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Regional and long-term patterns of lead concentrations in fluvial, marine and terrestrial systems and humans in Europe

lead concentration (mg/kg) 0 20 40 60 80 100

year 1829

year 879

year 519

year 1669

year 454

year 1729

Authoress: Hradec Kralove 450-1 ------1— C. Hagner Data source: Prange et at. 1997

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KS002627721 R: KS DE015308834

Regional and long-term patterns of lead concentrations in fluvial, marine and terrestrial systems and humans in Europe

Authoress: C. Hagner (Institute of Hydrophysics)

GKSS-Forschungszentrum Geesthacht GmbH • Geesthacht • 2000 Dr. C. Hagner Institute of Hydrophysics GKSS Research Centre Max-Planck-Strasse D-21502 Geesthacht Germany E-mail: [email protected]

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ISSN 0344-9629

GKSS-Forschungszentrum Geesthacht GmbH • Telefon (04152)87-0 Max-Planck-StraBe • D-21502 Geesthacht/Postfach 11 60 • D-21494 Geesthacht GKSS 2000/17

Regional and long-term patterns of lead concentrations in fluvial, marine and terrestrial systems and humans in Europe

C. Hagner

36 pages with 15 figures and 6 tables

*DE015308834* Abstract Lead contamination of abiotic and biotic systems has been studied closely since the early 1970s, when lead was firstly perceived as an environmental problem. Lead emission reduction policies were implemented throughout Europe during that time. Nonetheless, analyses of lead loads in aquatic systems, such as the River Elbe, showed no decline over time in either suspended matter or surface sediments. Regional differ­ ences in lead concentrations of fluvial systems were found, due to tidal influence, runoff and local emissions. Lead contamination of sediments from the North Sea was highest in estuaries. Concentrations in sediment cores were quite stable down to the depth of background values, due to bioturbation, flow, waves and meandering channels. Terrestrial soils in Europe were highly polluted in industrial and ore mining areas and large cities. No decline in lead concentrations was evident in foraminifers, bladder wrack or fish. It was found that contamination in sediments, mammals and fish was higher in coastal zones than in the open sea. In contrast to in aquatic organisms, positive impacts of lead reduction regulations were detected in terrestrial plants, which adsorbed or took up lead mainly through atmospheric lead deposition. European lead concentrations in plants decreased coincidentlywith lead emissions. That trend could also be identified in the blood lead levels of the human population in Europe: since 1979 they have declined in every group of the population. Mainly influenced by age, sex and the living environment, overall, the lead loads of humans had never been high enough to cause health danger.

Bleikonzentration in aquatischen, marinen und terrestischen Systemen sowie Menschen in Europa: regionale Differenzen und Langzeit-Trends

Zusammenfassung In den friihen 70er Jahren wurde die Belastung der Umwelt durch Blei erstmals als Problem wahrgenommen. Infolgedessen wurden zahlreiche Untersuchungen fiber Bleibelastungen sowohl in abiotischen als auch biotischen Systemen durchgeftihrt und europaweit MaBnahmen zur Reduktion von Bleiemissionen erfaBt. Trotzdem konnte weder in Schwebstoffen noch in Oberflachensedimenten, untersucht am Beispiel des Flusses Elbe, ein Rfickgang der Bleikonzentrationen im Zeitablauf festgestellt werden. Regional unterschiedliche Belastungsniveaus resultieren aus dem EinfluB der Tide, dem WasserabfluB und lokalen Emittem. In den Sedimenten der Nordsee wurden die hochsten Bleikonzentrationen in den Astuaren analysiert. Infolge von Bioturbation, Stromung und maandemden Kanalen sind die Bleibelastungen in den marinen Sedimenten relativ konstant, bis sie abrupt auf das Niveau des geogenen Backgrounds zurfickgehen. Studien fiber die Bleikonzentrationen in terrestrischen Boden in Europa ergaben Belastungsschwerpunkte in Industriegebieten, Erzabbauregionen und Ballungsraumen. Weder in Foraminiferen, Blasentang noch in Fisch sanken die Bleikonzentrationen seit den 70er Jahren. Wie auch in Sedimenten, wurden in Fischen und Meeressaugem der Nordsee die hochsten Bleibelastungen in den Ktistenregionen gemessen. Im Gegensatz zu aquatischen Systemen, konnten im Untersuchungs- zeitraum signifikante Rfickgange der Bleikonzentrationen in Landpflanzen nachgewiesen werden. Einen vergleichbaren Trend zeigen auch Studien fiber die Bleibelastung der europaischen Bevolkerung, die vorwiegend durch das Alter, das Geschlecht und den Lebensraum determiniert wird. Insgesamt war die Bleikonzentration im Blut seit 1979weit unter dem Niveau, das als gesundheitsgefahrdend definiert 1st. Manuscript received / Manuskripteingang in der Redaktion: 26. Mai 2000

