2009 International Nuclear Atlantic Conference - INAC 2009 Rio de Janeiro,RJ, Brazil, September27 to October 2, 2009 ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR - ABEN ISBN: 978-85-99141-03-8

PRELIMINARY ASSESSMENT OF THE ZOOPLANKTON COMMMUNITY COMPOSITION IN A REGION UNDER THE INFLUENCE OF A URANIUM MINE (CALDAS, SOUTHEASTERN BRAZIL).

Carla Rolim Ferrari 1, Maria José dos Santos Wisniewski 2, Cláudio Vitor Roque 1, Leilane B. Ronqui 1, Michelle B. Campos 1, Suzelei Rodgher 1, Marcos Roberto Lopes Nascimento 1 and Heliana de Azevedo 1.

1 Poços de Caldas Laboratory, Brazilian Nuclear Energy Comission. Rodovia Poços de Caldas-Andradas, Km 13, CEP 37701-970. Poços de Caldas, MG-Brazil. [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected]

2 Laboratory of Limnology -Federal University of Alfenas-UNIFAL-MG. Rua Gabriel Monteiro da Silva, 714, CEP 37130-000. Alfenas, MG-Brazil. [email protected]

ABSTRACT

The Ore Treatment Unit consists of an open cast mine (CM), its mining waste areas, facilities for the physical treatment of the ore, and a chemical treatment plant for uranium extraction. At CM, the processes of acid drainage create effluents, which are treated by chemical processes and, thereafter, disposed of in Antas dam. The objective of the present study was to make an inventory of zooplanktonic and describe the physicochemical characteristics of site CM and at the site of treated effluents disposal (site 41), located at Antas dam. Water samples were collected in October/08 and January/09, in order to describe the abiotic variables and the zooplankton community. The average values of conductivity at sites CM and 41 were 2415 and 422 µS/cm2, respectively. Values of pH at site CM remained acid, whereas, at site 41 we recorded values near neutrality. The concentrations of total nutrients at both sampling sites were higher in the rainy season. Zooplankton species richness present at site CM was lower than at site 41, and there were only two identified species Bosmina sp and americana. At site 41 we recorded more species, mainly of the Rotifera. Among Cladocera, we identified two species, regarding Copepoda, the orders Cyclopoida and Calanoida were present. At site CM the density values were lower compared to site 41. The preliminary assessment of the zooplankton community showed lower values of species richness and density at site CM, what may be probably explained by the adverse environmental conditions for zooplankton community.

1. INTRODUCTION

The importance of mining to the economy of a country is evident. Besides the economic impact and employment generation, mining activities in Brazil in its broad sense, has contributed to increasing the Human Development Index (HDI) of some municipalities, which have major Brazilian mines. However, besides the economic and social importance, the process of expansion and continuation of these activities in Brazil and worldwide, depends on incentives and the commitment of large mining companies with the preservation and recovery of the environment explored. In relation to the concerns regarding the impacts caused by mineral exploration, the issue of water and water resources is often one of the most obvious conflicts in the aspect of mining and society [1].

The Poços de Caldas Plateau is a region characterized by high natural radioactivity associated with volcanic rocks and mineral uranium deposits. In this region is located the Uranium Mine Osamu Utsumi, which was in operation from 1982 to 1995, the first mine to extract uranium ore in Brazil. This mining area is located in the dependencies of the ore processing unit complex (UTM), which consists of an open-pit mine (Osamu Utsumi Uranium Mine) and their areas of tailings from mining, facilities for physical treatment of the ore and chemical treatment plant to extract uranium. In the mine pit radioactive effluents are generated due to the processes of acid mine drainage (DAM), which are treated by chemical processes, and subsequently released in the Antas dam at the point P41. According to Nixdorf et al. [2] in acidic environments impacted by mining activity, such as some lakes, normally it is expected that specialized bacteria, some fungi, and few organisms are able to survive with a pH lower than 3. Wollmann et al. [3] also suggests that these acidic environments, are usually formed by simple food chains, consisting of few species, and can occur in complete absence of some groups that are considered very important in the plankton, such as crustacean zooplankton.

