 Mercury and Radionuclides in Forest Soils of Southwestern Georgia, USA: The Role of Older Anthropogenic and Naturally Occurring Mercury

J DAVID DEAN1, M RAVICHANDRAN2, DONALD B PORCELLA3, AND RICHARD G CARLTON4

1 AMEC Earth & Environmental, 1395 So Marietta Parkway, Bldg 300 Ste 210, Marietta, GA, USA 30067; E-mail: daviddean@ameccom 2 AMEC Earth & Environmental, 1395 So Marietta Parkway, Bldg 300 Ste 210, Marietta, GA, USA 30067; E-mail: raviravichandran@ameccom 3 Environmental Science & Management, 1034 Lindsay Court, Lafayette, CA, USA 94549; E-mail: dporcell@comcastnet 4 Quantitative Ecology, Environment Department, Electric Power Research Institute, 3412 Hillview Avenue, Palo Alto CA, USA 94304; E-mail: rcarlton@epricom

Abstract: Concentrations of mercury, radionuclides, and other analytes were measured in three soil profiles from relatively undisturbed, older growth forest soils of the Ichawaynochaway Creek watershed, Georgia, USA to investigate their penetration into the soil profiles and to assess how long they had been accumulating Bomb-fallout radionuclides, cesium (137Cs), plutonium (239,240Pu), deposited in the watershed in the past 50 years, and lead (210Pb; half-life of 22 yrs) were measured and used as analogues for recent atmospherically deposited mercury These radionuclides were observed to have penetrated to at least 16 cm in these soils, suggesting that accumulation of recent atmospherically deposited mercury is not limited to the top few centimeters Mercury profiles also differed markedly from recently deposited Cs, Pu, and Pb Based on transport modeling of radionuclides and mercury in soil profiles, it was estimated that atmospherically deposited mercury has been accumulating for at least 1,200 years and likely on the order of 6,000 years in this watershed Time frames of this magnitude are required to produce the observed concentration profiles for mercury, given the magnitude of the experimentally determined partition coefficients (K ) in this study d

Keywords: Atmospheric Deposition, Fate and Transport, Soils, Pre-Industrial Sources, Radionuclides

INTRODUCTION maximum amount of mercury a waterbody can assimilate without exceeding the appli- Over two thousand waterbodies across the cable water quality standard The watershed United States have been classified as im- models used in EPAs TMDL calculations paired due to elevated levels of mercury in contain a number of both implicit and fish tissue In response to these concerns explicit assumptions about the sources and and recent court orders, the US EPA has de- transport of mercury in the environment veloped mercury Total Maximum Daily and form the basis of the following three Loads (TMDL), which is a calculation of the hypotheses:

RMZ-M&G 2004, 51 950P ART 2 BIOGEOCHEMISTRY

>99 % of mercury load to the aquatic eses listed above, the Ichawaynochaway systems is derived from recent atmo- Creek watershed, which has a large watershed spheric deposition and that older an- to waterbody ratio, was studied Surface and thropogenic mercury or mercury from subsurface soil samples were collected from terrestrial sources play an inconsequen- various undisturbed areas in the watershed tial role in determining the levels of and analyzed those samples for mercury, ra- mercury in aquatic ecosystems, dionuclides (cesium, plutonium, radium, lead, recently deposited mercury was present beryllium), and other parameters The radio- in the upper 2 cm of the soil and was nuclides measured in this study have been available for transport to the impaired atmospherically deposited for varying lengths water body through runoff-induced sur- of time, and were used as analogues for re- face transport, and cent versus older atmospheric deposition of concentrations of mercury in sediments mercury The fate and transport of mercury and biota of impaired aquatic systems and radionuclides in soil profiles was then could be accounted for by recently at- modeled to understand the depositional his- mospherically-deposited mercury tory of mercury to this watershed alone

Consequently, most of the pollutant load re- RESULTS AND DISCUSSION ductions required by TMDLs are slated to come from current air emission sources Total Hg concentrations observed in the soil EPAs assumptions were based on studies organic horizons ranged from about 0 10 to performed in seepage lakes in the upper Mid- 0 25 µg g-1 Mineral soil concentrations typi- west and in the Florida Everglades, where cally ranged from 0 01 µg g-1 to 0 03 µg g-1 the dominant source of mercury loading was Higher Hg concentrations in the upper soil from the atmosphere However, in water- profile coincided with higher concentrations sheds where fluvial processes dominate the in iron (Fe), aluminum (Al), and total organic loadings of mercury to the waterbody, the carbon (TOC), suggesting that favorable re- enormous pool of terrestrial mercury plays a tentive conditions in the upper profile, rather larger and more significant role in determin- than increased deposition, is responsible for ing the loadings to the water body Using higher levels of Hg in surface soils Cesium atmospherically deposited radionuclides as and plutonium concentrations and invento- analogues, this study assessed the signifi- ries were similar to those observed in other cance of older anthropogenic and terrestrial studies, taking into account factors such as mercury in a system having a large water- latitude and vegetative cover Bomb-fallout shed to waterbody ratio radionuclides (Pu and Cs) deposited in the last 50 years had penetrated to at least 16 cm The overall goal of this study was to evaluate in these soils, suggesting that atmospheri- the question whether a major portion of the cally-derived Hg accumulation was not lim- Hg found in sediments and biota in large wa- ited to the top few centimeters On a mass tersheds is from older anthropogenic or ter- basis, the quantity of Hg in the mineral soils restrial sources To investigate the hypoth- (i e , below the top 1-2 cm organic layer)

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 951 ranged from 82 % to 98 % of the total soil profiles for Hg, given the magnitude of the inventory measured in undisturbed soils at experimentally determined K in this study d three locations It was also noted that the concentration profile for Hg differed markedly from those of Modeling was accomplished using an em- Cs, Pu (introduced in the past 50 years, and pirical model with physically-based coeffi- thus are reasonable analogues for recently cients Based on simulated concentration deposited Hg), and Pb (Figures 1 through 4) profiles of Hg and radionuclides in soil pro- Given this evidence, it can be concluded that files, it was estimated that Hg has been ac- recently deposited Hg accounts for only a cumulating for ~1,200 years and possibly up fraction of the annual export of Hg to the to ~6,000 years in this watershed Time waterbody and that older anthropogenic Hg frames of this magnitude were required in is a major contributor to Hg levels observed order to produce the observed concentration in pond sediments and aquatic biota

Figure 1 Simulated and observed 137Cs in watershed soils

Figure 2 Simulated and observed 239, 240 Pu in watershed soils

RMZ-M&G 2004, 51 952 PART 2 BIOGEOCHEMISTRY

Figure 3 Simulated and observed 210 Pb in watershed soils

Figure 4 Simulated and observed Hg in watershed soils

CONCLUSIONS Based on modeling of concentration profiles of mercury and radionuclides Results presented in this report provide use- in soil profiles, it is estimated that mer- ful insights into the fate and transport of cury has been accumulating for ~1,200 mercury in watersheds The following con- years and possibly up to ~6,000 years clusions were reached: in this watershed (whereas EPAs mod- Bomb-fallout radionuclides (Cesium- els attribute all of the mercury problem 137 and Plutonium-239, 240) deposited to recent deposition) in the last 50 years have penetrated to at least 16 cm in soil profiles, suggest- The findings from this study suggest that in ing that recently deposited mercury is undisturbed areas, Cs, Pu, and Hg are not not limited to the top 2 cm (where it lost in significant amounts to the aquatic sys- would be readily available for runoff- tem Therefore, it might be hypothesized that induced transport to waterbodies) land clearing and watershed development

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 953 have been important factors in mobilizing Hg likely to translate to reduced mercury load- from the watershed to the waterbody From ings to waterbodies that have large water- the estimated depositional period, it is con- shed area for a very long time cluded that recently deposited Hg accounts for only a fraction of the annual export of Hg to the waterbody and that older anthro- Acknowledgements pogenic Hg is a major contributor to Hg levels observed in pond sediments This sug- This work was supported by the Electric gests that even if atmospheric deposition of Power Research Institute and several of its mercury is significantly decreased, it is not member companies

RMZ-M&G 2004, 51 954 PART 2 BIOGEOCHEMISTRY

Curimata cyprinoides as a Fish Model for Analysis Goldmining and Damming Effects on Mercury Contamination of Freshwater Systems

Y D OMINIQUE1, R MAURY-BRACHET1, B MURESAN2, RVIGOUROUX3, S RICHARD3, D COSSA2, A MARIOTTI4 AND A BOUDOU1

1 LEESA, UMR CNRS 5805, University of Bordeaux 1, Place Dr Peyneau, 33120 Arcachon, France E-Mail: y*dominique@epoc*u-bordeaux1*fr 2 IFREMER, Département Polluants Chimiques, BP 21105, 44311 Nantes, France 3 HYDRECO, Laboratoire Environnement, 97388 Kourou, Guyane, France 4 BioMCo, UMR 7618, University Paris VI-CNRS-INRA, EGER, 78850 Thiverval-Grignon, France

Abstract: Sixty six fish belonging to the Curimata cyprinoides species were collected from the hydroelectric reservoir of Petit-Saut (French Guiana) and downstream, in the Sinnamary River, in order to study the effect of exposure conditions on mercury bioaccumulation levels! Total mercury (HgT) and MMHg concentrations were measured in different organs/tissues! HgT concentrations in the skeletal muscle were ten times higher in fish sampled downstream: 3!40 ± 0!94 µg g-1, dw / 0!32 ± 0!20 µg g-1, dw! In addition, the percentages of mercury as MMHg accumulated in four organs (muscle, liver, gills, and kidneys) were significantly higher in fish collected downstream! All these data are in agreement with the differences observed between MMHg concentrations in the surface water of the reservoir and downstream! Nevertheless, an important point concerns the diet of C cyprinoides, in direct relation with the trophic route of exposure! Nitrogen stable isotopes (δ15N) measured on muscle samples clearly show two food regimes: δ15N for fish living in the reservoir is 11!2 ± 0!4 and 8!6 ± 0!3 for fish collected downstream on the Sinnamary River! These values, compared with other fish species, correspond to an omnivorous/carnivorous regime for the reservoir fish and detritivorous/benthivorous regime for the downstream fish! Further research is required in order to quantify, using field experimental systems, the importance of the direct route of exposure; and to define more precisely the type of prey ingested and their Hg/MMHg burdens!

Key words: goldmining damming fish curimata cyprinoides - food regime

INTRODUCTION filled in 1994, flooding 360 km2 of equato- rial forest, and leading to a very slowly evolv- In French Guiana, the Petit-Saut hydroelec- ing anoxia in the largest part of the water tric reservoir, on the Sinnamary basin, rep- column (RICHARD ET AL%, 1997)% Nine years resents an ideal area for assessing the im- after flooding, the oxicline is located at pact of goldmining and reservoir construc- 5 m, for a maximal depth of 35 m% This res- tion on mercury contamination of freshwa- ervoir covers former gold-mining sites that th ter systems (CHARLET & BOUDOU, 2002; were very active at the end of the 19 cen- COQUERY ET AL%, 2003)% This reservoir was tury and receives large contributions from

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 955 present sites (Figure 1) Here we present a average of 006 ± 003 ng l-1 During the same comparative study of mercury bioaccumu- period, the waters of the Sinnamary River a lation levels in Curimata cyprinoides, fish few kilometres downstream, which mostly samples being collected from the hydroelec- consist of water from the anoxic part of the tric reservoir and downstream, in the reservoir, exhibited a mean MMHgD con- Sinnamary River, in order to study the effect centration of 053 ± 011 ng l-1 of exposure conditions on mercury bioaccumulation levels Curimata cyprinoides samples were collected in the reservoir (N=25) and downstream, in the Sinnamary River (N=41), with similar total weight (155 ± 45 g and 136 ± 22 g, respectively) and standard length (168 ± 15 cm and 165 ± 9 cm, respectively) Total mercury (HgT) and MMHg concentrations were measured in different organs and tissues: gills, liver, kidneys, skeletal muscle HgT concentrations in the skeletal muscle were ten times higher in fish sampled downstream: 340 ± 094 µg g-1, dw / 032 ± 020 µg g-1, dw In addition, the percentages of mercury as MMHg were higher in the four organs of the fish collected downstream (Figure 2)

Figure 1 Study area in French Guiana, including the Petit-Saut hydroelectricreservoir and the downdam zone, on the Sinnamary river Small whitecircles correspond to the four sampling stations on the reservoir andin the Sinnamary River, below the dam

RESULTS AND DISCUSSION

The vertical profiles of dissolved monomethylmercury (MMHgD) in the water column Figure 2 Percentages of monomethylmercury (MMHg) at the reservoir stations clearly show that the versus total mercury (HgT) in four organs of Curimata cyprinoides according to the sampling sites: reservoir anoxic layers represent an efficient compart- stations (Reservoir), in the oxic superficial layers of the ment for mercury methylation In April 2003, water column (0-5 m); river stations (River), down- the MMHgD concentrations in the waters of stream on the Sinnamary River (see Fig& 1)& the deepest layer of the reservoir were up to 1 ng l-1, while the oxic layer (0-5 m) had an

RMZ-M&G 2004, 51 956 PART 2 BIOGEOCHEMISTRY

All these data are in agreement with the dif- set up upstream and downstream the dam ferences observed between MMHg concen- with several fish species fed with uncontami- trations measured in the surface water of the nated artificial food, the importance of the reservoir and downstream in the Sinnamary direct route of exposure; (ii) to define more River Nevertheless, an important point con- precisely the type of prey ingested in the dif- cerns the diet of C cyprinoides, in direct re- ferent sites within the reservoir and down- lation with the trophic route of exposure stream and their Hg/MMHg burdens Nitrogen stable isotopes (δ15N) measured on muscle samples clearly show two food re- Acknowledgements gimes: δ15N for fish living in the reservoir is 112 ± 04 °/°° (N=8) and 86 ± This work was supported by the French Na- 03 °/°° for fish collected downstream on the tional Scientific Research Center (CNRS/ Sinnamary River (N=8) These values, com- PEVS, Mercury in French Guiana research pared with other fish species having a well program), the European Union (EC Feder defined food regime, correspond to an om- funds), the French Ministry of the Environ- nivorous/carnivorous regime for the reser- ment (DIREN in French Guiana), Electricité voir fish and detritivorous/benthivorous re- de France (EDF research branch) Yannick gime for the downstream fish Dominique was supported by a grant from EDF/Hydreco (CIFRE fellowship); Bogdan Further research is required in order (i) to Muresan was supported by a grant from EDF/ quantify, using open experimental systems CNRS (BDI fellowship)

REFERENCES

CHARLET, L & BOUDOU, A (2002) Cet or qui file un RICHARD, S, ARNOUX, A & CERDAN, P (1997) Evolu- mauvais mercure La Recherche 359, 52-59 tion in physico-chemical water quality in the COQUERY, M, COSSA, D, PERETYAZHKO, T, AZEMARD, reservoir and downstream following the filling S & CHARLET, L (2003) Methylmercury for- of Petit-Saut dam (French Guiana) Hydroecol mation in the anoxic waters of the Petit-Saut Appl 9, 57-83 reservoir (French Guiana) and its spreading in the adjacent Sinnamary River J Physique 107, 327-331

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 957 Bioaccumulation and Transport of Methylmercury by Lamprey

PAUL DREVNICK, MARTIN HORGAN, AND JAMES ORIS

Miami University, Department of Zoology, Oxford, Ohio, USA, drevnipe@muohio!edu

Abstract: Parasitic lamprey have the potential to accumulate high levels of methylmercury in contaminated ecosystems Adults feed primarily on blood of piscivorous fish Meth- ylmercury has a high affinity for red blood cells and can stay in circulation for a long time (>200 d), allowing for an efficient transfer of methylmercury from host to parasite Lamprey can accumulate methylmercury to concentrations ten times greater than that in their host fish Sea lamprey (Petromyzon marinus) in some waters of the Laurentian Great Lakes of North America, for example, have been reported to contain total mercury concentrations greater than 2500 ng/g The fate of this methylmercury is as yet unknown, but is likely transported to waters and sediments where spawning occurs Sea lamprey spawn in lotic environments after spending most of their adult (parasitic) lives in the ocean or large lakes, and die after spawning The delivery of methylmercury in lamprey carcasses may be a significant input of this contaminant to spawning grounds With data from published sources, we estimate that spawning sea lamprey deposited approximately 012 kg of methylmercury to tributaries of the Great Lakes in 2002, much of this in only a few tributaries of Lakes Huron, Michigan, and Superior Ecosystem effects of this methylmercury are not known, but may be important as the majority of fish species in the Great Lakes spawn in tributaries or nearshore mixing zones We will determine the contribution of lamprey to mercury cycling in tributaries of the Great Lakes and other systems by constructing mass balances for total mercury and methylmercury with best estimates from the literature and analyses of biota and sediment

Key words: methylmercury, lamprey, bioaccumulation, transport

RMZ-M&G 2004, 51 958 PART 2 BIOGEOCHEMISTRY

Relationship between watersheds characteristics in lakes of the boreal forest and mercury concentrations in fish through characterization of organic compounds

CAROLINE DUFOUR, MARC LUCOTTE & ROMAN TEISSERENC

Abstract: It is recognized that watersheds constitute one of the main Hg sources to lakes However since Hg cycling in lake environment is very complex, the relationship between watershed characteristics and Hg concentrations in fish is very difficult to establish It is also well known that organic carbon is an important vector of transport for mercury coming from the watersheds to the lake Many studies have used these pre- mises to state that there is a relationship between dissolved organic carbon concentration in lake waters and the Hg contamination in biota However, this hypothesis remains to be confirmed, as past studies were inconclusive In regards of these findings we propose that the methylation conditions are more related to the nature of organic matter than to its concentration So, we are studying the relationship between the molecular composition of dissolved and particulate organic carbon, as defined by lignin biomarkers, and Hg levels in fish species By linking the nature of organic compounds with watersheds characteristics, we are working to establish some simple physical indicators (presence of wetlands, distance of wetlands from the lakes, sizes of the watersheds, sizes of the lakes, slopes, types of vegetation and quaternary deposit) of fish Hg contamination These indicators coupled to biological indicators (fish species, size etc) will allow the fishers and the fish eating communities to rapidly estimate the potential level of Hg contamination of fish in a given lake Up to now, we are able to 1) identify distinct signatures of ligneous biomarkers for wetlands, soils and also dissolved and particulate matter and 2) determine the level of OM degradation in lakes water Preliminary results suggest that there is no simple relationship between state of OM degradation and Hg contamination of fish species

Key words: organic matter, watersheds characteristics, lignin biomarkers

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 959 Fractionation of Mercury Isotopes during Methylation by Sulfate-Reducing Bacteria

MARK DZURKO1, DELPHINE FOUCHER2, AND HOLGER HINTELMANN2

1Watershed Ecosystems Graduate Program, Trent University, Peterborough, Ontario, Canada 2Department of Chemistry, Trent University, Peterborough, Ontario, Canada

Abstract: Transient signals of methylmercury (MeHg) were measured by Multi Collector- Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS) for their isotopic composition! MeHg was separated using packed column Gas Chromatography (cGC) and data was integrated at 1 s! Various methods for isotope ratio determination were evaluated for their precision and accuracy for future use in fractionation studies of MeHg formed by sulfate-reducing bacteria! Peak area yielded the highest isotope ratio in relation to IUPAC values! Ratio drifts across the transient signal for this hyphenated technique was observed for all isotope pairs, necessitating the correction with internal standards!

Key words: methylmercury; sulfate-reducing bacteria; isotope ratio; fractionation; transient signals

INTRODUCTION Hg has seven stable isotopes occurring naturally in the environment: 196Hg (015 % natu- Measurement of natural fractionation of ral relative abundance), 198Hg (1002 %), mercury (Hg) isotopes is a powerful tool to 199Hg (1684 %), 200Hg (2313 %), 201Hg directly identify geochemical processes con- (1322 %), 202Hg (298 %) and 204Hg trolling the fate of mercury in the environ- (685 %) These currently accepted values ment Recent developments in precise iso- for isotopic abundances of Hg in nature were tope ratio measurements using MC-ICP-MS determined in 1954; however, deviations have led to increased interest in stable iso- from these values have been reported This tope geochemistry of heavy elements, such is not surprising - although these isotopes all as Cu, Se, and Sb Isotope fractionation of show the same chemical characteristics, their Hg has been observed in terrestrial[1,2] and reaction rates differ slightly due to their mass meteorite[3] materials, but it is still in ques- differences Reactions and physical pro- tion, if fractionation occurs via biological cesses such as evaporation, condensation, interactions In this study, we investigate the melting, crystallization, adsorption, desorp- likelihood for mercury (Hg) isotopes to un- tion and diffusion are examples of situations dergo biological fractionation, primarily where kinetic fractionation of Hg occurs In through the methylation and demethylation addition to chemical processes, biological processes performed by Sulfate-Reducing processes involving chemical reactions will Bacteria (SRB) also result in Hg fractionation Since Hg has

RMZ-M&G 2004, 51 960 PART 2 BIOGEOCHEMISTRY been found to be involved in microbial reac- rection Peak height isotope ratios were de- tions, Hg fractionation should occur during termined by calculation of the ratio for a methylation processes single value occurring at the peak apex Av- erage ratios reported was the average ratio The first objective of this investigation is to generated by the MC-ICP-MS across the determine a precise and accurate method for entire peak and the weighted ratio was the interpreting isotope ratios from transient sig- isotopic ratio generated by the MC-ICP-MS nals produced by the separation of MeHg for each data point divided by the sum of the through gas chromatography peak intensities across the respected peak The isotope ratios generated by the cold vapour introduction method were not tran- METHODS sient, rather steady-state The MeHg for cold vapour was reduced to Hg2+ by BrCl and fur- -1 ther reduced to Hg0 by SnCl MeHg standard solution (2 ng g ) underwent 2 aqueous-phase derivitization and was preconcentrated on Tenax resin MeHg was thermally desorbed at 200 0C and separated RESULTS AND DISCUSSION via packed GC column at 40 ml/min and at 85 0C Transient signals evolving from the A typical transient signal for Hg species, fol- chromatographic separation were evaluated lowing GC separation and MC-ICP-MS de- for their isotopic ratio information by calcu- tection, is shown in Figure 1 The peak tail- lating the Hg isotope ratios after integration ing and the clear isotope fractionation across of peaks Each MeHg peak for all evalua- the peak (Figure 2) demand an investigation tion methods utilized ~40 data points, span- into the most appropriate procedure to de- ning the entire peak Peak Area data integra- fine the start and finish of the peak integration was determined using Clarity Lite® chro- tion to facilitate precise and accurate isotope matography software after background cor- measurements

Figure 1 Separation and detection of MeHg (2 ng g-1) by GC-MC-ICP-MS

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 961

GUNTHER-LEOPOLD, ET AL [4] demonstrated a has not been incorporated into the isotopic similar trend in their ratio measurements of measure, as the raw ratios are only reported transient signal They too exhibited isotope here drift in their transient signals for isotope pairs and speculate that the cause for this lies not The Hg isotope ratios for MeHg standards, in the chromatographic column material, but evaluated with various integration methods, rather in the ICP-MS itself are recorded in Table 1 The data demonstrate that peak area determination gives the high- A significant feature of plasma source mass est ratio for most the isotope pairs Peak spectrometry is the large instrumental mass height is also close in its comparability to bias reflecting the tendency of heavier ions IUPAC values The variability around which to be extracted in preference to light ions This evaluation measure is quite high leading to phenomenon is mainly attributed to space- a possible explanation as to why one method charge effects in the plasma interface between is more representative for one isotope pair sample and skimmer cone and in the focus- and not for another These discrepancies may ing lens regions Irrespective of the space be eliminated or reduced once correction for charge effect, the lighter isotopes should pref- mass bias is incorporated in the evaluation erably be pumped down and, therefore, more of raw ratios light isotopes leave the central ion beam compared with the heavier isotopes[4] As with all isotope ratio measurements, certified reference materials are needed to vali- The data presented has not been corrected date the adequacy of the overall procedure for mass bias with an internal standard While In addition, such a reference material is 203Tl/205Tl ratios are generally accepted for needed as a benchmark to which all mea- internal mass bias correction for Hg[1,2,3], it surements can be compared to in terms of

Figure 2 Uncorrected 198Hg/202Hg isotope ratios across the transient signal of 2 ng g-1 MeHg separated by column gas chromatography The elution of MeHg from the chromatographic column is illustrated by the 198Hg and 202Hg intensity Integration time 1 s

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Table 1 Comparison of 198/202 isotope ratios for MeHg utilizing various evaluation methods of transient signal data Cold vapour system generated steady-state signal All values were determined using same time interval for MeHg, n=7

relative deviation from this common stan- external precision of repetitive measures by dard Only then, comparison of results among reducing all sources of variability ie different laboratories is truly possible changes in gas flow, column temperature, etc

The application of peak area integration on CONCLUSIONS transient signals for isotope ratio determination is a robust method, especially, when the Methylation time course experiments have peak suffers tailing and/or there is isotope determined that the SRB are capable of pro- fractionation on the chromatographic col- ducing sufficient MeHg for isotopic ratio umn Once confidence in the isotopic ratio measurements of high precision Initial Hg integration method is established, the true isotope ratio measurements performed by extent of Hg isotope fractionation by SRB coupling the GC column to the MC-ICP/MS can be determined and applied to form a bet- showed sufficient Hg metalloid separation, ter understanding of Hg biogeochemical cy- but MeHg fractionation was observed dur- cling ing the GC elution process, which necessi- tated integration of signals prior to the iso- Acknowledgements tope ratio calculation This research project was funded by an The external precision for all measurements NSERC grant to Holger Hintelmann is quite high, but is expected for transient (COMERN project 3111) signals Efforts will be made to improve the

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 963

REFERENCES

[1] HINTELMANN, H, LU, SHENGYONG (2003): High Pre- [3] KLAUE, B, KESLER, SE, BLUM, JD (2000): Inves- cision Isotope Ratio Measurements of Mercury tigation of Natural Fractionation of Stable Mer- Isotopes in Cinnabar Ores using Multi-Collec- cury Isotopes by Multi-Collector Inductively tor Inductively Coupled Plasma Mass Spectrom- Coupled Plasma Mass Spectrometry 11 th Annual etry Analyst 128, pp 635-639 International Conference on Heavy Metals in [2] EVANS, RD, HINTELMANN, H, DILLON, PJ (2001): the Environment, ed J Nriagu, Ann Arbor, MI, Measurement of High Precision Isotope Ratios USA, August 6-10, 2000 for Mercury from Coals using Transient Signals [4] GUNTHER-LEOPOLD, I, WERNLI, B, KOPAJTIC, Z, Journal of Analytical and Atomic Spectrometry GUNTHER, D (2004): Measurement of Isotope 16, pp 1064-1069 Ratios on Transient Signals by MC-ICP-MS Analytical and bioanalytical Chemistry 378, pp 241-249

RMZ-M&G 2004, 51 964 PART 2 BIOGEOCHEMISTRY

Assessing Methylmercury Formation in Lake Water Using a Stable Isotope Technique

CHRIS ECKLEY 1,2 & HOLGER HINTELMANN1

1Watershed Ecosystems Graduate Program, Trent University, Canada 2Department of Geography, University of Toronto, Canada; E-mail: chris!eckley@utoronto!ca

Abstract: The objective of this study was to determine where and under what conditions mercury is methylated in the water column of lakes A stable isotope technique was used to trace the formation of methylmercury in lake water incubation assays at in situ conditions Samples were collected from 5 lakes across Canada Methylation activity was only detected in the anoxic hypolimnia of lakes A peak in methylation activity was typically observed just below the oxycline The depth and rates of methylation activity changed seasonally with no methylation activity occurring after fall turnover Mercury methylation activity was concomitant with the zone of sulfate reduction (as measured by the decrease in sulfate concentration in lakes), indicating the likely involvement of sulfate reducing bacteria A simple correlation test between DOC concentrations and methylation rate constants indicated a positive relationship The demethylation rate constant in the anoxic hypolimnia was less than 012 d-1

Key words: Mercury methylation, lakes, water column, stable isotope

INTRODUCTION Rates of mercury methylation in lakes remain difficult to predict largely because the links Numerous studies have linked Methylmer- to pertinent biogeochemical cycles are nu- cury (MeHg) production to anaerobic micro- merous and complex! WATRAS ET AL![6,7] found bial activity in lake sediments[1, 2] with sul- that within a 30 km region with identical fate reducing bacteria (SRB) identified as the mercury inputs, there was a 50-fold range of main bacteria involved in mercury methyla- dissolved MeHg in the water column! This tion[3, 4]! The zone of greatest methylation has indicates that the processes occurring within been observed just below the oxic/anoxic the lakes (or within the watershed) are very transition zone in sediments underlying oxy- important in determining MeHg concentra- genated water where there is also a peak in tions and can be quite different between lakes sulfate reduction[2,3]! A similar redox bound- in the same region! ary exists in the hypolimnetic water of dimictic lakes during summer stratification! Historically, methodological constraints Mercury methylated in the water column made measuring methylation rates difficult may be more available for entry into the and subject to error! HINTELMANN ET AL![8] and aquatic food web because it does not need to HINTELMANN AND EVANS [9] developed a new diffuse out of the sediments! methodology for measuring rates of mercury methylation and demethylation using low

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 965 level additions of mercury stable isotopes in L658, oxic depths in July that did not have short term (< 1 day) incubations! methylation activity were shown to have methylation activity (014 d-1) when the re- The objective of this study is to determine gion became anoxic in September Similar where and under what conditions mercury results were found at Plastic Lake is methylated in the water columns of 5 lakes (In Ontario: L658, L442, Plastic Lake, Red Within anoxic hypolimnia, mercury was Chalk Lake, and in British Columbia: Elk methylated at different rates as a function of Lake)! Various zones in the water column depth At L658, over a span of less than half were sampled and the methylation rate con- a meter, three distinct methylation potentials stants obtained were compared with other were detected (varying over 010 d-1), indi- water parameters that have been associated cating narrowly defined microbial zones, or with methylation, such as sulfate/sulfide con- a concentration gradient of methylating bac- centrations, dissolved oxygen (DO), and dis- teria Variations in rates with depth were also solved organic carbon (DOC)! observed at L442, Red Chalk Lake, and Plas- tic Lake After fall turnover when the water became oxygenated and well mixed, methy- RESULTS AND DISCUSSION lation activity was not detected

Mercury methylation was detected in the The transition between oxic and anoxic con- water column of 4 of the 5 lakes studied with ditions has been widely reported as the peak rates ranging from zero to 014 d-1 In the lakes zone for methylation activity[5] While the where it was observed, it was only detected results of this study support this conclusion, in the anoxic hypolimnion waters This agrees it was also found that methylation activity with the generally accepted notion that me- continued well below the oxic/anoxic inter- thylation is mediated by anaerobic bacte- face in lakes For example, at Red Chalk a ria[4,10] Methylation was not detected in Elk maximum methylation rate constant was Lake, which is a monomictic lake and has less detected just below the oxic/anoxic inteface distinct stratification than the dimictic lakes at a depth of 100 m, but methylation activ- studied It is hypothesized that in this lake the ity was still detected, though at significantly redox potential may not have been low lower levels, at 110 m and 160 m from the enough to favor sulfate reduction In all of lake surface the lakes, demethylation rate constants in the anoxic hypolimnia were less than 012 d-1 Comparing L658, L442, and Red Chalk Lake shows a trend in decreasing methylation ac- Dissolved oxygen concentrations change tivity the further the oxycline was from the seasonally in boreal lakes with anoxia de- sediment A possible explanation for these veloping in many lakes in early summer and results is that bacteria communities originat- growing until fall turnover The zone of me- ing in the sediment are proliferating upwards thylation activity was observed to change into the water column following favorable seasonally as well, following the rise of an- conditions (fresh sources of sulfate) made oxic conditions up the water column At available by the increase in anoxia The

RMZ-M&G 2004, 51 966 PART 2 BIOGEOCHEMISTRY higher methylation potentials in lakes with Elevated hypolimnetic MeHg levels were smaller anoxic hypolimnia could result from observed in all the lakes with water column bacteria populations being denser near the methylation For example, at L658, the av- sediment (where bacteria are in much higher erage MeHg concentration in the hypolim- abundance) As anoxic conditions move fur- nion increased 50 % between July and Sep- ther from the sediment, the bacterial com- tember, while the epilimnion concentrations munities may become more diffuse remained roughly constant

While anoxic conditions are necessary for the activity of SRB, it is likely the changing CONCLUSIONS sulfate concentrations that drive the SRB upward in the water column In the lakes, Methylation activity was only detected in the where multiple sampling periods occurred, anoxic hypolimnia of lakes (rate constants sulfate concentrations decreased as methy- ranging from zero to 014 d-1) A peak in lation activity moved up the water column methylation activity was typically observed Sulfate reduction rates are typically 103 times just below the oxycline The depth and rates higher in lake sediments than in the water of methylation activity changed seasonally column, which can quickly deplete the pool with no methylation activity occurring after of sulfate in the sediment[11] In the water fall turnover Mercury methylation activity column, this is not likely to occur as fresh was concomitant with the zone of sulfate pools of sulfate become available as the zone reduction (as measured by the decrease in of anoxia increases during summer stratifi- sulfate concentration in lakes), indicating the cation likely involvement of sulfate reducing bacteria A simple correlation test between DOC Besides a terminal electron acceptor, SRB concentrations and methylation rate con- also need a carbon source The range in DOC stants indicated a positive relationship Based between lakes where methylation was de- on comparisons with ambient MeHg profiles, tected was 39 mg/L to 211 mg/L Correla- this study concludes that water column mer- tion analysis between methylation rates in cury methylation can be a significant source all the lakes and DOC, demonstrated a posi- of MeHg to the hypolimnia of some lakes tive and significant relationship (r2 = 062, p = 00006, n = 27) Because methylation ac- Acknowledgement tivity was only detected in anoxic waters where sulfate reduction was occurring, com- This work was supported by NSERC Strate- plexation with DOC was likely minimal (fa- gic funding to HH voring sulfide complexation), allowing the DOC to simply act as a stimulant to microbial activity While higher levels of DOC may directly stimulate SRB activity, it will also stimulate microbial species that consume oxygen and help create the anoxic conditions necessary for SRB activity

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 967

REFERENCES

[1] GILMOUR, C, HENRY, E (1991): Mercury Methyla- [7] WATRAS, C, BACK, R, HALVORSEN, S, HUDSON, R, tion in Aquatic Systems Affected by Acid Depo- MORRISON, K, WENTE, S (1998): Bioaccu- sition; Environmental Pollution 71, pp 131-169 mulation of mercury in pelagic freshwater food [2] KORTHALS, E, WINFREY, M (1987): Seasonal and webs; Science of the Total Environment 219, pp Spatial Variation in Mercury Methylation and 183-208 Demethylation in an Oligotrophic Lake; Applied [8] HINTELMANN, H, EVANS, R, VILLENEUVE, J (1995): Environmental Microbiology 53, pp 2397-2404 Measurements of mercury methylation in sedi- [3] KING, J, KOSTKA, J, FRISCHER, M, SAUNDERS, F ments by using enriched stable mercury isotopes (2000): Sulfate-Reducing Bacteria methylate combined with methylmercury determination by mercury at variable rates in pure culture and in gas chromatography-inductively coupled plasma marine sediment; Applied Environmental Micro- mass spectrometry; Journal of Analytical Atomic biology 66, pp 2430-2437 Spectrometry 10, pp 619-624 [4] COMPEAU, G, BARTHA, R (1985): Sulfate-Reducing [9] HINTELMANN, H, EVANS, R (1997): Application of Bacteria: Principle methylators of mercury in stable isotopes in environmental tracer studies the anoxic estuarine sediment; Applied Environ- measurement of monomethylmercury (CH Hg+) 3 mental Microbiology 50, pp 498-502 by isotope dilution ICP-MS and detection of [5] ULLRICH, S, TANTON, T, ABDRASHITOVA, S (2001): species transformation; Fresenius Journal of Mercury in the aquatic environment: a review Analytical Chemistry, 358, pp 378-385 of factors affecting methylation; Critical Re- [10] GILMOUR, C, HENRY, E, MITCHELL, R (1992): Sul- views of Environmental Technology 31, pp 241- fate stimulation of mercury methylation in fresh- 293 water sediments; Environmental Science and [6] WATRAS, C, MORRISON, K, HOST, J (1995): Con- Technology 26, pp 2281-2287 centration of mercury species in relationship to [11] INGVORSEN, K, ZEIKUS, J, BROCK, T (1981): Dy- other site-specific factors in the surface waters namics of bacterial sulfate reduction in a of northern Wisconsin lakes; Limnology and eutrophic lake; Applied Environmental Micro- Oceanography 40, pp 556-565 biology 42, pp 1029-1036

RMZ-M&G 2004, 51 968 PART 2 BIOGEOCHEMISTRY

Mercury Methylation By Sulfate-Reducing Bacteria Independent of Vitamin B 12

EILEEN B EKSTROM1 AND FRANÇOIS M M MOREL2

1Department of Civil and Environmental Engineering; 2Department of Geosciences, Princeton University, Guyot Hall, Princeton, New Jersey, USA, E-mail: eekstrom@princeton&edu, morel@princeton&edu

Abstract: Mercury methylation by sulfate-reducing bacteria (SRB) is the predominant mechanism for methylmercury production in freshwater and coastal systems, yet little is known about the biochemistry of Hg methylation in SRB Vitamin B has been long considered 12 to be the Hg methylating coenzyme in the enzymatic formation of methylmercury, since it was believed to be the only major methylating coenzyme which would donate a me- thylcarbanion (CH -) group able to bind with inorganic mercury In addition, vitamin 3 B can methylate mercury abiotically, and a corrinoid compound was found to be im- 12 portant in the methylation of Hg by Desulfovibrio desulfuricans LS Our recent work has demonstrated that Hg methylation is independent of the corrinoid-containing enzyme in the acetyl-CoA pathway in incomplete-oxidizer SRB strains that do not utilize the acetyl-CoA pathway for major carbon metabolism Based on cobalt limitation studies on the incomplete-oxidizer Desulfovibrio africanus, we propose that mercury methylation is in fact independent of vitamin B in this SRB strain In contrast, the com- 12 plete-oxidizer D multivorans appears to utilize vitamin B in mercury methylation 12 Separate pathways for Hg methylation among incomplete and complete- oxidizing SRB are emerging

Key words: SRB, sulfate, bacteria, methylmercury, vitamin B 12

INTRODUCTION ercury formation is key to understanding the parameters that control its production and In most aquatic ecosystems, in situ methylm- may prove useful for designing successful ercury formation plays a primary role in de- mitigation strategies termining the amount of methylmercury Vitamin B has been long considered to be reaching higher trophic levels Inorganic 12 mercury is methylated by sulfate-reducing the Hg methylating coenzyme in the enzy- bacteria (SRB) in the anoxic portion of the matic formation of methylmercury WOOD sediments or water column Although con- (1974) originally proposed that a methyl siderable work on the environmental factors corrinoid derivative is the methylating agent controlling methylmercury production has for inorganic mercury, since it was the only been completed, few studies have been con- major coenzyme capable of donating a methyl group in a carbanion (CH -) form ducted on the physiology and biochemistry 3 of mercury methylation by SRB Increased Methylcorrinoids were also found to be ca- knowledge of the mechanisms of methylm- pable of abiotic methylmercury synthesis