- 5 -

1 INTRODUCTION

In the 1970s Germany was the first country in Europe to implement an Environmental Protection Program. Within that program air pollution was one of the main topics. In the following years many regulations were brought to pass that enhanced air quality not only in Germany but throughout Europe. Regulations reducing lead emissions first came into force in Germany in 1972 and 1976. In 1984 unleaded gasoline was introduced into the German market. However, it was not until 1987 that the European Commission allowed the member states to prohibit the production and sale of leaded gasoline (Hagner 1999).

The discussion about lead pollution in the 70s focused on environmental and human health damage, whereas in the 80s people were more concerned about other air pollutants, such as nitrogen oxides (NOx), carbon monoxide (CO) and hydrocarbons (CxHy), causing widespread forest damage. That problem was thought to be solved by the catalytic techniques which required unleaded gasoline.

Due to the reduction of lead in gasoline in the EU, the atmospheric lead concentrations in Western Europe have decreased since the 80s. The objective of this paper is to investigate not only the impacts of long-term lead pollution on several environmental systems, but also the effects of recently decreasing lead concentrations in the atmosphere. Regional patterns of lead concentration in different environmental compartments are also analysed. In Section 2 lead contents of suspended matter and sediments are considered for example of the RiverElbe. Lead loads in marine sediments of the North Sea are analysed Section 3. Studies addressing lead contents in terrestrial soils are discussed in section 4. Sections 5 and 6 are concerned with lead concentration in different bioindicators and humans. Regional differences of lead levels as well as changes over time are discussed for fluvial, marine and terrestrial organisms and humans.

2 LEAD CONCENTRATIONS IN SUSPENDED MATTER AND SEDIMENTS OF THE RIVER ELBE

Heavy metals in aquatic systems originate from several sources. In oremountains, they are released by the action of weathering water. Metal production, recycling and ennoblement plants are important point sources of lead, which is emitted especially from paper industry plants, petrochemical plants, refineries, other smelting ore plants and non-iron industry plants. Additional sources of lead emissions deposited in aquatic systemsare sewage, leachate und dumps (Lozan/Kausch 1996).

Lead also enters the system by soil erosion or atmospheric lead deposition of diffuse sources on banks and in tributaries; it originates in these cases from organic compounds, such as gasoline, a major emission source (FOrstner/Mtlller 1974).

Vink et al. (1999) made an inventory of all point- and diffuse-source emissions of lead in the River Elbe basin (Table 1). It shows that in the period of 1992-1995 the sources of lead were mainly diffuse. Direct atmospheric lead deposition is only 17 % of the total lead emissions in the River Elbe; it is therefore of much lower relevance in fluvial than in terrestrial environments. -6-

Table 1: Estimated Emissions in the the Elbe Drainage Area for the Time Period 1992-1995. catchment lead emission in t/yr in the period 1992-1995 point sources 41.1 direct atmospheric deposition 41.4 erosion and surface runoff 87.3 groundwater 25.3 urban areas 40.9 total emissions 236

Data source: adapted from Vink et al. 1999.