Due to lack of scientific studies on the zooplankton community in regions that are influenced by uranium mining, this study was to carried out to characterize the composition and density of zooplankton species present in samples of acid effluent from the Osamu Utsumi uranium mine (point CM) and water samples collected at the point of treated effluent discharge Antas dam (point P41). The study of zooplankton organisms in extreme environments (high concentrations of stable and radioactive chemical elements, high rates of exposure to ionizing radiation, acid pH, and high conductivity) is of great importance to evaluate the effect of radioactive effluents in the composition of this community.

2. MATERIALS AND METHODS

2.1. Sampling Areas

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The sampling point located at the Osamu Utsumi Uranium Mine (point CM) of the Brazilian Nuclear Industries (INB) is located in the dependencies of the ore treatment unit complex (UTM), in the municipality of Caldas / MG.

Antas dam (Caldas-MG) was built to supply water to the Unit for treatment of uranium ore UTM-INB. Currently the reservoir receives, at the point of collection (point P41), radioactive effluent treated for acid drainage, from the Osamu Utsumi mine and piles of tailings from uranium mining.

Water samples were collected during Oct/08 and Jan/09 in point CM at 2 meters deep, in point P41 which is 0.5 m deep located in the central region of the Antas dam. Then the samples were brought to the laboratory for Radioecology analysis of abiotic variables and zooplankton community.

2.2. Physical and Chemical Variables The measures of electric conductivity were performed using a conductivity meter Digimed brand using selective electrode, pH was measured using a selective electrode, combined with a temperature sensor (WTW - 320). Concentration of total phosphorus was measured using the technique described by Valderrama [4]. Total nitrogen was measured using the methodology described by Mackereth et al. [5]. Analyses of uranium and thorium were performed using the methodology described by Fukuma et. al [6].

2.3. Zooplanktonic Community

The zooplankton organisms were collected by horizontal trawls and, where possible vertical, depending on the depth of the site, using a plankton net of 60µm mesh size. Then the organisms were fixed with 4% formaldehyde. Identification of organisms was made under optical microscope (Zeiss-Axioplan-2) with increased of up to 1000X, based on specialized literature (Elmoor Loureiro-[7], Koster [8] Reid [9] Matsumura-Tundisi [10]; Segers [11] Segers [12], among others. For quantitative analysis were performed counts of cladocerans and copepods in squared slabs of acrylic under stereoscopic microscope (Zeiss SV11-Stem) with increase of up to 66X, counting sub-samples or even the entire sample for rare organisms. For the sub-samples of 1mL were counted in Sedgewick-Rafter chamber under microscope with an increase of 200X.

3. RESULTS AND DISCUSSION

Concentrations of physical and chemical variables are shown on Table 1. In this study in the point CM, the average values of pH and electrical conductivity were (3.9) and (2 415 µS/cm2) respectively. In a study perfomed by Lessmann et al. [13] in Lake Plessa located in Lusatia,

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Germany, the average pH recorded (2.3) was considered more acid compared to the value of pH recorded in the point CM. On the other hand, the average electrical conductivity (4 450 µS/cm2) recorded in the same place, was also higher compared to the amount recorded in the point CM. Wollmann et al. [3] in a study performed in acid lake ML111, formed in the area of coal mining, also located in Lusatia, Germany, recorded values of maximum and minimum conductivity that ranged from 2 800 to 2 000 µS/cm2 respectively, while values of maximum and minimum recorded pH ranged from 2.6 to 2.9 respectively. These values were closer when compared to the conductivities and pH values recorded at point CM.

In point P41, where the treated effluent is discharged, the average value of conductivity was 422.5 µS/cm2, still considered high when compared to the average values of conductivity observed in some reservoirs, such as the reservoir of Tapacurá (Pernambuco) in a study performed by Almeida et al. [14] where these authors, recorded higher average value of conductivity in the dry season (245.9 µS/cm2). The average value of pH at the point P41 was considered neutral (7.0), a value similar to that recorded in some water bodies of the high Tietê-SP, as Guarapiranga reservoir (7.46) and Aguas Claras (7.08 ) in a study by Lucinda et. al [15].

For the average concentrations of total nutrients (total nitrogen and total phosphorus), no changes were recorded when comparing the results obtained in samples of points CM and P41 (Table 1). Kalin et al. [16] in a study of a lake mine, formed after the closure of an uranium mine in Canada, recorded values of total phosphorus ranging from 90 to 200 µg L-1, higher values when compared to values recorded in points CM and P41. In a study by Packroff [17] in Lake Cospuden located in Lusatia, Germany, influenced by mining activity, the author, recorded values of total nitrogen concentration that ranged from 500 to 1 100 µg L-1; values similar to those recorded in points CM and P41.