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 969

(RIDLEY, 1977) In the SRB strain, means to probe the metal requirements of Desulfovibrio desulfuricans LS, CHOI ET AL various biochemical processes# However, (1994) identified a corrinoid-containing pro- few trace metal limitation studies have been tein as critical for mercury methylation ca- conducted on bacteria, let alone anoxic bac- pacity based on propyl-iodide inhibition ex- teria# Vitamin B , which contains a cobalt 12 periments They later concluded that the reactive center, is used in a limited suite of corrinoid-containing protein responsible for methyltransferase and isomerization reac- Hg methylation in D desulfuricans LS is tions# Cobalt-limitation experiments can involved in the acetyl-CoA pathway (CHOI, therefore act as an effective means to ana- 1994a) lyze the connection between vitamin B and 12 Hg methylation# Based on our recent work (EKSTROM, 2003), the acetyl-CoA pathway does not appear to We have performed cobalt limitation experi- be the controlling mechanism of mercury ments on an incomplete-oxidizing strain, methylation in SRB Complete-oxidizing Desulfovibrio africanus, which does not use strains that require the acetyl-CoA pathway the acetyl-CoA pathway for Hg methylation, for major carbon metabolism have the ca- and the complete-oxidizer, Desulfococcus pacity to methylate mercury We have also multivorans, which could possibly use the examined four incomplete-oxidizing strains acetyl-CoA pathway for Hg methylation# that methylate Hg None of these strains uti- Growth of D africanus in later transfers ap- lize the acetyl-CoA pathway for either me- pears to recover from an initial cobalt-lim- tabolism or for mercury methylation, based ited growth period# Hg methylation in co- on enzyme activity and chloroform inhibi- balt-limited cultures of D africanus is not tion assays Low concentrations of chloro- significantly different than in metal-replete form have been shown to be an effective in- cultures, suggesting that methylmercury pro- hibitor of the acetyl-CoA pathway in SRB, duction is independent of cobalt-dependent and are likely to also act as a general vita- Vitamin B # In contrast, D multivorans, 12 min B inhibitor (WOOD, 1968; GHAMBEER, under cobalt-limited growth, methylated 12 1971) Thus, Hg methylation may not require mercury 3 times lower than metal-replete vitamin B in some and perhaps many in- cultures after normalizing to growth rate# 12 complete-oxidizing SRB strains Therefore, D multivorans appears to utilize vitamin B in mercury methylation# Sepa- 12 rate pathways for Hg methylation among EXPERIMENTAL DESIGN, RESULTS incomplete and complete- oxidizing SRB are AND DISCUSSION emerging, utilizing different methylating cofactors# To further investigate the coenzyme requirements of Hg methylation in SRB, we are Acknowledgements conducting trace metal limitation studies on selected SRB strains# Trace metal limitation This work was supported by the US Envi- experiments have been championed by phy- ronmental Protection Agency and the Na- toplankton physiologists as an effective tional Science Foundation#

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REFERENCES

CHOI, S-C, CHASE, T AND BARTHA, R (1994): Enzy- RIDLEY, W P, DIZIKES, L J AND WOOD, J M (1977): matic catalysis of mercury methylation by Biomethylation of toxic elements in the envi- Desulfovibrio desulfuricans LS; Appl Environ ronment; Science, Vol 197, pp 329-332 Microbiol, Vol 60, pp 1342-1346 WOOD, J M, KENNEDY, F S AND WOLFE, R S (1968): CHOI, S-C, CHASE, T AND BARTHA, R (1994a): Meta- The reaction of multi-halogenated hydrocarbons bolic pathways leading to mercury methylation with free and bound reduced vitamin B ; 12 in Desulfovibrio desulfuricans LS; Appl Biochem, Vol 7, pp 1707-1713 Environ Microbiol, Vol 60, pp 4072-4077 WOOD, J M (1974): Biological cycles for toxic ele- EKSTROM, E B, MOREL, F M M AND BENOIT, J M ments in the environment; Science, Vol 183, pp (2003): Mercury methylation independent of the 1049-1052 acetyl-CoA pathway in sulfate-reducing bacteria; Appl Environ Microbiol, Vol 69, pp 5414- 5422 GHAMBEER, R K, WOOD, H G, SCHULMAN, M AND LJUNGDAHL, L (1971): Total synthesis of acetate from CO2, methyltetrahydrofolate, and methyl- B by Clostridium thermoaceticum; Arch 12 Biochem Biophys, Vol 143, pp 471-484

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 971 Mercury in the Environment and Global Climate Change: Recent Evidence for Multiple Synergistic Relationships

VICTORIA EVANS1, AARON MANN1 & JOSH ROMEIS1

1Tetra Tech EM Inc , San Francisco, CA, USA

Abstract: This paper provides a discussion of recent scientific evidence that documents multiple synergistic relationships between mercury emissions, mercury cycling and factors related to global climate change (GCC) Researchers have previously hypothesized that GCC could enhance the mobilization and bioaccumulation of mercury in ways that could increase the risk of human exposure Recent scientific research has focused upon mercury emissions and mercury cycling in the environment and yielded a significantly improved understanding of the biogeochemical processes at work These studies provide insights from both field and laboratory measurements and from all of the environmental compartments involved in mercury cycling Taken together, the results of these scientific studies can document a relationship between mercury cycling and several GCC factors that promote the cycling of mercury in the environment, ie, increase the mobilization and bioavailability of mercury in the environment First, recent studies document that the rate of oxidation of elemental mercury increases with increased solar radiation This reaction increases the levels of reactive gaseous mercury (RGM), ie, a precursor of the bioavailable form of mercury Solar radiation has been found to increase the level of mercury released from soils, substrate and snow pack Second, an increase in the release of mercury from substrate is related to temperature as has been demonstrated during forest fires and at geothermal sites located in mercuriferous geology Third, episodic events such as rainfall increase emissions of mercury from soils Fourth, mercury bioaccumulation in fish has been closely linked to the production of dissolved organic carbon, with an increase in bioaccumulation levels possible with increased water temperature Based upon these and other findings, multiple synergistic relationships have been found to exist between mercury cycling and climate change As a result, this paper suggests a new term, the Muir Effect for describing multiple synergisms that occur in complex environmental cycles The Muir Effect is named after well-known American naturalist, John Muir and is inspired by his words that, When we try to pick out anything by itself, we find it hitched to everything else in the universe

RMZ-M&G 2004, 51 972 PART 2 BIOGEOCHEMISTRY

Total Mercury in Bottom Sediment Samples from Admiralty Bay, King George Island, Antarctic Region

DÉBORAH I.T. FÁVARO1, GLEVERSON P. M. C AVALLARO1, SANDRA R. DAMATO2, BARBARA P. M AZZILLI2; ELISABETE S. BRAGA3, G.E. BOSQUILHA3 & G.B.B. BERBEL3

1Laboratório de Análise por Ativação Neutrônica(LAN)-CRPq – IPEN/CNEN-SP, Av. Prof. Lineu Prestes 2242, CEP: 05508-000, São Paulo, Brazil, e-mail: [email protected] 2Divisão de Radiometria Ambiental - Centro de Metrologia das Radiaçëes–IPEN/CNEN-SP, Brazil 3LABNUT- Laboratório de Nutrientes, Micronutrientes e Traços nos Oceanos- Instituto Oceanográfico – Universidade de São Paulo, Brazil

Abstract: Brazilian Antarctic Program (PROANTAR) was implemented in January 1982. Brazilian activities in Antarctic are based at the “Comandante Ferraz” Antarctic Station (EACF), in four quarters settled on Brendsfield strait, Elephant, Nelson and King George (62°05’S and 58°25’W) Islands. Since 1982 several scientific projects have been developed and one of them is called Hydrogeochemistry of Admiralty Bay. One of the purposes of this recent project is to assess the content of heavy metals in sediment samples. The main goal of the present work was to determine total mercury concentration and phosphorus (organic and total) in sediments samples from Admiralty Bay, Antarctic region. Bottom sediments were collected during the sampling trip in January/February 2003 (21st Antarctic campaign -summer season) by using a steel Van Veen- type dredge. Although 21 sampling sites have been visited, only 14 sediment samples could be collected. After collecting the samples, they were frozen (-20 °C) and kept in this condition. In the laboratory all samples were previously dried at 40oC in a ventilated oven and passed through a 0.065 mm sieve and homogenized before analysis. For total mercury determination sediment samples were analyzed by FIA-CV-AAS technique using a FIMS 100 from Perkin Elmer. Samples

were digested by a mixture of HNO3, H2SO4 and H2O2 in Teflon vials. The vials were closed and left overnight at room temperature. In the following day, the vials were put into an aluminum block at 900C and left there for 3 hours. The validation of the methodology was performed by certified reference materials analysis: Buffalo River Sediment (NIST SRM 2704), Estuarine Sediment (NIST SRM 1646a) and Lake Sediment (BCR CRM 280). Relative standard deviation ranging from 1.3 to 2.9 and relative errors ranging from 0.5 to 3.7 were found in the reference materials analyses. The concentration of total mercury in the sediment samples varied from 53 to 210 µg kg-1 in all samples distributed along Admiralty Bay. Only sample 12 (point 12 - located at Mackellar Inlet) showed a total mercury concentration of 1789 ± 36 µg kg-1, value considered too high for this region. The sample 17 (point 17- located at the eastern part of Martel Inlet) showed the lowest value (53 ± 2 µg Hg kg-1). The values obtained for total phosphurus in the sediment samples were: the highest value at point 12 (838.9 µmol-P/g) and the lowest value, at point 17 (639.0 µmol-P/g). Inorganic P content was higher at point 12 (631.4 µmol-P/g) and lower at point 3 (494.7 µmol-P/g). Organic P showed the higher value in front of the Brazilian base (264.9 µmol-P/g) and the lower value at point 17 (44.0 µmol-P/g). At point 12, the percentage of inorganic P fraction was around 75 %. It indicates the terrestrial input of inorganic matter in this sediment with low contribution of organic matter. This remote zone seems to show mercury concentration values in the reference levels except for the sites that show important processes of accumulation or intense input from the soil of this region.

Key words: sediments, total mercury, antarctic region

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 973 Mercury and Trace Elements in Norwegian Lake Sediments - a National Survey

EIRIK FJELD AND SIGURD ROGNERUD

Norwegian Institute for Water Research, PO Box 173 Kjelsaas, N-0413 Oslo, NORWAY; E-mail: eirikfjeld@nivano, sigurdrognerud@nivano

Abstract: Concentrations of trace elements were determined in sediments from 231 lakes during a national survey in 19961997 The mercury concentrations had increased considerable in surface sediments (mainly 005 cm) compared to deeper pre-industrial sediments, especially in the boreal low-land areas in the south The differences between concentrations in surface and sub-surface sediments (051 cm) were in general minor, indicating that the mercury supply to the lakes have been rather stable during the latest decades The mercury concentrations in five dated sediment cores increased during the period of 19001980, followed by a decrease in the most recent sediment layers Multi- variate statistical analyses (redundancy analyses) showed that in the surface sediments, Hg together with Pb, Se, Bi and Sb formed a group closely associated to the organic sediment fraction Atmospheric depositions are the probable major sources for these elements, and the depositions are likely scavenged by sedimenting humic matter In the pre-industrial sediments, only Hg, Sb and Se were associated to the organic sediment fraction, whereas Pb and Bi here were indifferent with respect to the organic-inorganic gradient

Key words: mercury, trace elements, lake sediments, Norway

INTRODUCTION local sources of mercury pollution Concen- trations of several trace elements were de- Our main objective was to identify the spa- termined in surface sediments (mainly the tial gradients and the temporal trends in pol- 0-05 cm layer; 21 samples of the 0-1 cm lution history of Hg and other trace elements layer) and pre-industrial sediments (between by studies of lake sediments from Norway 3050 cm) Sub-surface sediment samples Further, we wanted to relate these patterns (05-1 cm layer) from 210 of the lakes were to anthropogenic and natural sources, and also analyzed In addition, mercury concen- identify other trace elements with similar trations and fluxes of mercury to lake sedi- pollution history and behavior The study is ments during the last decennium were esti- based on sediments from 231 lakes, sampled mated in dated sediment cores from five during a national survey in 19961997 lakes situated in the acidified area of South- (ROGNERUD AND FJELD, 1999; ROGNERUD AND ern Norway FJELD, 2001) The lakes have no significant

RMZ-M&G 2004, 51 974 PART 2 BIOGEOCHEMISTRY

RESULTS AND DISCUSSION centrations in surface and sub-surface sediments showed that there had been a marked Correlations indicated that mercury prima- increase in a confined area in south-west of rily was associated to the organic sediment Norway (005015 µg·g-1 LOI) This is an fraction (loss on ignition) in both surface and area where the annual precipitation has in- pre-industrial sediments (Spearman rho: : creased with about 10 % during the 1990s 076 and 064) Therefore, to adjust for dif- (FØRLAND ET AL, 2000) ferences in the sediments organic content, the concentrations were calculated per gram Analyses of the dated cores from South Nor- organic matter (LOI, loss on ignition) The way showed that the sedimentation rate of mercury concentrations in surface sediments organic matter varied significantly in several varied usually between 041142 µg·g-1 LOI of the lakes, probably due to regulations and (1090 percentiles), or a factor of 1456 human activities in the watersheds The mer- higher than the reference sediments The dif- cury flux, which is coupled to the organic ferences between the concentrations in sur- sediment flux, could therefore not be used face and pre-industrial sediments varied usu- as a proxy for the atmospheric deposition ally between 014103 µg·g-1 LOI, with the rates of mercury The sediment concentra- largest increase in boreal low-land areas in tions, adjusted for differences in the organic the south (Fig 1) The differences between sediment fraction, were probably better surface an sub-surface sediments were mi- suited as a pollution indicator From the on- nor, usually between -018017 µg·g-1 LOI set of the 1900s, the general trend in the five The map of the differences between the con- cores was that the mercury concentration

Figure 1 Generalized maps (krieged) showing the differences between mercury concentrations in surface sediments (0-05 cm) and pre-industrial sediments, and between surface sediments and sub-surface sediments (05-1 cm) The differences in concentrations (∆Hg) are given per gram organic matter (LOI, loss on ignition)

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 975 increased monotonically to the 1980s The the depositions are scavenged by sedi- maximum levels reached were in the inter- menting humic matter in lakes Chromium val 082210 µg·g-1 LOI This is an increase and copper were more associated to the in- with a factor of 42127 compared with the organic sediment fraction, which reflects pre-industrial levels After the 1980s, there their major geochemical sources was in general a moderate decrease in the concentrations to about 066156 µg·g-1 LOI In the pre-industrial sediments, only mercury, in the most recent sediment layers For some antimony and selenium were strongly asso- of the lakes, which is situated close to met- ciated to the organic sediment fraction This allurgic industries, we assume this decrease indicates that atmospheric depositions were largely reflects the reductions of local mer- the dominating sources for these elements cury emissions also in pre-industrial times Lead and bismuth shifted from being strongly associated A multivariate statistical analysis (redun- to organic matter in the surface sediments, dancy analysis) of several trace elements to be indifferent with respect to the organic- showed that mercury, together with lead, se- inorganic gradient in the pre-industrial sedi- lenium, bismuth and antimony, were strongly ments This change probably reflects a shift associated to the organic sediment fraction in their origin, from mainly geochemical in the surface sediments We assume this resources in pre-industrial times to atmospheric flects that atmospheric depositions now are depositions during the last century the major sources for these elements, and that

Figure 2 Mercury concentrations and accumulation rates in dated lake sediment cores from south Norway The concentrations are given per gram organic matter (LOI, loss on ignition)

RMZ-M&G 2004, 51 976 PART 2 BIOGEOCHEMISTRY

CONCLUSIONS selenium, bismuth and antimony formed a distinct group associated to the organic frac- The mercury concentrations in surface sedi- tion of the surface sediments, which reflects ments in Norwegian lakes were significantly the strong influence of atmospheric deposi- elevated compared to pre-industrial sedi- tions In the pre-industrial sediments, mer- ments, usually by a factor between 1456 cury, selenium and antimony were still as- The differences between surface and subsur- sociated to the organic sediments, whereas face sediments were in general minor, indi- lead and bismuth here showed no associa- cating that the mercury supply to the lakes tion This shift which probably reflects a have been rather stable during the last de- change towards a more geochemical origin cades An increase was found in an area where the annual precipitation had increased Acknowledgements during the 1990s Dated cores from industrialized areas in South Norway showed that This work was primarily financed by The the mercury concentrations increased dis- Norwegian State Pollution Control Author- tinctly during 19001980, followed by a slow ity (SFT) Additional fundings was supplied decrease in the latest decades Mercury, lead, by The Research Council of Norway and The Norwegian Institute for Water Research

REFERENCES

FØRLAND, E ROALD, L A, TVEITE, O E, HANSSEN- ROGNERUD, S & FJELD, E (2001): Trace element con- BAUER, I (2000): Past and future variation in tamination of Norwegian Lake Sediments; climate and runoff in Norway; DNMI KLIMA Ambio 30, pp 11-19 Report 19-00, the Norwegian Meteorological Institute, Oslo ROGNERUD, S & FJELD, E (1999): National survey of metals in lake sediments NIVA-report No 4024- 99 Norwegian Institute for Water Research, Oslo 71 p (In Norwegian)

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 977 The Effect of Organic and Inorganic Ligands

JR FLANDERS, CYNTHIA GILMOUR, CARRIE MILLER, ROBERT MASON & A RUSSELL FLEGAL

Abstract: The speciation of inorganic mercury (HgI) has been shown to be an important factor controlling the methylation of HgI by sulfate-reducing bacteria (SRB) in anaerobic sediments In particular, the presence of neutral mercury sulfide species controls the diffusion of HgI into SRB cells The formation rate of bioavailable HgI species is critical to understanding how Hg methylation changes through time and space after deposition to ecosystems We seek to understand the kinetics of Hg ligand formation in complex systems in order to model Hg bioavailability in ecosystems In this study, monomethylmercury (MMHg) production by a pure culture of a methylating SRB was used as a surrogate for the rate of formation of neutral HgS complexes from other Hg- ligand complexes We exposed the methylating SRB Desulfobulbus propionicus 1pr3 to HgI initially complexed with EDTA, thioglycolate, oxalate, or chloride, and measured MMHg production over the course of 72 hours The experiments were done in a defined culture medium in which neutral HgS would be the dominant dissolved HgI complex at equilibrium All work was carried out in defined fermentative media under anaerobic conditions using the modified Hungate technique MINEQL+ chemical speciation software was used to design the initial complexes and determine the chemical speciation of HgI under the experimental conditions Culture spiked with Hg - EDTA or Hg - thioglycolate complexes, ligands with relatively high stability constants for mercury, had higher MMHg concentrations per cell than treatments exposed to Hg - Cl or Hg - oxalate There were no differences in growth, pH, or sulfide among treatments Dissolved mercury concentrations did not differ among treatments, suggesting that differences in MMHg concentration were not due to enhanced solubility of HgI Chemical equilibrium modeling predicts that at equilibrium, the concentration of neutral mercury species would not differ among treatments, suggesting that the system was not at equilibrium Estimates of octanol-water partitioning of Hg during similar experiments also suggest that chemical equilibrium was not achieved in any of the ligand treatments within 24 hours These results suggest that the kinetics of neutral mercury sulfide species formation is affected by the presence and type of other ligands in the system The mechanism behind these altered kinetics is at present unknown, but our results suggest that thermodynamically stable complexes such as Hg- EDTA may be more kinetically labile than smaller, less stable complexes Alternatively, Hg-EDTA and Hg-thioglycolate complexes may be taken up directly by cells

Key words: mercury, sulfate-reducing bacteria, uptake

RMZ-M&G 2004, 51 978 PART 2 BIOGEOCHEMISTRY

Mercury in San Francisco Bay: Two centuries of contaminant fluxes

A RUSSELL FLEGAL, CH CONAWAY, EJ KERIN, AC LUENGEN, FJ BLACK & MM GILMORE

Environmental Toxicology/WIGS, University of California, Santa Cruz

Abstract: San Francisco Bay has received fluxes of industrial mercury since the middle of the nineteenth century, when the New Almaden mines went into production Discharges from that mining region, the most productive in North America, have continued to flow through the Guadalupe River and into the southern reach of San Francisco Bay since then Similarly, mercury from those mines used during the California Gold Rush have continued to flow from the Sierra Nevadas through the Sacramento and San Joaquin rivers into the northern reach for nearly two centuries, as have discharges from the New Idria cinnabar mine, the second most productive mercury mining region in North America The objectives of our research have been to quantify those fluxes and their impact on mercury loadings in the estuary A suite of complementary analyses have been made to quantify those fluxes on scales ranging from seasonal to annual to decadal to centuries Historic fluxes have been derived from sediment core data; seasonal to decadal fluxes have been determined from an ongoing sampling program of surface waters and sediments; and projections of future fluxes have been estimated from time series analyses Those analyses show order of magnitude perturbations of the mercury cycle in the estuary over the past 150 years, and they indicate mercury fluxes to the estuary will continue to be dominated by historic depositions of industrial mercury for decades, if not centuries Consequently, efforts to lower the level of mercury contamination in the estuary by reducing contemporary discharges of industrial mercury appear to be relatively small and ineffective

Key words: model, San Francisco Bay, biogeochemical cycles

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 979

Hg and Se Contents in Sediment of the Barra Bonita and Bariri Reservoirs (Medium Tietê River, SP – Brazil), and it Availability

D.D. FRAGOSO1, F.P.B. STOLF2, J. MORTATTI1, J.R. FERREIRA1, M.M. MELLO3 & S.S. DE SOUZA3

1Centro de Energia Nuclear na Agricultura – CENA-USP, Universidade de São Paulo, Av. Centenário 303, 13400-97, Piracicaba, Brazil 2Faculdade de Engenharia, Arquitetura e Urbanismo – Universidade Metodista de Piracicaba – UNIMEP, Rodovia Santa Bárbara/Iracemápolis, Km 01, 13450-00, Sta Bárbara D’Oeste, Venezuela 3Universidade Federal de São Carlos – UFSCA, Rod. Washington Luiz, Km 235, 13565 –, Sao Carlos, Brazil

Abstract: The barra Bonita and the Bariri Reservoirs located at 22029”Latitude South; 48034’ Longitude West and 22006’ Latitude South; 48045’Longitude West respectively, belong to the Medium Tiete River, the biggest one of the São Paulo State, Brazil, 1050 Km long. The Tietê River is devided by 7 dams in its total extension, being the Barra Bonita Reservoir (32,330 Km2 area; mirror of water 33,430 ha), positioned just upstream of the Bariri one (35,430 Km2; mirror of water 5,461 ha), being both of them with a similar geology. The aim of this paper was to assess for the actual levels of Hg in these ecosystems, as in 1981, high concentration of total Hg were found in carnivorous fishes (plagioscion squamossis), catched at Barra Bonita Reservoir. In addition to that it were included in these studies, data on Se biogeochemistry, due to the antaghonic whole of this chemical element to Hg in the environment, and to carry out work downstream, in the Bariri Reservoir. In this sense, eight sampling points were established, four per each Reservoir. From these sampling points, only one, BA1 (Barra Bonita – Point 1), were at the Piracicaba River, the main tributary of the Tietê River, positioned at its right side. The sampling station BA2, was positioned upstream this confluence point. All other sampling points were sequentially positioned downstream the main channel. Superficial water samples and sediments were sampled at each point, on March 2002, April, July and October 2003. Water samples were analysed for total Hg and Se by AFS, PSAnalytical Ltd. Physico-chemical parameters (conductivity, turbidity, dissolved oxygen, temperature, total dissolved solids, pH and redox potential - Eh) were measured at the water column by using an analyzer HORIBA U-22. Sediment samples were analysed for C, N, pH, Hg, Se and granulometry. For the estimation of potential toxicity of the sediments, analysis of acid-volatile sulfide (AVS) were performed and the content of Pb, Cd, Zn, Ni and Cu (Simultaneous Extracted Metals – SEM) determined by ICP-AES, Optima 3000, Perkin-Elmer. Results indicated very low concentrations of both Hg (< 2.00 ng/L) and Se (5.00 ng/L) in water basins. Hg and Se were at ng.g-1 range in sediments. At such levels and with abiotic factors presented, both compartments wouldn’t correlated to the high content of Hg observed in fish previously. The ratio of AVS/SEM varied in a wide range of magnitude, depending on the season and on the sampling points, being Hg presented also in the AVS extracts (HCl 0.5M). This could be an indication that this small fraction of the S2- reservoir could control de Hg availability, moreover due to the low activities observed for Se in these systems.

RMZ-M&G 2004, 51 980 PART 2 BIOGEOCHEMISTRY

Hg and Se contents in sediment of the Barra Bonita and Bariri Reservoirs (Medium Tietê River, SP – Brazil), and it availability

FRAGOSO, D. D.1, STOLF, F. P. B.2, MOURA, M. A. M.3, DE SOUZA, S. S.1, MORTATTI, J.1 AND FERREIRA, J.R.1, 4

1Centro de Energia Nuclear na Agricultura – CENA-USP, Universidade de São Paulo. Av. Centenário 303, 13400-970 – Piracicaba, SP, Brasil 2Faculdade de Engenharia, Arquitetura e Urbanismo – Universidade Metodista de Piracicaba – UNIMEP, 13450-000 - Rodovia Santa Bárbara/Iracemápolis, Km 01 – Sta Bárbara D’Oeste, SP, Brasil 3Universidade Federal de São Carlos – UFSCAr; Rod. Washington Luiz, Km 235, 13565 – 905 – São Carlos, S.P, Brasil 4Instituto de Pesca – Agência Paulista de Tecnologia dos Agronegócios – APTA – Av. Francisco Matarazzo 455, 05001-900, São Paulo, SP, Brasil; E-mail: [email protected].

Abstract: The purpose of this paper was to assess the levels of Hg in the Barra Bonita and Bariri Reservoirs, because in 1981, high concentrations of total Hg were found in carnivorous fishes (plagioscion squamossis), from the Barra Bonita Reservoir. In addition, data on Se biogeochemistry, due to its antaghonic relationship with Hg in the environment, and a similar work at the Bariri Reservoir were carried out. Eight sampling locations were established, four in each Reservoir. From these sampling locations, only one, BA1 (Barra Bonita – Point 1), was at the Piracicaba River, the main tributary of the Tietê River,. The sampling station BA2, was positioned upstream of this confluence. All other sampling locations were sequentially positioned downstream. Superficial water samples and sediments were sampled at each location, on March 2002, and April, July and Octo- ber 2003. Water samples were analysed for total Hg and Se by AFS, using a PS Analyti- cal Ltd instrument. Physico-chemical parameters (conductivity, turbidity, dissolved oxygen, temperature, total dissolved solids, pH and redox potential - Eh) were measured at the water column by using an analyzer HORIBA U-22. Sediment samples were analyzed for C, N, pH, Hg, Se and granulometry. For the estimation of potential toxicity of the sediments, analysis of acid-volatile sulfide (AVS) were performed and the concentrations of Pb, Cd, Zn, Ni and Cu (Simultaneous Extracted Metals – SEM) were determined by ICP-AES, using a Perkin-Elmer Optima 3000. Results indicated very low concentrations of both Hg (< 2.00 ng.L-1) and Se (5.00 ng.L-1) in the water basins. Hg and Se were at ng.g-1 levels in sediments and probably the high concentrations of Hg previously observed in fishes catched at the Barra Bonita Reservoir, were either due to the methylation of the inorganic mercury in this compartment, or by an alloctone source. The ratio of AVS/SEM varied over a wide range of magnitude, depending on the season and on the sampling points, being Hg presented also in the AVS extracts (HCl 0.5 M). This could be an indication that this small fraction of the S2- reservoir could control de Hg availability, moreover due to the low activities observed for Se in these systems.

Key words: mercury, selenium, biogeochemistry, reservoirs, AVS.

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 981

INTRODUCTION RESULTS AND DISCUSSION

Natural chemical cycles and movement of In all situations the levels of Hg and Se in contaminants, occur faster in aquatic systems water were lower than the limit of detection than in terrestrial ones, where through the (LOD) of the AFS method, being established food chain potentially reaches human con- in the experimental conditions as 2 and 5 ppt [1] sumers . Rivers, which integrateing the land respectively. As observed in the water pro- and the hydrosphere, and play a whole in the files, the pH varied slightly both with depth biogeochemical cycles of elements, are of and spatially being alkaline. Eh decreases [2] great current concern . Such is the case of with depth, varying from negative to posi- the Tiete Hydrographic Basin, the biggest tive values. Although the concentrations of river of São Paulo State, which is 1000 km total Hg and Se were very low, with the ob- long, and receives a wide range of pollut- served range of Eh and pH variables, few ants loads, including those from the agricul- chemical species of Hg as Se could be ex- tural activities, were considered potentially pected in these ecosystems. No thermal [4] important source of Hg . In addition to that, stratification was observed in the water col- hydroelectric reservoirs can cause a rise of umn during the different sampling periods. [5] Hg content in edible fishes . The Tietê River The sediment granulometry, classified as to- has over seven dams along its length, and in tal sand, silt and clay, varied between the two 1981, high concentration of Hg were detected reservoirs and also from point to point in the in a carnivorous fishes (Plagioscion same reservoir. Figure 1 indicates the degree squamossis), caught from the Barra Bonita of such variation for sediment samples col- [6] Reservoir . Selenium, an essential element, lected at the Barra Bonita in July 2003. The has been shown to reduce the bioaccumu- percentage of clay decreases from point BA1 [7] lation of Hg in aquatic systems , and has towards BA4, positioned closer to the dam. even been recommended as a possible treat- It was observed smaller granulometry varia- ment to reduce the contamination level of tions for two samples collected at same time [8] fish in Swedish Lakes . The complexity of for the same point. This is probably because [9] the global Hg cycle is well recongized, and the bottom sediment has been mobilized and [10] Se can be strongly involved . The Barra re-suspended by sand exploration boats op- Bonita and the Bariri Reservoirs are located erating in both reservoirs. Although partition- about midway along the length of the Tiete ing of metals to suspended sediment is River. At these locations, we investigated Hg known to be important, granulometry did not and Se biogeochemical interactions, in which predict the Hg and Se concentrations in the Se controls the availability of Hg to the biota. sediment. Total Hg and Se concentrations Sampling of surface water and sediments varied in the range of 0.04 to 0.6 ppm and were carried out in both ecosystems at dif- 0.04 to 2.4 ppm respectively. By employing ferent seasons, as described in the above ab- sequential approaches (acetic acid, hydroxy- stract. lamine and hydrogen peroxide), only Hg and not Se were not detected in all extractants. On the other hand, very low concentration

RMZ-M&G 2004, 51 982 PART 2 BIOGEOCHEMISTRY of Zn, Cu, Cd, Pb and Ni were observed. varied widely, and was usually higher than Volatile Acid Sulphate (AVS) and its ratio to 1, leading to a very low potentiality for met- the total amount of micro-equivalents of the als delivery to the environment. Highest ra- above metals were also determined. Only Hg tios were always observed at point BA2, the was detected in the acid extract, and at very sampling location nearest to the pollution low concentrations. The AVS/SZn,Cd,Ni,Pb,Cd source on the Tiete River.

Figure 1 Granulometry percentage of particles presented in a sediment samples from the Bariri Reservoir, collected on July, 2003 Positioned from left to the right, points BI1, BI2, BI3 and BI4 respectively, are separated in Km

CONCLUSIONS contents and the absence of Se in AVS extracts indicate a competition between Se and Environmental compartments, such as wa- S for Hg species in these ecosystems. ter and sediment, of the Barra Bonita and the Bariri Reservoirs do not present high Acknowledgements concentrations of Hg and Se. Considering the Our gratitude to Fundação de Amparo à observed values of the AVS/SZn,Cd,Ni,Pb,Cd, ratios, sediments shouldn’t be considered the Pesquisa do Estado de São Paulo – FAPESP, source Hg and other metals to the biota, as for the grant in the Research Project n0: shown out in 1981. The presence of low Hg 00/14460-3.

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 983

REFERENCES

[1] [6] BURGER, J. & SNODGRASS, J. (2001): Metal levels in EYSINK, G. G. J. L., PÁDUA, H. B. & MARTINS, M. C. Southern Leopard Frogs from the Savannah (1988): Presença do mercúrio no ambiente; River Site: location and body compartment ef- Ambiente, Vol. 2, No. 1, pp. 43-50. [7] fects; Environmental Research Section, Vol. 86, SOUTHWORTH, G. R., PETERSON, M. J. & RYON, M. G. pp. 157-166. (2000): Long-term increased bioaccumulation [2] WETZEL, R. G. (1975): Limnology; W. B. Saundres. of mercury in largemouth bass follows reduc- Philadelphia, 743 p. tion of waterborne selenium; Chemosphere 41, [3] CETESB (1986): Avaliação do níveis de pp.1101-1105. [8] contaminação por mercúrio na água, sedimento PAULSSON, K. & LUNDBERGH, K. (1991): Treatment e peixes na Represa de Barra Bonita e seus rios of mercury contaminated fish by selenium ad- formadores: Piracicaba e Tietê, São Paulo, dition; Water, Air and Soil Pollution 56, pp. 833- CETESB, 115 p. 841. [4] [9] SHANKER, K., MISHRA, S., SRIVASTAVA, S., SRIVASTAVA, MASON, R. P., MOREL, F. M. M. & HEMOND, H. F. R., DASS, S., PRAKASH, S. & SRIVASTAVA, M. M. (1995): The role of microorganisms in elemen- (1996): Study of mercury-selenium (Hg-Se) in- tal mercury formation in natural waters; Water, teractions and their impact on Hg uptake by the Air and Soil Pollution 80, pp. 775-787 [10] radish (Raphanaus sativus) plant; Food and BJORNBERG, A., HAKANSON, L & LUNDBERGH, K. Chemical Toxicology 34, pp. 883-886. (1988): A theory on the mechanisms regulating [5] JACKSON, T. (1991): Biological and environmental the bioavailability of mercury in natural waters; control of mercury accumulation by fish in lakes Environmental Pollution 49, pp. 53-61. and reservoirs of Northern Manitoba, Canada; Canadian Journal of Fisheries and Aquatic Sci- ence, Vol. 48, No. 12, pp. 2449-2470.