2.1 Regional Patterns of Lead Loads

In the years 1979 and 1980 the “Arbeitsgemeinschaft zur Reinhaltung der Elbe (ARGE-Elbe)” (1980) analysed the longitudinal distribution of lead concentrations in water and sediments of the River Elbe from Schnackenburg to the North Sea. The results showed that in limnetic systems over 90 % of lead was bound to suspended matter. Moreover, the Elbe was highly polluted with lead from sources above Schnackenburg. However the mean lead concentration of non-filtrated water from the tidal Elbe between Geesthacht and Scharhoem was below 50p.g/l, the European threshold for drinking water (ARGE-Elbe 1980).

The highest lead concentrations occurred in regions with weakly turbulent flows, for example, groyne fields, where suspended matter was deposited during periods of low discharge. During periods of high discharge the sediments in the groyne fields were resuspended and transported downstream towards the tidal Elbe. That resulted in high lead concentrations in the river section between Geesthacht and Hamburg (ARGE-Elbe 1980).

The analysis of lead concentrations in the suspended matter and sediments of the River Elbe from Schnackenburg to the sea was repeated in the years 1984-1998 (ARGE-Elbe 1998). The samples of suspended matter were taken continuously, but analysed only once a week, as a composite sample (Figure 1).

During the period 1984 to 1998 the lead concentrations in suspended matter did not show a clear decline, despite the gasoline lead content regulations in the 70s and 80s. This could be due to two different reasons. Firstly lead pollutants in aquatic systems were not mainly determined by lead emissions from automobiles but from soil erosion and fluvial discharges. Secondly, suspended matter was permanently deposited, suspended again and transported further. Therefore, older and younger sediments on the surface are always well mixedin rivers (Ackermann 1998).

The influence of the tide and runoff are quite obvious. Between the source and Hamburg the lead concentration of suspended matter was determined mainly by rates of water discharge. In theory high discharges with constant lead emission causes a low level of lead concentration due to the dilution effect. That can be seen in the years 1987/88 and 1995/97 (Figure 1). Accordingly, high lead -7- concentrations result from low water discharges, as, for example, in the years 1985/86 and 1990-1995. These contusions were also found in a study by Schleichert (1999).

>— Pb-Bunlhaus — - Pb-Schnackcnburg

A ! ii1/ 11U 11I,

a a

o 2000

s 8 a a a

Figure 1: Lead Concentration (mg/kg) in Suspended Matter (s20pm) and Monthly Mean Runoff (m3/sec) from the River Elbe 1984—1998.

Data source: ARGE-Elbe 1999a.

During low-discharge periods the flow velocity was extremely small, leading to the deposition of the highly contaminated suspended matter. Those sediments were later resuspended, particularly during the first phase of a flood wave, and transported downstream (Spott 1999). It can be shown that lead discharges and concentrations were positively correlated with water discharge, i.e., the peaks were mainly coincident (Figure 1). As the flood continued, less-contaminated sediment, the large-grain-size particles from the banks, were resuspended, and the mean value of the lead concentration in suspended matter declined.

The sample stations Cuxhaven, Grauerort, Blankenese and Seemannshoeft are located in the tidal Elbe, i.e., between Hamburg and the North Sea (Figure 2). Compared to the other two stations, Bunthaus and Schnackenburg, the lead concentrations in the tidal Elbe were significantly lower. Less- contaminated marine particulate matter was transported upstream and mixed with higher polluted fluvial particles; this is called the “dilution effect” (Forstner/Muller 1974). Moreover, the dredging of highly polluted sediments from the harbour of Hamburg reduced the lead concentration of the suspended matter of the tidal Elbe (Lozan et al. 1996). -8-

-5 250 —^— Pb-Cuxhavcn ...... Pb-Graucrorl ------Pb-BIankcnese — *0— Pb-Scemannshoft