Concentrations of uranium in point CM were high, ranging from 4.25 mg L-1 in Oct/08 to 3.7 mg L-1 in Jan/09. At the treated effluent discharge, point P41, concentrations of uranium ranged from (<0.05 to <0.004) due to the sensitivity of the method. It was not possible to detect the exact value of its concentration (limit <0.004). The amount recorded in the month of Jan/09 (<0.004) at the point P41 is in accordance with the current limits established by legislation (CONAMA Resolution 357, which stipulates that the maximum limit for total concentration of uranium in water bodies should be less than or equal to 0.02 mg L-1). Concentration of thorium in Oct/08 and Jan/09 at point CM was 0.1 mg L-1. In point P41 there were records of concentration of <0.05 in Oct/08 and 0.004 mg L-1 in Jan/09.

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Table.1. Values of physical and chemical variables from points CM and P41 in october/08 e january/09, average and standard deviation.

Variables P41 P41 Average S.D CM CM Average S.D Out/08 Jan/09 Out/08 Jan/09

pH 7.2 6.7 7.0 0.4 4.1 3.7 3.9 0.3

Conductivity 765.0 79.5 422.3 484.7 2600.0 2230.0 2415.0 261.6 (µS.cm-2) Total phosphorus 2.2 11.2 6.7 6.4 5.6 10.4 8.0 3.4 (µg L-1) Total nitrogen 700.0 840.0 770.0 99.0 700.0 770.0 735.0 49.5 (µg L-1)

Uranium <0.05 <0.004 4.25 3.17 3.71 0.8 (mg L-1) Thorium <0.05 0.004 0.10 0.11 0.11 0.0 (mg L-1)

Composition of the zooplankton community in the point CM was low in relation to that one verified in point P41, with registration of only two species identified, the Cladocera Bosmina sp in Oct/08 and Rotifera Keratella americana in Jan/09. In point P41 there was higher number of species, with emphasis on the group Rotifera, where five species were recorded: Ascomorpha sp, Conochillus sp, Keratella cochlearis, Keratella sp, and Polyarthra sp. Among the Cladocera, 2 species were identified: Diaphanosoma sp and Bosmina sp. In relation to the Copepoda, the orders Cyclopoida and Calanoida were present.

Kalin et al. [16] studying the phytoplankton composition in an acid lake formed after the closure of an uranium mine, recorded in the last years of his study, the presence of Rotifera Kerattela sp in relatively high density, from 8 to 16 individuals in each liter of sample collected. In the CM point, area also impacted by mining of uranium and occurrence of acid drainage, the only species of Rotifera recorded was Keratella americana in low density (1.41 ind m-3) in Jan/09. In point P41, Keratella sp and Keratella cochlearis were recorded at neutral pH. Lucinda et al. [15] in a study performed in Lake Rodrigo Pires, a water body located in the basin of the upper Tietê-SP, recorded the highest relative frequency (61%) of the species Keratella cochlearis, reflecting his habit not specialized, as well as their ability to tolerate wide variations of pH (5,18) recorded in this environment. In this study, Cladocera Bosmina sp was recorded in both collection points. In point CM this species was recorded only in Oct/08 at low density (9.9 ind m-3); at the point P41, this species was present only in Jan/09, in a higher density (526.15 ind m-3). In environment influenced by mining of uranium in a study conducted in Canada, there were no records of Copepoda and Cladocera (Kalin et al. [16]). In the point CM the presence of Cladocera Bosmina sp, even at low densities (9.9 ind m-3) may indicate that this species has the ability to withstand environmental stress, which has adverse conditions for reproduction and survival of zooplankton species.