RMZ-M&G 2004, 51 984 PART 2 BIOGEOCHEMISTRY

Mercury Flux from Remote Forested Areas

KUMAR GANESAN

Abstract: Mercury flux measurements were done in remote forested sites and in contaminated sites The mercury emissions from soils which were contaminated even 30 years ago are releasing mercury into atmosphere In addition, mercury flux measurements in remote forested areas in Montana showed measurable levels of mercury emissions

Key words: mercury flux, remote forested areas, mercury release to atmosphere

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 985 Fish Growth Rates Control Mercury Concentrations in certain Sport Fish Species from Eastern Canadian Lakes

STEVE GARCEAU1, MARC LUCOTTE1, MICHEL SIMONEAU1, DENIS LALIBERTÉ2 AND CATHERINE LAROSE1

1COMERN, Université du Québec à Montréal, CP 8888 Succursale CENTRE-VILLE, Montréal (Qc) Canada, H3C 3P8 2Ministère de lEnvironnement, Édifice Marie-Guyart, 7e étage 675 Boul René Lévesque, boîte 22, Québec (Qc), Canada, G1R 5V7 Email: garceausteve@uqamca

Abstract: Mercury concentration in fish can vary dramatically even among nearby lakes, and thus many studies have attempted to determine possible environmental causes for these differences Previous studies have shown that Hg accumulation in fishes is highly influenced by food web structure, diet and fish growth In a previous research, we observed major differences in Hg concentrations among walleye (Stizostedion vitreum) populations of twelve large natural lakes located in four different regions of Québec When considering all walleye populations of the twelve lakes together, we demonstrated that Hg concentrations were significantly correlated to fish growth rates (r=09108; p<0001) This suggested that faster growing walleye will have lower Hg concentrations compared to slower growing fish for a specific length Following these results, we tested this discovery on other species of interest for sport fishermen The purpose of this study was to determine whether fish growth rates would affect the Hg concentrations in sauger (Stizostedion canadense) and lake trout (Salvelinus namaycush) muscles Our study sites for the sauger were three lakes from the Abitibi region and one fluvial lake in the St- Lawrence River For the lake trout, we have studied three lakes of the Chibougamau region Hg concentrations versus total lengths of fish were described using polynomial regressions whereas growth rates were estimated by the Von Bertalanffy growth model Our preliminary results show that the saugers in the Abitibi region have Hg levels in muscles differing from one lake to the other whilst their respective growth rates are only slightly different For the sauger in Lake St-Pierre, we observed that low Hg concentrations in fish were correlated to faster growth rates as what was found for the walleye As for the lake trout in the Chibougamau region, we observed significant differences between the mercury levels in fish of the three lakes while their growth rates were similar These differences seem to be related to the maximum ages reached by the fish rather than to their growth rates Depending on the fish species, the fish growth rates appear to play a role ranging from minor to determinant in the differences observed in the Hg concentrations in fish from one lake to the other

Key words: mercury, growth rates, walleye, sauger, lake trout

RMZ-M&G 2004, 51 986 PART 2 BIOGEOCHEMISTRY

INTRODUCTION with high level of Hg bioaccumulation- and of their importance the local sports fishers Mercury concentrations in fish of comparable lengths exhibit important inter-lake variability, even within the same region and RESULTS AND DISCUSSION this for all fish species Many researches have attempted to link these discrepancies to Methods: physical-chemical characteristics of the lakes All lakes sampled for the present study have (size of the lake, size and nature of the catch- been chosen for being typical large lakes fre- ment, ratio of the watershed to the surface quently used by local Canadian communi- of the lake, pH, total and dissolved organic ties for their fish resources Fish have been carbon and water color) Our previous re- caught using experimental gill nets Total search on walleye (Stizostedion vitreum) has mercury concentrations in fish muscles have shown that fish growth rate can influence the been determined by cold vapor atomic ab- mercury concentrations in fish We found sorption spectrometry (CV-AAS) We have major differences in growth rates and in used the polynomial regression described in lengths vs Hg concentrations between the SIMONEAU ET AL (2004) to characterize the different walleye populations of twelve large relationship between fish length and mercury natural lakes located in four different regions levels in fish tissues This procedure is pow- of Québec (SIMONEAU ET AL, 2004) When erful enough to fit either linear or non-linear considering the walleye populations of the regressions Sauger and lake trout ages have twelve lakes together, growth rates were sig- been estimated by the Société de la Faune et nificantly correlated to Hg concentrations des Parcs du Québec (Lanaudière, (r=09108; p<0001) This suggests that faster Chibougamau and Abitibi regions) Von growing walleye will have lower Hg con- Bertalanffy growth rate model was used to centrations compared to slower growing fish determine the growth rate of each popula- for a specific length The scope of this pre- tion sentation is to validate the relative importance of fish growth rates on Hg concentra- Results and discussion: tions in muscles for other fish species than 1) Sauger: Scatter plots of total lengths ver- walleye, namely: the sauger (Stizostedion sus mercury concentrations for the three stud- canadense) and the lake trout (Salvelinus ied lakes of the Abitibi region and the Lake namaycush) Our study sites for the sauger St Pierre within the St Lawrence River are were three lakes of the Canadian Boreal for- presented in Figure 1A Hg concentrations est, in the Abitibi region (Preissac, Duparquet in sauger of the Abitibi region (Duparquet, and Malartic lakes) and one fluvial lake in Preissac and Malartic lakes) are higher com- the St-Lawrence River system (Lake St- pared to the sauger of the Lake St Pierre All Pierre) For the lake trout, we have studied individuals from the sauger population of the three lakes of the Chibougamau region (Aux Lake Preissac, caught during our sampling Dorés, Chibougamau and Waconichi lakes) exceed the 05 ppm Hg commercialization The sauger and lake trout species were cho- limit In Lake Malartic, saugers are around sen because of their predatory status thus the 05 ppm Hg threshold while the saugers

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 987 in Lake Duparquet have lower Hg concen- through the sampling of many more fish from trations between 0 20 and 0 42 mg/kg Fig- other lakes of the same region The saugers ure 1B presents the Von Bertalanffy growth from Lake Saint-Pierre have the lowest Hg curves (total lengths versus ages) for the 4 concentrations (under 0 25 mg/kg) and have lakes Contrary to what has been observed the highest growth rates in the sampled for the walleye, our preliminary results for sauger populations These results are simi- the sauger reveal pretty similar growth rates lar to what has been observed for the wall- in all three Abitibi lakes (Duparquet, Preissac eye populations (SIMONEAU ET AL, 2004) It and Malartic) whilst Hg concentrations are thus appears that growth rate plays a role on clearly distinct from one lake to the other Hg concentrations in sauger, but that other This observation still needs to be confirmed factors do also play an important role

Figure 1 A) Mercury concentrations vs total lengths; B) Von Bertalanffy growth curves for sauger (Stizostedion canadense) from the Abitibi and St Lawrence River regions

2) Lake trout: Scatter plots of total fish est Hg levels (up to 4 mg/kg) compared to lengths versus mercury concentrations for the lake trout from Waconichi and Aux Dorés three lakes of the Chibougamau region are lakes but lake trout from the three lakes show presented in Figure 2A Figure 4 presents the similar growth rates However there are im- Von Bertalanffy growth curves (total lengths portant differences in fish ages: Lake trout versus ages) for lake trout in the 3 lakes Lake in Lake Chibougamau reach very old ages trout from Lake Chibougamau have the high- (up to 40 years) compared to Aux Dorés (up

RMZ-M&G 2004, 51 988 PART 2 BIOGEOCHEMISTRY to 22 years) and Waconichi (up to 14 years thus appears that growth rates might not play old) lakes This results in higher Hg concen- a key role in explaining Hg levels in lake trations in large fish from Lake Chibougamau trout but more fish data from different lakes compared to fish from the two other lakes It are needed to complete our study

Figure 2 A) Mercury concentrations vs total lengths; B) Von Bertalanffy growth curves for lake trout (Salvelinus namaycush) from the Chibougamau region

CONCLUSIONS the relation is not observed It seems that factors in the ecology of the lake trout, such The relationship between fish growth rate as fish longevity, affect the bioaccumulation and Hg concentrations in fish muscles ob- of Hg However, fish growth rates should be served for the walleye is not universally ap- considered as a key parameter for the study plicable to all fish species For the sauger: of mercury levels in fish along with other the relation seems fairly applicable while environmental parameters modulated by other factors For the lake trout

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 989

Acknowledgements

This work was supported by the Natural Sci- ences and Engineering Research Council of Canada, through the activities of the Collabo- rative Mercury Research Network, based at the Université du Québec à Montréal (Canada) and by the Ministry of Environ- ment Québec

REFERENCES

SIMONEAU, M, LUCOTTE M, GARCEAU S, LALIBERTÉ D, (2004) Fish Growth Rates Control Mercury Concentrations in Walleye (Stizostedion vitreum) from Eastern Canadian Lakes Submit- ted to Environmental Research

RMZ-M&G 2004, 51 990 PART 2 BIOGEOCHEMISTRY

Methyl Mercury Accumulation in Zooplankton from Canadian Shield Lakes Impacted by Fire or Clearcut Logging: a Three-Year Study

EDENISE GARCIA & RICHARD CARIGNAN

University of Montreal, Departement of Biological Sciences, Quebec, Canada; E-mail: edenise&garcia@umontreal&ca

Abstract: Methyl mercury (MeHg) concentrations were determined in bulk zooplankton from 38 boreal Canadian lakes with logged, burnt or undisturbed catchments, between 1996 and 1998 MeHg concentrations in zooplankton from cut lakes were significantly higher than in reference lakes during mid-summer of the three study years Higher MeHg levels were observed in cut lakes in comparison to burnt lakes only in the first year following disturbances Differences between burnt and reference groups were not significant MeHg levels varied seasonally in the three treatments: concentrations were the lowest in late spring, then peaked in mid-summer and decreased in late summer An inter-annual decreasing trend in MeHg was also observed along the three study years The pattern of distribution of MeHg along the study period in the three treatments paral- leled that of DOC, which is an important vector of Hg from watershed soils to lake water In cut and burnt lakes, MeHg in zooplankton showed a significant relationship with the disturbed area to lake volume ratio These findings suggest that effects of forest disturbances on Hg cycling and bioavailability can be detectable over years after the occurrence of the impact

Key words: methyl mercury, zooplankton, clear-cutting, wildfire, watershed disturbance

INTRODUCTION zooplankton in 38 boreal Shield lakes (GARCIA AND CARIGNAN, 1999) One year af- Forest disturbances such as clear-cutting and ter disturbances, MeHg levels were higher wildfires are known to affect the export of in zooplankton from logged lakes in com- dissolved organic carbon (DOC) in runoff parison to burnt or undisturbed lakes (CARIGNAN ET AL, 2000) Since mercury tends to associate to the organic matter in the up- Here we examine the trends in MeHg in zoop- per layer of the soil, such disturbances can lankton during the first three years after wa- increase the loading of Hg to aquatic sys- tershed disturbances in the same lakes Sea- tems, and can stimulate the bacterial methy- sonal and inter-annual variations in MeHg lation of inorganic Hg as well as Hg uptake levels are compared within and among the (IKINGURA AND AKAGI, 1999) In a previous logged, burnt and reference groups study, we compared the effects of forest clearance by wildfire and logging on methyl Nine cut lakes had 9-72 % of their catch- mercury (MeHg) contamination of bulk ment logged in 1995, whereas other nine

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 991 lakes had 50-100 % of their catchment af- Rapid dilution during spring freshet may re- fected by high intensity fires in this same sult in decreased DOC and Hg concentration year The catchments of reference lakes in lakes, which can explain the lowest MeHg (N = 20) have remained undisturbed for at levels observed in zooplankton following least 70 years Water and zooplankton were snow melt During mid-summer, higher wa- sampled in each lake from 1996 to 1998 ter temperature would have favored both bac- within two weeks of ice-out (late May to terial methylation of inorganic Hg and MeHg early June), in mid-summer (July), and in late uptake by zooplankton The positive relation- summer (late August to mid-September) ship between MeHg and epilimnetic temperature in the three groups of lakes supports this observation (r between 062 and 069, RESULTS AND DISCUSSION p < 00001) In late summer, lower runoff coupled with lower water temperature would Seasonal and inter-annual variations have resulted in a decrease in MeHg levels in in MeHg zooplankton compared to mid-summer

MeHg levels in zooplankton showed marked Inter-annual decreasing trends in mean seasonal trends during the three-year period, MeHg levels in zooplankton were observed regardless of treatment Concentrations were in the three groups of lakes (Figure 2, the lowest in late spring then peaked in mid- ANOVA, p < 005), but were not significant summer and decreased in late summer in all treatments A similar decreasing trend (Figure 1a) Several mechanisms may ex- was observed in the epilimnetic temperature plain this seasonal variability in MeHg, in- in the cut, burnt and references lakes, and cluding runoff and DOC loading to lakes In could explain in part the variations in MeHg general, seasonal variations in MeHg in zooplankton Changes in hydrological matched those of DOC in the three treatments conditions in the study area would also be (Figure 1b) expected to be related to such variations

a b

Figure 1 Trends in MeHg levels in zooplankton (a) and in DOC concentrations (b) in late spring, mid and late summer from 1996 to 1998#

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However, in 1997, the wettest year, even if MeHg in zooplankton tended to decrease in runoff levels were 23% higher than in 1996, the three treatments"

Figure 2 Average (late spring to late summer) MeHg concentrations in zooplankton from cut (open bars, N = 9), burnt (black bars, N = 9) and reference lakes (gray bars, N = 20) for the first three years following disturbances# Error bars represent 95 % confidence intervals# Dif- ferent letters indicate mean differences (ANOVA or RMA, p < 0#05)#

Among-treatment variations in MeHg The correlation between MeHg and the logged area to lake volume ratio indicates that MeHg in zooplankton from logged lakes was forest harvesting influences MeHg concen- consistently higher than in reference lakes trations in zooplankton" Such influence can in mid-summer in the three study years, be attributed in part to the higher amount of whereas in late spring and late summer DOC reaching the cut lakes in comparison to MeHg levels did not differ significantly be- reference and burnt lakes" Because Hg tends tween these two groups of lakes (Figure 1), to associate with humic substances in the up- except in spring 1998" MeHg levels in zoop- per layer of the soil, the impact of logging on lankton from burnt lakes were lower than in the bioavailability of Hg in aquatic systems cut lakes, but differences were significant may be initially controlled by an increased only in late spring and mid-summer 1996" co-transport of Hg-bound to organic matter" MeHg in burnt and reference lakes did not The positive relationship between MeHg lev- differ significantly" A significant correlation els in zooplankton and DOC loading to lake between MeHg in zooplankton and the dis- water or DOC concentration in the three turbed area: lake volume ratio was observed groups of lakes support this mechanism" In- in cut (Log MeHg = 3"93 + 0"48 CUT/VOL; puts of organic matter in lake water can also e r = + 0"59, p < 0"01) and in burnt lakes affect Hg speciation by stimulating the bac- (Log MeHg = 4"22 + 0"10 CUT/VOL; r = + terial methylation of Hg (FRENCH ET AL", 1999) e 0"57, p < 0"05)" and by decreasing MeHg photodegradation

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 993 rates (SELLERS ET AL, 1996) However, despite duction in cut lakes was enhanced due to the the differences in DOC concentrations be- higher amounts of substrate for methylation tween cut and reference lakes during late (inorganic Hg) and for bacterial activity spring and late summer, differences in MeHg (DOC) entering the lakes, in association with between the two treatments were not signifi- higher water temperature in mid-summer cant in those seasons, except in early spring The observed seasonal variations in MeHg 1998 Thus, higher DOC concentrations alone emphasize the importance of taking into ac- could not explain the observed among-treat- count the sample period in comparative stud- ment differences in MeHg Contrary to for- ies of MeHg accumulation in short-lived or- est harvesting, intense wildfires had no no- ganisms such as zooplankton ticeable impact on MeHg contamination of zooplankton, possibly due to Hg losses to the Acknowledgements atmosphere This research was supported by an Ameri- can States Organization scholarship to E CONCLUSIONS Garcia, and by the Canadian Network of Centres of Excellence on Sustainable Forest Higher MeHg concentrations in zooplank- Management We thank Dolors Planas and ton from cut lakes relative to reference lakes Sébastien Lamontagne for providing the were only detectable during mid-summer in chlorophyll a and the DOC loading data We the three study years Based on our findings also thank Alain Patoine, Ginette Méthot, we can speculate that bacterial MeHg pro- Nelson Driscoll and Johnattan Holmes for assistance in field and laboratory

REFERENCES

CARIGNAN, R, DARCY, P & LAMONTAGNE, S (2000): IKINGURA, J R & AKAGI, H (1999): Methyl mercury Comparative impacts of fire and forest harvest- production and distribution in aquatic systems; ing on water quality in Boreal Shield lakes; Can Sci Total Environ 234, pp 109-118 J Fish Aquat Sci 57 (suppl 2), pp 105 -117 SELLERS, P, KELLY, C A, RUDD, J W M & FRENCH, K J, SCRUTON, D A, ANDERSON, M R & MACHUTCHON, A R (1996): Photodegradation of SCHNEIDER, D C (1999): Influence of physical methylmercury in lakes; Nature 380, pp 694-697 and chemical characteristics on mercury in aquatic sediments; Wat Air Soil Pollut 110, pp 347-362 GARCIA, E & CARIGNAN, R (1999): Impact of wildfire and clear-cutting in the boreal forest on methyl Hg in zooplankton; Can J Fish Aquat Sci 56, pp 339-345

RMZ-M&G 2004, 51 994 PART 2 BIOGEOCHEMISTRY

The Relationship Between Hg(II) Photoreduction and DOC Fluorescence in Clear and Humic Waters

EDENISE GARCIA1, XAV I E R R ST SIMON2, BOUCHRA YAAKOUBD2 & MARC AMYOT1

1University of Montreal, Departement of Biological Sciences, Quebec, Canada E-mail: edenise garcia@umontreal ca 2INRS-Eau, Terre et Environnement, Quebec, Canada

Abstract: We compared diurnal variations in dissolved gaseous mercury (DGM) concentration and in losses of DOC fluorescence (DOCF) in four boreal Canadian Shield lakes, in one beaver pond, and in one wetland, which were chosen to represent a spectrum from clear water to humic conditions$ We also determined the contribution of UVB, UVA and visible light on DGM photoproduction in the four lakes$ Our results showed a strong relationship between DGM concentrations and light intensity, and between DGM production and losses in DOCF, in all study sites$ We also observed higher rates of DGM formation and of DOCF bleaching in the presence of UV radiation$ Under UVB light, production of DGM was higher in clear lakes than in the humic ones$ Inversely, in the UVA range, DGM production tended to be higher in humic lakes$ We suggest that DOCF bleaching can be used as a proxy for the rate of the formation of reactive species that may alter the redox state of mercury$ We also have indications that DGM production is more important in clear than in humic waters$

Key words: dissolved gaseous mercury, photoreduction, DOC fluorescence

INTRODUCTION a process often termed photobleaching (DEL VECCHIO & BLOUGH, 2002)' Decreases in Several studies have proposed the participa- DOC fluorescence (DOCF) can give there- tion of dissolved organic carbon (DOC) in fore an estimation of the formation of photoprocesses leading to the formation of photoreactants affecting DGM formation' In dissolved gaseous mercury (DGM) in aquatic this context, the objective of this study is to systems (NRIAGU, 1994; AMYOT ET AL', 1997)' investigate the relationships between DGM Although different mechanisms have been photoproduction and losses in DOCF across suggested, the photoinduced reduction of lakes and wetlands of varying humic con- Hg(II) is not well understood yet' The ab- tent and quality' The wavelength-dependency sorption of light, particularly in the UV of DGM photoproduction and of losses in range, by chomophoric DOC (CDOC) can DOC fluorescence is also addressed here' result in the formation of reactive species such as hydrogen peroxide (H O ) that may Our study was conducted during the summers 2 2 alter the redox state of metals, including Hg' 2002 and 2003 in four Canadian Shield lakes, The interaction with UV radiation can also one beaver pond and one wetland, the Bay St' affect the optical properties of CDOC, lead- François, located in the St' Pierre Lake, a flu- ing to losses in absorbance and fluorescence, vial lake of the St' Lawrence River (Table 1)'

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 995

Table 1 Physical and chemical characteristics of study sites

Subsurface water was collected during the (DGM ) observed following sunlight ex- max night using quartz tubes and was exposed to posure varied from one system to another, the full range of surface-level solar radiation ranging from 106 pg·L-1 to 315 pg·L-1$ These (11-hour experiments) or to different ranges values represented from 4 % to 23 % of total of surface-level solar radiation (6-hour ex- Hg in the study systems$ The % of total Hg periments)$ Variations in DGM concentra- as DGM was negatively related to DOC con- tions and in DOCF (355 nm excitation 455 centrations (Figure 1)$ nm emission) were determined$ DOCF varied from 11 QSU to 90 QSU, being significantly higher in humic than in clear RESULTS AND DISCUSSION waters (Table 1)$ Considering the diversity of the study systems lakes, wetland, and Variations in DGM and in DOCF beaver pond the DOCF seemed to reflect among-system variations in the quality of the In all the study systems except for Lake organic matter$ Despite the large range in Croche, DGM increased with cumulative DOCF, losses in DOCF in different aquatic solar radiation and then tended to reach a systems were quite similar, ranging from 22 plateau$ In Lake Croche, DGM levels in- % to 31 %$ creased from sunrise until early afternoon, decreasing afterward likely due to Hg0 Similarly to DGM concentrations, DOCF photoxidation$ The amount of DGM at the bleaching increased exponentially with cu- onset of incubations (DGM ) varied from 13 mulative solar radiation$ As sunlight faded, 0 pg·L-1 to 76 pg·L-1 and at the plateau from 66 over the course of the afternoon, a plateau pg·L-1 to 280 pg·L-1$ Maximum DGM levels tended to be reached$

RMZ-M&G 2004, 51 996 PART 2 BIOGEOCHEMISTRY

(OH*), DOM-derived peroxy radicals (ROO*), triplet states of humic compounds, aquated electron (e- ) (LEIFER, 1988; STUMM aq AND MORGAN, 1996)" These photoreactants are able to alter redox conditions, and are produced in a process concurrent to losses in DOCF"

The importance of different wavebands in the DGM photoproduction and DOCF losses Figure 1 Relationship between % of total Hg as DGM and DOC concentration in the study sites (R2 = 090, p < 0001) Under the full solar spectrum, the rates of photoinduced DGM production ranged from DOCF varied from 11 QSU to 90 QSU, be- 14 pg·L-1·h-1 to 32 pg·L-1·h-1" Among-system ing significantly higher in humic than in clear variations in DGM production were not sig- waters" Considering the diversity of the study nificant" Most DGM production (61 to 73 systems lakes, wetland, and beaver pond %) occurred under UV radiation (UVA + the DOCF seemed to reflect among-system UVB), whereas visible light alone accounted variations in the quality of the organic mat- for at most 27 % of the DGM photoproduc- ter" Despite the large range in DOCF, losses tion" Under UVB radiation, the highest rates in DOCF in different aquatic systems were of DGM formation were observed in the quite similar, ranging from 22 % to 31 %" clearest lakes, Violon and Croche" Inversely, under UVA radiation, DGM production rates Similarly to DGM concentrations, DOCF tended to be higher in the humic lakes, Ours bleaching increased exponentially with cu- and Cromwell" In fact a strong positive cor- mulative solar radiation" As sunlight faded, relation was observed between DGM pro- over the course of the afternoon, a plateau duction under UVA and DOC concentrations tended to be reached" (r = 0"99, p < 0"01), whereas DGM production under UVB was negatively correlated Diel variations in DGM were positively re- to DOC (r = - 0"99, p < 0"01)" These find- lated to losses in DOCF in the different sys- ings can be related to differences in UVA and tems (R2 between 0"67 and 0"96, p < 0"001)" UVB penetration in waters with varying These findings point to a significant role of DOC concentrations" photochemical transformations of DOC in the photoreduction of Hg(II)" It is known that Similarly to DGM production, DOCF was a large portion of photons arriving in natural more affected by UV than by visible radia- waters is absorbed by chromophoric dis- tion" Losses in fluorescence were high in the solved organic carbon" The excited CDOC UVA range and very low under UVB, in clear can then act as sensitizer or can generate and in humic waters" photoreactive intermediates, such as hydrogen peroxide (H O ), hydroxyl radicals 2 2

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 997

CONCLUSIONS due to differences in UVA and UVB penetration in waters with varying humic content%% Taken together, our results suggest that DOCF bleaching can be a sensitive indica- Acknowledgements tor of the photoreduction of Hg(II) independently of the amount of DOC% We have also We thank Nicolas Milet, Justin Shead and indications that DGM production is more Alexandre Poulain for help in the field and important in clear than in humic waters% In laboratory, and Hendrick Van Leeuwen for addition, DGM formation varies with the meteorological data% We also acknowledge wavelength of the incident radiation, likely funding from the Collaborative Mercury Reasearch Network (COMERN) to M%A%

REFERENCES

AMYOT, M, LEAN, D, & MIERLE, G (1997): Photo- LEIFER, A (1988): The kinetics of environmental chemical formation of volatile mercury in high aquatic photochemistry theory and practice; Arctic lakes; Environ Toxicol Chem 16, pp ACS Professional Reference Book, New York 2054 2063 NRIAGU, J O (1994): Mechanistic steps in the pho- DEL VECCHIO, R & BLOUGH, N V (2002): toreduction of mercury in natural waters; Sci Photobleaching of chromophoric dissolved or- Total Environ 154, pp 1 8 ganic matter in natural waters: kinetics and STUMM, W AND MORGAN, JAMES J (1996): Aquatic modeling; Mar Chem 78, pp 231 253 Chemistry; John Wiley and Sons, Inc, New GRANELI, W, LINDELL, M, AND TRANVIK, L (1996): York Photo-oxidative production of dissolved inorganic carbon in lakes of different humic content; Limnol Oceanogr 41, pp 698 706

RMZ-M&G 2004, 51 998 PART 2 BIOGEOCHEMISTRY

Soil Plant Mercury Uptake (Pollution) from some Granitic Quarry Sites in Southwestern Nigeria

AM GBADEBO1 & PO DASO1

1Department of Environmental Management and Toxicology College of Environmental Resources Management University of Agriculture, P$M$B$ 2, Abeokuta, Afghanistan, e-mail: jumaid2000@yahoo$co$uk

Abstract: The result of this investigation reveals that concentration of mercury in the soils collected from five granitic quarry sites located in Abeokuta and Igbo-Ora ranges from 002 to 007 µg/g with a mean value of 004 µg/g This is found to be relatively higher than the mercury concentration range of 001 to 004 µg/g with a mean value of 002 µg/g from soils collected 2 km away from the quarry sites Also, mercury uptake by Talium triangulare and Tridax procumbens species obtained from the five quarry sites indicate concentration range of 000 007 µg/g in roots, stems and leaves of these plants This is found to be higher than the maximum value of 003 µg/g obtained from the same plant species collected from the control sites It can be inferred that there is some level of mercury pollution in the study area This may be attributed to the natural value of mercury in the soil, human induced activities such as pesticide application during farming, use of explosive for blasting and release of this metal into the surrounding environment from the parent rocks due to quarrying activities

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 999 The Influence of Drying and Rewetting on Hg and S Cycling in Everglades Soils

CYNTHIA GILMOUR, DAV I D KRABBENHOFT, WILLIAM OREM & GEORGE AIKEN

Abstract: This poster presents the results of a laboratory experiment designed to examine the impacts of drying and rewetting on the biogeochemistry of Everglades soils and the production of methylmercury (MeHg) The study was designed to validate hypotheses based on field observations of the biogeochemical processes that control pulses of MeHg production following rewetting of dried or burned soils in the Everglades ecosystem Some Everglades soils produce high levels of toxic MeHg when rewet following periods of dryness Methylmercury production is also high in some newly constructed Ever- glades water treatment wetlands (Storm Treatment Areas or STAs), either upon initial wetting and/or upon wetting after a dry period Field data collected in the northern Wa- ter Conservation Areas (WCA) of the Everglades by the Aquatic Cycling of Mercury in the Everglades (ACME) group when the ecosystem rewet after a severe drought in 1999 showed very high MeHg production in soils in northern WCA 3A (burned), and to a lesser extent in WCA 2A (dried out), in the weeks following rewetting The high levels of MeHg production coincided with high levels of sulfate in the surface water and sediment porewater (roughly 100x normal concentrations) in these burned and dried areas following rewetting Data suggested that the sulfate originated from oxidation of reduced soil sulfur as a result of the drought and fire Since MeHg is produced in Ever- glades sediments primarily by the activity of sulfate reducing bacteria, it was hypothesized that the release of sulfate from the soils stimulated MeHg production to the ex- ceptionally high levels observed following the drought and fire The experiments involved collecting small cores from the central Everglades and from an STA, drying these cores under controlled laboratory conditions for various time periods, and then rewetting the cores with site water After rewetting, soil, water and inter- stitial water chemistry was followed through about 2 months Experimental cores were also spiked with Hg stable isotopes (as HgCl2) in order to track the partitioning and methylation of fresh, labile Hg relative to Hg stored in the dried soils Results from the experiments confirm the observations from field studies that drying and rewetting of Everglades soils produces large pulses of MeHg Significant increases in MeHg in sediments and surface water were observed in dried and rewet cores from both the central Everglades and STA sites, relative to in situ concentrations Reduced sulfur concentrations in solid phase soils decreased during drying, and sulfate concentrations increased dramatically in the overlying water following rewetting of the dried cores from both sites This increase in sulfate was similar to what had been observed in field studies following the 1999 drought and burn in the northern Everglades No ob- servable dissolution of Hg from the solid phase was observed The results support the hypothesis that MeHg production is stimulated in rewet soils by oxidation of organic matter and reduced sulfur pools in sediments during drying periods The drying and rewetting appears to provide fuel for Hg methylation and microbial sulfate reduction and MeHg production primarily through oxidation of reduced S to sulfate Release of Hg from soils, and degradation of organic matter during dryout appear to be less important Build-up of sulfide (sulfide has been shown to inhibit MeHg production) and/or depletion of labile organic matter may end the pulse of MeHg production that follows rewetting of soils

Key words: methylmercury, wetland, sulfur

RMZ-M&G 2004, 51 1000 PART 2 BIOGEOCHEMISTRY

Response of methylmercury production to changes in Hg loading: A comparison of Hg isotope addition studies

CYNTHIA GILMOUR, DAV I D KRABBENHOFT, DIANE ORIHEL, ANDREW HEYES & ROBERT MASON

Abstract: Over the last few years, we have made Hg stable isotope additions to aquatic systems at a number of scales and in a variety of ecosystem types Our overall objective has been to answer the question How much does methylmercury in ecosystems change in response to a change in mercury loading? Imbedded in this question are the issues of timing of response, magnitude of response, the influence of scale, and the differences in responses across watershed components To address this question, we have used two powerful techniques that are novel to the Hg research community, one, the use of stable Hg isotopes, and two, the manipulation of systems of various sizes, from mesocosms to an entire boreal lake and its watershed The use of Hg stable isotopes allows the tracking of new Hg spikes separately from Hg already accumulated in ecosystems Here we present a comparison of Hg bioavailability for methylation across a series of Hg stable-isotope addition experiments Included in the comparison will be Hg addition experiments conducted at different scales in two different ecosystems, the Florida Ever- glades and the boreal Experimental Lakes Area in northwest Ontario Some of the studies also examined the influence of sulfate, dissolved organic carbon, and the drying and rewetting of soils on methylation A general conclusion from all of the studies is that Hg newly deposited to zones of methylation is more readily converted to methylmercury (MeHg) than is the existing Hg pool in sediments and soils Mercury spiked into all of the aquatic enclosures examined, and into boreal L658, was rapidly transported to the primary zone of methylation at the sediment surface In all of the aquatic studies, a significantly larger fraction of this new Hg in surface sediments was found as MeHg relative to existing pools The geochemical behavior of new Hg in sediments is also different than that of existing Hg pools, supporting the idea that recently deposited Hg is more bioavailable for microbial methylation Many of the isotope spike experiments have examined the response to a one-time Hg addition In the L658 study, however, 202Hg additions have been semi-continuous during the open water season since 2001 The L658 study will answer an important question - how long it will take to reach a new equilibrium concentration of MeHg in sediments and biota after a change in deposition rate Through 2003 (the third year of dosing), the concentration of Me202Hg has continued to increase in surficial sediments However, the rate of increase appears to be slowing, suggesting that a new equilibrium concentration of MeHg in sediments will occur within a few years of a change in Hg deposition rate The response of sediment MeHg to a range of Hg doses has been linear in most of our studies However, the slope of the response has varied dramatically among study sites, based on the delivery rate of Hg to sediments, and the biogeochemistry of sediments The aquatic additions studies at various size scales have shown that the eventual amount of MeHg formed, and the timing of its formation, is highly dependant on the rate and magnitude of Hg delivery to zones of methylation For example, in shallow ecosystems where Hg is delivered rapidly to sediments, the response to Hg spikes is rapid and strong However, the response to Hg dosing is highly muted in clear waters where photochemistry removes Hg from the water column before sedimentation It appears that the more rapidly Hg is delivered to zones of methylation (generally sediments), the higher the fraction converted to MeHg

Key words: methylation, stable isotopes, aquatic

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1001 Mercury and methylmercury budgets for the first two years of Hg stable isotope additions to METAALICUS Lake 658

CYNTHIA GILMOUR, CHRIS BABIARZ, KEN BEATY, HOLGER HINTELMANN, JAMES HURLEY, DAVID KRABBENHOFT, STEVEN LINDBERG, KEN SANDILANDS, MICHAEL TURNER & REED HARRIS

Abstract: A whole-watershed Hg loading experiment is being conducted at Lake 658 in the Experimental Lakes Area in northwest Ontario The overall objective of the project is to determine the magnitude and time frame of the response of methylmercury (MeHg) in biota to a change in Hg loading Mercury additions have been made to this first-order lake and its watershed since June 2001, at about 4X annual atmospheric wet deposition A unique aspect of this study is the addition of Hg entirely as stable isotopes, so that newly deposited Hg can be tracked separately from existing pools Use of three Hg stable isotopes allows separate analysis of the fate of Hg added to the lake, upland and wetland This presentation will focus on budgets and the biogeochemical behavior of the Hg stable isotope added directly to the surface of L658 (202Hg) Budgets for total Hg and MeHg have been constructed for both native Hg and for 202Hg for the first two years of stable isotope additions (2001 and 2002) The budgets were constructed from spatially and temporally intensive measurements of Hg and MeHg concentrations in water, seston, sediment and epiphyton, as well as most processes in the biogeochemical cycle of Hg, including direct measurements of deposition, evasion, sedimentation, methylation and demethylation (in many compartments) A robust hydrologic budget for the lake was constructed using gauged inflows, outflows and lake level information, plus estimates of ungauged inflows based on similar, well-constrained basins at the ELA Using this information, we were able to achieve mass balance for 202Hg in L658 Information on MeHg accumulation in food webs, and on Hg fate and transport in the uplands and wetlands of the L658 basin, and on dose-response studies in smaller plots and enclosures will be presented in parallel presentations MeHg production and bioaccumulation from the lake spike began rapidly (days to weeks) following the first addition in June 2001 Of the three isotopes added to the L658 catchment, the isotope added directly to the lake surface (202Hg) was most quickly transported to sites of methylation, methylated, and accumulated in the food web By fall, about 50 % of Hg in lake water and sedimenting particles was 202Hg, versus <1 % in surface sediments During 2001 and 2002, a larger fraction of 202Hg was methylated than was native Hg in surface sediments, and in the dissolved phase in the water column Rates of MeHg production from various Hg pools provide information on their relative bioavailability for methylation Me202Hg was predominantly produced in near-surface sediments, and in anoxic bottom waters, although some methylation also occurred in an adjoining wetland lake level rise forced lake water horizontally into methylation zones in the wetland Methylation and demethylation were very dynamic, with demethylation being the major loss mechanism for MeHg Sedimentation was the major sink for inorganic Hg The biogeochemical behavior of newly added 202Hg was different in many ways from the behavior of native Hg Examples include partitioning behavior in sediments and water, and bioavailability for methylation in sediments and in anoxic bottom waters As time has passed, however, the behavior of the 202Hg pool in sediments has became more similar to the native Hg pool, probably reflecting the aging of new Hg through time

Key words: deposition, stable isotopes, lake

RMZ-M&G 2004, 51 1002 PART 2 BIOGEOCHEMISTRY

Mercury in the Madeira River Basin, Rondônia, Brazil

JOÃO PAULO O GOMES; DEBORAH PEREIRA LINHARES; ELISABETE LOURDES NASCIMENTO; AILTON RODRIGUES FERREIRA; ÂNDRIO DOS SANTOS RIBEIRO; ÉDERSON RODINEY DANTAS RODRIGUES; WANDERLEY RODRIGUES BASTOS & ENE GLÓRIA DA SILVEIRA

Laboratório de Biogeoquímica Ambiental, Universidade Federal de Rondônia - UNIR% BR 364, Km 9,5 +55 69 217-8538 Porto Velho RO, Brazil; E-mail: labmerc@unir%br%

Abstract: With objectives of evaluating the environmental impact caused in the basin drainage of the Gold mining activity reached a peak intensity in the Madeira River watershed during the1970s and 1980s$ In order to assess the environmental impact, we assessed Hg levels in two abiotic matrices: bottom sediments and suspended solids in the Lower Madeira River$ Chemical extraction of Hg adsorbed to particles was determined following the BASTOS ET AL$ (1998) methodology and quantification of Hg was determined by cold vapor generation atomic absorption spectrophotometry$ It was observed that generally, Hg concentrations in the lakes, both in bottom sediments (66$26 ± 34$80 µg$kg-1) and particles in suspension (34$25 ± 28$71 µg$kg-1), were higher than concentrations found for Madeira River in the marginal bottom sediments (57$49 ± 22$55 µg$kg-1) and in the suspended particles (27$38 ± 5$97 µg$kg-1)$ However, all of the concentrations are below the value of the world average values established by WHO (200 µg$kg-1)$

Key words: Amazon, mercury, bottom sediment, suspended solids$

INTRODUCTION In Rondônia State there was a high anthropogenic activity between the 1970s and The Madeira River is a tributary of the south- 1980s with the large elemental mercury ern margin of the Amazon River It has (Hg0) releases from the gold mining amal- 1,459 km of reach and average flow of gamation The loss of Hg in that process ac- 23,000 m3/s It is formed by the confluence counted for up to 40 to 45 % of the total Hg of the Mamoré and Beni rivers, draining part used, as effluent was discharged directly in of the Andean plateau It is divided into two the river and with the remaining of Hg different sections along its course The up- evaded to the atmosphere (PFEIFFER & per section, called Upper Madeira, extends LACERDA, 1988) FERREIRA & APPEL (1990) between the origins up to Porto Velho It is estimate about 370 tons of Hg were intro- mostly non-navigable due to several rapids duced in the region just for the year 1989 The lower section, Lower Madeira, is totally About 160 tons were not recovered indicat- navigable for a reach of 1,099 km between ing that it was most likely transferred to the Porto Velho-RO and Itacoatiara-AM Ac- regional environment There are no present cording to SIOLI ET AL (1967), it is classified official records for the Hg releases into at- as a white-yellowish waters river, rich in dis- mosphere and aquatic environment in the solved organic matter and suspened solids region, and gold mining continues at a lower

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1003 activity level compared to previous decades tal Hg could also undergo chemical trans- The Hg released directly in the aquatic sys- formation in the atmosphere (oxidation) and tems tends to be adsorbed onto suspended be deposited locally through rainfall solids and transported, which in time influence the deposition characteristics of lakes The study area is illustrated in Figure 1 and tributaries (igarapés) during the flood A total of 28 samples were collected along and dry seasons, making these systems res- the course of Madeira: 8 sedimentation zones ervoirs of Hg sedimentation The fine sedi- of Madeira River, 18 points in the lakes and ments are a useful proxy for the environmen- 2 points in the igarapés that receive influ- tal Hg concentration and provide informa- ence of Madeira River during the flood tion about past deposition Several other fac- events Bottom sediments samples were col- tors influence the geochemical behavior of lected with an Eckmam dredge, sieved Hg, such as the pH, redox potential and sol- through a 200 um mesh Suspended solids ids interaction and influence partitioning samples were collected on cellulose mem- between the dissolved and particulate phase branes (045 µm pore size) Samples were It is a key process in the transport and pos- extracted withHCl-HNO (3:1) and oxidized 3 sible bioaccumulation of Hg in the environ- with 5% KMnO During analysis samples 4 ment (BONOTTO & SILVEIRA, 2003) were reduced with NH OHHCl and NaBH 2 4 Certified reference samples (IAEA-356) Hg volatilizes and dispersed through atmo- were run, with 97 % recovery Total Hg was sphere, and could have a long residence in quantified by cold vapor generation coupled the atmosphere during dry periods Elemen- atomic absorption spectrophotometer (BASTOS ET AL, 1998)

Figure 1 Location of the study area: Low Madeira River

RMZ-M&G 2004, 51 1004 PART 2 BIOGEOCHEMISTRY

RESULTS AND DISCUSSION tration in drainage basin that possibly is related with the hydrodynamic micro-basin and Hg concentrations in bottoms sediments in are influenced by antropic and natural Hg the sedimentation areas of Madeira river var- dispersion However, the Hg concentrations ied among 3253 to 8218 µgkg-1 (Figure 2) found were below the world average In lakes, Hg varied from 816 to 14815 µgkg-1 and in the igarapés from Levels of Hg in suspended solids (Figure 3), 388 to 4816 µgkg-1 The highest Hg con- varied from 2000 to 3330 µgkg-1 in the centrations were found in the bottom sedi- Madeira River and from 1000 to 8458 ments of lakes, due their hydrodynamic char- µgkg-1 in lakes The Hg levels in the Ma- acteristics as reservoirs, with sedimentary deira River showed a smaller variation in deposition and accumulation of Hg In gen- relation to lakes (2738 + 597 µgkg-1) Large eral, the Hg levels in bottom sediments of differences in the average Hg concentration lakes were greater than those of the Madeira along of particles in the Madeira basin, re- River and igarapés However, the lakes flect hydrodynamic differences of flow and presented a high variability of Hg concen- suspended solids between the main channel

Figure 2 Hg concentration in bottom sediments

Figure 3 Hg concentration in suspended solids

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1005 and the lakes Seasonal influences can re- dispersed through resuspension and redepo- suspend Hg-rich particles and remobilized sition of suspended solids This allows Hg to those particles This is of great concern be- be transported to lakes and igarapés a great cause Hg associated with river sediments distance from gold mining activities in the re- may be constantly remobilized and redepos- gion This environment may also influenced ited, making the Hg continually available for be by erosion of soils, agriculture, and burn- uptake and bioaccumulation through the food ing of the forests that additionally affect Hg chain levels in waters of the Andean drainage basin

Acknowledgements CONCLUSIONS This work was supported by the UNIR, These results show that Hg is present in the PNOPG/CNPq No 550882/01-4, RIOMAR aquatic system of Madeira River basin and Foundation and SEBRAE-RO