3 S 3 8

—. 2500 I 2000 — ------M—Aa------:------

—i -■ r"»—i—i—i—«—i—i—i—i—i—i—i—i—i—i—i—i—i—>—i—i—i—i—i—i—i—i—i—i—i—>—i—>—i—i—i—i—i—* 32323232323S3S8S8S8S8 88388833 SSSS2d22B3SSS3S2!:22gS 8SSSS222 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 date Figure 2: Lead Concentration (mg/kg) in Suspended Matter (s20pm) and Monthly Mean Runoff (m3/sec) from the Tidal River Elbe 1984-1998.

Data source ARGE-Elbe 1999a.

It follows that the lead concentration of “fresh” sediments is directly related to the pollution level of the suspended matter. Additionally, it is not constant over time but influenced by changing river hydrology and sediment fractions. The lead concentration in the sediment is, for example, highly correlated with the variation of the proportion of sediment in the <;20p.m fraction. The total amount of lead in river sediments increases when the percentage of the sediment fraction smaller than 20pm rises. During the period 1984-1998, the lead levels of neither suspended matter nor “fresh” sediment declined significantly, even though this was expected from falling lead levels in the atmosphere (ARGE-Elbe 1999b). The majority of the lead pollution is still caused upstream of Schnackenburg in the Elbe catchment area of the former East Germany and the Czech Republic.

Regional patterns of lead concentration in suspended matter (s20pm) and surface sediments (s20pm) in estuaries of rivers discharging to the North Sea are influenced by the following factors (Ackermann 1998):

- the amount of particulate-matter discharge into the tidal river from upstream and the lead concentration therein;

- the quantity of suspended matter and lead concentration in marine particles from the Wadden Sea transported upstream in the tidal river;

- local lead emissions;

- resuspension of highly contaminated, long-term stable sediments in the Wadden Sea;

dredging of lead-polluted sediments, for example, in harbours. -9-

During high water discharges, the fluvial suspended matter is transported a long way downstream. In addition in a phase of high water discharges the less-contaminated marine particles diffuse into the upper parts of the estuary and lower the lead pollution level. This mixing of fluvial and marine particulate matter determines the variation of the lead concentration in time and space (Ackermann 1998). Local lead emitters, such as plants or inflowing tributaries, hardly influence the pollution level in estuaries. The intense tidal flow distributes the particulate matter of these point sources over a wide area so that they have little impact on the overall lead concentration of estuaries (Ackermann 1998).

Within the scope of the International Joint-Monitoring Program and the National Monitoring Program of the North Sea, the development of the lead concentration in surface sediments (2-15cm depth) at the mouth of the Elbe between Gliickstadt and Friedrichskoog was analysed in the years 1986-1994 (ARGE-Elbe 1996).

Table 2 shows that the lead concentrations in the inner and outer Elbe mouth increased during the investigation period (ARGE-Elbe 1996, Koopmann et al. 1994). Lead concentrations in the years 1992 and 1994 were twice as high as in other years. The mean value of the lead concentration in the German Wadden Sea was also highly exceededin those years.

Due to the significant influence of upstream water discharges on the sediment composition in the tidal Elbe, the lead concentration of the surface sediment may vary widely from year to year at a same sample station. While in one year marine sediments can dominate, in other years the sediments may be mainly of a highly polluted fluvial origin. In that case the variability in sediment lead concentrations is not caused by changing lead deposition but by different amounts of water discharge and its dilution effect (ARGE-Elbe 1996).

Table 2: Lead Concentration (mg/kg) in the Surface Sediment (s20pm) of the Inner and Outer Mouth of the River Elbe and the German Wadden Sea.

lead com;entration (mjVkg) surface-sediment (2-15cm depth) lead minimum maximum Mean standard deviation inner Elbe mouth 1986-1990 34 149 59 18.0 1991-1994 23 177 83 11.0 outer Elbe mouth 1986-1990 24 98 47 6.5 1991-1994 42 152 90 3.7 German Wadden Sea, 1989-1992 11 142 64 24.0

Data sources: ARGE-Elbe 1996, Koopmann et al. 1994.