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In a study by Wollmann et al. [3] in three mining acid lakes (ML111, ML117, and ML Fenix) with pH values varying from 2 to 4, it was found that the zooplankton community was composed of pelagic species, which form a pioneer community, composed of a much simpler food chain. In Lake Phoenix, with a pH of 3.9, these authors recorded the species of Cyclopoida Diacyclops sp. At the Lakes ML111 and ML 117 where there was record of lower pH values (2.6 and 2.8) than in Lake Phoenix, Diacyclops sp. was absent. According to these authors, in such acid environments the number and species composition of communities phytoplankton and zooplankton are clearly influenced by pH, ie, the increase in pH is directly related to higher species richness. Lessmann et al. [13] in their study also found that more acid environments are related to few species of phytoplankton and zooplankton communities. In this study, the presence of orders Cyclopoida and Calanoida were recorded only at the point P41 where the pH was neutral, supporting the conclusions of Wollmann et al.[3]. Nixdorf [2] studying some acid lakes in Lusatia, Germany, influenced by coal mining, verified the presence of some species of rotifers as Cephalodella hoodi, Elosa worallii, Brachionus sericus, and the cladoceran Chydorus sphaericus, which were characteristic of these environments. In point CM these species are absent. Nixdorf [2] also noted in their study that increasing the pH was directly related to the increase in the number of species and the development of a more complex food chain. In this study, the increase in pH at the point P41, was also related with the highest species richness. The species Ascomorpha sp, Conochillus sp, Keratella cochlearis (rotifers), and Diaphanosoma sp (cladoceran) were recorded only at the point P41.

The values of numerical density of zooplankton community in point P41 showed an increase in time, with record of highest value in the month of Jan/09 (1166.08 ind m-3). Moreover, at the point CM the values of density were lower when compared to the results observed at the point P41, occurring density values reduction with time, ranging from 9.90 ind m-3 in Oct/08 to 1.41 ind m-3 in Jan/09 (Figure. 1).

750 Cladocera 500 Copepoda 250 Rotífera )

-3 10.5

9.0

7.5

6.0

4.5

Density (individuals m (individuals Density 3.0

1.5

0.0 PM Oct PM Jan P41 Oct P41 Jan

Figure 1. Density of Cladocera, Copepoda and Rotifera.

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4. CONCLUSIONS

Preliminary analysis of the zooplankton community, showed lower values of species richness and density of point CM, which may be related to adverse environmental conditions not favorable to development of the zooplankton community, such as acid pH, high concentrations of electrical conductivity, low concentrations of nutrients, and presence of radionuclides (uranium and thorium) found in that environment. It was found that an increase of pH was directly related to an increased number of species. The presence of Keratella americana and Bosmina sp. species in point CM, may be related with the increased resistance of these species to extreme environmental conditions found in the point CM.

ACKNOWLEDGMENTS

We thank the FAPEMIG and technician Armando Luiz Bruschi for the extreme important support provided during this study.

REFERENCES

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12. H. Segers, Rotífera. The Lecanidae (Monogononta). In: Guides to the identification of the Microinvertebrates of the Continental Waters of the World, SBP Academics The Hague, The Nertherlands, (1995). 13. D. Lessmann, R. Deneke, R. Ender, M. Hemm, M. Kapfer, H. Krumbeck, K. Wollmann, Nixdorf, B, “Lake Plessa 107 (Lusatia, Germany)-na extremely acidic shallow mining lake”, Hydrobiologia, 408/409, pp. 293-299 (1999). 14. V. L. Almeida, M. E. L. Larrazábal, A. N. Moura, M. M. Júnior, “Rotifera das zonas limnética e litorânea do reservatório de Tapacurá, Pernambuco, Brasil”, Sér. Zool., 96, pp. 445-451 (2006). 15. I. Lucinda, I. H. Moreno, M. G. G. Melão, T. Matsumura-Tundisi, “Rotifers in freshwaters habitats in the upper Tiête River Basin, São Paulo State, Brasil” Acta Limnol. Bras., 16, pp. 203-224 (2004). 16. M. Kalin, Y. Cao, M. Smith, M. M. Olaveson, “Development of the Phytoplankton Community in a pit-lake in relation water quality changes”, Wat. Res., 35, pp. 3215-3225 (2001). 17. G. Packroff, “Protozooplankton in acidic minig lakes with special respect to ciliates”, Hydrobiologia, 433, pp. 157-166 (2000). 18. Brasil. Resolução Nº 357, de 17 de Março de 2005. Resolução do CONAMA para a classificação de águas de acordo com sua composição e os teores máximos de substâncias potencialmente prejudiciais. São Paulo. Legislação (2005).

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