REFERENCES

BASTOS, W R, MALM, O, PFEIFFER, W C & CLEARY, FERREIRA, R C H & APPEL, L E (1990): Fontes e D (1998): Establishment and analytical quality usos de mercúrio no Brasil; In Proceedings of control of laboratories for Hg determination in Forest90, Rio de Janeiro (contribuição técnica) biological and geological samples in the Ama- PFEIFFER, W C & LACERDA, L D (1988): Mercury zon-Brasil; Ciência e Cultura Journal of the imputs to the Amazon region, Brazil; Environ Brazilian Association for the Advancement of Technol Lett, 325-350 Science 50(4), 255-260 SIOLI, H (1967): Hydrochemistry and geology in the BONOTTO, M D & SILVEIRA, E G (2003): Preference Brasilian Amazon, Amazon region, Kiel 1(3), rations for mercury and other chemical elements 267-277 in the Madeira River, Brazil; Journal of South America Earth Science 15, 911-923

RMZ-M&G 2004, 51 1006 PART 2 BIOGEOCHEMISTRY

Mercury Transformation by Anaerobic Bacterial Communities Selected from Estuarine Sediments

GOÑI M S1, DIAS M1, MONPERRUS M2, SALVADO J C1, AMOUROUX D2, DURAN R1, DONARD O2, CAUMETTE P1, GUYONEAUD R1

1Labortoire dEcologie Moléculaire EA3525, Université de Pau, BP1155, 64013 Pau cedex 2Laboratoire de Chimie Bio-Inorganique et Environnement, CNRS UMR 5034 , Université de Pau, 64013 Pau cedex

Abstract: The fate of mercury species in environment strongly depends on microbial activities and environmental conditions Specially, methylation is one of the major processes, which transform the inorganic forms of the metal into toxic and easily bioaccumulated organic forms Thus, we designed an experimental set up to study mercury biotransformation in estuarine ecosystems Sediments were incubated in slurries and polluted with inorganic mercury (HgCl ) Mercury methylation was observed only in slurries main- 2 tained under anoxic conditions The main microbial populations were isolated and identified by partial sequencinq of 16S rDNA The methylation, studied by GC-ICP-MS, demonstrated that only sulphate reducing bacteria were the methylators among this community, which also comprise denitrifiers and fermentative bacteria

Key words: mercury, methylation, estuary, sediments, sulphate reducing bacteria

INTRODUCTION derance of evidence indicates that sulfate reduction is linked to mercury methylation, The biogeochemical mercury cycle strongly the mechanism(s) by which methylation oc- depends on microbial activities and environ- curs is poorly understood, and the bacterial mental conditions Bacterial methylation is population that mediate methylation have not one of the major process which transforms been described in detail the inorganic forms of the metal into toxic and easily bioaccumulated organic forms The biogeochemical mercury cycle is com- Microbial mercury methylation has been pleted by demethylation which can occurs shown to occur in a variety of environments by a reductive or an oxidative pathway The Several studies have indicated that sulfate mercury reduction is encoded by the micro- reducing bacteria are the primary mercury bial mer operon that is widespread among methylators in anoxic sediments[1] Factors microorganisms[3] Although mercury oxida- influencing microbial methylmercury pro- tion has been reported in anoxic sediments, duction include microbial community com- the involvement of sulfate reducing bacteria position, mercury availability, carbon avail- remains to be demonstrated[4] Thus, the un- ability, and the abundance of electron accep- derstanding of the mechanisms involved in tor such as sulfate[2] Although the prepon- the biogeochemical mercury cycle is make

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1007 difficult by the fact that both bacterial com- were characterized by 50 % humidity and munities methylators and demethylators co- 29 % of organic carbon content To evalu- exist in the same environmental conditions ate mercury methylation potential, Adour estuarine sediments were incubated in slur- The Adour estuary, located on the Atlantic ries (100 g in 500 ml filtered river water) coast in the south west of France, receive containing 0,2 µg/l of inorganic mercury inputs of inorganic mercury and shows high (Hg2+) Slurries were incubated under oxic mercury methylation potential[5] To better and anoxic conditions Abiotic transforma- understand bacterial activities involved in the tion controls were obtained by autoclaving biogeochemical mercury cycle of the Adour sediments at 120°C for 20 min Samples were estuarine sediments, slurries experiments stored at -20°C before analysis At the end were conducted The current study focuses of this experiment, the anoxic slurries served on identifying community structure and reas inocula to isolate the major microbial lationships between microbial community populations The pure strains obtenained composition, mercury methylation potential, were identified (16S rDNA sequencing) and and environmental conditions (oxic, anoxic) their methylation capacities were tested by using stable mercury isotopes

RESULTS AND DISCUSSION 2 Evaluation of mercury methylation 1 Experimental set up potential

Sediment samples were collected at the Inorganic mercury methylation to methyl Adour estuary, southwest of France At sam- mercury was clearly demonstrated in anoxic pling site, water salinity was 3 Sediments slurries (Figure 1) Obviously this mercury

Figure 1 Methylmercury formation in slurries experiments Adour estuarine sediments were incubated under n anoxic and oxic conditions Controls of abiotic transformation under anoxic (w)and oxic (x) conditions respectively

RMZ-M&G 2004, 51 1008 PART 2 BIOGEOCHEMISTRY methylation pathway was related to biotic 3 Bacterial community composition processes The abiotic control did not show any measurable methylmercury The biologi- In order to identify the populations respon- cal production of methylmercury can be due sible for mercury methylation, several to bacterial methylators only in anoxic con- anaerobic bacterial strains were isolated for ditions suggesting that anaerobic communi- their ability to resist to inorganic mercury ties such as sulphate reducing bacteria, as compounds and have been characterized All already reported[1], play an important role on these strains were identified (Table 1) and mercury speciation comprise facultative anaerobes (Pseudomo- nas sp, Bacillus sp, Purple non sulfur bacteria) and strict anaerobes (Sulfate-reducers, Clostridia)

Table 1 Strains identification and percentage of methylation

4 Mercury methylation CONCLUSIONS

Among all these strains, only the sulfate re- Under anoxic conditions, biotic methylation ducers were significatly responsible for mer- was demonstrated in Adour estuarine sedi- cury methylation (Table 1) Experiments by ments Several anaerobic bacterial strains GC-ICP-MS with radioisotopes (201CH Hg+ 3 were isolated for their ability to resist to and 199Hg2+) were undertaken to investigate mercury compounds and have been charac- mercury methylation in these bacterial species terized They were investigated for mercury resistance and mercury methylation capaci-

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1009 ties Among all these strains, only the sul- the genus Desulfomicrobium showed very fate reducers were significatly responsible high methylation rates These strains were for mercury methylation Some of the iso- used for further studies on the mercury me- lated strains (ADR 2, ADR 26) pertaining to thylation activity

REFERENCES

[1] COMPEAU, G C AND BARTHA, B (1985): Appl [4] OREMLAND, R S, CULBERTSON, C W AND WINFREY, Environ Microbiol 50, 498-502 M R (1991): Appl Environ Microbiol 57, 130- [2] MACALADY, J L, MACK, E E, NELSON, D C AND 137 SCOW, K M (2000): Appl Environ Microbiol [5] MONPERRUS, M, GUYONEAUD, R, TESSIER, E, 66, 1479-1488 SCANCAR, J, DURAN, R, GOÑI, M S, AMOUROUX, [3] OSBORN, M K, BRUCE, K D, STIKE, P AND RITCHIE, D, DONARD, O F X AND CAUMETTE, P : J Phys D A (1997): FEMS Microbiol Rev 19, 239- IV France 107, 883-886 262

RMZ-M&G 2004, 51 1010 PART 2 BIOGEOCHEMISTRY

Comparative effects of dietary methylmercury on gene expression in liver, skeletal muscle and brain of the zebra fish (Danio rerio)

P G ONZALEZ, Y DOMINIQUE, JP BOURDINEAUD & BOUDOU A

LEESA, UMR CNRS 5805, University of Bordeaux 1, Place Dr Peyneau, 33120 Arcachon, France E-Mail: p*Gonzalez@epoc*u-bordeaux1*fr

Abstract: Effects of dietary methylmercury (MeHg) were examined on gene expression in three organs (liver, skeletal muscle and brain) of the zebra fish (Danio rerio) Adult male fishes were fed during 7 and 21 days with three different diets: a control diet (C0: 0 02 µgHg g-1, dry weight, dw) and two diets (C1 and C2) contaminated by MeHg at 5 and 13 5 µgHg g-1, dw Nine genes known to be involved in the oxidative stress response, metal-binding and active efflux were selected Expression levels of the nine genes were investigated by quantitative real-time RT-PCR and normalized according to the actine gene expression In the same way, mercury concentrations (µg g , dry weight) were determined in the three organs after the two exposure durations The bioaccumulation levels in the three organs were similar for each exposure condition For each tissue, a quasi-proportionality between bioaccumulation levels and (1) the two contamination pressure (C2 diet/C1 diet), and (2) the two periods (21/7 days) was observed Genetic analysis evidenced a specific tissue expression rate for the nine genes, but differences in the genetic response delay appeared between organs A 7 days exposure to MeHg induced the CoxI-gene as well as the cytoplasmic and mitochondrial superoxide dismutase- genes expression in muscle, while no significant effect was observed in brain and liver This induction was emphasized after 21 days feeding in muscle and was also detected in liver

Key words: Fish, methylmercury, bioaccumulation, gene expression, real-time PCR

INTRODUCTION scarce Recent investigations have evidenced that diet is the primary source of MeHg con- Mercury is an important but toxic element tamination for fish in the natural waters [3] Indeed, acute exposure to methylmercury In this context, we investigated the effect of (MeHg) is lethal and chronic low-dose con- dietary MeHg on gene expression in the liver, sumption of MeHg-contaminated fish can the brain and the skeletal muscle of the ze- cause severe damages to organs, notably the bra fish (Danio rerio) D rerio constitutes a central nervous system and the immune sys- good laboratory model since its genome has tem In spite of its toxicity, little is known been recently reported making gene se- about the toxicological effects of MeHg on quences available in databases In order to the growth and survival of wild fishes [1-2] investigate MeHg effects, nine genes were In the same way, reports about the fish ge- selected Five genes are known to be in- netic response to MeHg comtamination are volved in the oxidative stress response: cy-

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1011 toplasmic and mitochondrial superoxide MT2 was more expressed at the basal level dismutases (Sod), pyruvate carboxylase, cy- in liver than in brain or skeletal muscle! How- tochrome C oxidase subunit I (CoxI) and ever, differences in the genetic response de- HSp70 We also investigated the expression lay appeared between organs! level of the two metallothioneins (MTs) reported for D rerio (MT1 and MT2) MTs, Indeed, in liver, no significant variations which possessed a low molecular weight and were determined for the nine genes after are rich in cystein residus, are involved in 7 days exposure to MeHg! However, after chelating and sequestration into cell of metal 21 days, the expression levels of the CoxI ions [4] In the same way, expression of a gene gene and the two superoxide dismutase genes belonging to the ABC transporter family were induced in this organ! It is to be noted (Tap) was analysed ABC transporters are that a concentration effect was observed in membraneous proteins which use ATP as the expression level of the CoxI gene and energy source and are able to extrude the two superoxide dismutase genes! The cy- xenobiotics by active efflux [5] The prion toplasmic superoxide dismutase gene had a gene expression was used as brain specific 2-fold increased expression in the C1 diet, marker Expression levels of these nine genes while it had a 4-fold increased in the C2 diet were investigated by quantitative real-time as compared to the C0 diet! In the same way, PCR and normalized according to the actine the CoxI gene was 2-fold induced in C1 and gene expression For each gene specific 8-fold in C2! primers were determined In muscle, a 7 days exposure to MeHg induced the CoxI gene and the two superoxide RESULTS AND DISCUSSION dismutase genes expression for fishes fed with 13!5 µgHg!g-1, dw, while no differences Adult male fishes were fed during 7 and were observed between control and fishes 21 days with three different diets (4 % body fed with 5 µgHg!g-1, dw! The CoxI gene, the mass per day): a control diet (C0: cytoplasmic and the mitochondrial superox- 0!02 µgHg!g-1, dry weight, dw) and two di- ide dismutase genes presented a 64-fold, a ets (C1 and C2) contaminated by MeHg at 4-fold and a 8-fold increased expression, re- 5 and 13!5 µgHg!g-1, dw! To avoid water con- spectively! These expressions were empha- tamination, one third of the water volume in sized in muscle after 21 days feeding and each experimental unit was changed every detected for the two contamination diets! two days! During all the experiment, water Cytoplasmic superoxide dismutase expres- temperature was maintained at 24 ± 0!5 °C! sion had a 8-fold increase, CoxI displayed a After each exposure duration, liver, brain and 64-fold increase and the mitochondrial su- skeletal muscle samples were taken! Three peroxide dismutase a 16-fold increase! replicates were analysed, each constituted by pooled organs from four different fishes! In contrast, no significant expression changes were observed for the nine genes in brain The genetic analysis evidenced a specific tis- whatever the contamination pressure and the sue expression rate! Indeed, as an example, time exposure to MeHg!

RMZ-M&G 2004, 51 1012 PART 2 BIOGEOCHEMISTRY

These genetic results have to be correlated The bioaccumulation levels in the three organs to the mercury concentrations determined in were similar for each exposure condition, with the three organs after the two exposure du- a quasi-proportionality between the two con- rations (Table 1)! tamination pressures (C2 diet/C1 diet) and the two trophic transfer periods (21/7 days)#

Table 1 Mercury concentrations (µgg-1, dry weight) determined in liver, brain and skeletal muscle of D rerio after 7 and 21 days exposure to 5 (C1) and 135 (C2) µgHgg-1, dw in the food ingested

CONCLUSIONS dant enzymes indicates an adaptive onset of the redox defence system We investigated the effect of dietary methylmercury exposure on gene expression in Surprisingly, no increase in the expression the liver, the brain and the skeletal muscle level of MTs were detected during our ex- of D rerio The expression levels of nine periments, while these proteins are involved genes involved in the response to oxidative in chelating heavy metals and in response stress generated by metasl, the sequestration against various stresses such as organic com- mechanisms or their active efflux have been pounds, heat, glucocorticoïds, X-ray, UV [7] analyzed by quantitative real-time PCR Re- sults showed that an earlier response was Whatever the contamination pressure, no sig- observed in muscle after 7 days exposure to nificant changes in the expression level for MeHg at 135 µgHgg-1, dw This early re- the nine genes selected were observed in brain, sponse suggested that muscle constituted the while bioaccumulation in this organ was simi- primary target of MeHg This genetic re- lar to those determined in liver and in muscle sponse concerned only the CoxI gene and the This finding has to be correlated with recent two superoxide dismutase genes expression report in Salmo salar brain where variations Expression levels of the same three genes in the activity levels of the superoxide were also increased in liver but only after 21 dismutase enzymes were observed for fish fed days of exposure The fact that the same with 5 or 10 µgMeHgg-1 during 4 months [8] genes were induced in different tissues, sug- This indicates that our exposure time may be gests that contamination by MeHg generated to short to observe genetic variations and that an oxidative stress MeHg is known to accu- other genes have to be investigated Indeed, mulate in mitochondria and is able to dis- mercury is known to inhibit the expression of rupt the mitochondrial chain transport, lead- genes like Na+/K+-ATPase [9], the monoamine ing to the formation of free radical and lipid oxidase [10] or the acethylcholine esterase [11] peroxidation [6] Induction of these anti oxi-

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1013

These differences in the genetic response Acknowledgements delay between organs, while the contamination pressure was identical, suggested that This work was supported by the French Na- specific tissues molecular mechanisms were tional Scientific Research Center (CNRS/ induced in response to MeHg exposure PEVS, Mercury in French Guiana research These results open the way to future pros- program), the European Union (E C Feder pects which could investigate the whole ge- funds) and the French Ministry of the Envi- nome response at the organ level to under- ronment (DIREN in French Guiana) stand the specific defenses developed by tissues to resist to MeHg

REFERENCES

[1] HAMMERSCHMIDT, CR, SANDHEINRICH, MB, WIENER [7] ANDREWS, GK (1990): Regulation of metallo- JG & RADA, RG (2002): Effect of dietary me- thionein gene expression Prog Food Nutr Sci thylmercury on reproduction of fathead min- 14, pp 193-258 nows Environ Sci Technol 36, pp877-883 [8] BERNTSSEN, MHG, AATLAND, A & HANDY, RD [2] WIENER, JG & SPRY, DJ (1996): Toxicological sig- (2003): Chronic dietary mercury exposure cause nificance of mercury in freshwater fish In En- oxidative stress, brain lesions, and altered vironmental contaminants in wildlife: interpret- behaviour in Atlantic salmon (Salmo salar parr) ing tissue concentrations, Beyer WN, Heinz Aquat Toxicol 65, pp 55-72 GH and Redmon-Norwood AW, Editors [9] VERMA, S, TONK, I, GUPTA, A & DALELA R (1983): Lewis Publishers, Boca Raton, Florida, USA, In vivo effects of mercury chloride on tissue p297-339 ATPases of Notopterus notopterus Toxicol Lett [3] HALL, BD, BODALY, RA, FUDGE, RJP, RUDD, 16, pp 631-639 JWM & ROSENBERG DM (1997): Food as the [10] RAM, R & SATHYANESAN, A (1985): Mercurial in- dominant pathway of methylmercury uptake by duced brain monoamine oxidase inhibition in fish Wat Air Soil Pollut 100, pp 13-24 the teleost Channa punctarus (Bioch) Bull [4] VASAK, M & HASLER, DW (2000): Metallo- Environ Contam Toxicol 35, pp 620-626 thioneins: new functional and structural insights [11] GILL, T, TEWARI, H & PANDEE, J (1990): Use of Curr Opin Chem Biol 4, pp 177-183 the fish enzyme system in monitoring water [5] DASSA, E & BOUIGE, P (2001) : The ABC of ABCS: quality: effects of mercury on tissue enzymes a phylogenetic and functional classification of Comp Biochem Physiol 97C, pp 287-292 ABC systems in living organisms Res Microbiol 152, pp 211-229 [6] KONIGSBERG, M, LOPEZ-DIAZGUERRERO, NE BUCIO, L & GUTIEEZ-RUIZ, MC (2001) : Uncoupling effect of mercury chloride on mitochondria isolated from an hepatic cell line J Appl Toxicol 21, pp 323-329

RMZ-M&G 2004, 51 1014 PART 2 BIOGEOCHEMISTRY

A bioassay framework for the study of methylmercury bioavailability to freshwater algae

PATRICK R GORSKI1, DAVID E ARMSTRONG1 & JAMES P HURLEY1

1University of Wisconsin-Madison, WI, USA; E-mail: prgorski@wisc!edu

Abstract: The main purpose of this study was to develop a batch algal culture bioassay under well-defined conditions for use at ambient mercury concentrations that could be used to assess the bioavailability of methylmercury (MeHg) by algae The alga Selenastrum capricornutum grew well in Fraquil media, which had been trace-metal cleaned by passing the media through Chelex resin columns The algal also showed exponential growth at 20 ng/L of MeHg Acid-leached polycarbonate flasks were used and achieved consistent mass balances with MeHg additions, even under lighted conditions This bioassay provides the basis to due further studies on the bioavailability of MeHg For example, rates of MeHg uptake and loss could be measured Also, having a defined media allows for MINEQL+ software modeling to test bioavailability questions related to chemical component speciation within the media This further allows for predictions of bioavailability of mercury in natural waters

Key words: methylmercury, algae, bioavailability, bioaccumulation, ligands

INTRODUCTION bioassay in a well-defined media to first understand the behavior of MeHg and algae in Methylmercury (MeHg) accumulates in a simple system This bioassay approach then some, but not all, aquatic food chains The could be applied to more complex matrix entry point of MeHg into the base of the such as natural waters aquatic food chain is usually with algae Although there have been many studies that report field concentrations of mercury (Hg) METHODS in fresh water algae or seston, mechanisms of accumulation and uptake by algae are still After attempting experiments with several poorly understood If these mechanisms and algae (greens, cryptophytes and diatoms), processes were described, scientists might be Selenastrum capricornutum (UTEX 1648) able to predict characteristics that are con- was chosen due to its ease of growth in the ducive to bioaccumulation lab, prior use in other studies, presence in natural samples, edibility to zooplankton, and Natural waters are a complex matrix of or- use as an U#S# EPA test organisms# ganic and inorganic ligands that can poten- Selenastrum is a relatively small (~10 µm tially complex MeHg This complexation long), crescent-shaped, unicellular green may inhibit, or promote, bioavailability of alga# The algal cultures were grown axeni- MeHg to algae We propose using an algal cally in acid-leached polycarbonate flasks

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1015 and within laminar flow hoods# The area was concentration of MeHg in the media was illuminated by 24 hours continuous cool below detection limit (0#02 ng L-1) and be- white fluorescent lighting (3300 Lux), kept low 1#0 ng L-1 for HgT# The algae were also under constant HEPA filtration and within below detection limit for MeHg# an environmental chamber kept at 20 °C# The alga was maintained in full-recipe me- Before experiments, the alga was grown for 7 dia# For experiments, the media was made days in Fraquil media The alga was then trans- without Cu, Zn and EDTA to avoid compe- ferred (~5 mL) to Fraquil media deficient in tition between MeHg, Cu and Zn for bind- disodium ethylenediamine tetraacetate ing sites on the algae and avoid binding of (EDTA), Cu and Zn and grown for 5 more MeHg to EDTA instead of the algae# days in order to purge (i e , growth dilute) any trace contaminants in the algae The alga was Our polycarbonate flask cleaning procedure then inoculated (4000 cells mL-1) into flasks was first to immerse flasks for 2-3 days in containing deficient Fraquil for experiments reagent-grade 20 % HNO at room tempera- 3 The main endpoint of our tests was the con- ture# We then filled the flasks with 10 % centration of MeHg in the media (ng L-1) and trace metal grade (TMG) HCl and placed organisms (ng g dry weight-1 or ag cell-1) over them in a 40 °C overnight# The flasks were a set amount of time (usually 24 hours) stored completely filled with 1 % TMG HCl# Bioavailable MeHg was measured as the The flasks were rinsed with Milli-Q water amount of MeHg taken up relative to controls between each acid leaching step# Omission of the step using 10 % HCl at 40 °C gave The alga was grown in Fraquil media 1, which poor recovery of MeHg at the end of the ex- has been used for other trace-metal algal periment, possibly because residual HNO 3 experiments# The salts were prepared accord- in the flasks destroyed MeHg# ing to Morel et al# with nutrients according to PRICE ET AL# 2 and then pumped (~7 mL Aqueous (filtrate) and particulate (QFF fil- minute-1) through resin columns to remove ter with alga) samples for MeHg analysis any possible trace metal contamination# The were distilled and then analyzed using tradi- nutrients and salts portions of the media were tional GC and CVAFS techniques# Cell den- passed through separate columns and com- sity was enumerated with a flow cytometer bined afterwards# The columns consisted of (Coulter counter)# Teflon tubing filled with 3#0 g of clean Chelex 100 resin (200-400 mesh; Bio-Rad Laboratories, Richmond, CA, USA)# The RESULTS AND DISCUSSION Chelex resin was cleaned in several-steps, similar to PRICE ET AL# 2# After mixing, me- In the first experiment, preconditioned (ex- dia was sterilized with an acid-leached 0#2 posed to a spike at experimental concentra- µm capsule filter to avoid possible contami- tion for 24 hours and then media was dis- nation associated with autoclaving# The me- carded) and non-preconditioned flasks were dia was routinely assayed for sterility using spiked with MeHg (~2 ng L-1) exposed to LB (Luria-Bertani) broth# The background lighted experimental conditions for 24 hours!

RMZ-M&G 2004, 51 1016 PART 2 BIOGEOCHEMISTRY

As a control, a MeHg-spiked Teflon bottle From these results, we felt confident in us- was incubated in the dark! At the end of the ing acid-leached polycarbonate flasks under experiment, half of the flasks were acidified lighted conditions for our experiments! Al- to 1% HCl and the contents of others were though an earlier investigation showed poured-off into Teflon bottles and then acidi- photo-degradation of MeHg in the field un- fied! All four polycarbonate flask treatments der full-spectrum sunlight 3, our results were similar in MeHg concentration (Figure showed no photo-degradation of MeHg un- 1a)! Preconditioning of the flasks, or acidi- der cool white fluorescent lighting! fication of the media in the flasks, showed no effect on recovery of MeHg compared to Selenastrum was grown in both Fraquil with initial and final concentrations (ANOVA, a full compliment of ingredients and also in F=2!25, p>0!05)! Concentrations were Fraquil without Cu, Zn and EDTA! The ini- slightly higher in the initial and final mea- tial density was 4000 cells mL-1 for both ex- surements which, although single measure- periments! The first experiment was run for ments, were in Teflon and the final measure- 3 days and the second for 8 days (Figure 2)! ment was kept dark! The second container Through the first 4 days, growth was similar experiment (Figure 1b) showed no difference in the two types of media! It was not until between light and dark treatments or precon- day 5 that the cell density diverged between ditioning (P=preconditioning), and was also the media types! The deficient media was within the variability of the three initial con- sufficient for our purposes, since experiments centration measurements (ANOVA, F=0!37, were run for 2 days or less! For the first 24 p>0!05)! Finally, we compared polycarbon- hours, the growth rate followed an exponen- ate flasks and Teflon bottles under light and tial growth curve and doubling time was dark conditions (no preconditioning)! There roughly 10 hours (Figure 3a)! Furthermore, was no significant difference between light there were no signs of toxic effects (i!e! re- and dark or polycarbonate or Teflon contain- duced growth) on algal growth up to 24 hours ers (Figure 1c, ANOVA, F=1!87, p>0!05)! when comparing a control (no MeHg) with

Figure 1a-c Three experiments testing preconditioning, bottle type and photodegredation of MeHg

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1017 a 2 ng L-1 MeHg-spiked treatment (Figure The alga was then exposed to MeHg 3a) Fitting the growth curve data using a (20 ng L-1) over a 48-hour period and rate first order model gave k =007 hr-1 where k constants were measured for uptake and loss G G is the pseudo first-order growth rate constant of MeHg Afterwards, a competitive ligand (Figure 3b) experiment with EDTA was used to estimate the conditional equilibrium constant for the MeHg-algae complex and applied to a MINEQL+ model

CONCLUSIONS

Our polycarbonate acid-leaching protocol maintains cleanliness and recovery of MeHg Preconditioning of flasks is not necessary The alga chosen grew well in Fraquil media, Figure 2 Algae grown with and without EDTA even if the media was deficient in EDTA, Cu, Zn and contained MeHg The bioassay shows excellent applicability to questions of bioavailability of Hg

Acknowledgements

This work was supported by the US Envi- ronmental Protection Agency, Science to Achieve Results (STAR) program; grant #GR827629-01-0 The development of the bioassay was enhanced along the way with help from Martin Shafer, Lisa Cleckner, Ri- chard Back, Kris Rolfhus, Dawn Karner, Jocelyn Hemming, Miel Barman, Linda Gra- ham and David Krabbenhoft

Figure 3a-b Algal growth

RMZ-M&G 2004, 51 1018 PART 2 BIOGEOCHEMISTRY

REFERENCES

[1] MOREL, F M M, WESTALL, J C, RUETER, J G, [2] PRICE, N M, HARRISON, G I, HERING, J G, HUDSON, CHAPLICK, J P (1978): Description of the algal R J, NIREL, P M V, PALENIK, B, MOREL, F M growth media Aquil and Fraquil; Ralph M (1989): Biological Oceanography 6, pp Parsons Laboratory for Water Resources and 443-461 Environmental Engineering, Massachusetts In- [3] SELLERS, P, KELLY, C A, RUDD, J W M, stitute of Technology MACHUTCHON, A R (1996): Nature 380, pp 694-697

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1019 Effect of methylmercury on the rat mast cell function and photosynthetic activity of microalgae

ELIZABETH GRAEVSKAYA1, AKIRA YASUTAKE2, RYOJI ARAMAKI2, TATYANA KRENDELEVA1, GALINA KUKARSKICH1, TARAS ANTAL1, DMITRII MATORIN1, ANDREW RUBIN1

1Biophysical Department, Biological Faculty, Lomonosov Moscow State University, Vorobevy Gory, Moscow, 119992 Russia; E-mail: graevsk@biophys*msu*ru 2 National Institute for Minamata Disease, 4058-18 Hama, Minamata, Kumamoto 867-0008, Japan

Abstract: Methylmercury (MeHg) treatment can modify mast cell function in vivo and in vitro depending on concentration and time Using the cells prepared from methylmercury-intoxicated rats, we observed the suppression of calcium ionophore A23187- and 48/80-induced histamine release, which was enhanced with the time after the treatment The pre-incubation with methylmercury in vitro at a 10-8 M concentration for 10 min significantly enhance A23187 and compound 48/80-stimulated degranulation Our results in vivo and in vitro provide the first proof that exposure to MeHg affects mast cell function For diatomea microalgae Thalassiosira weissflogii we found that 10-6 and 10-7 M MeHg led to a slow decrease in the PS II activity following the prolonged lag phase, whereas the algae was not sensitive to the same concentrations of HgCl The 2 both toxicants decreased the rate of PS II reparation, as well as increased a heat pathway of excitation dissipation in PS II antennae complexes For green microalgae Chlamy- domonas reinhardtii it was shown that MeHg at concentrations under 10-6 M decreased the maximal efficiency of energy utilization in PS II Incubation with 5 10-6 M of HgCl 2 up to 5 hrs did not affect both ratios as compared to the control values Our data testify that MeHg treatment of algae cells evoke the damage on the donor side of PS II as well as damage of the electron transfer chain at several sites The effect of methylmercury is much stronger than the effect of mercury chloride on photosynthetic processes

Key words: methylmercury, mercuric chloride, mast cells, microalgae, photosynthesis

INTRODUCTION ticular, its known as inhibitor of vitally important functions in the plant cells (DE FILIPPIS Heavy metals pollute both aquatic and terres- ET AL, 1993) and a significant neurotoxicant trial areas as result of anthropogenic activity causing Minamata disease for animals (IPCS, Mercury has been the most toxic element 1990) In animal models MeHg was estab- among heavy metals Organic compounds of lished also as a modulator of the immune sys- mercury including methylmercury (MeHg) tem Mast cells are known to be among the could be especially dangerous for living or- most important effector immunocompetent ganisms due to the strong toxic effect as well cells participating in various biological reas the ability for accumulation in the food sponses Evaluation of toxic effect of MeHg chains MeHg affects drastically metabolic on algae cells seems to be important to study processes in the animal and plant cells In par- since phytoplankton forms the base level of

RMZ-M&G 2004, 51 1020 PART 2 BIOGEOCHEMISTRY aquatic food pyramid and could determine (20 mg/kg)& In the cells prepared from conditions of ecosystem at whole The goal of MeHg-treated rat 8 days after the final ad- this paper is to elucidate the methylmercury- ministration, A23187-stimulated histamine evoked effects on the immunocompetent mast release was suppressed by 50 % of the con- cells of rat and primary reactions of photosyn- trol level& The suppression of histamine re- thesis in diatomea microalgae Thalassiosira lease was enhanced with time and on days weissflogii and green microalgae Chlamy- 12 and 15 up 70-90 %& Suppression in com- domonas reinhardtii pound 48/80-stimulated release was also significant and on day 15 the release was inhibited by 50 % (Fig& 1)& Our results in vivo pro- RESULTS AND DISCUSSION vide the first proof that exposure of rats to MeHg affects mast cell function& These data We investigated the effects of MeHg on the reveal a higher sensitivity of calcium iono- rat mast cell degranulation induced by non- phore stimulated histamine release to immunological stimuli (the selective libera- MeHg exposure in vivo in comparison with tor of histamine, compound 48/80, and cal- compound 48/80-stimulated release& cium ionophore A23187) both in vivo and in vitro& Using the cells prepared from meth- Our in vitro experiments demonstrated that ylmercury-intoxicated rats through a 5-day MeHg of the minimal concentration (10-8 M) treatment of MeHgCl (10 mg/kg/day), we enhanced histamine release from the mast observed the suppression of calcium iono- cells in conjunction with active stimulation phore A23187- and 48/80-induced histamine with polyamine compound 48/80 or calcium release, which was enhanced with the time ionophore A23187 (Fig& 2)& This effect was after the treatment (Fig& 1)& Similar suppres- dependent on the preincubation time: with sion was observed in the ionophore-stimu- prolongation of preincubation period up to lated release, when cells were prepared from 30-min, MeHg in the whole concentration a rat after a single treatment of MeHgCl range significantly reduced the effects of

Figure 1 Histamine release from mast cells of MeHg-intoxicated rats Asterisks (*) indicate values that differ significantly from those of the control rats (P<0 05)

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1021

Figure 2 Histamine release from methylmercury-treated mast cells stimulated with A23187(A) or compound 48/80 (B) Asterisks (*) indicate values that differ significantly from those with liberators alone (P<0 05) both the calcium ionophore A23187- and to MeHg as compared to chloride mercury compound 48/80-stimulated histamine re- effects in diatomea microalgae Thalassiosira lease& Increase in MeHg concentration also weissflogii and green microalgae Chlamy- suppressed the effects& The inhibition of the domonas reinhardtii cells& histamine release at the higher MeHg concentration suggested a toxicological rel- MeHg as well as HgCl suppressed signifi- 2 evance of these effects& cantly efficiency of photochemical energy conversion in PS II (PS II activity measured As its known in plants photosynthesis is the as the ratio Fv/Fm) in the cells of most sensitive target for heavy metals& Pulse- Thalassiosira weissflogii at concentration amplitude-modulation (PAM) fluorometric higher than 10-6 M, followed by cells elimi- method was involved for estimation of sen- nation (Fig& 3)& A slow decrease in PS II ac- sitivity of primary photosynthetic reactions tivity was registered at lower concentrations

Figure 3 Dependence of half time of PS II inactivation (t ) in T weissflogii on HgCl (solid 1/2 2 circles) and MeHg (open circles) concentration

RMZ-M&G 2004, 51 1022 PART 2 BIOGEOCHEMISTRY

(10-6 and 10-7 M), meanwhile HgCl2 did not MeHg at concentration higher than 10-6 M$ affect activity of PS II at these concentra- Meantime it was insensitive to the toxicant tions at lower concentration (Fig$ 4)$ The level of inhibition depended on the time of incuba- Study of the population heterogeneity showed tion and was always stronger at illumination that PS II inactivation after the treatment by (50 µE m-2 s-1) than in the dark conditions$ these concentrations of MeHg was not com- Incubation of cells with HgCl at concentra- 2 plete and part of the cells retained high level tion 5 10-6 M did not cause change in PS 2 of PS II activity (data is not shown)$ It is fea- activity as compared to the control values sible that these cells could determine adapta- (data is not shown)$ Analysis of the fast fluo- tion of algae to toxic effects$ Both of the toxi- rescence kinetics after the treatment of al- cants declined the rate of PS II activity re- gae cells by MeHg testified to the damage covery at the concentration 5*10-6 (data is of the PS II function both on the donor and not shown)$ This result could be attributed to acceptor side (electron transfer from Q to A the inhibition of protein synthesis that leads Q ) (data is not shown)$ Examination of the B to diminished PS II reparation$ photochemical fluorescence quenching parameters during incubation with MeHg also In contrast to Thalassiosira weissflogii pho- confirmed an increase in the fraction of Q - B tosynthetic apparatus of green algae Chlamy- nonreducing reaction centers (data is not domonas reinhardtii was more sensitive to shown)$

Figure 4 Dependence of half time of PS II inactivation in C reinhardtii on MeHg concen-

tration in the dark (1) and light 50 µE m-2 s-1(2)

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1023

CONCLUSIONS damage of photosynthetic electron transfer chain mainly due to the inhibition of PS II In total the present study has demonstrated activity Primary reactions of photosynthe- that mercury poisoning modified the most sis in studied algae species revealed high important functions of animal and plant cells sensitivity to methylmercury mainly at do- In animal models methylmercury treatment nor and acceptor sites of PS II can modify mast cell function depending on concentration and time The results obtained Acknowledgements may contribute to a better understanding of pathological and immunomodulatory effects This research was supported by the Research of methylmercury in animal models In Development Corporation of Japan (JRDC) microalgae cells methylmercury evokes and by the Russian Foundation for Basic Research

REFERNCES

DE FILIPPIS, L F, ZIEGLER, H (1993): Effect of suble- International Program of Chemical Safety (IPCS) thal concentrations of zinc, cadmium and mer- (1990): Environmental health criteria 101, me- cury on the photosynthetic carbon reduction thylmercury; World Health Organization, p 144, cycle of Euglena; J Plant Physiol , Vol 142, Geneva pp 167-172

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A new dynamic chamber for examining the exchange of Hg(0) between foliage and the atmosphere

JENNIFER A GRAYDON1, VINCENT L ST LOUIS1, HOLGER HINTELMANN2, STEVE E LINDBERG3 AND DAVE KRABBENHOFT4

1University of Alberta, Edmonton, Canada; E-mail: jgraydon@ualberta$ca; vince$stlouis@ualberta$ca 2Trent University, Peterborough, Canada; E-mail: hhintelmann@trentu$ca 3Oak Ridge National Laboratory, Oak Ridge, USA; E-mail: sll@ornl$gov 4U$S$ Geological Survey-WRD, Middleton, USA; E-mail: dpkrabbe@usgs$gov

Abstract: We present the design of a new dynamic open chamber system to quantify Hg(0) exchange between living canopy foliage and the atmosphere in the field Using this new Hg(0) flux chamber in conjunction with isotopically enriched stable Hg tracers, we 1) examined the ambient light spectrum responsible for the photoreduction of newly deposited spike 202Hg(II) on foliage, and 2) compared spike 200Hg(0) evasion rates from foliage with loss of spike 200Hg(II) from foliage over time The fact that a portion of Hg(II) deposited in wet deposition is intercepted by the canopy, photoreduced and then evaded back to the atmosphere has implications for modeling net deposition of Hg to watersheds

Key words: canopy, flux chamber, re-emission, surface/air exchange, METAALICUS

INTRODUCTION HANSON ET AL%, 1995), or particulate/reactive gaseous Hg (RGM) can be dry deposited to Forest canopies contribute significantly to foliar surfaces% However, Hg(0) released fluxes of monomethyl Hg (MMHg) and to- from soils below the canopy through vola- tal Hg (HgT; all forms of Hg) to watersheds tilization can also be taken up via stomata, (LINDBERG, 1996; REA ET AL%, 1996; ST% LOUIS resulting in Hg being recycled within the ET AL%, 2001; GRIGAL, 2002)% At the Experi- forest community% Plants may also accumu- mental Lakes Area (NW Ontario, Canada), late Hg from soil waters by root uptake and almost all the increased flux of Hg under the translocation to foliage (e%g%, GODBOLD AND forest canopy occurs as litterfall (ST% LOUIS HÜTTERMANN; 1988, BISHOP ET AL%, 1998)% ET AL%, 2001), and as a result, it is important Plant foliage also provides an excellent sur- to understand whether litterfall constitutes a face for photochemical reduction of newly new and/or recycled input of Hg to the for- deposited Hg(II) remaining in the forest est floor% For litterfall to be considered a new canopy following precipitation events, affect- input, the Hg in/on foliage must originate ing net deposition of Hg(II) to the forest floor from the atmosphere% For example, atmo- (LINDBERG ET AL%, 1998)% The amount of re- spheric Hg(0) can be assimilated into foli- duction and re-emission of Hg to the at- age through stomata (LINDBERG ET AL%, 1991; mosphere is important because it ultimately