Other analyses of sediment cores from the floodplain of the River Elbe show a great variety of lead concentrations in the upper layers according to different soil types. The highest levels of lead pollution, in the range 305-319 mg/kg (in the «s20pm sediment fraction at 0-20 cm depth), were - 10- measured in alluvial aquents and fluvisol (FAO Soil Taxonomy). These values are comparable to lead concentrations in the vicinity of smelting plants. Low lead levels were found in sandy soils (ARGE- Elbe 1980).

A study undertaken by the National Working Group “Dangerous Substances - Quality Objectives for Surface Aquatic Systems” evaluated the lead concentration in different aquatic systems (Umweltbundesamt 1997). Quality Objectives for various goods and kinds of use were defined (Table 3).

Table 3: Quality Objectives of the National Working Group “Dangerous Substances - Quality Objectives for Surface Aquatic Systems” and the International Rhine Commission (IRC) for Lead Concentrations.

protected good or kind of use quality obje :tives National Working Group IRC aquatic biotic system 100 mg/kg or 3.4 p.g/1 100 mg/kg suspended matter and sediment 100 mg/kg or 3.4 ng/1 drinking water 50 ixg/1 fishery 5 (xg/1

Quality Objectives for lead concentrations are in p.g/1 for water and in mg/kg for suspended matter.

Data source: adapted from Umweltbundesamt 1997.

From 1991 to 1994 the Quality Objectives in Table 3 were compared with the lead concentration in samples (Table 4) taken at different stations along the RiverElbe. The number of stations in which the measured lead value exceeded the Quality Objective decreased slightly over time, but even in 1994 the percentage of stations violating the threshold was 32 % (Umweltbundesamt 1997).

Table 4: Lead Concentration (mg/kg) in Aquatic Organisms, Suspended Matter and Sediment Compared with Quality Objectives.

year number of sample number of stations (in %) where the Quality stations* Objective was exceeded 1991 29 41.4 1992 32 40.6 1993 40 30.0 1994 47 31.9

♦Position of the sample stations: Schmilka, Magdeburg, Schnackenburg, Zollenspieker, Seemannshoft, Teufelsbriick, Grauerort. The Quality Objective was defined as 100 mg Pb/kg. Data source: adapted fom Umweltbundesamt 1997. -11-

2.2 Changes in Lead Contents of Fluvial Sediments over Time

Lead Concentrations in vertical sediment cores Cuxhaven indicate the development of heavy metal deposition tS? Hamburg in a defined area. For the determination of changing lead levels over time in the catchment area of the Germany River Elbe, Prange et al. (1997) analysed sediment SchnackenbuigxHavelberg Tangermunde/ %_ cores from the floodplain and subaquatic sediments, P S' i.e. underwater sediments. The pollution levels were Magdeburg/ dated using 14 C and 137Cs methods. The floodplain sediment cores were used to determine the geological background value of lead in the Elbe Dresden catchment (Figure 3).

loudnimLitomerice) Czech ft. The geological background value of lead in Republic Prague*^. floodplain sediments of the River Elbe was found to vary between 30 and 40 mg/kg. The lead Figure 3: The River Elbe from it’s Source concentration increases at a shallow depth in the to the Mouth. sediment, i.e., anthropogenic lead deposition is relatively new. As can be seen in Figure 4, anthropogenic input must be younger than 168 lead concentration (mg/kg) years, this finding is corroborated by results from another sediment core from the Elbe catchment area in Germany.