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1025 influences the residence time of Hg in aquatic Hg stable isotope tracers, we examined the and terrestrial pools, and hence the amount ambient light spectrum responsible for the of Hg subsequently available for methyla- re-emission of newly deposited spike tion and bioaccumulation 202Hg(II) from foliage, and compared spike 200Hg(0) evasion rates from foliage with loss Both micrometeorological and enclosure tech- of spike 200Hg(II) from foliage over time niques have been used to measure exchange of Hg(0) at the biosphere/atmosphere interface The most common chamber design used RESULTS AND DISCUSSION to quantify gas exchange is an open system arrangement (so-called dynamic flux cham- Tracer (as spike 202Hg(0)) re-emission fluxes bers), where there is a net flow of air through were highest immediately after wet applica- the chamber Here, Hg(0) flux is estimated tion (intended to simulate wet deposition) of from the product of airflow rate and the dif- spike 202Hg(II) to the foliage, and decreased ference in Hg(0) concentration in air entering over time When selective filters were draped and exiting the chamber (WALLSCHLÄGER ET over the chamber to prevent either UV-A, AL , 1999) It is extremely important that there UV-B, or all solar radiation from reaching is a relatively high turnover rate of air through the foliage, we observed reductions in the the chamber so that the environment within evasion of spike Hg(0) In contrast, presence the chamber is as homogeneous and similar of UV filters had no obvious effect on the to the external environment as possible magnitude or direction of the ambient (non- (WALLSCHLÄGER ET AL , 1999; GILLIS AND isotopic) Hg(0) flux These results suggest MILLER, 2000) Furthermore, since there is that the flux of ambient Hg(0) from foliage evidence that a significant amount of foliar may a function of both photoreduction of Hg(0) exchange occurs via stomata (DU AND ambient Hg(II) on foliar surfaces and trans- FANG, 1982; LINDBERG ET AL , 1992; HANSON port of ambient Hg(0) through the evapo- ET AL , 1995, LINDBERG, 1996), it is also criti- transpiration stream This conclusion is con- cal that chamber designs do not interfere with sistent with numerous flux measurements normal physiological responses (e g , photo- made on black spruce and jack pine trees, synthesis and transpiration) of enclosed foli- which almost always showed net evasion of age It is also important that chamber materi- ambient Hg(0) to the atmosphere when at- als not block spectral wavelengths such as ul- mospheric concentrations were near global traviolet radiation (UV) potentially important background levels of ~1 5 ng/m3 for the photochemical reduction of Hg(II) to Hg(0) (KIM AND LINDBERG, 1995) As part of the Mercury Experiment to Assess Atmospheric Mercury Loadings We designed a new dynamic open chamber in Canada and the United States system that allows both full spectrum light (METAALICUS), we also used the chamber transmission and enclosed intact foliage to to quantify the proportion of the spike 200Hg(II) maintain normal physiological function loaded onto the forest canopy in wet deposi- while Hg(0) flux rates are quantified Using tion that was photoreduced and subsequently this Hg(0) flux chamber in conjunction with evaded back to the atmosphere as spike Hg(0)

RMZ-M&G 2004, 51 1026 PART 2 BIOGEOCHEMISTRY

Evasion rates of spike Hg(0) were highest CONCLUSIONS immediately after the aerial application in May, and decreased to levels barely above Results from experiments employing our detection by the end of the summer Canopy new dynamic Hg(0) flux chamber and stable foliage was also collected for analysis of spike Hg isotope tracer techniques suggested that Hg(II) concentrations over this time period UV wavelengths may be important in driv- We modeled the expected loss of spike Hg(II) ing photoreduction and re-emission of newly from foliage over time using the actual cham- deposited Hg(II) (in simulated wet deposi- ber spike Hg(0) flux measurements to deter- tion) from canopy foliage Modeling exer- mine the proportion of observed spike Hg(II) cises indicate that in addition to being re- loss from foliar surfaces accounted for by emitted as Hg(0) and being carried to the spike Hg(0) evasion to the atmosphere Spike forest floor in throughfall, there may be an- Hg(0) re-emission rates could not account for other loss mechanism of newly deposited the rapid exponential decline in foliar con- Hg(II) from foliage Accurate quantification centrations of spike Hg(II) after the aerial of re-emission of the portion of Hg(II) in wet spike application, even when maximum esti- deposition intercepted by the canopy is cru- mates of growth dilution and losses of spike cial for modeling net deposition of Hg to Hg(II) in throughfall were included If the watersheds chamber spike Hg(0) emissions values were accurate, these results suggest another pos- Acknowledgements sible loss mechanism of spike Hg(II) from foliage, such as cuticle sloughing This work was supported by NSERC, CCI/ CBAR and the Alberta Heritage Fund

REFERENCES

BISHOP, K H, LEE, Y, MUNTHE, J & DAMBRINE, E GRIGAL, D F (2002): Inputs and outputs of mercury (1998): Xylem sap as a pathway for total mer- from terrestrial watersheds: a review; Environ cury and methylmercury transport from soils to Rev, Vol 10, pp 1-39 tree canopy in the boreal forest; Biogeochemis- HANSON, P J, LINDBERG, S E, TABBERER, T A, OWENS, try, Vol 40, pp 101-113 J G & KIM, K H (1995): Foliar exchange of DU, S-H & FANG, S C (1982): Uptake of elemental mercury vapor-evidence for a compensation mercury vapor by C and C species; Environ- 3 4 point; Water, Air and Soil Pollution, Vol 80, mental and Experimental Botany, Vol 22, No pp373-382 4, pp 437-443 KIM, K H & LINDBERG, S E (1995): Design and ini- GILLIS, A & MILLER, D R (2000): Some potential er- tial tests of a dynamic enclosure chamber for rors in the measurement of mercury gas ex- measurements of vapor-phase mercury fluxes change at the soil surface using a dynamic flux over soils; Water Air and Soil Pollution, Vol chamber; Sci Tot Environ, Vol 260, No 1-3, 80, No 1-4, pp1059-1068 pp 181-189 GODBOLD, D L & HÜTTERMANN, A (1988): Inhibition of photosynthesis and transpiration in relation to mercury-induced root damage in spruce seed- lings; Physiol Plant 74, pp 270-275

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1027

LINDBERG, S E (1996): Forests and the global bio- REA, A W, KEELER, G J, & SCHERBATSKOY, T (1996): geochemical cycle of mercury: the importance The deposition of mercury in throughfall and of understanding air/vegetation exchange pro- litterfall in the Lake Champlain watershed: a cesses In Global and Regional Mercury Cycles: short-term study; Atmos& Environ, Vol 30, No Sources of Fluxes and Mass Balances (W 19, pp 3257-3263 BAEYENS ET AL, Eds), Kluwer Academic, Bos- ST LOUIS, V L, RUDD, J W M, KELLY, C A, HALL, ton pp 359-380 B D, ROLFHUS, K R, SCOTT, K J, LINDBERG, LINDBERG, S E, HANSON, P J, MEYERS, T P & KIM, S E, & DONG, W (2001): Importance of the K H (1998): Air/surface exchange of mercury forest canopy to fluxes of methyl mercury and vapor over forests the need for a reassessment total mercury to boreal ecosystems; Environ& of continental biogenic emissions; Atmospheric Sci&Technol&, Vol 35, No 15, pp 3089-309 Environment, Vol 32, No 5, pp 895-908 WALLSCHLÄGER, D, TURNER, R R, LONDON, J, LINDBERG, S E, MEYERS, T P, TAYLOR, G E, TURNER, EBINGHAUS, R, KOCK, H H, SOMMAR, J, & XIAO, R R, & SCHROEDER, W H (1992): Atmosphere- Z F (1999): Factors affecting the measurement surface exchange of mercury in a forest - re- of mercury emissions from soils with flux cham- sults of modeling and gradient approaches; Jour- bers; Journal of Geophysical Research-Atmo- nal of Geophysical Research-Atmospheres, Vol spheres, Vol 104, No D17, pp 21859-21871 97, No D2, pp 2519-2528 LINDBERG, S E, TURNER, R R, MEYERS, T P, TAYLOR, G E & SCHROEDER, W H (1991): Atmospheric concentrations and deposition of Hg to a deciduous forest at Walker Branch Watershed, Tennes- see, USA; Water, Air and Soil Pollution, Vol 56, pp 557-594

RMZ-M&G 2004, 51 1028 PART 2 BIOGEOCHEMISTRY

Relationship between mercury and selenium in the brain of river otter (Lutra canadensis) and wild mink (Mustela vison) from Nova Scotia, Canada

KEVIN J R HAINES1, R DOUGLAS EVANS2, AND MIKE OBRIEN3

1Watershed Ecosystems Graduate Program, Trent University, Peterborough, ON, Canada; E-mail: khaines@trentu#ca 2Environmental and Resource Studies, Trent University, Peterborough, ON, Canada; E-mail: devans@trentu#ca 3Furbearers and Upland Game, Department of Natural Resources, Kentville, NS, Canada; E-mail: obrienms@gov#ns#ca

Abstract: We have analyzed the brain concentrations of mercury and selenium in otter and mink in order to assess whether or not selenium could be counteracting mercury neurotoxicity in these animals Animals were collected from areas of Nova Scotia where mercury concentrations in biota are known to be high A significant positive relationship was observed between mercury and selenium in otter brain, while no relationship was observed between the two elements in mink brain Results suggest that otters may be compensating for mercury neurointoxication by increasing their accumulation of selenium in the brain, while this possibly protective mechanism does not appear to exist in mink

Key words: wildlife, toxicity, methylmercury, selenium, brain

INTRODUCTION which leads to impaired vision Severe methylmercury poisoning can result in death The addition of a methyl group to mercury (CLARKSON, 1997) (Hg) greatly increases the tendency of this toxic metal to bioaccumulate in fish Ani- Selenium (Se) has received much attention mals that are highly reliant upon fish as a for its possible role as a detoxifier of mer- food source can face significant health risks cury in the body A number of piscivorous from exposure to methylmercury Methylm- wildlife species known to accumulate very ercury accumulates in all tissues and organs, high body burdens of mercury have been including the brain, which is the critical tar- documented to also accumulate equal molar get during methylmercury intoxication amounts of selenium (CUVIN-ARALAR AND (CLARKSON, 1997) The neurological symp- FURNESS, 1991) Interestingly, however, the toms associated with methylmercury poison- fish that make up the diets of these animals ing reflect where the toxin has deposited do not tend to contain equal amounts of mer- Methylmercury preferentially accumulates in cury and selenium The establishment of a the cerebellum, which leads to impaired 1:1 mercury-to-selenium ratio within pis- motor activity, and in the occipital cortex, civorous animals themselves is presumed,

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1029 therefore, to reflect a mechanism whereby selenium is providing protection against mercury intoxication (CUVIN-ARALAR AND FURNESS, 1991)

River otter (Lutra canadensis) and wild mink (Mustela vison) are both semi-aquatic, fish- eating mammals of the family Mustelidae, and are found in waterways across much of North America" Fish represents close to 90 % of the otters diet and between 25 and 50 % of the minks diet" Because of their highly Figure 1 Map of Nova Scotia, Canada, where otter piscivorous diets, otter and mink can both and mink were collected The counties used for col- be expected to accumulate high body bur- lection were Digby, Yarmouth, Shelburne, and Queens dens of mercury, and previous studies have Significant, positive relationships were ob- shown this to be true (EVANS ET AL", 2000)" served between mercury and selenium in No previous studies, however, have quanti- brains of both interior and coastal otters" As tatively examined the relationship between shown in Figure 2, selenium accumulates in mercury and selenium in the brains of these molar excess of mercury in the brain until a animals" threshold mercury concentration of approximately 20 nmol/g has been reached" In inte- The purpose of this study was to assess rior otters that had passed this threshold, the whether or not mercury and selenium co-accumulate in the brain of otter and mink as they do in the tissues of other piscivorous animals" The establishment of a one-to-one molar ratio between the two elements could indicate a mechanism whereby selenium is counteracting mercury neurotoxicity"

RESULTS AND DISCUSSION

A total of 66 otter and 34 mink collected from Nova Scotia fur trappers were selected for the present study (Fig" 1)" Animals were classified as interior or coastal depending on where they were trapped" Animals were trapped from areas where mercury concentrations in biota are known to be high" Figure 2 Relationship between molar concentrations of mercury and selenium in brain of interior (black circles) and coastal (white squares) otters The dashed line represents the 1:1 line of equivalence

RMZ-M&G 2004, 51 1030 PART 2 BIOGEOCHEMISTRY relationship between mercury and selenium No relationship whatsoever was observed was highly correlated (linear regression, between mercury and selenium in the brains n=12, R2=0858, p<0001) and the molar ra- of either interior or coastal mink As shown tio approached one (Se = 1139Hg 8833) in Figure 3, almost all Nova Scotia mink In coastal otters that had passed this thresh- contained a molar excess of mercury in rela- old, the relationship between mercury and tion to selenium in the brain In coastal mink, selenium was correlated (linear regression, total mercury concentrations explained 10 % n=10, R2=0546, p=0015) and the molar ra- of the variation in selenium concentrations tio approached one (Se = 0875Hg 2839) in the brain (linear regression; n=11; R2=0104; p=0332) In interior mink, total mercury concentrations explained only 1% of the variation in selenium concentrations in the brain (linear regression; n=23; R2=00112; p=0631)

CONCLUSIONS

Otters appear to increase their accumulation of selenium in the brain in response to increasing concentrations of mercury, while this phenomenon does not appear to exist in mink

If the establishment of a 1:1 molar ratio between mercury and selenium reflects a mecha- Figure 3 Relationship between molar concentrations nism whereby selenium is counteracting mer- of mercury and selenium in brain of interior (black circles) and coastal (white squares) mink The dashed cury toxicity, then mink appear to be more at line represents the 1:1 line of equivalence risk of mercury neurointoxication than otters

REFERENCES

CLARKSON, T W (1997): The toxicology of mercury; EVANS, R D, ADDISON, E M, VILLENEUVE, J Y, Critical Reviews in Clinincal Laboratory Sci- MACDONALD, K S & JOACHIM, D G (2000): ences 3, pp 369-403 Distribution of inorganic and methylmercury CUVIN-ARALAR, M L A & FURNESS, R W (1991): among tissues in mink (Mustela vison) and ot- Mercury and selenium interaction: A review; ter (Lutra canadensis); Environmental Research Ecotoxicology and Environmental Safety 21, pp Section A 84, pp 133-139 348-364

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1031 Methylmercury and total mercury in plant litter decomposing in upland forests and flooded landscapes

BRITT HALL & VINCENT ST LOUIS

Abstract: The objectives of this study were to examine effects of flooding on the leaching of total mercury (THg) from, and the production of methylmercury (MeHg) in, decomposing tissues from plants common to boreal upland forests at the Experimental Lakes Area in northwestern Ontario We used litterbags to study changes in THg, MeHg, carbon (C) and nitrogen (N) content of 12 different plant tissues (birch, alder, blueberry, and Labrador tea leaves, bunchberry plants, jack pine needles, Sphagnum spp, Polytrichum spp, and Pleurozium spp mosses, lichen, and fresh and extensively decomposed wood) placed on unflooded boreal forest soils and in experimentally created reservoirs over an ~800 day period Initial rates of decomposition as indicated by differences in the percentage of C and N mass left in the tissues over time were slower in plant tissues placed on unflooded soils compared to the same tissues that were inundated in reservoirs Depending on tissue type and initial THg concentrations, decomposing litter on both unflooded and flooded soils was either a source or a sink for THg In tissues that lost THg, initial THg concentrations were greater than 30 ng g-1 and represented a source of THg to the surrounding environment, whereas plants that had initial concentrations of less than 30 ng g-1 lost THg Initial rate of change in THg were more rapid in plant tissues placed in reservoirs compared to the same plant tissue placed on unflooded soils, but there were no differences in final THg masses after 800 days Plant tissues placed in reservoirs exhibited large increases in MeHg mass, whereas MeHg mass decreased in the same plants placed on unflooded soils This is the first study examining THg and MeHg cycling in decomposing plants in upland boreal forests and reservoirs

Key words: methylmercury, plants, reservoirs

RMZ-M&G 2004, 51 1032 PART 2 BIOGEOCHEMISTRY

Abiotic Mercury Methylation in Pore Waters of Coastal Marine Sediments

CHAD HAMMERSCHMIDT1 & WILLIAM FITZGERALD2

1Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, 06340, Groton, CT, USA, e-mail: chad&hammerschmidt@uconn&edu 2Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, 06340, Groton, CT, USA, e-mail: wfitzger@uconnvm&uconn&edu

Abstract: Little is known about the occurrence or biogeochemical significance of abiotic monomethylmercury (MMHg) production in the environment Recent laboratory studies have demonstrated that a considerable potential for artifact MMHg production exists during analysis of sediments We examined abiotic Hg methylation in sediment pore fluids from Long Island Sound and New York/New Jersey Harbor Pore waters were filter sterilized; this provides a relatively organic-rich environmental media without significant disturbance of the natural chemistry that may result from autoclaving or chemical sterilization Preliminary results show that chemical methylation of Hg is rapid, and the reaction is limited by availability of an unknown methylating agent The concentration/activity of methylating agent in filtered pore water was unrelated to bulk dissolved organic carbon or sedimentary organic matter and ranged 517 pN Such activities are less than the concentration of inorganic Hg in pore water of most coastal marine sediments Our results suggest that chemical methylation of Hg in coastal marine pore waters is limited by availability of an unknown chemical methylating agent; thus, rates of in situ abiotic methylation may be constrained by the kinetics of methylating agent regeneration in pore water, which could include sediment-water partitioning or bacterial remineralization processes

Key words: sediment, methylmercury, abiotic, methylation, pore water

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1033 Bioaccumulation of Methylmercury in Long Island Sound

CHAD HAMMERSCHMIDT1 & WILLIAM FITZGERALD2

Abstract: Coastal fisheries are the major source of human exposure to toxic methylmercury (MeHg) Humans are exposed to MeHg principally by consumption of marine fish, most (about 75%) of which are from the coastal zone However, and unfortunately, the bioaccumulation of MeHg in coastal marine systems has received scant scientific attention We examined MeHg in four ecologically representative and commercially relevant fishes from Long Island Sound (LIS) These include alewife (Alosa pseudoharengus), winter flounder (Pseudopleuronectes americanus), American lobster (Homarus americanus), and bluefish (Pomatomus saltatrix) MeHg comprised most of the total Hg in axial muscle of finfishes MeHg bioaccumulates in the food web of LIS; concentrations in suspended particulate matter, most of which is autochthonous, are greater than those in water and less than those in zooplankton Levels of MeHg are highest in piscivorous bluefish, less in invertivorous lobster and flounder, and lowest in planktivorous alewife Bluefish from LIS have 2-3 fold more MeHg that those of comparable size from nearby New York Bight Preliminary results show that MeHg concentration is unrelated to fish size (length, weight) for each of the study species in LIS, likely due variations in dietary MeHg of these migratory species The absence of agreement between size and MeHg content of coastal fishes, unlike that in many freshwater systems, suggests that human consumption advisories for Hg in marine species that are based on fish length may not reliably protect public health from the potential effects of dietary MeHg exposure

Key words: methylmercury, fish, bioaccumulation, marine, Long Island Sound

RMZ-M&G 2004, 51 1034 PART 2 BIOGEOCHEMISTRY

Biogeochemical Controls on the Production and Distribution of Methylmercury in Sediments of Long Island Sound, New York/New Jersey Harbor, and the Adjacent Continental Margin

CHAD HAMMERSCHMIDT1, WILLIAM FITZGERALD2, CARL LAMBORG3, PRENTISS BALCOM4, PIETER VISSCHER5 & LAURA BAUMGARTNER6

1Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, 06340, Groton, CT, USA, e-mail: chad)hammerschmidt@uconn)edu 2Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, 06340, Groton, CT, USA, e-mail: wfitzger@uconnvm)uconn)edu 3Woods Hole Oceanographic Institution, Mail Stop #25, Woods Hole Oceanographic Institute, 06340, Woods Hole, MA, USA, e-mail: clamborg@whoi)edu 4Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, 06340, Groton, CT, USA, e-mail: prentiss)balcom@uconn)edu 5Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, 06340, Groton, CT, USA, e-mail: pieter)visscher@uconn)edu 6Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, 06340, Groton, CT, USA, e-mail: lkb00002@uconnvm)uconn)edu

Abstract: Near shore marine sediments are a repository of pollution-derived legacy Hg, and they host active communities of sulfate-reducing bacteria, the principal group of microorganisms mediating transformation of inorganic Hg to monomethylmercury (MMHg) This combination in biologically productive near shore environments results in considerable production of MMHg Organic matter is a principal control on the distribution of inorganic Hg (Hg(II) = total Hg MMHg) and MMHg in coastal systems Partitioning with sedimentary organics governs levels of Hg(II) in pore water and influences microbial MMHg production Potential rates of Hg methylation vary inversely with the distribution coefficient of Hg(II) and positively with the concentration of dissolved Hg(II), mostly as HgS(0) or an organic-Hg complex, in low-sulfide pore waters Hg methylation is inhibited in high-sulfide sediments Bioturbation enhances production of MMHg; subsurface peaks in Hg methylation potentials coincide with anomalies in a bioturbation index that indicate physical disturbance of sediment Much of the MMHg synthesized in near shore sediments is mobilized to overlying water In situ sedimentary production is the major source of MMHg to near shore systems, and it can account for most of the MMHg in primary producers Hence, bioturbation may redistribute legacy Hg within the sedimentary column to zones where SRB actively methylate Hg(II) that is de-sorbed from the organic particulate phase, creating a potential for methylation, mobilization, and bioaccumulation of pollutant Hg that was buried during the past 150 years

Key words: organic matter, methylmercury, Sediments, methylation, marine

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1035 Biogeochemical Cycling of Methylmercury in Lacustrine and Tundra Wetland Systems of Arctic Alaska

CHAD HAMMERSCHMIDT1, WILLIAM FITZGERALD2, CARL LAMBORG3, C -MAO TSENG4 & PRENTISS BALCOM5

1Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, 06340, Groton, CT, USA, e-mail: chad(hammerschmidt@uconn(edu 2Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, 06340, Groton, CT, USA, e-mail: wfitzger@uconnvm(uconn(edu 3Woods Hole Oceanographic Institution, Mail Stop #25, Woods Hole Oceanographic Institution, 02543, Woods Hole, MA, USA, e-mail: clamborg@whoi(edu 4National Center for Ocean Research, National Center for Ocean Research, National Taiwan University, PO Box 2, Taipei, Taiwan, e-mail: cmtseng@ncor(ntu(edu(tw 5Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, 06340, Groton, CT, USA, e-mail: prentiss(balcom@uconn(edu

Abstract: Little is known about the biogeochemistry of monomethylmercury (MMHg) in arctic lakes and their wetland watersheds We examined the cycling of MMHg in four arctic Alaskan lakes in July 2002 and 2003 These ultra-oligotrophic systems are distinguished from those in temperate climes by their low levels of sulfate, alkaline pH, and nearly constant sunlight during summer In situ sedimentary production and mobilization is the principal source of MMHg (about 90%) in our study lakes, with inputs from surrounding wetland tundra and atmospheric deposition contributing considerably less The functional group of microorganisms methylating Hg in sediments was examined with inhibitor incubations Bioaccumulation and sedimentation account for about 10% of the MMHg delivery; the rest is lost to water-column decomposition Incubation experiments with surface water show that MMHg degradation is entirely photochemical This investigation indicates that the cycling of MMHg in arctic freshwater systems is controlled by microbial production in the sediments and photochemical degradation in the water column

Key words: sediment, Arctic, methylmercury, Lakes, methylation

RMZ-M&G 2004, 51 1036 PART 2 BIOGEOCHEMISTRY

Bioaccumulation of Dietary Methylmercury in Adults and Eggs of Fathead Minnows (Cyprinidae)

CHAD HAMMERSCHMIDT1 & MARK SANDHEINRICH2

1University of Connecticut, Department of Marine SciencesGroton, CT, 06340, Groton, USA, e-mail: chad#hammerschmidt@uconn#edu 2University of Wisconsin-La Crosse, 1725 State StreetLa Crosse, WI, 54601, La Crosse, USA, e-mail: sandhein#mark@uwlax#edu

Abstract: Maternal transfer is the principal source of methylmercury (MeHg) to embryos of oviparous fishes We examined accumulation of dietary MeHg in adults and eggs of female fathead minnows (Pimephales promelas), a fractional spawner Juvenile fish were fed one of four diets until sexual maturity (phase 1): a control diet (006 µg Hg g-1 dry weight) and three diets contaminated with MeHg at 088 (low), 411 (medium), and 846µg Hg g-1 dry weight (high) At sexual maturity, male and female fish were paired, again fed one of the four diets, and allowed to reproduce (phase 2) To assess the significance of diet during gametogenesis on concentrations of MeHg in eggs, some females were fed diets during phase 2 that differed from those during phase 1 After about 220 d of exposure to the phase-1 diet, MeHg in adults averaged 048 (control diet), 340 (low), 1449 (medium), and 2005 µg Hg g-1 dry weight (high) MeHg in eggs was related positively to that in females and averaged about 30 % of the adult concentration Mean levels in eggs were 006 (control diet), 084 (low), 411 (medium), and 729 µg Hg g-1 dry weight (high) A power function, with dietary concentration and number of days of dietary exposure as the dependent variables, accounted for 98 % of the variability in MeHg concentration of adults and eggs Females fed a contaminated diet during phase 1 and a control diet during phase 2 depurated MeHg; the rate of decline in egg MeHg varied with diet of the female during phase 1 MeHg increased rapidly in eggs from females fed a control during phase 1 and a contaminated diet during phase 2; after 10 d, eggs from fish fed the low MeHg diet were five times the concentration of those fed a control diet These results indicate that female diet during gametogenesis is a substantial source of MeHg to fish eggs Accordingly, the potential coincidence of gametogenesis with seasonally enhanced levels of MeHg in the food web, which could result from watershed inputs related to the vernal thaw or sedimentary release of MeHg preceding a spring plankton bloom, may increase the predisposition of developing fish embryos to detrimental effects of maternally transferred MeHg

Key words: reproduction, fish, bioaccumulation

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1037 Mercury concentration in blackflies Simulium spp (Diptera, Simuliidae) from soft water streams in Ontario, Canada

K M HARDING1*, P DILLON1 AND J GOWLAND2

1Watershed Ecosystems Graduate Program, Trent University, Peterborough, Ontario *contact author: katieharding@trentu ca 2University of Guelph, Guelph, Ontario

Abstract: Aquatic systems are considered very sensitive to inputs of mercury (Hg) because the bioaccumulation rates of this element are greater than any other metal We measured the amount of total Hg in Simulium spp (Diptera, Simuliidae) from 17 soft water streams from the District of Muskoka and Haliburton County (Ontario, Canada) Black- flies contained a range of 007-064 ppm Hg (dry weight) The concentration of Hg is much higher than has been found in other filter feeding insects, and represents a potential source of Hg to fish Mercury concentration between Simulium spp at different sites was strongly correlated with dissolved organic carbon (adjusted r2= 063, p=0005) and pH (adjusted r2= 049, p=0001)

Keywords: mercury, bioaccumulation, black flies, Simuliidae

INTRODUCTION site relationship, indicating a need for more research Although several studies have noted an increase in anthropogenic mercury (Hg) loading to riv- Through their food gathering methods, ers[1], there is limited knowledge of the poten- blackflies in dense aggregations can signifi- tial impact of this loading on biota[2] The ef- cantly alter the fine particulate matter and fects of water chemistry on Hg bioavailability DOM downstream[8] Each blackfly uses to fish are well documented[3, 4]; however, there large filtering rays covered with mucus to is little comparable information concerning the collect and ingest a wide range of particle effects on invertebrate communities[2, 5] Lake sizes[9] They consume mostly detritus and stream acidity is often correlated with Hg (67 %) and bacteria (33 %), along with small concentration, and organisms found in acidic amounts of algae (<1 %)[8] The detritus con- conditions have higher tissue concentrations of sists primarily of fine particulate organic Hg[3, 4, 6] SJÖBLOM ET AL[7] has shown that when matter and large DOM fractions ranging in dissolved organic matter (DOM; measured as size from 1 µm to 1 nm[9-12] Although DOM, dissolved organic carbon, DOC) binds to Hg it pH and other water chemistry parameters decreases the bioavailable fraction of Hg Grieb generally correlate with Hg and methylmer- et al[3] found evidence of this in natural sys- cury concentrations in fish, these factors af- tems, however others[5, 6] have found the oppo- fect uptake at the level of primary producers

RMZ-M&G 2004, 51 1038 PART 2 BIOGEOCHEMISTRY

without affecting higher trophic transfer[2] RESULTS AND DISCUSSION Blackfly larva (Diptera: Simuliidae) are known to feed on both fine particulate mat- The total Hg concentration in blackflies ter and larger DOM fractions[10, 11] and are ranged from 006 to 064 ppm Hg dry weight therefore a significant potential point of en- (DW) among sites (see Figure 1) Inflows try for Hg uptake into the food chain had significantly (t = 548, p<0001) higher 45 Simuliidae are a significant food source to Hg concentration than outflows Levenes fish, and can consist of 50-90 % of stomach Test of Equality of Error Variances demon- content in Arctic grayling, Thymallus strated that the variation between inflows and arcticus[13] outflows was significantly different (Levene stat= 547 p= 0024) The level of Hg in The purpose of this study was to determine blackflies from this region is relatively high the amount of bioavailable Hg in selected compared with other filter feeding insects streams by measuring the concentration of In insects, as in fish[2, 14] the amount of Hg Hg in Simulium spp (Diptera, Simuliidae) present in tissues is strongly correlated with Blackflies were chosen for their feeding hab- trophic level The only other existing study its and for their significance in the food chain on Hg in blackflies found that in Eastern Blackflies also tend to aggregate in stream Tennessee they had relatively low (007 ppm) ripples, simplifying collection of large num- concentrations[15] Consequently, the black- bers of individuals We also examined the flies in this study were found to have sur- relationship between blackfly Hg body bur- prisingly high concentration of Hg, as much den and stream water chemistry, including or more than predatory insects from other DOC, and pH We sampled 13 soft water studies streams in the District of Muskoka and Haliburton County, Ontario The catchments DOC (r2 =063) and pH (r2 =049) were found a a are primarily forested with some cottage de- to be strongly correlated with Hg concentra- velopment and are underlain by Precambrian tion in Simulium spp (Figure 2)The high metamorphic plutonic and volcanic silicate acidity of several sites in this region is un- bedrock likely to have a direct toxic effect on Simu-

Figure 1 Observed Hg concentration in ppm dry weight (DW) in blackflies from inflows and outflows of 7 lakes The bars represent range of observed values

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1039

Figure 2 Relationship between average Hg concentration in Simulium sp and a) pH, b) dissolved organic carbon (DOC) Water chemistry values are an average of samples from 31- March through 19-June 2003 DW= dry weight lium spp, since they are fairly acid tolerant[16]; larger size fractions of DOM and fine par- however, when water pH drops, Hg methy- ticulate organic matter More research is lation increases[17], which increases the needed to determine how blackflies receive amount of biologically available Hg High their Hg body burden, though we hypoth- acidity correlates with elevated mercury and esize that they are receiving it from the frac- methylmercury concentrations in fish[3, 4, 6] tion bound to DOM This is supported by and zooplankton[5] The positive correlation the significant correlation between Simulium between Hg body burden and DOM is analo- spp Hg concentration and DOM (Figure 2) gous to that found in other studies[5, 6] Dis- solved organic matter and pH together explained 62 % (R2 =0 62, F = 10 6, p= 0 003) a 12 CONCLUSIONS of the variation in Hg in blackflies This data indicates that as DOM concentration in- The observed concentration of Hg in black- creases, Hg bioaccumulation increases flies from some of the inflows was as high Therefore, DOM does not have a protective as the levels observed in predatory insects effect on Hg bioaccumulation in blackflies from other regions These results suggest that blackflies may be a good biological monitor In the water column Hg can be present as for Hg levels in streams The high concen- free ionic Hg, organic Hg bound to DOM, tration of Hg observed in blackflies repre- or bound to particulates Most of the Hg in sents a potential Hg source to insectivorous freshwater is predominantly bound to the birds and fish More research is needed to higher molecular weight fraction of DOM[18], determine the concentration of methylmer- however at present we have no data on the cury present in these blackflies and the trans- relative proportion of Hg bound to different fer of Hg and methylmercury from black- sizes of fine particulate organic matter and flies to higher organisms DOM Blackflies consume primarily the

RMZ-M&G 2004, 51 1040 PART 2 BIOGEOCHEMISTRY

REFERENCES

[1] INNANEN, S (1998): The ratio of anthropogenic to [11] WOTTON, R S (1996): Colloids, bubbles, and ag- natural mercury release in Ontario: three emis- gregates- a perspective on their role in suspension scenarios; The Science of the Total Envi- sion feeding; Journal of the North American ronment, Vol 213 pp 25-32 Benthological Society, Vol 15, No 1, pp 127- [2] MASON, R P, LAPORTE, J-M AND A NDRES, S (2000): 135 Factors Controlling the Bioaccumulation of [12] Ross, D H and Craig, D A (1980): Mechanisms Mercury, Methylmercury, Arsenic, Selenium, of fine particle capture by larval black flies and Cadmium by Freshwater Invertebrates and (Diptera: Simuliidae); Canadian Journal of Zo- Fish; Archives of Environmental Contamination ology, Vol 58, pp 1186-1192 and Toxicology, Vol 38, No 3, pp 283 - 297 [13] Jones, N E, Tonn, W M and Scrimgeour, G J [3] GRIEB, T M ET AL (1990): Factors affecting mer- (2003): Selective feeding of age-0 Arctic gray- cury accumulation in fish in the upper Michi- ling in lake-outlet streams of the Northwest Ter- gan peninsula; Environmental Toxicology and ritories, Canada; Environmental Biology of Chemistry, Vol 9, pp 919-930 Fishes, Vol 67, No 2, pp 169-178 [4] GREENFIELD, B K ET AL (2001): Predicting mer- [14] HALL, B D ET AL (1997): Food as the dominant cury levels in yellow perch: use of water chem- pathway of methylmercury uptake by fish; Wa- istry, trophic ecology, and spatial traits; Cana- ter Air and Soil Pollution, Vol 100, pp 13-24 dian Journal of Fisheries and Aquatic Sciences, [15] LINDSAY, R C AND DIMMICK, R W (1983): Mer- Vol 58, No 7, pp 1419-1429 cury residues in wood ducks and wood duck [5] WESTCOTT, K AND KALFF, J (1996): Environmental foods in eastern Tennessee; Journal of Wildlife factors affecting methyl mercury accumulation Diseases, Vol 19, No 2, pp 114-122 in zooplankton; Canadian Journal of Fisheries [16] CHMIELEWSKI, C M AND HALL, R J (1993): Changes and Aquatic Sciences, Vol 53, No 10, pp 2221- in the emergence of blackflies (Diptera: 2228 Simuliidae) over 50 years from Algonquin Park [6] WREN, C D ET AL (1991): Relation between Mer- streams: is acidification the cause? Canadian cury Concentrations in Walleye (Stizostedion- Journal of Fisheries and Aquatic Sciences, Vol Vitreum-Vitreum) and Northern Pike (Esox- 50, pp 1517-1529 Lucius) in Ontario Lakes and Influence of En- [17] GILMOUR, C C AND HENRY, E A (1991): Mercury vironmental-Factors; Canadian Journal of Fish- methylation in aquatic systems affected by acid eries and Aquatic Sciences, Vol 48, No 1, pp deposition; Environmental Pollution, Vol 71, 132-139 pp 131-169 [7] SJÖBLOM, Å, MEILI, M AND SUNDBOM, M (2000): [18] HINTELMANN, H, WELBOURN, P M AND EVANS, R The influence of humic substances on the spe- D (1997): Measurement of complexation of ciation and bioavailability of dissolved mercury methylmercury(II) compounds by freshwater and methylmercury, measured as uptake by humic substances using equilibrium dialysis; Chaoborus larvae and loss by volatilization; The Environmental Science and Technology, Vol 31, Science of the Total Environment, Vol 261, No No 2, pp 489-495 1-3, pp 115-124 [8] HERSHEY, A E ET AL (1996): Organic matter pro- cessing by larval black flies in a temperate wood- land stream; Oikos, Vol 75, pp 524-532 [9] BRAIMAH, S A (1987): The influence of water velocity on particle capture by the labral fans of larvae of Simulium bivittatum Malloch (Diptera: Simuliidae); Canadian Journal of Zoology, Vol 65, pp 2395-2399 [10] WOTTON, R S (1976): Evidence that blackfly larva can feed on particles of colloidal size; Nature, Vol 261, p 697

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1041 The METAALICUS Project: Overview of Study and Results To-Date

REED HARRIS

Abstract: METAALICUS is a whole-ecosystem experiment examining the relationship beween atmospheric mercury deposition and fish mercury concentrations! Stable, non- radioactive isotopes of inorganic Hg(II) are being added to an 8!3 ha lake and its 44 ha watershed in the Experimental Lakes Area (ELA), Ontario, Canada! Using isotopes provides the ability to follow newly deposited mercury separately from background mercury! Different Hg(II) isotopes are being applied to uplands, wetlands and the lake surface to distinguish the contributions of each of these sources to fish mercury levels! Detailed Hg sampling, process studies and modeling are being carried out to construct mass balances and follow pathways and transformations for Hg(II) and methylmercury through the watershed and lake! Beginning in 2001, and continuing each year since (3 years to-date), annual wet deposition of atmospheric Hg(II) has been increased experimentally 3-4 fold relative to long term average wet deposition rates to the area! Annual mercury additions to the lake surface were 22 µg/m2 each year, distributed over 9 spikes during the ice-free season! Upland and wetlands have received isotopes once per year in the May-June period! The average annual application rates for the upland and wetland areas are 20 and 25 µg/m2/yr respectively for the 2001-2003 period! During the first season of additions (2001), concentrations of inorganic mercury in the surface waters of Lake 658 approximately doubled as a result of the mercury isotope (202Hg) added directly to the lake surface and increased to a lesser extent again in 2002! Inorganic 202Hg added to the lake surface was also detected as methylmercury in the first season in the water column, sediments and biota, including fish! Concentrations of 202Hg-labelled methylmercury in water, sediments and biota have continued to increase in 2002 and 2003! Different response dynamics have been observed for the buildup of added mercury as methylmercury in different compartments! Initial efforts to simulate the L658 experiment with a mass balance model of aquatic Hg cycling were unable to match the rate at which the isotope applied to the lake as inorganic mercury was observed as methylmercury in the system! The apparent higher bioavailability for methylation of newly added mercury compared to older mercury may be a factor! Results to- date suggest that the system has not yet stabilized in response to the annual isotope additions directly to the lake surface, and there is a need to continue the loading phase of the study beyond the initial 3 years! Inorganic mercury isotopes added to the terrestrial system have been measured in the uplands and wetlands and observed at near-detection levels in lake waters by late 2002 (upland isotope only), but were not yet detectable in fish at the time of preparation of this document! Isotopes will be applied to the ecosystem for a fourth year in 2004! The need to continue the loading phase of the experiment for 1-2 additional years will be assessed as results continue to emerge!

Key words: isotope, loading, response

RMZ-M&G 2004, 51 1042 PART 2 BIOGEOCHEMISTRY

Predicting the Response of Fish Mercury Concentrations to Changes in Atmospheric Hg Deposition a Regional Approach

REED HARRIS, DON BEALS, TAMARA SALTMAN1 & DAVID HUTCHINSON

1US Environmental Protection Agency, 1200 Pennsylvania Ave, NW, 20460, Washington DC, USA

Abstract: A study was carried out to develop a regional approach to model the sensitivity of fish mercury concentrations to changes in atmospheric mercury deposition, and to examine the strengths and weaknesses of such an approach This approach could be useful to couple with predictions from atmospheric computer models that use a national (or international) grid to predict the effects of emissions reductions strategies on atmospheric mercury deposition rates in different regions For this initial study, outputs from an atmospheric fate and transport model (REMSAD) were coupled with a probabilistic, Monte Carlo version of the Dynamic Mercury Cycling Model (D-MCM), developed by EPRI This study was supported by the US Environmental Protection Agency Mercury concentrations observed for a desired size or age fish from many lakes in a region form a distribution with a mean value, minimum, maximum, and standard deviation Furthermore, the range of site conditions observed in lakes in the same region can also be represented with distributions, eg for surface water pH, dissolved organic carbon, bathymetry, hydrology, and fish growth rates (more factors were varied in actual simulations) The D-MCM model was run repeatedly, selecting input values for many input variables from distributions characterizing a region The result was a distribution of predicted fish mercury concentrations that was compared to the observed distribution for a region The model was then calibrated if necessary and load reduction scenarios were simulated to predict how the distribution of fish mercury concentrations in a region would change Two regions were simulated for this pilot exercise: the Adirondacks in New York State and a region consisting of 6 counties in north-central Wisconsin In both cases, the model was calibrated to reasonably match the distribution of currently observed fish mercury concentrations (age 3-4 yellow perch in the Adirondacks, age 6-7 walleye in north-central Wisconsin) The model predicted a nearly linear response of fish mercury concentrations to changes in atmospheric deposition in both regions modeled, but significant differences were predicted regarding the timing of the response, due to the different lake and watershed characteristics of the regions The near linear response emerged from a series of necessary assumptions that require scientific confirmation The pilot exercise also demonstrated that the predicted response of fish mercury concentrations in some lakes can potentially be strongly influenced by the response of the watershed to changes in atmospheric mercury deposition An incomplete understanding of watershed mercury dynamics and limited data currently limit our ability to fully explore these influences however Simulations were also carried out to consider the effects of emissions control strategies that simultaneously reduced atmospheric Hg deposition and acid deposition, for example resulting in a 20 % reduction in mercury deposition and one unit pH increase The model predicted additional reductions in fish mercury concentrations compared to a scenario with changes in mercury loading alone

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1043

A benefit of this modeling approach is that it not only allows a comparison of the effects of changes in atmospheric mercury deposition on a regional basis, but also provides insights into the factors responsible for different regional responses For example, lakes in the Adirondacks region had a stronger watershed influence and different predicted response dynamics than the north-central Wisconsin region, which had a higher percentage of seepage lakes Unresolved questions about mercury cycling in the environment currently constrain the predictive capability of this and other mechanistic models, but this is expected to improve as the state of knowledge advances

Key words: modeling, fish, regional

RMZ-M&G 2004, 51 1044 PART 2 BIOGEOCHEMISTRY

Distribution and speciation of mercury in Hongfeng reservoir, Guizhou, China

TIANRONG HE 1,2, XINBIN FENG1,*, HAIYU YAN 1,2, GUANGLE QIU1,2, QIANJIN DAI1,2, LIHAI SHANG1,2

1State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Science, Guiyang 550002, China; * Corresponding author, e-mail address: Xinbinfneg@mailgyigaccn 2Graduate School of the Chinese Academy Science, Beijing 100039, China

Abstract: Hongfeng reservoir was established in 1960 and is an alkaline, hyper-eutrophic and seasonal anoxic reservoir due to the contamination from domestic and industrial waste waters In this paper we examined the distribution and speciation of mercury in the reservoir and discussed their controlling factors such as pH, dissolve oxygen, dissolve organic carbon on the distribution of mercury in this old aged reservoir, which is disturbed by anthropic activities

Key words: Distribution; speciation; mercury; Hongfeng reservoir

INTRODUCTION poorly understood% So distribution and speciation of mercury and controlling factors It is widely known that high mercury con- such as pH, dissolve oxygen, dissolve or- centration in fish are common in many newly ganic carbon in all kinds of reservoirs need impounded reservoirs for hydroelectric and more detailed survey% flood control purposes (SCHETAGNE ET AL%, 1996; BODALY ET AL%, 1984; PORVARI, 1998)% Hongfeng reservoir established in 1960 with The studies from reservoirs in North America a surface area of 572 km2 and a volume of also indicate that the duration of mercury 601×108 km3 is located at the suburb of contamination is difficult to evaluate% Time Guiyang city in Guizhou province where coal that high mercury concentration returns to is the main energy source of industry and liv- background mercury levels depends on en- ing Calcareously and sienna are dominant in vironment, water quality of reservoir, some drainage area and the bedrock of the water- may occur in a relatively short time span, shed is limestone Hongfeng reservoir is a approx% 5 years while some need several hyper-eutrophic and seasonal anoxic reservoir decades and even there are some old reser- due to the contamination from domestic and voir which still have high mercury concen- industrial waste waters, but so far no waste- tration in fish (BODALY ET AL%, 1984; waters with high Hg concentrations have been SCHETAGNE ET AL%, 1996; PORVARI, 1998)% identified The source of Hg pollution to However, mechanisms leading to MeHg pro- Hongfeng reservoir may be mainly come from duction and decrease in reservoirs are still deposition of the atmospheric mercury

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1045

The water, pore water, and fish samples from November 2003 while the THg concentra- Hongfeng reservoir were collected in No- tions were relative constant through out wa- vember 2003 and February 2004 using metal ter column (6&24 to 8&24 ng/l in Daba col- clean protocols& Two sampling sites lie in umn and 5&05 to 8&88 ng/l in Houwu column) southern basin (Houwu) and northern basin except for high concentrations at bottom (Daba) of the reservoir (Fig& 1), and there and watersediment interface (10&47 to are fishing farms and waste water from 15&18 ng /l) in February 2004& Temperature power plant at Houwu& Water samples were may contribute to this deference& In Novem- taken from different depths (0, 4, 8, 12, 16, 20, 24, 28, and 30 m), and sediment cores were taken and sliced into 1 to 2 cm subsamples onsite at each sampling site& Total Hg (THg), reactive Hg (RHg), dissolved total Hg (DHg), dissolved gaseous mercury (DGM) and total dissolved mercury in pore water in sediments were measured by gold trap pre-concentration and CVAFS detection& Total methyl mercury (TMeHg), and dissolved methyl mercury were measured by distillation followed by aqueous phase ethylation, precollection on a Tenax trap, isothermal gas chromatography and cold vapor atomic fluorescence detection& At the same time, dissolved organic carbon (DOC), chlorophyll and water quality parameters such as pH, temperature, dissolved oxygen, TDS were measured& Field blanks and duplicates were taken regularly (>10 %) Figure 1 Locations of sampling stations throughout each cruise in order for quality controlling&

RESULTS AND DISCUSSION

Reactive mercury and total mercury distribution

Concentrations and distribution of THg and RHg are presented in Fig& 2& The THg concentrations lay within a range of 5&05 to 11&85 ng/l in Daba water column and 7&17 to 14&13 ng/l in Houwu water column in

RMZ-M&G 2004, 51 1046 PART 2 BIOGEOCHEMISTRY ber 2003, water temperature began to de- cury concentrations were evidently elevated crease fleetly leading to mix strongly be- in pore water& Concentrations of DHg lay tween surface and bottom of water column& within a range of 20 to 30 ng/l in most Strong mixing resulted in a peak value in samples, while higher concentrations ap- middle part of water column& On the other peared in some samples& This suggested most hand, in February 2004, water column had of the mercury entering in reservoir was pre- become even by 3-month long mixing, more- dicted to be buried in sediments& over, water temperature began to increase and mixing was being over, so Hg concen- MeHg concentration and distribution trations were relative constant, and maximum lay in bottom and watersediment in- TMeHg lay within a range of 0&12 to terface& This maximum Hg concentration 0&38 ng /l in water columns& Dissolved me- was resulted from increment of particulate thylmercury concentrations ranged from 0&05 mercury (to 9&78 and 9&82 ng/l for bottom to 0&2 ng/l& TMeHg were a litter higher in and interface at Houwu)& The high particu- the deeper water at two sample sites in Nov& late mercury concentrations maybe result 2003 and at Houwu in Feb& 2004& TMeHg from the resuspension of sediment or sub- concentrations changed from 0&16 to side of suspended solids because of the de- 1&09 ng/l in pore water of the sediment ex- crease of flux and velocity of water flow in cept three high peak values (8&6, 10&85, winter& 3&91 ng/l at different depths) appeared in Houwu core in Feb& 2004& The maximum Concentrations of RHg varied between 0&14 values appear at the surface of sediments core to 1&67 ng/l in two cruises& The unfiltered at two sample sites in Nov& 2003& RHg had a strong negative correlation with THg at Houwu (r2=0&78) while it had a posi- Cyprinoid, crucian, shrimp, snail samples tive correlation with THg at Daba (r2=0&75) were collected in 2003 and methyl mercury in November 2003& There are no strong cor- was measured& Methyl mercury concentra- relations between RHg and THg in Febru- tions were relatively low compared to those ary 2004 sampling campaign& At Houwu, from other natural waters& The highest con- RHg concentrations decreased from 2 m un- centration appeared in cyprinoid flesh& til the water-sediment interface in water col- Methlymercury concentration in shrimp umn and the concentration reduced to sample was below the detection limits& High 0&19 ng/l at the water/sediment interface& pH may contribute to so low methyl mer- Howevere at Daba, the RHg concentration cury concentration in fishes& started to increase at 16 m and reached the maximum of 1&67 ng/l at the water/sediment DGM concentration and distribution interface& In Feb& 2004, DGM concentrations changed At the same time, DHg in pore water were from 0&024 to 0&092 ng /l& DGM concentra- measured in two cruises& Spatial and tempo- tions were highest at the surface of water ral variability in DHg was small in pore wa- columns and decreased with depth& DGM ter between two cruises& Total dissolve mer- concentration was higher in surface water at

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1047

Daba than that at Houwu This difference reservoir were investigated in Nov2003 and may be attributed to the timing of collecting Feb2004 THg and TMeHg concentrations samples It was sunny when samples were in water column, pore water and fish sug- taken at Daba, while it was rainy at Houwu gested that mercury concentration in DGM distribution in Feb2004 suggested Hongfeng Reservoir has returned to back- sunlight play an important role in the pro- ground mercury levels There were spatial duce of DGM and temporal variabilities in distribution and speciation of mercury in the reservoir and Spatial and temporal difference most of the mercury entering in reservoir was predicted to be buried in sediments Spatial The concentration of dissolve organic car- and temporal difference suggested other pol- bon, suspend solids, total Hg, and methyl lutants such as N, P from fishing farm and mercury all show higher at Houwu than those other wasted water may have changed dis- at Daba in November 2003, but there are no tribution of Hg in reservoir, though no waste- evident differences at two sample sites in waters with high Hg concentrations have Feb 2004 This may be attributed to that the been identified in the surroundings temperatures of winter column were very low and that the fishing farms work stopped in Acknowledgements winter This suggested that other pollutants such as N, P from fishing farm and other The authors would like to thank Dr Lian waste water at Houwu might have changed Liang for helping us to set up methylmer- the distribution of Hg in reservoir cury analysis method in our group, and to thank Hongmei Jiang, Shunlin Tang for assistance in field and laboratory work This CONCLUSIONS work was financially supported by Chinese Academy of Sciences through Hundred The distributions and speciation of mercury Talent Plan and their controlling factors in Hongfeng

REFERENCES BODALY, R, HECKY, R AND FUDGE, R ( 1984): Increases in dish mercury levels in lakes flooded by the Churchill River diversion Northern Manitoba; VERTA, M, REKOLAINEN, S AND KINNUNEN, K (1986): Can J Fish Aquat Sci, No 41, pp 682-691 Causes of increased fish mercury levels in Finn- SCHETAGNE, R, VERDON, R, LANGLOIS, C AND DOYON, J- ish reservoirs; Publications of the Water Re- F (1995): Mercury evolution (1978-1975) in fishes search Institute National Board of Waters; No of the La Grande hydroelectric complex, Quebéc, 65, pp 44-58, Finland Canada; Manuscript, Poster presented in Fourth ALFTHAN, G, JÄRVINEN, O, PIKKARAINEN, J AND VERTA, International Conference on Mercury as a global M (1983): Mercury and artificial lakes in north- pollutant Hamburg, Germany, August 4-8, 1995 ern Finland Possible ecological and health con- Porvari, U (1998): Development of fish mercury consequences; Nordic Counc Arct Med Res Rep; centrations in Finnish reservoirs from 1979 to No 35, pp77-81 1994; The Science of the Total Environment, No 213, pp 279-290

RMZ-M&G 2004, 51 1048 PART 2 BIOGEOCHEMISTRY

Mercury in soil of the Rondônia (Amazon/Brazil): geostatistic like analysis tool of influence anthropic: A study of case

1 2 JOÃO CARLOS HERRMANN ; JOSE VICENTE ELIAS BERNARDI ; WANDERLEY RODRIGUES BASTOS2 & ENE GLÓRIA DA SILVEIRA2

1Criminalistic Institute/RO; E-mail: jcherrmann@igcombr, 2Environmental Biogeochemistry Laboratory/UNIR; E-mail: labmerc@unirbr

Abstract: In this study seeking to identify if the anthropic performance through the pasture establishment in Amazonian is or is not contributing to the liberation of total mercury of soil, it was established a soils samples regular grid for total Hg in a contact forest/ pasture areas, with the approximate dimensions of 1,000 m by 800 m, transects spaced each 200 m and samples to each 100 m in the transect, over yellow latosols alic and plan topography, it was obtained an average concentration of 149&20 ± 12&79 µg&kg-1 of total mercury& The samples situated in the forest area, in number of 25, had presented average of 149&14 ± 12&47 µg&kg-1 and the samples situated in the pasture area, in number of 30, average of 149&24 ± 13&05 µg&kg-1& Doing geostatistical use, through the spherical semi- variogram model and of kriging algorithm, were produced concentration maps of total Hg that showed the space dependence between the Hg concentration in soil, demonstrating however, the independency of this distribution regarding to the utilization of the area& Thus, the geostatistical tools applied in the studied case indicate that the human action through the pasture establishment, didnt contribute for the dispersion differentiation of total Hg contained in soil, regarding to a contiguous forest area, taken as a natural dispersion standard&

Key words: mercury, geoestatistic, forest, pasture, Amazon&

INTRODUCTION occupation of the area, deforestation and establishment of farming, started to be pointed Until recently the studies on Hg in Amazo- as factor of acceleration in the process of lib- nian area were concentrated in the originat- eration of Hg of soil, being this process made ing from anthropic action, mainly gold min- responsible by great part of contamination ing, pointed as source of environmental con- then diagnosed (ROULET ET AL, 1998) Look- tamination then diagnosed in valley of great ing for to contribute with this discussion and rivers (PFEIFFER ET AL, 1989) Only in the half being used the geostatistic as analysis tool, of the 90s, the researches went back to the a grid of sampling of soils was executed for soils of area, where high Hg concentrations total mercury determination in a pasture/for- were verified, starting then to be pointed as est area, involving the two environment to natural sourses of this element (ROULET ET identify if the establishment of pasture was AL, 1996) The human activities related to provoking or not differentiation in pattern of space dispersion of mercury

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1049

MATERIALS AND METHODS RESULTS AND DISCUSSION

Because this is a study on the presence of Through the accomplished analyses it was total mercury in soil, still looking for to iden- obtained a medium concentration of 14920 tify if the action activities anthropic were or ± 1279 µgkg-1 of total Hg (12211 not interfering in dispersion, it was opted to 18279 µgkg-1) The located samples in the accomplish the samples in horizon A among forest area, in number of 25, presented aver- 0 to 25 cm of depth of soil, presumably the age of 14914 ± 1247 µgkg-1 (12211 most affected for the human activities, such 17791 µgkg-1) and the located samples in as the burning and agriculture The sampling the pasture area, in number of 30, presented grid was established in such a way that ap- average of 14924 ± 1305 µgkg-1 (12738 proximately 50 % of extension included a 18279 µgkg-1) The medium values pre- forest area and the remaining, next to that sented by both areas are similar, not allow- one, however used with pasture, whose im- ing diagnosing any significant difference plantation happened in 1997, with dropped among the environment, fitting to emphasize of forest, burning of forest biomass and sub- the presence of largest value in pasture area, sequent burning of pasture in successive as well as the largest variability among the years Five lines were drawn with magnetic Hg concentrations Through the trend sur- North/South orientation, separated approxi- face analysis (Figure 1), it was verified that mately of 200 meters one of other, with this varies from E to W, while the relation- samples to each 100 meters in lines, being ship forest/pasture takes place from North collected 55 soil samples, located in space to South, revealing therefore, independence for coordinated UTM obtained with use of among the trend surface the relationship for- GPS The samples, initially, had humidity the est/pasture In case there was differentiation homogenized, drizzled in fraction 200 mesh in Hg concentration in function of the use of (<74 µm) and analyzed at Biogeochemistry the area, with the presumably occurrence of Laboratory of Federal University of smaller values in pasture area, the tendency Rondônia, through the use of an atomic surface would have a space behavior similar absorption spectrophotometer, FIMS-400 to the behavior space forest/pasture For the model (Flow Injection Mercury System) with execution of ordinary point kriging, a semi- automatic analyzer Of each sampling point variogram was elaborated, being used the two analysis batteries were accomplished, spherical model, through which was dem- being the final result acted by average of 8 onstrated the anisotropy of distribution, the measures of total Hg concentration of each space dependence among the total Hg until point The obtained results were treated then a maximum range of 510 m and sill of with the geostatistical use, tends as tools the 215 µgkg-1 This model was used for execu- trend surface analysis, the semi-variogram tion of process of ordinary point kriging as and the ordinary point kriging, through which interpolation technique (Figure 2), having ob- were produced maps that illustrate the be- served the presence of positive and negative havior of space dispersion of total Hg anomalies, so much in forest area as in pas-

RMZ-M&G 2004, 51 1050 PART 2 BIOGEOCHEMISTRY ture area, without, however, being diagnosed Hg, that it could specifically be related to the any variation in pattern of dispersion of total use of area, as forest, or as pasture

Figure 1 Trend surface of 1st degree (scale in µgkg-1)

Figure 2 Map of isolines of total Hg obtained through the ordinary point kriging (scale in µgkg-1)

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1051

CONCLUSIONS kriging, does not present any pattern that can be related to the use of area, showing anoma- Through the present work, it was verified that lies so much in forest area as in pasture area, the total Hg medium contained in soil of stud- with apparent random distribution, possibly ied area comes high, as well as the one of related to the wide lateral variability of these other areas of the Amazon! The medium val- concentrations! The geostatistic was shown ues found in forest area and in pasture area a useful and appropriate tool for the under- do not present significant differentiation! The standing of the behavior of the space disper- trend surface of 1st degree of dispersion of sion of total mercury concentration in soil, total Hg, showed independent behavior of as well as of their tendencies! space relationship forest/pasture! The semi- variogram elaborated for the process of or- Acknowledgements dinary point kriging indicates that the Hg concentration behaves as a regional variable! This work was supported by the Criminalistic The map of isolines of total Hg concentra- Institute, UNIR, PNOPG/CNPq No! 55!0882/ tion obtained through the ordinary point 01-4, RIOMAR Foundation and SEBRAE-RO!

REFERENCES

PFEIFFER, W C, LACERDA, L D, MALM, O, SOUZA, C ROULET, M, LUCOTTE, M, SAINT-AUBIN, A, TRAN, F, M, SILVEIRA, E G & BASTOS W R (1989): RHÉAULT, I, FARELLA, N, DA SILVA, E, Mercury concentrations in inland waters of gold- DEZENCOURT, J, SOUSA PASSOS, C J, SOARES, G mining areas in Rondônia, Brazill; Science of S, GUIMARÃES, J R D, MERGLER, D & AMORIM, Total Environment 87-88, 233-240 M (1998): The geochemistry of mercury in cen- ROULET, M, LUCOTTE, M, REAULT, I, TRAN, F, FARELLA, tral Amazoniam soils developed on the Alter- N, CANUEL, R, MERGLER, D & AMORIM, M do-Chão formation of the lower Tapajós River (1996): Mercury in Amazonian soils: accumu- Valley, Pará state, Brazil; The Scienceof The lation and release; Proceedings of the Fourt In- Total Environment 1-24, 223-231 ternational Symposium on the Geochemistry of the Earths Surface, 22-28 july, Ilkley, UK, 1996, 453-457

RMZ-M&G 2004, 51 1052 PART 2 BIOGEOCHEMISTRY

Spatial and temporal dynamics of Hg methylation in a boreal wetland: results from METALLICUS

ANDREW HEYES, KRABBENHOFT DAVID , ROBERT MASON1 & CYNTHIA GILMOUR

1University of Maryland Center for Environmental Science, PO Box 38, 20688, Solomons, USA, e-mail: mason@cblumcesedu

Abstract: Mercury cycling with a boreal wetland has been extensively studied as part of the METALLICUS (Mercury Experiment to Assess Atmospheric Loadings In Canada and the United States) project that is being conducted at the Experimental Lakes Area, Canada& The objectives of METALLICUS are to understand the timing and magnitude of responses to a change in the Hg deposition rate& A different Hg stable isotope has been delivered to the upland, lake and wetland components, of an entire watershed (Lake 658) at roughly four times the annual deposition rate since 2001& The movement and transformations of these isotopes are being tracked through the watershed& The Lake 658 watershed was chosen, in part, because a significant proportion of the watershed drains through a wetland that adjoins the lake& Wetlands are important areas of methylmercury (MeHg) production& The specific objectives of the Lake 658 wetland studies are to evaluate the timing of the movement of the Hg isotopes, added to the watershed, through the wetland, evaluate the timing and amount of MeHg produced from these isotopes, and to assess to what extent MeHg produced in the wetland accumulates into food webs& The wetland is mainly a treed bog, but where the wetland grades into the lake and takes on a marsh like character& Water flow is generally lake-ward, although high water levels have resulted in this marsh area being temporarily inundated with lake water& In the Lake 658 wetland, Hg methylation potentials and MeHg concentrations peak at or just below the top of the water table, which is generally well below the wetland surface& Mercury methylation, as assessed by direct addition of a Hg isotope to a peat sample, occurs in all areas of the wetland but generally increases in intensity of towards the lake& The increase in Hg methylation coincides with increasing rates of decomposition driven carbon metabolism& The Hg isotope was delivered to the wetland surface by a combination of aerial and hand spraying& As a result newly deposited Hg first falls on vegetation& Little of the Hg isotope delivered to the wetland surface in 2001 had moved to the depth were methylation is most active by the following year, thus little methylation had been observed as of 2002& While the Hg isotope added to the wetland can be seen in the porewater, translocation is slow& We have not seen evidence of the Hg isotope added to the upland in the wetland& However, methylation Hg isotope added to the lake was observed at the wetland margin in 2002, after the wetland was inundated by lake water& In the first two years of additions, the only methylation we have observed in the wetland is the methylation of Hg isotope added to the lake& However, the area of where this methylation occurred did not receive a dose of the isotope added to the wetland because of the high water& Because of its activity and proximity to the lake, Hg cycling within the margin of the wetland has been most important to date in export of isotopic MeHg from the wetland& However, our budgets of ambient Hg indicate that Hg deposited on uplands and wetlands contribute significantly to the mass of Hg in the lake food web& Therefore we anticipate Hg isotopes will be delivered to the lake from the upland and wetland watershed compartments in future years& The timing and magnitude of the movement, and subsequent methylation in the wetland and lake will be critical to modeling the effects of changing Hg deposition on aquatic food webs&

Key words: methylation, wetlands, microbiology

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1053 A comparison of methylmercury bioaccumulation in Striped Bass (Morone saxatilis) populations in Maryland, USA: Reservoirs and the Chesapeake Bay

DEBBY HEYES1, ROBERT MASON1, CINDY GILMOUR2 & ANDREW HEYES1

1University of Maryland, Chesapeake Biological Laboratory1Williams St#, 20688, Solomons, MD, USA, e-mail: dheyes@cbl#umces#edu 2Academy of Natural Sciences, Estuarine Research Center10545 Mackall Rd#, 20685, St# Leonard, MD, USA

Abstract: Located in the mid-Atlantic region of the US, Maryland receives fairly high rates of atmospheric Hg deposition Measured deposition rates range from 15 to 30 ug/m2 year, depending proximity to sources Mercury-based fish consumption advisories are in place for all Maryland reservoirs, but not for Maryland estuaries or coastal waters Our budget data for the Chesapeake and its tributaries show that atmospheric deposition is the main source of inorganic Hg to the Bay Further most of the MeHg found in the Bay is produced in situ within Bay sediments and wetlands For this study, we posed the following questions: what are the concentrations of total Hg and MeHg in muscle tissue of top predator fish in the tidal portion of the Chesapeake Bay, and what are the relationships between location in the bay, season caught, and Hg concentration? One objective was to assess Hg levels in fish for the State of Maryland to aid decisions on consumption advisories However, we also sought to examine MeHg bioaccumulation in adjacent coastal and freshwater ecosystems with similar Hg deposition rates, as the amount of MeHg production and bioaccumulation appears to vary substantially between freshwater and marine ecosystems The bioaccumulation of MeHg in Chesapeake Bay fish is further compounded by the complex nature of their life cycles relative to freshwater fish The Chesapeake Bay has a diverse collection of fish populations, some of which are resident to the bay Others are migratory, spending long periods of time in the open ocean We have examined Striped Bass collected in various locations and seasons in Chesa- peake Bay since 1992 Fish weighing up to about 5 kg, and collected between 1992 and 2002, had tissue MeHg concentrations that ranged up to about 700 ng g-1 wet wt In 2003, larger Chesapeake Bay fish were targeted, and were collected mainly during the spring spawning run Fish up to 18 kg were examined However, MeHg concentrations per unit weight were lower than in past collections, ranging from 10 to 400 ng g-1 wet wt Striped Bass are anadromous (spawing in tidal freshwaters, but spending much of their adult lives at sea), however, the length of time each fish spends in the bay varies greatly We hypothesized that larger-sized spawning populations examined in spring 2003 may have spent more of their lives in the ocean, and therefore accumulated less MeHg per unit weight To test this idea, we examined otolith Sr:Ca ratios to determine the relative time fish were in the estuary compared to the open ocean Otoliths from the large fish collected in 2003 were compared with smaller fish (up to about 2 kg) collected in fall 2002 Previous studies have shown that striped bass that spend substantial time at sea

RMZ-M&G 2004, 51 1054 PART 2 BIOGEOCHEMISTRY

have Sr:Ca ratios on the order of 6x10-3, while freshwater fish have Sr:Ca ratios approaching 1x10-3 We found that the larger-sized 2003 spawning population had Sr : Ca ratios averaging 6x10-3, indicative of mainly oceanic fish, while the smaller fish collected in fall 2002 had a lower average ratio of 45x10-3 We conclude that MeHg:size ratios in estuarine stripe bass are variable, and are a function of their migratory habits Further, when compared on a size-normalized basis to Striped Bass in two Maryland reservoirs, Chesapeake Bay Striped Bass had lower MeHg levels This was also the case for Largemouth Bass These data highlight the relative sensitivity of freshwater aquatic systems to MeHg production and bioaccumulation

Key words: fish, bioaccumulation

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1055 Mercury and methylmercury in Spring Lake, Minnesota: A mass balance approach comparing redox transformations, MeHg photodegradation, sediment loading, and watershed processes

NEAL A HINES AND PATRICK L BREZONIK

Department of Civil Engineering, University of Minnesota, 500 Pillsbury Dr SE, Minneapolis, MN 55454, USA hine0012@umnedu

Abstract: Processes of Hg and MeHg cycling are described for Spring Lake, a small bog T lake in northern Minnesota, USA, within the Marcell Experimental Forest! We quantified redox transformations, photodegradation of MeHg, internal and external loading for both Hg and MeHg, and modeled Hg cycling using the software StellaÒ! Measure- T ments on sediment cores allowed for separate treatment of lake and sediment environments! Atmospheric deposition is the main input of Hg , but MeHg is supplied by T a combination of atmospheric, near-shore wetland, and biotic sources (methylation)! Photodegradation annually removes about twice the lake burden of MeHg (20 mg), and burial removes slightly more than one lake burden per year! The residence time of MeHg in the lake was 84 d during the ice-free season, compared with only 4!5 days for the residence time of MeHg on settling particles (seston) in the spring! The rate of photoreduction (1!1 h-1) was twice that of photooxidation (0!58 h-1)! Losses of Hg from evasion T of Hg0 during the daytime in 2001 and 2002 averaged 1!1 ng m-2h-1! The evasional loss of Hg0, 365 mg (Mar! Nov!), was much smaller than the Hg loss from burial T (1435 mg)!

Key words: lake, methylmercury, elemental mercury, evasion, photodegradation

INTRODUCTION SITE DESCRIPTION

Mass balance studies have been performed The Marcell Experimental Forest, a unit of for total mercury (Hg ) and methylmercury the Chippewa National Forest, was set aside T (MeHg) in surface waters [1-5], but conclu- by the U S Forest Service for research pur- sions regarding the relative importance of poses in 1960 Spring Lake, the focus of this sediments, atmosphere, in-lake chemical study, has a surface area of 8 9 ha, a mean transformations, and landscape in affecting depth of 2 m, and no direct inflow or out- aqueous concentrations of mercury have not flow channels The lake water is stained by been consistent Many mass budgets lack humic material and has moderately high site-specific data on aqueous reactions, such DOC (11 mg L-1) as photodegradation of MeHg and photo-redox transformations of Hg0 and Hg2+ These The lake is well mixed after ice-out and does important components in the cycling of mer- not stably stratify during summer The for- cury are considered in this study ested bog around the lake is dominated by RMZ-M&G 2004, 51 1056 PART 2 BIOGEOCHEMISTRY

black spruce (Picea mariana), sphagnum RESULTS AND DISCUSSION moss (Sphagnum magellanicum, Sphagnum angustifolium), and ericacous shrubs Average concentrations from 2000 to 2003 were Hg = 1 45 ng L-1 + 0 87 (n = 78), T MeHg = 0 11 ng L-1 + 0 095 (n = 99), and METHODS Hg0 = 0 051 ng L-1 + 0 038 (n = 38) Con- centrations of Hg0 and air concentrations (aq) Field sampling included: (1) five sediment (estimated at 1 5 ng m-3) were used to model cores (210Pb dated), (2) sediment porewater evasion rates using a mass transfer coeffi- using acrylic equilibrators, (3) lakewater, (4) cient from Liss and Slater [9] and modified seston (0 7 µm QFF), (5) zooplankton (> 300 by Schroeder (K = 0 09 m h-1) [10] The ol mm), (6) fish, (7) near-shore wetlands, (8) average daytime evasional loss was wet deposition (Mercury Deposition Net- 1 1 ng m-2 h-1 from 2001 to 2002 work, Frontier Geosciences) Samples were collected using clean techniques (pow- First order loss rates for photo-redox trans- der-free polyethylene gloves, downwind) and formations and photodegradation of MeHg were preserved with 0 8 % HCl (Baker are summarized in Table 1 The rate of pho- Instra-Analyzed) Photodegradation of toreduction is within the range reported by MeHg was measured in situ (a) as a function AMYOT ET AL (1-2 h-1) for the St Lawrence of depth (3, 10, 25, 40, 60, cm) and (b) in River [11] Photooxidation has been reported surface water (3 cm) over time (8 days) more frequently and ranges from 006 to Experiments were performed with filtered 06 h-1 in freshwaters [12] Few studies have water (0 7 µm QFF) and spiked with quantified photodegradation of MeHg in the MeHgCl at 8 to 16 ng L-1 Photoreduction field; our results are similar to those of SELL- was measured in the field incubating 2 L of ERS ET AL (0043 d-1, epilimnion at ELA, N purged lakewater (Hg0 initial = 0) in Ontario, Canada) [5] Studies have shown that 2 (aq) full sunlight for 1-2 h Laboratory photo- photoredox transformations depend on UV chemical studies to quantify photooxidation light [11, 12] Thus, to model lakewide rates of are described elsewhere [6] Analysis of Hg photoreduction and photooxidation, a photic T [7] and MeHg [8] was performed with a zone of 15 cm was used, corresponding to the Tekran 2500 analyzer Recovery of Stan- depth of 90 % attenuation of UV-A The depth dard Reference Materials ranged from 91 5 profile of MeHg photo-degradation showed to 97 9 % (IAEA MeHg in sediment, NRC loss of MeHg up to 50 to 60 cm, which corre- DORM2, TORT2, MESS3, NIST 3133) sponds to the depth of 90 % attenuation of Lakewater was analyzed for Hg0 by purging PAR For MeHg lakewide photodegradation, 2 L of lakewater with clean N a photic zone of 50 cm was chosen 2

Table 1 First order loss rates for photochemical reactions in the surface water of Spring Lake

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1057

Wet and Dry Deposition Porewater profiles indicated a small diffusive flux of MeHg from sediment to water Annual wet deposition of Hg (data from (5 ng m-2 mo-1) during spring although T MDN) was 69 µg m-2 yr-1 for 2003 The run- porewater concentrations of MeHg were ning average from 1998 to 2003 was relatively low (~05 ng L-1) Sediment and 85 µg m-2 yr-1 + 16 (sd) The annual wet porewater data are described in more detail deposition of MeHg for 2003 was elsewhere [16] 010 µg m-2 yr-1 (MDN) Others studies at similar latitudes in North America and Seston Scandinavia at forested sites showed wet deposition ranging from 51 to 10 µg m-2 yr-1 Mean concentrations of Hg and MeHg on T for Hg and 008 to 012 µg m-2 yr-1 for seston showed higher concentrations per dry T MeHg [13] Data from 2003 at Marcell fit into mass (Hg = 470 ng g-1 + 73, MeHg = T this range 62 ng g-1 + 49) relative to the surficial sediment concentrations (Hg = 153 + 21 ng g-1, T Sediments and porewater MeHg = 27 ng g-1 + 21) A residence time for particulate MeHg and Hg from seston T The sediment at Spring Lake is organic to sediment was calculated by multiplying (544 + 51 %) and the depth-averaged wa- the sedimentation rate (0013 g cm-2 yr-1, av- ter content was 953 + 07 % (n = 203) Based erage from the top 3 cm of the 5 cores) by on the average of the five cores, the accu- the difference between seston and sediment mulation of Hg from 1990 to 2000 was MeHg times the lake surface area The MeHg T 214 µg m-2 yr-1 + 79 (sd) The background seston-to-sediment residence time was 45 d flux of Hg was estimated using the mean of early in the year (MayJune) and 27 d later T samples dated between 1800 and 1850, yield- in the year (AugOct), similar to the Hg T ing 50 µg m-2 yr-1 + 31 (sd) The ratio of residence time (26 d) During settling, there these two numbers (modern/background) is net demethylation provides a measure of how much Hg accumulation has increased compared to pre-in- Near shore wetlands dustrial times The range from the five cores is 29 to 72 and the average is 43 The aver- Estimating mass loads from the surrounding age is similar to other lake sediment cores wetlands of Spring Lake required both hy- from northern North America, which gener- drologic and chemical measurements Nine ally show two- to four-fold increases [14, 15] shallow bog wells and four channeled areas For MeHg in sediments, there was a sharp connected to the lake were sampled six times down-core decline suggesting first-order throughout 2003 The data show that filtered decay Accumulation of MeHg was corrected concentrations of MeHg and Hg were stable T for decay and was estimated at 037 µg m-2 throughout the year at about 02 ng L-1 and yr-1 + 028 (sd) at the very surface of the 30 ng L-1, respectively Hydrologic data were sediment Diagenetic processes result in net available from two adjacent wetlands (S-2, demethylation rather than a historic increase S-6) The average of upland and bog runoff in MeHg production within the lake was computed on a daily basis and multi-

RMZ-M&G 2004, 51 1058 PART 2 BIOGEOCHEMISTRY plied by MeHg or Hg concentration and the net loss of Hg0 during nighttime and this was T respective landscape area at Spring Lake, sometimes observed in the data as low con- producing a daily mass load to Spring Lake centrations of Hg0 at sunrise Field data also showed that Hg0 concentrations in deeper Modeling water sometimes were higher than in the photic zone The program Stella (v 80) was used to model inputs and outputs of completely The mass balance model for Hg , MeHg and T mixed strata Monthly inputs and outputs Hg0 maintained lakewide concentrations (aq) were defined and modeled results were com- near the multi-year average Wet deposition pared with field data The lake was divided supplied 53 % of the Hg input but only T into three strata: photic zone, surface mixed 15 % of the MeHg input To reproduce the layer, and bottom zone, and mixing was de- observed lake concentration of MeHg, lake fined by surface diel temperature changes, methylation was estimated at 00007 d-1, pro- typical of small, shallow lakes [17] Elemen- viding 76 % of MeHg inputs Because of tal mercury was modeled by itself on a time photodegradation and demethylation on scale of hours, and Hg , MeHg and Hg0 were seston, the lake is a net demethylator Near T modeled together on a time scale of months shore wetlands supplied less than 10 % of the input of both Hg and MeHg Residence T Consistent diel surficial trends in Hg0 were times of Hg and MeHg in the lake were cal- T not observed [6], possibly because of daily culated by dividing lake burdens by the sum turnover of the surface mixed layer driven of the monthly outputs (Hg = 41 d, MeHg = T by diel temperature changes A mass balance 84 d) The longer residence time for MeHg model of Hg0 showed that daytime photore- reflects the fact that it is produced as well as duction produced enough Hg0 to sustain con- degraded within the lake, whereas Hg is not T centrations close to the average at Spring generated but, rather, buried or vented to the Lake Evasional losses in the model led to a atmosphere

REFERENCES

[1] KOTNIK, J, HORVAT, M AND JEREB, V (2002): Mod- [4] HENRY, E A ET AL (1995): Total mercury and meth- elling of mercury geochemical cycle in Lake ylmercury mass balance in an alkaline Velenje, Slovenia; Environmental Modelling & hypereutrophic urban lake (Onandoga Lake, NY); Software 17(7), pp 593-611 Water, air, & soil pollution 80, pp 509-518 [2] MEILI, M (1991): Fluxes, pools, and turnover of [5] SELLERS, P, KELLY, C A AND RUDD, J W M (2001): mercury in Swedish forest lakes; Water, Air, and Fluxes of methylmercury to the water column Soil Poll 56, pp 719-727 of a drainage lake: The relative importance of [3] IVERFELDT, A, MUNTHE, J AND HULTBERG, H (1996): internal and external sources; Limnol and Terrestrial mercury and methylmercury budgets Oceanogr 46(3), pp 623-631 for Scandinavia NATO ASI Series, Series 2: [6] HINES, N A AND BREZONIK, P L (2004): Mercury Environment 21(Global and Regional Mercury Dynamics in a small Northern Minnesota lake: Cycles: Sources, Fluxes and Mass Balances), pp Water to Air Exchange and Photoreactions of 381-401 Mercury; Marine Chemistry, Bill Fitzgerald ASLO special issue (in press)

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1059

[7] EPA, Method 1631 (1998): Mercury in water by [13] ST LOUIS, V L ET AL (2001): Importance of the oxidation, purge and trap, and cold vapor atomic Forest Canopy to Fluxes of Methyl Mercury and fluorescence spectrometry US EPA: Washing- Total Mercury to Boreal Ecosystems; Environ ton, DC Sci Technol 35(15), pp 3089-3098 [8] HORVAT, M, BLOOM, N S AND LIANG, L (1993): [14] SWAIN, E ET AL (1992): Increasing rates of atmo- Comparison of distillation with other current spheric mercury deposition in midcontinental isolation methods for the determination of me- North America; Science 257, pp 784-787 thyl mercury compounds in low-level environ- [15] LOCKHART, W L ET AL (1998): Fluxes of mercury mental samples Part 1 sediments; Analytica to lake sediments in central and northern Canada Chimica Acta 281, pp 135-152 Inferred from dated sediment cores; [9] LISS, P W AND SLATER, P G (1974): Flux of gases across Biogeochem , pp 163-173 the air-sea interface; Nature 247, pp 181-184 [16] HINES, N A, AND ENGSTROM, D R (2004): Sedi- [10] SCHROEDER, W ET AL (1992): Volatilization of mer- ment and sediment porewater profiles and fluxes cury from lake surfaces; Sci Tot Env 125, pp of mercury and methylmercury in a small seep- 47-66 age lake in Northern Minnesota; Environ Sci [11] AMYOT, M ET AL (2000): Distribution and transfor- Technol (submitted Feb 2004) mation of elemental mercury in the St Lawrence [17] HERB, W R AND STEFAN, H G (2004): Tempera- River and Lake Ontario; Can J Fish Aquat ture stratification and mixing dynamics in a shal- Sci 57 (Supp 1), p 155 low like with submerged macrophytes; Lake and [12] LALONDE, J D ET AL (2004): Photoinduced Oxida- Reservoir Management 20 tion of Hg0(aq) in the Waters from the St Lawrence Estuary; Environ Sci Technol 38, pp 508-514

RMZ-M&G 2004, 51 1060 PART 2 BIOGEOCHEMISTRY

Methylation and Demethylation of Mercury Throughout the Idrija River System

MARK E HINES1, JADRAN FAGANELI2 & MILENA HORVAT3

1Department of Biological Sciences, University of Massachusetts Lowell, Lowell, MA 01854, USA, e-mail: mark_hines@uml'edu 2Marine Biological Station, National Institute of Biology, Piran, Slovenia 3Department of Environmental Science, Jozef Stefan Institute, Ljubljana, Slovenia

Abstract: The Idrija Mercury Mine was active for 500 years and Hg has been distributed throughout the system all the way to the northern Adriatic Sea over 100 km away! Total Hg and methylmercury (MeHg) vary greatly throughout the system, and sharp increases in both occur several tens of km for the mine, especially around impoundments and estuarine regions! Radiotracer methods were used to investigate Hg transformations throughout the system and almost every habitat studied actively transformed Hg! Re- ductive demethylation dominated in riverbanks, but methylation was noted as well! Sedi- ments behind impoundments exhibited rapid methylation near the surface with reductive demethylation gradually replaced by the oxidative path with depth! Methylation was more active in estuarine sediments and demethylation was primarily via the oxidative pathway! MeHg concentrations were also much higher in estuarine sediments than in the upstream impoundment deposits! Mercury levels decreased offshore in the Gulf of Trieste, but dissolved species did not! Seasonal changes in redox and bioturbation in the Gulf affected Hg transformation rates and the relative importance of oxidative vs! reductive demethylation! The Idrija system is widespread and dynamic encompassing the gamut of Hg biogeochemistry!