The very low mobilisation rate of lead in sediments, which allows the dating of historical pollution levels, is a serious problem for the bioremediation of the Elbe floodplains because they remain contaminated for a very long time period (Miehlich 1994). year 879 The young age of anthropogenic lead pollution has year 519 been confirmed by the analysis of floodplain year 1669 sediment cores from Pevestorf (Elbe, 485 km from year 454 the source) and Moorwerder (Elbe, 612 km from the year 1729 source) (ARGE-Elbe 1988). The maximum level of lead concentration was found at depths of about 35 cm (Pevestorf) and 25 cm (Moorweder). Below those soil layers the heavy metal concentration was Figure 4: Lead Concentration in Sediment much lower and at a constant level. That indicats not Cores (s20^m) from the Floodplain of the anthropogenic but geological lead deposition. River Elbe. Moreover, it is clear that the lead concentrations Data source: Prange et al. 1997. - 12- in young sediments originated from anthropogenic sources and not the oremountains (ARGE-Elbe 1988).

Subaquatic sediments from the RiverElbe are indicators of recent lead deposition (Prange et al. 1997). Three sediment cores are represented in Figure 5. The lead concentrations in the cores from Hradec Kralove and Litomerice (near Roudnice), both in the Czech Republic (see Figure 3), are roughly similar. It is assumed therefore, that the River Moldau has no influence on the lead loads of the Elbe. The lead pollution levels in the sediment cores in Litomerice and Hradec Kralove did not change significantly over time. A decline due to decreasing lead emissions from automobiles cannot be seen. Vesely (1999) argued that the most important sources of lead pollution in the sediments in the upper part of the River Elbe have been and still are chemical factories and not automobile emissions (see also Table 1).

lead concentration (mg/kg) 100 200 300 400 500

Figure 5: Lead Concentration (mg / kg) in Subaquatic Sediment Cores (s20pm) from the River Elbe.

Data source: Prange et al. 1997.

The lead levels from the sediment core in Tangermtinde (Figure 5) are influenced by the Mulde and Saale tributaries, and the oremountains. In that area the lead loads are much higher than in the Czech Republic. They reached their maximum in the 70s (Prange et al. 1997). This maximum was caused mainly by the lead pollution in the tributaries from industrial areas and large cities, which are suspected to have been the main emitters of lead (Prange 1999). Additionally, the lead deposition was determined by the economic growth and recession in the former East Germany which started in the 70s. This would also explain the erratic decline of lead concentrations in the upper layers of the sediment core after the reunification of Germany in 1989.

These conclusions are confirmed by the study of Guhr (1995), who analysed the sources of heavy metal contamination of the River Elbe in the former Eastern Germany. Mining activities and residues and smelting plants located in the Ore Mountains and the Harz Mountains were important lead emitters. In addition, the metal-working, metal-processing and chemical industries, primarily in the -13- central German industrial area, and insufficient or non-existent sewage treatment contributed to the pollution of the River Elbe. Point sources of lead pollution were located in the following drainage areas of the River Elbe: ,

- smelting industry (Freiberger Mulde) and manufacture of red lead in Bitterfeld in the drainage area of the River Mulde;

- recycling of car batteries in Calbe, copper ore smelting at Mansfeld, production of thermo­ stabilizers in Greiz-DOhlau in the drainage area of the River Saale;

- production of tetraethyl lead in Premnitz in the drainage area of the River Havel (Guhr 1995).

Despite the extensive closure of industries which were heavy emitters not only of lead but also of other heavy metals in East Germany in recent years, an improvement of the water, suspended matter and sediment quality could not be identified by the study of Muller and Furrer (1994).

3 LEAD LOADS IN MARINE SEDIMENTS

Due to the high input of lead from Great Britain and the European continent, and a limited dilution on account of the shallow water, the southern part of the North Sea is one of the most polluted marine areas in the world. A particularly high degree of contamination can be observed in the river estuaries, for example, the Rhine, Weser and Elbe. In addition, dumping of waste materials was practiced in several areas, which also contributed to the high pollution level (Fdrstner/Wittmann 1983).