Key words: idrija mine, methylation, demethylation, impoundments, marine sediments

INTRODUCTION km from the mining region (HINES ET AL 2000) This is especially noticeable in the middle and Five Hundred years of activity at the Idrija lower sections of the Soca/Isonzo River, and Mercury Mine has left a legacy of contami- in the Isonzo estuary In addition, the MeHg nation along the 100 km route from the mine to total Hg ratio increases toward the sea, sug- to the northern Adriatic Sea Mercury concen- gesting that MeHg formation is very active trations are elevated in air, waters, sediments, along the entire path, especially near impound- and riverbanks, and mercury (Hg) is trans- ments and estuarine areas To investigate the formed in several different types of habitats accumulation of MeHg in the Idrija system, throughout the system (HORVAT ET AL 2002) Hg transformations were determined in dif- However, mercury concentrations and specia- ferent seasons in riverbank soils, in sediments tion vary greatly along the path to the sea, and in the Idrijca and Soèa Rivers, and in sedi- in some cases, both total Hg and methylmer- ments within the Isonzo estuary and several cury (MeHg) levels increase greatly several km into the Gulf of Trieste

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1061

MATERIALS AND METHODS riverbank soils in this reach actively transformed Hg with a dominance of demethylation (k 09-55 % day-1) Significant me- Mercury methylation potentials were deter- deg 203 thylation was also noted (k 0-06 % day-1) mined using Hg and a toluene extraction meth procedure MeHg demethylation potentials The methyl group of MeHg was converted 14 almost exclusively to CH in these soils indi- were determined using C-MeHg and moni- 4 toring the production of 14CH and 14CO cating that demethylation was catalyzed by 4 2 (HINES ET AL 2000) Pore water (Hg, MeHg, an organomercurial lyase enzyme of the bac- nutrients, Fe, SO 2-, ΣH S) and solid phase terial Hg detoxification system (mer) (BARKAY 4 2 (Hg, MeHg, organic C, N, S, reduced S) ET AL 2003; MARVIN-DIPASQUALE ET AL 2000) chemistry were also determined in many in- stances (HINES ET AL 1997) Sediments behind a hydropower dam impoundment in the Soca River exhibited active methylation and demethylation of Hg, RESULTS AND DISCUSSION but methylation was restricted primarily to the upper few cm, which also displayed the Virtually every habitat studied had the po- highest concentrations of dissolved Hg tential to transform Hg to some degree Sedi- (48 ng/L) and MeHg (67 ng/L) (Fig 1) Demethylation was quite active with CH ments were primarily cobble in the 40 km 4 stretch of the Idrija River prior to its accounting for >60 % of the C released at confluence with the Soca River, and these the surface and decreasing to ~10 % at deposits yielded little activity However, 10 cm, suggesting that any contribution of

Figure 1 Depth profiles of methylation (k ) and demethylation (k ) rate constants, and meth deg dissolved total Hg and MeHg in freshwater sediments behind an impoundment and in estuarine sediments

RMZ-M&G 2004, 51 1062 PART 2 BIOGEOCHEMISTRY the reductive path to demethylation was de- with depth, indicating that SO 2--reducing 4 creasing with depth The persistence of CH bacteria were probably responsible the oxi- 4 release was probably also due to the domi- dative demethylation of MeHg as well as its nance of methanogenesis, which produces formation It has been shown that significant, some CH during oxidative demethylation but low concentrations of SO 2- enhance the 4 4 (MARVIN-DIPASQUALE ET AL 2000) formation of MeHg (GILMOUR ET AL 1992)

Methylation activity in sediments collected Hg and MeHg levels in marine sediments in the estuarine region was more rapid than decreased from the mouth of the Isonzo River in the impoundment sediments with a sub- into the central Gulf of Trieste (Hg 45 to tot surface maximum, and the ratio of methyla- 10 µg/g; MeHg 40 to 02 ng/g), whereas tion to demethylation (rate constants) was dissolved Hg and MeHg did not vary sig- twice that noted in the freshwater impound- nificantly Methylation and demethylation ment muds (Fig 1) All C released from activity in marine sediments decreased with MeHg during its degradation was recovered depth (Fig 2), except in summer when a sub- as CO indicating that demethylation oc- surface maximum was noted at the maximum 2 curred entirely by the oxidative pathway depth of bioturbation (data not shown) The Dissolved total Hg was 10-20 fold higher in methyl group of MeHg was converted pri- the estuarine pore waters (up to 600 ng/L) marily to CO in marine sediments, except 2 than in the freshwater sediments, and MeHg for a slight production of CH in surficial 4 in estuarine pore waters was ~5-fold higher sediments in winter; a phenomenon that in- The estuarine sediments contained a little creased offshore inversely to rates of bacte- more than 10 mM SO 2-, which decreased rial sulfate reduction (data not shown) 4

Figure 2 Depth profiles of mercury transformation rate constants at three sites in the Gulf of Trieste in March Site D6 is closest to shore and the river mouth, CZ is most offshore Black columns represent CH and white CO production during demethylation of MeHg 4 2 RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1063

It appeared that the offshore increase in CH of MeHg formation and cycling, and strong 4 production from MeHg was due to an en- sources of MeHg that are tens of km from hancement of the expression of mer proteins the source Often MeHg formation is nearly in response to sediment oxidation balanced by MeHg demethylation, and the pathway of demethylation varies in response to changing biogeochemical conditions CONCLUSIONS Acknowledgements Despite the point source of Hg in the Idrija mining region, the deposition of material in Funded by the US National Science Foun- riverbanks, impoundments, and marine sedi- dation (EAR 0322022, EAR 9975407, EAR ments causes a dynamic far-reaching system 9696015, INT 9724012) and the Slovene Ministry of Education, Science, and Sport

REFERENCES

BARKAY, T, MILLER, SM AND SUMMERS, AO (2003): HORVAT, M, JEREB, V, FAJON, V, LOGAR, M, KOTNIK, Bacterial mercury resistance from atoms to eco- M, FAGANELI, J, HINES, ME AND BONZONGO, systems FEMS Microbiol Rev, Vol 27, pp J-C J (2002): Mercury distribution in water, 355-384 sediment and soil in the Idrijca and Soca river GILMOUR, CC, HENRY, EA AND MITCHELL, R (1992): systems Geochem Explor Environ Analysis Sulfate stimulation of mercury methylation in Vol2, pp 287-296 freshwater sediments Environ Sci Technol Vol MARVIN-DIPASQUALE, MC, AGEE, J, MCGOWAN, C, 26:, pp 2281-2287 OREMLAND, RS, THOMAS, M, KRABBENHOFT, D HINES, ME, FAGANELI, J AND PLANINC, R (1997): Sedi- AND GILMOUR, CC (2000): Methyl-mercury mentary anaerobic microbial biogeochemistry degradation pathways: a comparison among in the Gulf of Trieste, northern Adriatic Sea: three mercury-impacted ecosystems Environ influences of bottom water oxygen depletion Sci Technol Vol 34, pp 4908-4917 Biogeochem Vol 39, pp 65-86 HINES, ME, HORVAT, M, FAGANELI, J, BONZONGO, JCJ, BARKAY, T, MAJOR, EB, SCOTT, KJ, BAILEY, EA, WARWICK, JJ AND LYONS, WB (2000): Mercury biogeochemistry in the Idrija River, Slovenia, from above the mine into the Gulf of Trieste Environ Res , Vol 83, pp 129-139

RMZ-M&G 2004, 51 1064 PART 2 BIOGEOCHEMISTRY

Distribution of inorganic and methylmercury in METAALICUS Lake 658 after addition of stable mercury isotopes

HOLGER HINTELMANN1, NIVES OGRINC1, 2, KEN SANDILANDS3, BRIAN DIMOCK1

1Trent University, 1600 West Bank Drive, Peterborough, Ontario, K9J7B8, Canada# 2J# Stefan Institute, Dept# of Environ# Sciences, Jamova 39, 1000 Ljubljana, Slovenia# 3Department of Fisheries and Oceans, 501 University Crescent, Winnipeg, Manitoba, R3T 2N6, Canada

Abstract: After applying stable isotopes of 202Hg to Lake 658 of the Experimental Lakes Area, approximately 2 % of the added isotope was present as methylmercury in the water column" In 2001, the first year of the application, 202HgT in surface water fluctuated between 1"5-2 ng/L" In 2002, it varied from 2-3 ng/L" After fall turnover, concentrations leveled out at 0"7 ng/L in 2001, increasing to 1"0 ng/L in 2003" Ambient HgT was typically 2"2 ± 0"8 ng/L everywhere in the lake" Me202Hg peaked eventually at 25 pg/L (ambient MeHg: ~ 125 pg/L) in the epilimnion and reached in the hypolimnion levels of up to 300 pg/L (ambient MeHg: 1050 pg/L)"

Key words: methylmercury, methylation, METAALICUS, lake water, stable mercury isotopes

INTRODUCTION ing in early summer and commencing until mid-fall$ The applications resulted in a uni- This presentation summarizes the dynamics form distribution of the isotope within 24 of in-lake processes observed during the ini- hours after spiking$ During the experiment, tial two years of the METAALICUS project$ water profiles were collected to follow the To evaluate the relationship between atmo- distribution of the isotope into the water col- spheric loading and ensuing Hg concentra- umn and to record the evolution of methylm- tions in fish, the mercury load to Lake 658 ercury formation from the added spike$ Wa- at the Experimental Lakes Area (ELA) was ter samples were filtered in-line on quartz increased by addition of a Hg solution en- fibre filters using a teflon cartridge to obtain riched with 202Hg(II)$ concentrations of dissolved and particulate Hg and MeHg$ The Hg additions created a regular sawtooth pattern of 202Hg levels in MATERIALS AND METHODS surface water as shown in Figure 1$

The isotope was delivered to the lake sur- During the summer months, the majority of face through biweekly additions of the iso- the added isotope was constrained to the ep- topic Hg$ Spikes were added nine times start- ilimnion$ Two weeks after spiking, the first

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1065

Figure 1 Evolution of lake Hg spike (Hg enriched with 202Hg) concentration during the first two years of Hg additions to Lake 658 Mercury was added biweekly during the summer season

Figure 2 Evolution of Me202Hg water column profiles representing new Me202Hg from the added 202Hg during the first year of Hg additions isotopic methylmercury was observed at the ing of epilimnetic HgT and hypolimnetic bottom of the lake near the sediment water MeHg into the whole lake volume interface Isotopic and ambient MeHg accumulated in the anoxic zone of the hypolim- Acknowledgements nion in late summer As illustrated in Figure 2, concentration profiles for HgT and MeHg This work was supported by funding from were uniform throughout the water column the Electric Power Research Institute (EPRI) after fall turnover, indicating complete mix-

RMZ-M&G 2004, 51 1066 PART 2 BIOGEOCHEMISTRY

Rates of mercury methylation and methylmercury demethylation in wetlands near Hamilton Army Airfield on San Francisco Bay

HOLGER HINTELMANN1, BRIAN DIMOCK1, JOY ZHU1, HERBERT L FREDRICKSON2, ELLY P H BEST2

1Trent University, 1600 West Bank Drive, Peterborough, Ontario, K9J7B8, Canada# 2U#S# Army Engineer Research & Development Center, Environmental Laboratory, CEERD-EP, 3909 Halls Ferry Road, Vicksburg, Mississippi 39180-6199, USA

Abstract: Rates of mercury methylation and demethylation were measured in a coastal wetland using stable isotopes of mercury and methylmercury After incubation intact cores for a period of 5 hours, measured methylation rates varied from 005 to 15% of the injected 199Hg(II) isotope While ambient levels of total mercury averaged 350 ng/g and were quite consistent between 0 and 10 cm depth, levels of ambient methylmercury varied quite dramatically from 02 to 38 ng/g

Key words: mercury methylation, demethylation, wetland, stable mercury isotopes, sediment

INTRODUCTION near San Francisco Emphasis is on the effect marsh vegetation has on net formation The quantitative effect of MeHg production rates Assays were carried out under dark/ and export from coastal wetland areas on con- light conditions to test if diurnal factors contamination of aquatic food webs supporting trol Hg methylation, directly or indirectly fish production and piscivorous wildlife has through changes in redox conditions in the received little attention Since wetlands often sediment root zones differ significantly in their MeHg producing potential, site specific information is needed The influence of wetland plant species and SAMPLING the situation of the vegetation within the marsh on MeHg yields needs to be determined be- Samples were taken collected June 2003 near fore one can fully assess the expected MeHg the waters edge in a tidal marsh that floods formation in a particular ecosystem during high tide at three sites Site 1 was mainly vegetated by cordgrass (Spartina), To estimate standing pool sizes of MeHg in Site 2 was dominated by pickelweed coastal marshes this study evaluated the me- (Salicornia) and Site 3 was a mudflat not thylation and demethylation potential for covered by above ground vegetation at all different wetland types near the Hamilton Samples were cored using a metal auger, in Army Air Field (HAAF) in San Pablo Bay which 10 cm diameter acrylic plastic tubes

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1067

(length: 30 cm) were inserted Additionally, RESULTS epiphyton was sampled by scraping surface sediment covered with epyphyton (~ 35 cm2) Overall, rates of mercury methylation showed into a 50 mL centrifuge tube A control large variability within and among sites Me- sample consisted of surface sediments, which thylation activity ranged from 005 to 15 % had the epiphyton cover removed prior to of added isotope methylated per day in sedi- sampling Cores were injected with a cock- ments as shown in figure 1 Plants did incor- tail of 199Hg(II) and Me200Hg at three depths, porate inorganic Hg isotope and showed am- incubated for 5 hours, frozen in the field and bient MeHg levels between 03 and 18 ng/g transported to the laboratory Injected core (dw), but isotopic methylmercury was de- segments were cut and concentrations of tected only sporadically Roots were associ- HgT and MeHg (ambient and enriched iso- ated with high levels of inorganic and meth- topes) wee measured ylmercury originating from the isotope spike

Figure 1 199Hg methylation in % over a 5 hour incubation period, measured at 2 cm, 5 cm and 10 cm depth at three locations (Hamilton Army Air Field, Control marsh, Bel Marin) for three types of vegetation (Salicornia, Spartina and mudflats)&

RMZ-M&G 2004, 51 1068 PART 2 BIOGEOCHEMISTRY

Influence of Phosphorus on Methyl Mercury Levels in Wetlands

JONATHAN HOLMES AND DAVID LEAN

Biology Department, University of Ottawa, 150 Louis Pasteur, P!O! Box 450, Station A, Ottawa, ON, Canada, K1N 6N5

Abstract: Recent evidence in the Florida Everglades has shown that phosphorus enrichment has enhanced methyl mercury (MeHg) levels in water, sediment, and fish The objective of our research was to determine if a simple relationship exists between phosphorus and MeHg in water and sediment of impacted and pristine temperate wetlands located in Ontario, Quebec, and Nova Scotia, Canada The contribution of pore water and sediment MeHg to overlying water was investigated in four wetlands that were chosen to reflect a range of total phosphorus The results provide a general warning that increased phosphorus levels could increase MeHg levels in wetlands Phosphorus levels are important, but their effects depend on the concentrations and interactions of other common wetland factors such as pH, Eh, Fe, Ca, dissolved organic carbon, and sulfide

Key words: temperate wetlands, phosphorus, methyl mercury, sulfide, pore water

INTRODUCTION wetlands in Canada through increased phosphorus loading from fertilizer use The focus Wetlands are known sources of methyl mer- of our research was to determine if a simple cury (MeHg) In fact levels found in lakes and relationship exists between phosphorus and rivers often correlate to the percent area of MeHg in water and sediments of impacted wetlands within the drainage basin (ST LOUIS and pristine wetlands Wetland water samples ET AL, 1996) Recent evidence in Everglades were collected for MeHg and total phospho- National Park, Florida, USA, has shown that rus from 60 wetlands located in Ontario, Que- agricultural nutrient runoff enhance MeHg bec, and Nova Scotia, Canada, during sum- formation (STOBER ET AL, 1998) Phosphorus mer months 2000-2002 The moderating in- enrichment of the Everglades has resulted in fluence of factors known to effect MeHg lev- drastic changes to microbial and periphyton els (sulfate, sulfide, pH, DOC, etc) was also communities, and created anoxic bottom wa- determined Small fish were monitored to ters and sediments ideal for MeHg produc- determine the bioavailability of MeHg tion Increased mercury levels in small fish (Gambusia sp) were related to enhanced For the first time, depth profiles for MeHg MeHg levels in water and sediments in sediment were measured using pore water peepers This was done in the sediments Although this problem was first identified in of four wetlands selected to reflect a range a subtropical environment, we ask if a simi- of total phosphorus The depth pattern of lar problem could also occur in temperate MeHg production and potential diffusion

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1069 rates to overlying waters were calculated in the Everglades MeHg concentrations The role of pore water sulfide and sulfate were highly correlated with total phospho- was also considered rus up to about 100 µg P/L At this level, we propose sulfide concentrations become sufficient to suppress MeHg formation RESULTS AND DISCUSSION One of the highest levels of MeHg found was MeHg and Phosphorus in a wetland created only three years ago by Ducks Unlimited (at 200 ug P/L) This illus- A total of 60 wetlands were sampled across trates that there is a time factor as well To- a range of phosphorus concentration (8 to tal Hg in 3 species of small fish (central mud 1300 µg P/L) MeHg levels varied from minnow, 5 Spine Stickleback, and Red Belly <20 to 1100pg MeHg/L Some MeHg val- Dace) were highly correlated with wetland ues even exceeded the maximum recorded MeHg water concentration

Figure 1 MeHg plotted vs total phosphorus levels found in water collected from 60 wetlands during summer months 2000-2002

MeHg sediment depth profiles amount of MeHg (Figure 2d), compared to the other three wetlands, figure 2a shows that Wetland surface water concentrations of Coopers Marsh did not correspondingly MeHg correlated positively with sediment have the least MeHg in pore water This was MeHg concentrations H15C1 had the most unexpected, since the concentration of sul- MeHg in both sediment and water column fide in Coopers Marsh water near the sedi- (Figure 2), followed by Stillwoods, Baie St ment water interface was 5 to 10 times Francois, and Coopers Marsh A positive greater than in the other 3 wetlands Excess correlation is also visible between wetland sulfide accumulation is thought to limit pore water and sediment MeHg concentra- MeHg production by removing potentially tions, except in Coopers Marsh While bioavailable inorganic Hg via precipitation Coopers Marsh sediment had the least as HgS (K , 10 -36 4) (s) , sol

RMZ-M&G 2004, 51 1070 PART 2 BIOGEOCHEMISTRY

Figure 2 Pore water profiles for MeHg, a); sulfide, b); sulfate, c); and sediment MeHg, d); in 4 temperate wetlands, June 2002 MeHg concentration in water column of H15C1, Stillwoods, Baie St Francois, and Coopers Marsh were 0 701, 0 296, 0 116, and 0 078ng/L respectively

It has been suggested that neutral Hg spe- solution, increasing the bioavailability of Hg cies such as HgS may diffuse passively as HgS and subsequent methylation by (aq) (aq) across biological membranes and thus be SRB available for methylation (BENOIT ET AL, 1998, 1999) Laboratory evidence indicates The high sulfide levels found above the sedi- that humic and fulvic acids enhance the dis- ment water interface in Coopers Marsh sug- solution of HgS under oxic and anoxic con- gests that redox conditions supported the ditions (RAVICHANDRAN ET AL, 1998), and also production or presence of sulfide above the inhibit the precipitation and aggregation of interface and/or that the Fe(II) buffering ca- HgS, (RAVICHANDRAN ET AL, 1999) Bacteria pacity at the sediment/water interface no can promote and inhibit mineral dissolution longer limited sulfide diffusion out of the (WELCH AND VANDEVIVERE, 1994) Given that sediments Redox conditions (as measured dissolved organic carbon (DOC) concentra- by Eh) in H15C1, Stillwoods and Coopers tion in the water column and sediment or- marsh at the sediment/water interface were ganic content (as determined by percent loss similar and comparable to redox conditions on ignition) was highest in Coopers Marsh, associated with microbial sulfate reduction it is suggested that elevated levels of MeHg However iron concentrations were much in Coopers Marsh pore water could be the lower in Coopers Marsh than the other wet- result of DOC mediated metacinnabar dis- lands (2 to 10x), and sulfide was present

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1071 above sediments This would indicate that fide, precipitation of metacinnabar was in- iron buffering prevented sulfide diffusion hibited by DOM until a concentration of ap- from the sediments in the other wetlands proximately 35 mg/L Ca was present In H15C1 and Stillwoods the Ca concentrations Water MeHg concentrations in H15C1, were high, 51, 73 ppm respectively, but only Stillwoods, and Baie St Francois appear to 11 ppm in Coopers Marsh DOC levels at be related to maximum pore water levels a the above sites were similar, 12, 13, and few centimeters below the sediment water 15 mg/L respectively We infer that DOC interface, and are presumably a result of dif- mediated dissolution at Coopers Marsh was fusion from sediment pore water However, much more likely than at the other two sites the level of MeHg in Coopers Marsh pore water do not appear to have translated via Total Hg measured in Coopers Marsh sedi- diffusion to the MeHg level found in the ment was 14 to 48 times higher than the water column possibly because of the con- other wetlands, however a much greater considerably higher sulfide content above the centration of MeHg was present in pore wa- sediment water interface In the presence of ter and sediment of H15C1 and Stillwoods H S, MeHg reacts to form volatile dimethyl This demonstrates that Hg methylation is a 2 Hg, (CRAIG AND MORETON, 1983) High dis- function of Hg availability rather than the solved sulfide levels above the sediment total pool of Hg in sediments water interface suggest that any diffusion of MeHg from pore water to the water column Sulfate depth profiles in all four wetland may have been inhibited due to the forma- (Figure 2c) showed slight or sharp peaks in tion of dimethyl Hg Dimethyl Hg is highly the first 5 cm of sediment possibly due to volatile (50 mm at 20 °C, as compared to the presence of chemotrophic or phototrophic MeHg 00085 mm) and is extremely un- sulfide oxidizing bacteria Sulfate levels in stable the water column and pore water did not correlate to MeHg levels present in the water, High pore water MeHg levels in H15C1 and pore water, or sediment Stillwoods as compared to Coopers Marsh are not likely a result of increased bioavailability of Hg as HgS , caused by (aq) CONCLUSIONS humic and fulvic acid interaction and dissolution of metacinnabar Polyvalent cations This research provides a general warning that enhance metacinnabar aggregation even in increased phosphorus levels could increase the presence of DOM, but the magnitude of levels of MeHg in wetlands and that this the effect is dependent on the concentrations MeHg can be exported from the wetlands to of DOM, Hg, and Ca (RAVICHANDRAN ET AL, downstream areas Although phosphorus lev- 1999) In this 1999 study, a relatively large els are important, their effects depend upon concentration of poly valent cations was the concentrations and interactions of other found to be required to produce this effect common wetland factors such as pH, Eh, In the experiment using anoxic water of 10 DOC, Fe, polyvalent cations (ie Ca), and mg/L DOC, 10 ug/L of Hg, and 32 ppm sul- sulfide

RMZ-M&G 2004, 51 1072 PART 2 BIOGEOCHEMISTRY

Acknowledgements

This work was supported by the National Sciences and Engineering (NSERC) Re- search Network called the Collaborative Mercury Research Network (COMERN) and an NSERC Strategic Grant to DL$

REFERENCES

BENOIT, J M, GILMOUR, C C, MASON, R P, HEYES, A ST LOUIS, V L, RUDD, J M, KELLY, C A, BEATY, K (1999): Sulfide Controls on mercury speciation G, FLETT, R J, ROULET, N T (1996): Produc- and bioavailability to methylating bacteria in tion and loss of MeHg and loss of total Hg from sediment pore water; Environ Sci Technol 33, boreal forest catchments containing different pp 951-957 types of wetlands; Environ Sci Technol 30, pp CRAIG, P J, MORETON, P A (1983): Total mercury, 2719-2729 methylmercury, and sulfide in River Carron sedi- STOBER, J ET AL (1998): South Florida Ecosystem ments; Mar Pollut Bull 14, p 408 Assessment Monitoring for adaptive manage- RAVICHANDRAN, M, AIKEN, G, REDDY, M M, RYAN, J ment: Implications for ecosystem restoration; N (1998): Enhanced dissolution of Cinnabar Final Technical Report Phase I, EPA 904-R- (Mercuric Sulfide) by dissolved organic matter 98-002 isolated from the Florida Everglades; Environ WELCH, S A, VANDEVIVERE, P (1994): Effect of mi- Sci Technol 32, pp 3305-3311 crobial and other naturally occurring polymers RAVICHANDRAN, M, AIKEN, G, RYAN, J N, REDDY, M on mineral dissolution; Geomicrobiology Jour- M (1999): Inhibition of precipitation and ag- nal 12, pp 227-238 gregation of metacinnabar (Mercuric Sulfide) by dissolved organic matter isolated from the Florida Everglades; Environ Sci Technol 33, pp 1418-1423

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1073 Mercury and selenium in fish species in the Idrijca river polluted due to past mercury mining

MILENA HORVAT1, MIHAEL TOMAN2, JOT STERGAREK2, JO E KOTNIK1, VESNA FAJON1, DARIJA GIBIÈAR1

1Department of Environmental Sciences, Joef Stefan Institute, Jamova 39, Ljubljana, Slovenia; E-mail: milena#horvat@ijs#si 2 Univesity of Ljubljana, Biotechnical Faculty, Slovenia

Abstract: Various fish species were sampled in summer 2003 in the Idrijca river polluted by past mercury mining activity in Idrija, Slovenia The results obtained showed much lower results as compared to those measured during active mercury mining, however, the concentrations of mercury in fish muscle and liver are still high downstream of the former mercury mine and do not show expected decrease after more than 10 years of the complete of mercury mining

Keywords: mercury mining, river, fish, total mercury, selenium, muscle, liver

INTRODUCTION about 0"2 % in marine waters" Concentra- tions of Hg in sediments and flood plain soils The Idrija mercury mine is situated 50 km also increased by several fold downstream, west of Ljubljana, Slovenia, and it is a site with MeHg ranging from 0"01 to 0"1 % in of the second largest Hg mine in the world, riverine and marine sediments, and less than which was in operation continually for 0"01 % of MeHg in flood plain soil (HORVAT 500 years until about 20 years ago" The Idrija ET AL", 2002)" mine has severely enhanced the mobilization of Hg by mining activities, and Hg-laden Due to chemical transformation (reduction, material remains in the region" Mercury and methylation, oxidation, demethylation) and methylmercury were measured in various transport of mercury enriched particles into environmental compartments during the pe- the river system and the Gulf of Trieste, the riod 1995-2004" Some recent measurements mercury problem is of local, regional and of mercury in water, sediments and soil are global concern" The results of some studies shown to be very high" Total Hg in the Idrijca indicate that Hg is actively accumulated in river water increased downstream of the terrestrial and aquatic food webs, which leads mine (from a few ng/L to up to 500 ng/l), to an increased exposure of inhabitants fre- with methyl Hg (MeHg) accounting for quently consuming food, in particular fish, 1"5 % above the town of Idrija, 0"2 to 0"7 % produced in contaminated area (HORVAT ET after Idrija, 2-3 % in river reservoirs and only AL", 2004)"

RMZ-M&G 2004, 51 1074 PART 2 BIOGEOCHEMISTRY

EXPERIMENTAL are mainly bottom feeders" European graying rainbow and brown trout feed mainly on In this work we collected river fish species invertebrates, and insects flying above the at four different locations (Figure 1)" The first water as well as on smaller fish" was above the city of Idrija (reference point), second in the town if Idrija and the third and Samples of muscle, skin, brain, liver, kid- the fourth location were about 20 and 40 km ney, gills were collected from fresh fish and downstream, respectively" Fish were caught stored in deep freezer until further process- in summer of 2003" At each location several ing" Total mercury and selenium were deter- fish of the same species were collected" The mined by radiochemical neutron activation following fish species were sampled: marble analysis (KOSTA AND BYRNE, 1973)" Only fish trout (Salmo marmoratus), brown trout muscle and liver samples has so far been (Salmo trutta), rainbow trout (Salmo analysed for total Hg and Se, while MeHg gairdneri/Oncorhynchus mykiss), European has not been analysed as yet" graying (Thymallus thymallus), Italian barbell (Barbus plebejus), mrenic (Barbus meridionalis canimus) and hybrid/crossbreed RESULTS between marble and rainbow trout (Salmo sp)" Feeding habits of Italian barbell and The results have shown that highest concen- mrenic are similar" They feed on insect lar- trations of mercury in fish muscle and liver vae, crabs, and other insects in water" They are strongly affected by the location and the fish species" As expected, lowest concentrations were found at location 1, upstream the mercury mine" Concentrations of total Hg in fish muscle increased significantly in Idrija, followed by a step decrease at the second station, about 15 km downstream" An increase was observed at the station number 4, close to the inflow of the Idrijca river into the reservoir" Similar trend was also observed for mercury levels in liver, but with much higher concentrations, mainly due to accumulation and retention of inorganic mercury in the fish"

Results are expressed as a mean ±standard deviation based on fresh weight basis" FW"" fresh weight; n"a" not analyzed as yet"Hg in fish muscle"

Figure 1 Fish sample were taken at location 1 to 4

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1075

Table 1 Concentrations of total mercury and selenium in fish muscle and liver samples

A positive correlation between total Hg in mine Further interpretation of the data will fish muscle and liver (r2=0 60) was found A be possible when data on Hg speciation is positive correlation between the size and available mercury concentrations in muscle was found only for marble trout (r2= 0 7614) and Euro- Unfortunately, a very few measurements of pean graying (r2= 0 7206) These two spe- mercury in fish was done in the past A short cies were caught at a number and size to al- review of the values reported for the period low statistical evaluation Other fish species between 1973 to 1991 are given in Table 2 were of relatively small sizes (young spe- The highest concentrations of total mercury cies) and the evaluation of the size vs Hg were reported in fish from Idrija in 1971, concentrations was not meaningful No cor- which is due to active mercury mining and relation between mercury concentration in large inputs of mercury into the river water fish liver vs size was found In general, In 1980 and 1991 very limited data is avail- mercury levels in fish liver was higher than able, and it is in the same order of magni- in fish muscle, in particular in fish caught in tude as in 2003 This means that in recent Idrija and downstream from the mercury years, after more than 10 years of closure of

RMZ-M&G 2004, 51 1076 PART 2 BIOGEOCHEMISTRY mercury mine, Hg concentrations in fish has Concentrations of Selenium in fish muscle not decreased as expected, while Hg in sedi- is similar in all fish species, except Europen ments and air decreased significantly graying with highest concentrations at all (HORVAT ET AL , 2002; KOTNIK ET AL , this is- stations Selenium in liver is significantly sue) Comparison with Hg concentrations in higher than in muscle, with higher variations other temperate rivers is difficult, as the fish among fish species There is no correlation species, size and location might influence Hg between Se and Hg in muscle and liver Se- levels significantly (BURGER ET AL , 2001) It lenium was also analysed in 1980 and the is interesting to note that the concentrations results are comparable with those reported of mercury in fish muscle in areas after mer- in this study Selenium concentrations are cury mine are similar to those reported in also similar to those found in marine fish of the Gulf of Trieste (HORVAT ET AL , 1999) and the Adriatic sea (HORVAT ET AL , 1987) middle Adriatic (HORVAT ET AL , 1987)

Table 2 Concentrations of mercury and selenium in Idrijca river over time, expressed on a wet weight basis

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1077

CONCLUSIONS from reservoirs on Soèa river and further downstream Mercury concentrations in fish of the Idrijca river is significantly increased after the Acknowledgements former mercury mining sites When the analysis of MeHg in fish muscle are avail- This work was supported by the Ministry of able it will be possible to consider potential Education, Science and Sport of the R concern for those frequently consuming fish Slovenia through a programme P532 and the from contaminated sites It is also important project Z2-3502 The financial support of the to note that Hg in fish may also be of con- Phare project SLO108020012 is also ac- cern for wild life as well as for birds feeding knowledged The technical assistance of Ms on fish from the river It will also be of im- A Prosenc and the help of fishing associations portance to investigate mercury uptake in fish of Idrija and Tolmin are also acknowledged

REFERENCES

HORVAT, M, JEREB, V, FAJON, V, LOGAR, M, KOTNIK, J, BURGER, J GAINES, K F, BORING, C S, STEPHENS, JR FAGANELI, J, HINES, M E, BONZONGO, J-C (2002): W L, SNODGRASS, J, GOCHFELD, M (2001): Mercury distribution in water, sediments and soil mercury and selenium in fish from the Savan- in the Idrijca and Soèa river systems; Geochem nah River: Species, Trophic Level, and Loca- Explor Environ Anal Vol 2, pp 287-296 tion Differences; Environ Res Sec A, Vol 87, KOSTA, L, BYRNE, ANTHONY A R, ZELENKO, V, pp 108-118 STEGNAR, P, DERMELJ, M, RAVNIK, V (1974): HORVAT, M, KONTIÆ, B, KOTNIK, J, OGRINC, N, JEREB, Studies on the uptake, distribution and transfor- V, FAJON, V, LOGAR, M, FAGANELI, J, HINES, mation of mercury in living organisms in the M, RAJAR, R, IRCA, A, AGAR, D, PETKOVEK, Idrija region and comparative areas; Vestn Slov G AND DIZDAREVIÆ, T (2004): Remediation of KemDru, Vol 21, pp 49-76 mercury pollution sites, due to mining acrivities; HORVAT, M COVELLI, S, FAGANELI, J, LOGAR, M, Crit Rev Anal Chem, Vol 33(4), pp 1-6 MANDIÆ, V, RAJAR, R, IRCA, A, AGAR, D BYRNE, A R AND KOSTA, L (1974): Simultaneous de- (1999): Mercury in contaminated coastal envi- termination of mercury and seleniuem by radio- ronments; a case study: the Gulf of Trieste; Sci chemical neutron activation analysis; Talanta, Tot Environ, Vol 237/238, pp 43-56 Vol 21, pp1083-1090 PLANINC, R, BAJT, O, HORVAT, M, FAGANELI, J, KOTNIK, J, KOCMAN, D, HORVAT, M, LOGAR, M, GORENC, B (1993): An outline of chemical pol- GIBIÈAR, D, FAJON, V (2004): Distribution in lution of the coastal waters of the southeastern Soèa river catchment area; RMZ, this issue (Slovenian) part of the Gulf of Trieste; Acta KOTNIK, J, DIZDAREVIÈ, T, HORVAT, M (2004): Cur- Chim Slov, Vol 40/4, pp 349-368 rent and past mercury distribution in air over HORVAT, M, ZVONARIÆ, T, STEGNAR, P, PROSENC, A, Idrija region; RMZ, this issue KONDA, D, SABADIN, A (1989): Realtionship between total mercury, methylmercury and selenium in fish muscle from the Adriatic Sea; (Ed, J-P VERNET) Heavy metals in the Envi- ronment, Vol 1, pp 36-40, Geneva 1989

RMZ-M&G 2004, 51 1078 PART 2 BIOGEOCHEMISTRY

Long-Term Increase of Methyl Mercury in Runoff after clear Felling at Gårdsjön, Sweden

HANS HULTBERG

Abstract: Since summer 1999 very high concentrations of methyl mercury have been observed in runoff from a long term monitoring catchment (F1) at Gårdsjön, Sweden! During several months in autumn 1999 methyl mercury concentrations of more than 3 ng/L were measured which was 10 to 50 times higher than measured before! Similar observations were made in a nearby catchment (F2)! During years 2000 to 2002 methyl mercury concentrations decreased in both catchments but were still higher than before the summer 1999! In 2003 and 2004 monthly methyl mercury concentrations in catchment F2 varied between 0,5 to 5 ng/L or 10 to 50 times higher than measured before 1999! During the autumn 1999 total mercury increased by a factor of 2 to 3 and decreased back to original concentrations of 2 to 5 ng/L! The high methyl mercury concentrations occurred after a clear felling of the forest in catchment F2 during the summer 1999! This resulted in changes of the hydrology in the valley bottom of catchment F1 as well as over all of catchment F2 where the heavy tractor transport of timber occurred! The tractor caused deep tracks in the forest soil and surface runoff of water started running along the tracks on the catchment slopes! Organic soils have accumulated total mercury and methyl mercury deposited by wet and dry atmospheric deposition over long time periods! Compared to the atmospheric deposition of total mercury it needs hundreds and even thousands of years to explain the large soil pool of total mercury! Methyl mercury accounts for some 1 or 2 % of the total soil pool of mercury! Methyl mercury, which to a large degree is bound to low molecular water-soluble fulvic acids, is much more water soluble than the total mercury! The dramatic effects on hydrology in the catchment slopes together with the high water solubility of methyl mercury may explain the long-term high methyl mercury concentrations in surface runoff at Gårdsjön during 1999 to 2004! Implications to methyl mercury content in fish in lakes in areas with industrialised forest practices will be discussed!

Key words: soil, forestry, hydrology

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1079 Uptake of Methyl Hg in Lake Superior - Nearshore vs Offshore Processes

JAMES P HURLEY 1, HELEN MANOLOPOULOS 1,RICHARD C BACK 2, KRISTOFER R ROLFHUS 1, PATRICK R GORSKI 1, CHRISTOPHER L BABIARZ 1, RICHARD STOOR 1 AND LISA CLECKNER 1

1 University of Wisconsin-Madison, Madison, WI 53706 (2) Lake Superior State Univ, Sault Ste Marie, MI 49783 (hurley@aquawiscedu)

The United States Environmental Protection characteristics and conditions which affect Agency (USEPA), through its Science to the production of MeHg within the Lake Achieve Results (STAR) program, funded Superior basin, and its subsequent transport nine projects in the US in its Mercury: Trans- into the lake via tributaries Groundwater port and Fate through a Watershed subpro- sampled at two sites of contrasting land cover gram from 1999-2003 The project Water- type (coniferous vs deciduous forest) con- shed Influences on Fate and Transport of tained relatively high concentrations of Mercury in Lake Superior project was de- MeHg (up to ~ 06 ng L-1 in August) During veloped to assess the importance of water- periods of low flow in the summer, anoxic sheds in controlling sources, transport, fate, and low redox conditions are promoted in and bioavailability of mercury (Hg) in the the subsurface that enhance microbial activ- Lake Superior basin, a northern temperate ity and MeHg production During periods of Great Lakes system More specifically, the high flow in response to precipitation events objectives of the study were to: 1) Determine or spring snowmelt, MeHg is flushed and the speciation and bioavailability of Hg trans- transported to down gradient surface waters ported to Lake Superior by rivers that drain depleting concentrations in the wells representative and contrasting watersheds; 2) A strong link between MeHg in the subsur- Determine the importance of watershed-spe- face and the hydrologic cycle was observed cific characteristics (land cover, land use, at both sites These results indicate that, surficial deposits) that control physical and (a) subsurface transport and/or production of chemical forms of Hg transported down- MeHg can be an important source of MeHg stream; 3) Identify key mechanisms control- to surface waters, and (b) MeHg can be ex- ling Hg bioavailability and speciation in near- ported from forested systems and not only shore zones relative to open lake regions; and, wetlands as was previously thought (STOOR 4) Provide process-level information to com- 2001) The importance of the hyporheic zone, pliment concurrent development of Hg fate the subsurface interface between groundwa- and transport models of the Lake Superior ter and surface water, as a source of MeHg ecosystem (HURLEY ET AL 2001) to streams in both wetland and forested areas was also revealed through this study An in depth study was conducted on the Concentrations of MeHg in both bottom pore Tahquamenon River watershed to investigate waters and stream water increased during the

RMZ-M&G 2004, 51 1080 PART 2 BIOGEOCHEMISTRY summer when methylation was promoted in Two studies were conducted to investigate the hyporheic zone, and decreased in Sep- the mechanisms of MeHg transport through tember when conditions were less favorable the mixing zone by: (a) collecting size- for methylation Previous studies have cal- fractioned seston (< 35, 35 - 153, 153 - 243, culated MeHg efflux to a stream by compar- > 243 µm) from the river mouth and offshore ing MeHg concentrations in wellside streams to examine the changing distribution of and using differences in well level to calcu- chemical species within the particulate late water flow Our studies have shown the phase, and (b) collecting colloidal (110 kDa importance of also measuring hyporheic pro- 045 mm) and truly dissolved (<10 KDa) cesses and potential efflux The concentra- fractions from the mouth, offshore and a rep- tions of MeHg in hyporheic porewaters are resentative mixing zone sample to examine consistently higher than background well the changing distribution of chemical spe- concentrations cies within the aqueous phase (< 045 mm) (MANOLOPOULOS ET AL 2003) The < 35 mm High loads of Hg entering Lake Superior fraction represented the majority of mass, through tributaries are generally retained in MeHg and chl-a at both sites, and overall nearshore waters Elevated Hg concentra- concentrations decreased between the mouth tions were observed in all lake compartments and offshore with the exception of chl-a in these riverine mixing zones emphasizing which showed the opposite trend When ex- the significance of this source to nearshore amined on a mass basis however, MeHg was waters and the biogeochemical cycling of Hg more concentrated in the larger fractions with (CLECKNER ET AL 2003) In order to study the the 153 - 243 mm fraction being more im- influence of river plumes on Hg dynamics portant in the river mouth and the > 243 µm in Lake Superior nearshore waters, we con- fraction in the offshore As larger particles ducted a series of studies in the Tahquamenon settled out between the mouth and offshore, River/Whitefish Bay mixing zone Despite this would suggest that MeHg is transported expected decreases in analyte concentrations to the offshore through smaller particles due to dilution of the river plume with lake where it is assimilated by larger, more bio- water, an enrichment in the MeHg content logically active particles Our ultrafiltration of particles always occurred at the outer edge study revealed that MeHg enters the lake of the plume An increase in the MeHg par- from the river associated predominantly with titioning coefficient (log K ) of over an or- colloidal material but in the offshore where d der of magnitude was also noted between the the amount of DOC and proportion of col- inner and outer edge of the plume The bio- loids decreases, MeHg is mainly associated logical enrichment of the suspended particle the truly dissolved phase pool indicated by the increase in chl-a coupled with the concomitant increase in A large portion of our study was devoted to particulate MeHg relative to other parts of developing appropriate tools and methods to the lake, suggests an enhancement of MeHg examine the mechanisms of MeHg uptake bioaccumulation in these regions This trend by the lower food web in fresh waters The was also observed in other Lake Superior greater challenge was to develop a method mixing zones (St Louis River, Fish Creek) appropriate for Hg analysis incorporating

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1081 clean trace metal techniques A batch cul- Three cruises conducted on Lake Superior ture bioassay using Selenastrum capri- aboard the EPA research vessel R/V Lake cornutum was successfully developed and Guardian provided us with significant infor- applied to various water types Methyl Hg mation on the temporal and spatial distribu- uptake experiments combined with model- tion of Hg species in the water, sediments ing efforts revealed that uptake into cells was and biota (ROLFHUS ET AL, 2003) Total Hg not a steady state process over the 48 hour in surface waters averaged 057 ± 007 and study and was mainly affected by uptake rate 047 ± 003 ng L-1 in April and August, re- (k ) and cell growth (k ), while the depura- spectively, while MeHg concentrations in 1 G tion rate (k ) was not noticeable Uptake was August averaged 51 ± 09 pg L-1 accounting 2 rapid within the first 15 minutes and became for approximately 1 % of HgT The observed comparatively slower between 1 and 6 hours sub-ng L-1 concentrations are more compa- The partitioning of MeHg between the me- rable to those measured in open ocean wa- dia and algae (bioconcentartion factor) was ters than inland lakes Total Hg and MeHg ~ 105 L kg-1 from 025 hr through 24 hr, but in surface sediments (0 2 cm) averaged decreased to 104 when the algae growth in- 83 ± 12 ng g-1 dw and 021 ± 003 ng g-1 dw, creased by a factor of 10 When the bioassay respectively Distribution coefficients for was conducted in high DOC water from the HgT and MeHg (log K = 39 ± 02 and d Tahquamenon River, uptake was inhibited 24 ± 02, respectively) in Lake Superiors relative to low DOC lake water, presumably clay-rich, organic-poor sediments are gen- due to complexation of Hg by DOC erally low relative to other aquatic systems, suggesting that Hg is more mobile in Lake Using data collected through our field stud- Superior than other aquatic systems In-situ ies on the open waters and GIS based stud- methylation rates in deep sedimenst were ies estimating watershed loading to the lake, found to be extremely small, < 1 %/day, but along with supplementary data from the lit- may be higher in shallower, warmer erature, we constructed a preliminary mass nearshore sediments Concentration gradi- balance for HgT and MeHg in Lake Supe- ents of aqueous HgT and MeHg were ob- rior (BABIARZ, 2001; BABIARZ ET AL, 2001; served in surface waters and sediments with ROLFHUS ET AL, 2003) The mass balance in- the highest values occurring in April, par- dicates that the supply of HgT is dominated ticularly along the northwestern shoreline of by atmospheric deposition (58 %), followed the lake most likely due to mixing with tribu- by tributary inputs (21 %) and that of par- tary inputs, while consistently lower values ticulate remineralization (19 %), while were observed in offshore regions of Lake sources of MeHg are more evenly divided Superior between the atmosphere, tributaries, groundwater, remineralization and in-situ methyla- Mercury concentrations in offshore bulk tion Evasion of Hg0 is the principal removal zooplankton collected in April ranged from process of HgT followed by sedimentation, 35 to 50 ng MeHg/gdw and from 80 to while MeHg is mainly removed by sedimen- 130 ng HgT/gdw (BACK ET AL, 2003) In Au- tation and photo-demethylation gust, concentrations ranged from 15 to 25 ng MeHg/gdw and from 20 to 70 ng HgT/gdw

RMZ-M&G 2004, 51 1082 PART 2 BIOGEOCHEMISTRY

Concentrations of both HgT and MeHg mea- low the thermocline at 37 m during our depth sured in April were significantly higher than profile study These observations suggest that those measured in August most probably the Hg in surface waters, perhaps deposited from result of a dilution effect due to an increase the atmosphere, is more bioavailable than Hg in zooplankton mass MeHg in zooplankton in deeper waters (HURLEY ET AL, 2003) Con- generally ranged from 30 to 56 % of HgT centrations in Mysis relicta ranged from 33 to Higher concentrations of MeHg were found 54 ng MeHg/gdw throughout the lake, while in zooplankton from the epilimnion which concentrations in chironomid larvae were is consistent with the enhanced bioaccu- 8 ng MeHg/gdw and 32 ng MeHg/gdw in mulation of MeHg observed immediately be- amphipods

REFERENCES

BABIARZ, CL (2001) Colloidal phase partitioning of HURLEY, JP, MANOLOPOULOS, H, BABIARZ CL, mercury in fresh waters PhD Dissertation, SAKAMOTO, H, ROLFHUS, KR, BACK, RC, University of Wisconsin-Madison, Madison, WI SHAFER, MM, ARMSTRONG, DE AND HARRIS, BABIARZ, CL, HURELY, JP, HOFFMANN, SR, ANDREN, RC (2003) Methyl mercury in Lake Superior: AW, SHAFER MM AND ARMSTRONG DE (2001) Offshore processes and bioaccumulation J Partitioning of total mercury and methylmercury Phys IV 107: 641-644 to the colloidal phase in freshwaters Environ MANOLOPOULOS, H, HURLEY, JP, BABIARZ, CL,, BACK, Sci Technol 35: 4773-4782 RC AND ROLFHUS, KR (2003) Riverine mix- BACK, RC, GORSKI, PR, CLECKNER, LB AND HURLEY, ing zones as regions of enhanced methylmer- JP (2003) Mercury content and speciation in cury bioaccumulation in Lake Superior J Phys the plankton and benthos of Lake Superior Sci IV 107: 83-86 Total Environ 304: 327-348 ROLFHUS, KR, SAKAMOTO, HE, CLECKNER, LB, CLECKNER, LB, BACK, RC, GORSKI, PR, HURLEY, JP STOOR, RW, BABIARZ, CL, BACK, RC, AND BYLER, S (2003) Seasonal and size-specific MANOLOPOULOS, H AND HURLEY, JP (2003) The distribution of methylmercury in seston and distribution of mercury in Lake Superior zooplankton of two contrasting Great Lakes Environ Sci Technol 37(5): 865-872 embayments J Great Lakes Res 29(1): 134- STOOR, RW (2002) Groundwater contributions of 144 methyl mercury to a Lake Superior watershed HURLEY, JP, CLECKNER, LB AND SHAFER, MM (2001) MS Thesis, University of Wisconsin-Madison, Watershed influences on mercury transport to Madison, WI Lake Superior Verh Internat Verein Limnol 27: 3425-3428

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1083 Time course of elevated mercury in fish in hydroelectric reservoirs of northern Manitoba

WOLFGANG JANSEN1, DREW BODALY1, ART DERKSEN1, DAVE GREEN2, NEIL STRANGE1, ROBERT FUDGE1, ANDREW MAJEWSKI1

1Freshwater Institute, Department of Fisheries and Oceans, 501 University Crescent, R3T 2N6, Winnipeg, MB, Canada* 2Manitoba Department of Water Stewardship, Suite 160, 123 Main Street, R3C 1A5, Winnipeg, MB, Canada; E-mail: jansenwa@dfo-mpo*gc*ca*

Abstract: Mercury (Hg) concentrations in lake whitefish, northern pike and walleye muscle tissue were determined from hydroelectric reservoirs in northern Manitoba for as long as 27 years after flooding and were compared to a set of 64 non-flooded reference lakes" In lake whitefish, a deep-water benthivore, Hg increased rapidly after flooding, reaching peak concentrations within 3-5 years of impoundment" Peak concentrations in whitefish after flooding were usually 0"25-0"4 µg/g (w"w") compared to pre-impoundment concentrations of 0"1-0"15 µg/g and a 95 % confidence limit for the mean of 13 reference lakes of 0"03-0"06 µg/g" Within 12-20 years after impoundment, mean Hg concentrations in most whitefish populations were similar to pre-impoundment means" In the piscivorous species northern pike and walleye, peak concentrations were generally observed 4-8 years after flooding" Hg concentrations in these species usually exceeded 1"0 µg/g, and, in two reservoirs, were higher than 2"0 µg/g in walleye, compared to pre- impoundment concentrations of 0"3-0"5 µg/g and 95 % confidence limits for the mean of 61 and 64 reference lakes of 0"36-0"47 and 0"35-0"47 µg/g, for pike and walleye, respectively" In most reservoirs Hg concentrations in pike and walleye returned to background levels within 20-25 years of impoundment" Peak concentrations and the period of elevated values were related to the amount of flooding" In comparison, Hg concentrations in fish from one reference lake with a long-term data record did not change significantly over 20 years" Hg concentrations in fish muscle tissue, time to reach peak levels, and time to return to background concentrations after initial impoundment were similar to or less than those observed in other boreal reservoirs"

Key words: fish, reservoir, mercury, bioaccumulation, boreal forest"

RMZ-M&G 2004, 51 1084 PART 2 BIOGEOCHEMISTRY

Mercury Methylation/Demethylation Potentials in Soils from Idrija Hg Mining Area, Slovenia, Studied using 197Hg2+, CH 197Hg+ and 14CH Hg+ Radiotracers 3 3

VESNA JEREB1, SERGIO RIBEIRO GUEVARA2 & MILENA HORVAT1

1Department of Environmental Sciences, Joef Stefan Institute, Ljubljana, Slovenia 2Laboratorio de Análisis por Activación Neutrónica, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica, Argentina

Abstract: The aim of our work was to investigate methylation and demethylation potentials of soils from Idrija Hg mining area, Slovenia Methylation of Hg2+ results in MeHg+, a high neurotoxin, - this process was studied using 197Hg2+ radiotracer Demethylation process (detoxification) of CH Hg+ results either in formation of CH and Hg0, known as 3 4 a reductive demethylation, or in formation of CO and unidentified Hg moiety, known 2 as an oxidative demethylation The transformation was studied using CH 197Hg+ and 3 14CH Hg+ radiotracers The latter was used to follow the formation of gaseous products 3 (14CH and 14CO ), which indicates the prevailing detoxification mechanism mentioned 4 2 above In this work, the following soil samples were investigated: IAEA Soil-1 (dried, sieved and homogenised soil, a candidate for RM, sampled from a floodplain about 40 km downstream Idrija, just before Idrijca River merges Soca River), Baca soil (fresh soil from the sampling point of Soil-1) and chimney soil (sampled at the Hg ore smelter chimney in Idrija) In addition, we tested sediment from Hg non-polluted area (Ljubljana wetland) Samples were spiked with radiotracers of high specific activity and incubated in dark for up to several days at room temperature and mostly under aerobic conditions Me197Hg (-formed in methylation experiments and remained fraction in demethylation + experiments) was acid-leached from the samples and extracted into toluene, which was subsequently measured on well-type HPGe detectors The gaseous products from 14CH Hg+ demethylation were trapped in NaOH solution and counted on liquid scintilla- 3 tion counter after the addition of scintillation cocktail CH was combusted to CO in 4 2 CuO column at high temperature prior to trapping in NaOH solution The results obtained show no net methylation potential in the samples studied On the other hand, the fractions of demethylated MeHg+ added to the samples were high, ranging from few percent up to 40% at the most contaminated site 14C-radiotracer studies suggest reductive demethylation in soil, as the oxidative reductive demethylation potential ratio was about 01 This finding indicates the presence of Hg-resistant microorganims which demethylate MeHg+ encimatically after the induction of mer (mercury resistance) genes

Key words: soil, radiotracers, Hg transformations

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1085 The Speciation and Bioavailability of Mercury in Sediments of Haihe River, China

GUI-BIN JIANG, JIAN-BO SHI & LI-NA LIANG

Abstract: Tianjin city has been an important industrial base in China for a long time Haihe River is a central river passing through the Tianjin city and inpouring into Bohai Sea at last However, Haihe River has been polluted seriously by industrial, domestic and agricultural effluents in recent years In order to investigate and evaluate the mercury pollution in Haihe River, twenty-three sediment samples in thirteen sites along the Haihe River were collected on July 12-13 and Sept 6-7 2003, respectively The total mercury (HgT) in sediments were digested with 50% (v/v) aqua regia then determined by coldvapor atomic fluorescence spectrometry (CVAFS) The methylmercury (MeHg) were determined by high performance liquid chromatography on-line coupled with cold-vapor atomic fluorescence spectrometry (HPLC-CVAFS) Because the total organic carbon (TOC) in sediments plays an important role in the methylation of inorganic mercury, the TOC contents in Haihe River sediments were also analyzed The HgT concentrations in sediments ranged from 554 ng g-1 to 87791 ng g-1 (average: 8971 ng g-1) and the MeHg concentrations were between 07 ng g-1 and 217 ng g-1 (average: 27 ng g-1) The MeHg contents were correlated with HgT (r=035) and TOC concentrations (r=077) Sequential selective extractions (SSEs) procedure, a widely used technique for understanding element distribution in the solid, has also been presented for mercury speciation in sediments and soils recently Based on selective extractions, BLOOM ET AL[1] separated the mercury in sediments and soils into five fractions including (a) water soluble, (b) human stomach acid soluble, (c) organo-chelated, (d) elemental Hg, and (e) mercuric sulfide In our work, the above five-step sequential extraction scheme was used for analyzing the bioavailability of mercury in Haihe River sediments The total Hg in each fraction could be determined by CVAFS after oxidation with BrCl solution and good recoveries were obtained The ratios of HgT in each fraction to total Hg in sediments were studied in detail The results showed that mercury in Haihe River sediments ex- isted mainly as elemental Hg (from 237% to 658%, average: 444%) and mercuric sulfide (from 243% to 744%, average: 390%)

Key words: mercury speciation, bioavailability, sediments

Reference: [1] BLOOM N S, PREUS E, KATON J, HILTNER M, Anal Chim Acta,2003, 479, 233-248

RMZ-M&G 2004, 51 1086 PART 2 BIOGEOCHEMISTRY

Damming Effect on the Distribution of Mercury in Wujiang River

HONGMEI JIANG1, 2, XINBIN FENG1*, QIANJING DAI1, 2, YUCHUN WANG 3

1 State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Science, Guiyang 550002, China! 2 Graduate School, Chinese Academy of Science, Beijing 100039, China! 3 China Institute of Water Resources and Hydropower Research, Beijing 100044, China! *Corresponding author; E-mail: xinbin!feng@mail!gyig!ac!cn

Abstract: Seasonal changes in total mercury concentrations in surface water were observed for the Wujiang River, with higher values at times of greater flow The total mercury in this river was mostly associated with suspended particles; particulate mercury constituted on an average of 84 % of the total mercury flux during the high flow period, and 52 % of the total mercury flux at low flow Significant losses of Hg from the water were observed in and/or downstream of the reservoir In addition, concentrations of particulate mercury in the downstream of reservoir appeared to be enhanced by sediment resuspension and shoreline erosion caused by the flood discharge, while the filtered portion decreased These observations suggested that reservoirs played an important role controlling the transport and fate of mercury in the Wujiang River

Key words: damming, reservoir, mercury

INTRODUCTION The Wujiang River, which flows in a karst environment in Guizhou Province, is the Dam construction is a common anthropo- largest tributary in the upper of Yangtze River genic intervention of rivers It is estimated basin The drainage basin of the Wujiang that there are now more than 40,000 large River is situated between 26°10 and dams throughout the world, with an aggre- 29°45N and between 104°05 and 108°30E gate storage capacity of about 6,000 km3 [1] It covers a drainage area of approximately Through flow regulation dams provide ben- 87,920 km2, with an average stream flow of efits for many segments of society Con- over 650 m3/s and an annual runoff of versely, impounding rivers also changes the 5,400,000 hm3 Many reservoirs have been characteristics of a water body from rivers constructed for hydroelectric power genera- to reservoirs, affecting not only the hydrol- tion and flood control in Wujiang River ba- ogy but also their physical, chemical, and sin, which may significantly change the char- biological characteristics Reservoir con- acteristics of this river A background sur- struction may disrupt the natural bio- vey of mercury distribution in the Wujiang geochemical cycles of metals and possibly River was carried out during both the high affect the whole catchment including down- flow period (July 2002) and low flow period stream ecosystems (December 2002) Based on this survey,

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1087

Figure 1 The locations of lead-zinc mines, coal mines and Hg mines as well as sampling sites in the mainstream of Wujiang River samples on the mainstream were selected to all, higher total mercury concentrations and examine the damming effect on the distribu- fluxes were observed at high flow compared tion of mercury in Wujiang River (Fig# 1)# to low flow (Fig# 2)# This study is essential in predicting future impacts of mercury cycling due to the con- The total mercury concentrations in whole struction of the Three-Gorges Dam in the water samples were positively correlated to Yangtze River basin# particulate mercury (Fig# 3a), and the particulate mercury constituted on an average of 84 % of the total mercury during high flow RESULTS AND DISCUSSION period# During low flow, however, 52 % of the total mercury is in the particulate phase, Hg distributions: The distribution of mercury indicating that larger amounts of Hg are in the main channel of the Wujiang River transported in the particulate phase especially was similar to the whole river basin, and in high flow period# Particulate Hg distribu- which has been reported previously[2, 3]# Over- tions were similar to those for total Hg in

RMZ-M&G 2004, 51 1088 PART 2 BIOGEOCHEMISTRY

Figure 2 Concentrations of total mercury in the mainstream of Wujiang River

Figure 3 Plot of HgT vs HgP (a) and HgD (b) in the mainstream of Wujiang River both seasons The filter-passing concentra- trations in water samples collected below tion generally increased with the increasing Pudding Reservoir were lower than Liucong of total concentration, but the correlation was River, though the latter did not have obvi- significant only in winter (R=0 82, a<0 01; ous mercury point sources This phenomenon Fig 3b) can be explained by rapid particle settling due to the transition of the river into a reser- Trap effect: Comparisons of particulate and voir[4] Thus, with the sedimentation of the dissolved mercury concentrations in two suspended particles, the reservoir reduced headwaters rivers (the Sancha River and the both the turbidity and the Hg concentration Liucong River), shows that the reservoir be- of water haves as an artificial terminal sink for particulate mercury The water sample in the Flood discharge: In order to characterize the Sancha River collected before the Puding effect of flood discharge on the distribution Reservoir had elevated mercury concentra- of mercury in the downstream of the dam, tions due to the proximity of the lead-zinc samples were collected downstream of the mines and coal mines However, water Wujangdu Reservoir Concentrations of the samples collected below the Puding Reser- particulate and dissolved mercury in water voir, showed that both HgP and HgD con- samples collected upstream of the Wujiangdu centrations were significantly reduced Reservoir exhibited different distribution (Fig 4) Furthermore, the mercury concen- patterns, with particulate mercury during

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1089

Figure 4 The distribution of HgP and HgD in the two headstream of Wujiang River

Figure 5 The distribution of HgP and HgD in the mainstream of Wujiang River below the Wujiangdu Reservoir high flow periods being generally higher than solved mercury concentrations, on the con- samples from low flow periods On the other trary, were obviously diluted (except site 14) hand, dissolved mercury exhibited a reverse The effect of flood discharge faded near the character (Fig 5) These temporal distribu- end of the Wujiang River due to the tion patterns are attributed mostly to the ef- confluence of the relative large magnitude fects of flood discharge of the Wujiangdu of the tributary The relatively higher dis- Reservoir Flood discharge leads to the resolved mercury in site 14 may be resulted suspension of sediment and enhanced the from a point discharge source This point shoreline erosion, thus, particulate mercury source became less significant because of the concentrations gradually increased Dis- existence of a reservoir downstream

RMZ-M&G 2004, 51 1090 PART 2 BIOGEOCHEMISTRY

CONCLUSIONS dilute the dissolved mercury in the downstream riverine environment In short, dam The concentration of mercury in the main- construction significantly affects the distribu- stream of Wujiang River showed an obvious tion of mercury in theWujiang River system seasonal change The particulate fraction of mercury constituted a large portion of total Acknowledgements mercury in both seasons The pilot study indicated that the reservoir could act as a trap This work was financially supported by Chi- to reduce the mercury concentrations and nese Academy of Sciences through Hun- fluxes in river water On the other hand, the dred Talent Plan and CAS innovation flood discharge of reservoirs could signifi- project (KZCX2-105), and by Chinese Natu- cantly enhance the particulate mercury and ral Science Foundation (40173037)

REFERENCES

[1] MCCULLY, P (1996): Silenced rivers-the ecology and [4] MASON, R P, FITZGERALD, W F, HURLEY, J, HANSON, politics of large dams; Zed Books, London A K, DONAGHAY, P L AND SIEBURTH, J M [2] JIANG, H, FENG, X, DAI, Q, TAO, F AND LIU, C (1993): Mercury biogeochemical cycling in a (2003): The distribution and speciation of mer- stratified estuary; Limnol Oceanogr 38, pp cury in Wujiang river; J Phys IV France 107, 1227-1241 pp 679-682 [3] JIANG HONG-MEI, FENG XIN-BIN, DAI QIAN-JING AND WANG YU-CHUN (2004): A primary study on speciation and distribution of mercury in Wujiang river; Environmental Chemistry (In press)

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1091 Mercury in Sediments, Porewaters, and Fish from the Medway Estuary, UK

SARAH JOHNSON

Department of Earth and Environmental Sciences, University of Greenwich, Pembroke, Chatham Maritime, Kent$ ME4 4TP, UK; E-mail: Sarah$Johnson@gre$ac$uk

Abstract: Mercury distribution in sediments, porewater and fish from the Medway Estuary was investigated Sediment mercury concentrations were typical of an industrialised estuary, ranging between 16-1302 µg kg-1 (dry weight) Three sediment hotspots contained mercury concentrations, which are likely to cause adverse affects to organisms Porewater mercury concentrations ranged between <001-175 µg L-1, and were not correlated with mercury in the solid phase Mercury concentrations in fish flesh ranged between 001-062 mg kg-1 (wet weight), with all specimens being within the EU limit for human consumption Total mercury concentrations rise with increasing fish length and successively higher trophic levels, which is indicative of bioaccumulation and biomagnification

Key words: bioaccumulation, fish, sediment, porewater

INTRODUCTION therefore detailed information about contaminants in the estuary is valuable Further- Geochemical knowledge of mercury in sedi- more, baseline contaminant concentrations ment and porewaters can provide informa- are important as they allow future investigation about the overall mercury contamina- tions to determine whether mercury levels tion of an aquatic system, as bottom sedi- have fluctuated over time The Medway Es- ments are an established sink for mercury tuary is lacking a comprehensive investiga- and a potential source of mercury to the over- tion of mercury and therefore was selected lying water column and food web In addi- as the subject of this study The distribution tion, details of mercury concentrations in fish of mercury in sediment, porewaters and fish from a number of trophic levels provide in- is examined along with the influence of formation about bioaccumulation and the trophic level and size, as well as the impli- potential consequences of fish consumption cations for human consumers on human health Cold vapour atomic absorption spectrometry The Medway Estuary, Kent, southeast En- was used to analyse 40 surficial sediment and gland has had historical significance, both porewater samples, and 194 fish and shell- industrially and as a major seaport The fish from 13 species Other sediment vari- Medway is presently promoting fisheries, ables considered included particle size dis- recreation and industrial development, and tribution and sediment organic matter

RMZ-M&G 2004, 51 1092 PART 2 BIOGEOCHEMISTRY

RESULTS AND DISCUSSION and clay content or fine grain content (<64 µm) are insignificant (r = 038 and 006 Mercury concentrations in the surficial sedi- respectively, p<005), and consequently ment are typical of an industrialised estuary, granulometric normalisation procedures ranging between 16-1302 µg kg-1, with an were ineffective The lack of correlation be- overall mean of 305 µg kg-1 (dry weight) tween sediment mercury and particle size Porewater mercury concentrations range be- may be due to various surface coatings on tween <001-175 µg L-1, with an overall the coarser grain fraction EWAIS (2000) noted mean of 057 µg L-1, and are not correlated that manganese and iron (hydr)oxide coat- with mercury in the solid phase This indi- ings can cement clay particles to sand grains cates that porewater mercury is not solely thereby potentially increasing the capacity controlled by an exchange equilibrium be- of sand to sorb metals Figure 1 shows a map tween the two phases Furthermore, sediment of the spatial distribution of sediment mer- mercury concentrations are not correlated cury concentrations throughout the estuary with organic matter content This may be due in relation to NOAA (National Oceanic and to differences in the chemical composition Atmospheric Administration) screening of the organic matter, as different types of quick reference tables (BUCHMAN, 1999) The organic matter have varying abilities to bind Medway drains a densely populated, mercury Particle size distribution can influ- industrialised area and therefore mixing of ence the amount of mercury in a given weight higher contaminated sediments with lower of sediment, and hence the spatial pattern of contaminated marine sediments has probably mercury throughout the estuary However, contributed to the observed landward to sea- the correlations between sediment mercury ward decrease in mercury concentrations

Figure 1 Mercury concentrations in surficial sediments of the Medway Estuary, shown in relation to NOAA screening quick reference tables (BUCHMAN, 1999)" TEL: threshold effects level PEL: probable effects level

RMZ-M&G 2004, 51 7TH INTERNATIONAL CONFERENCE ON MERCURY AS A GLOBAL POLLUTANT 1093

The highest sediment mercury concentra- (0+05 mg kg-1)+ Shrimp are located on the low- tions (828, 838 and 1302 µg kg-1) are ob- est trophic level of the species examined in served at three locations in close proximity this study+ Eel and bass share the joint maxi- to Bloors Wharf (Figure 1)+ Mercury con- mum mercury concentration for individual centrations at these locations exceed the species (0+28 mg kg-1), both are carnivorous, probable effects level (696 µg kg-1) suggested located at the highest trophic level of all the by NOAA (BUCHMAN, 1999), and therefore species studied+ Additionally, eels spend adverse effects to organisms would be fre- much of their time near bottom sediment, quently expected in this area+ These three especially for feeding, and to a slightly lesser locations are close to a disused wharf where extent this is also true of bass+ This factor is ships were previously scrapped+ TEWARI important in the bioaccumulation of mercury, (2001) showed that sediment mercury con- as contaminated sediment can be ingested centrations at a disused ship scrapping yard during feeding and burrowing+ These find- in Alang, India were elevated in comparison ings corroborate with those of LAWSON to a control site+ Sources of contamination (1998), where fish located on a higher trophic from scrapping operations in the Medway level accumulated higher mercury concen- may include antecedent paint materials that trations than those on a lower trophic level+ possibly contained mercury as a fungicide or bactericide+ Fish size can serve as a useful indicator of age+ Green (2003) reported a strong correla- Mercury results for fish and shellfish are tion between size and mercury content in listed in Table 1+ Mercury concentrations in fish, indicating an accumulation with age+ the flesh range between 0+01-0+62 mg kg-1, The results of this study are consistent with with an overall mean of 0+15 mg kg-1+ Of all the literature showing a strong correlation the species examined, the minimum flesh between specimen length and mercury con- mercury concentration is observed in shrimp tent (r = 0+61, p<0+05)+

Table 1 Summary of mean total mercury concentrations (wet weight, mg kg-1) in fish from the Medway Estu- ary, all analyses conducted in triplicate range of entire data set in parentheses"

RMZ-M&G 2004, 51 1094 PART 2 BIOGEOCHEMISTRY

Liver mercury concentrations range between mercury concentrations to be characteristic 001-096 mg kg-1, with an overall mean of of an industrialised estuary, with sediment 019 mg kg-1 (Table 1) There is a strong cor- mercury ranging between 16-1302 µg kg-1 relation between mercury concentrations in (dry weight) and porewater mercury rang- flesh and liver (r = 070) and a z-Test was ing between <001-175 µg L-1 Mercury con- performed to determine whether overall, the centrations in sediment and porewater are not liver contained more mercury than the flesh correlated with each other, nor is there a cor- The z-Test results show no significant differ- relation between sediment mercury and or- ence between the flesh and liver mercury con- ganic matter or grain size Three sediment centrations The liver has been suggested by mercury hotspots around Bloors Wharf ex- RIGET (2000) as a long-term storage organ for ceed NOAAs probable effects level mercury, often in older fish Consequently the (696 µg kg-1) Fish flesh mercury concentra- 45 largest fish were subjected to a z-Test, but tions range between 001-062 mg kg-1 (wet still no significant difference was found weight) All species are within the EU mercury limit for safe human consumption, and The EU mercury limit (EU directive 93/351/ therefore unlikely to cause problems to hu- EEC) for safe consumption of most species man health Mercury increases with increas- in this study is 05 mg kg-1 with the excep- ing fish length and successively higher tion of bass and eel, which have a limit of trophic levels, which indicates bioaccumu- 10 mg kg-1 All species analysed in this study lation and biomagnification are within these limits, and therefore unlikely to cause problems to human health Acknowledgements

CONCLUSIONS This work was supported by the Engineering and Physical Sciences Research Council This study investigated the distribution of mercury in the Medway Estuary and found

REFERENCES

BUCHMAN, M F (1999): NOAA Screening Quick Ref- LAWSON, N M & MASON, R P (1998): Accumulation erence Tables, NOAA HAZMAT Report 99-1, of mercury in estuarine food chains Bio- Seattle WA, Coastal Protection and Restoration geochemistry; 40, pp 235-247 Division, National Oceanic and Atmospheric RIGET, F, DIETZ, R, JOHANSEN, P & ASMUND, G (2000): Administration, 12 p Lead, cadmium, mercury and selenium in Greenland EWAIS, T A, GRANT, A & FATTAH, A T A (2000): The marine biota and sediments during AMAP phase 1 role of surface coatings on sediments in sedi- Sci Total Environment; Vol 245, pp 3-14 ment: water partitioning of trace elements and TEWARI, A, JOSHI, H V, TRIVEDI, R H, SRAVANKUMAR, radionuclides; J Environ Radioactivity, Vol 49, V G, RAGHUNATHAN, C, KHAMBHATY, Y, No 1, pp 55-64 KOTIWAR, O S & MANDAL, S K (2001): The GREEN, N W & KNUTZEN, J (2003): Organohalogens and effect of ship scrapping industry and its associ- metals in marine fish and mussels and some relation- ated wastes on the biomass production and ships to biological variables at reference localities in biodiversity of biota in in situ condition at Alang Norway Mar Pollut Bull;Vol 46, pp 362-377 Mar Pollut Bull; Vol 42, No 6, pp 462-469 RMZ-M&G 2004, 51