Sources of lead deposition to the North Sea, estimated in 1980, were: atmospheric lead deposition, 50 %; dumping, 30 %; and fluvial lead, 20 % (Schwedhelm/Irion 1985). The high percentage of atmospheric lead discharges was mainly caused by combustion of coal, oil and gasoline, and must be even higher today because dumping of sewage sludge in the German Bight has been prohibited since 1981.

The lead influx into marine ecosystems occurs mainly through dust, dry deposition and precipitation. The function of these processes is determined by seasonal differences. In summer warm air rises from the earth’s surface so that there is a high exchange between air layers. A high proportion of lead emissions is deposited near to the emitter. Therefore, the amount of lead which is transported over long distances is much smaller in summer than in winter and the Wadden Sea is less contaminated (Kapitza/Eppel 1999).

3.1 Regional Differences in Lead Contamination in the North Sea

In a study by Gadow/Schafer (1973), analysing the lead concentration in sediments (s2pm) from the inner German Bight, three pollution centres were defined: the mouth of the RiverWeser, an area north of the Elbe mouth, and east of Helgoland. Regional differences in lead concentrations were explained by disparities between suspended matter discharges and deposits from the rivers Weser, Elbe and - 14 -

Eider. This conclusion was confirmed by a great number of other sediment investigations, as, for example, in the analysis of FOrstner/Wittmann (1983). They also considered estuaries to be major problem areas, especially at the outer reaches of heavily populated and industrialized regions, because large amounts of waste materials were transported into the coastal marine systemsby rivers.

In the years 1981 and 1982 Schwedhelm/Irion (1985) analysed heavy metal loads in surface sediments (0-2 cm depth) from the Wadden Sea between Sylt and Dollart. Lead concentrations were enhanced up to ninefold, measured in Wadden sediments between the estuaries of the rivers Elbe and Weser (Table 5). The mean value of enhancement factors was found to be 3.8. The lowest lead concentrations were found in the North Frisian Wadden.

Table 5: Lead Concentrations in Surface Sediments (s2pm) from the Wadden Sea, 1981-1982.

minimum maximum mean background sample station (ppm) (ppm) (ppm) value (ppm) Sylt 35 60 48 15 North Frisian Wadden 36 51 42 15 Wadden between the rivers Elbe and Weser 44 . 135 76 15 East Frisian Wadden 29 128 62 15

The depth of the sediment samples (s 2pm) was 0-2 cm.

Data source: adapted from Schwedhelm/Irion 1985.

Again, the higher lead loads in the East Frisian Wadden, including Jade and Dollart, were explained by local emissions from large industrial areas nearby and by riverine lead discharges to the German Bight. Additionally, the lead loads from the long-standing practice of dumping sewage sludge from the cities Hamburg and Elmshom in the mouth of the rivers Elbe and Weser were suspected to be transported in the Wadden area by tidal flow (Schwedhelm/Irion 1985).

Overall, the lead concentrations in the Wadden sediments were much lower compared to the fluvial lead loads. Only a small amount of the fluvial pollution discharges reached the Wadden Sea after it had passed through the open sea where most of the contaminated suspended matter were deposited (Postma 1982).

The German “Rat der SachverstSndigen ftir Umweltfragen” (RSU) (1980), the German Council for Environmental Issues, concluded that during the 70s in the open North Sea lead concentrations were too low to cause any acute or chronic damage to organisms. However, the lead levels in the coastal zones, especially in the vicinity of river mouths, were found to be enhanced (RSU 1980).

From 1989 to 1992 a mapping of lead loads in the surface sediments (0-10 cm depth) of the German Wadden Sea was carried out by Koopmann et al. (1994). Distribution patterns of lead concentrations were determined and the main pollution areas specified (Figure 6). Lead was transported in the - 15 -

German Bight by an anticlockwise circulation; thus, the pollutants were deposited along the Dutch, the German and the Danish coasts throughout the whole of the Wadden Sea (Koopman et al. 1994).

The lead concentration in the surface 7“ 8* 9* sediments varied between 11 pg/g and 142 pg/g, with the mean value calculated to be 55 “ — ?; Lead * s 30 pg/g 64 pg/g. Thus, the results compared well o 30-60 pg/g with the measurements of Schwedhelm/Irion ° 60-90 pg/g 4- 90-120 pg/g (1985). Relative to the geological A > 120 pg/g background levels of lead concentration in the Wadden Sea, estimated in other studies to be about 15-37 pg/g, the concentration level was enhanced (Schwedhelm/Irion 1985, Schwedhelm/Irion 1983, Laane 1992). The range of variation of 585 pg Pb/g was quite high in both areas, not only in the part of the Wadden Sea in Lower Saxony but also that in Schleswig-Holstein. Again, the most polluted areas were determined to be the estuaries of the rivers Weser and Elbe Figure 6: Lead Concentrations (pg/kg) in Surface and the coastal zone of Lower Saxony Sediments (0-10 cm depth) of the Wadden Sea. (Koopman et al. 1994). Data source: Koopmann et. al.1994.

3.2 Determination of Long-Term Patterns of Lead Deposition Using Sediment Cores

From analyses of sediment cores it is possible to draw conclusions from the lithology of, and the anthropogenic impacts on, the catchment area. The concentrations of pollutants in vertical cores show changes in heavy metal deposition through time.

In the 70s Fdrstner/Reineck (1974) analysed lead loads in sediment cores taken southeast of Helgoland. From the minimum values of the lower sections of the sediment core, which they considered to be the background values for that area, the lead concentrations increased uniformly until a maximum value was reached at a sediment depth of 15 to 20 cm. Significant increases of lead concentrations in the core layers of the 50s were thought to be caused by lead additives in gasoline and growing gasoline consumption.

Sediment cores from the Wadden Sea between Sylt and Dollart were taken in 1981-1982 by Schwedhelm/Irion (1985). Lead concentrations were determined in the s2pm sediment fraction. Figure 7 shows that lead loads are highly enhanced in recent sediments. The mean value of the lead concentration was found to be 15.13 ppm, the standard deviation 5.21 ppm. To measure the background value for lead, deep sediment layers were analysed. -16 •

lead concentration (mg/kg) The curve is quite characteristic of Wadden

40 60 80 sediments. They are continuously mixed by tidal flows, waves, bioturbation and shifting channels. In that way, recent, contaminated surface sediment is shifted to sediment layers at various depths. Therefore, the lead O 100 • concentration remains at a specific level even into older sediment layers until it decreases •o 150* abruptly to the geological background. Down to this depth, anthropogenically contaminated 200 * sediments have been mixed in recent times 225 *

250 ‘ (Schwedhelm/Irion 1985). The depth of the anthropogenic lead contamination depends on

Sediment Core Seefelder 300 ' the mixing mechanism. In quite stable Wadden areas where the mixing is caused only by flow, Sediment Core Friedrichskoog waves and bioturbation, the pollution level is Figure 7: Lead Concentrations (mg/kg) in only a few centimeters deep. Sediment Cores (s2pm) from the Wadden Sea. A high contamination depth is observed in Data source: Schwedhelm/Irion 1985. sediments of meandering Wadden channels, which erode at their cut side and deposit this material in longitudinal oblique layers at the slide side. This is illustrated in Figure 8, by a sediment core from “Caeciliengroden”, an area southwest of the Jade Bay which is today lead concentration (mg/kg) flooded only during storm surges.

In the upper layer, to a depth of 60 cm, the lead contamination is quite constant. At 60 cm the heavy metal concentration decreases abruptly to the geological background and does not change until 450 cm. In a fossil soil layer, between 238 cm and 267 cm depth, however, the lead concentration is significantly lower due to different soil characteristics.

Figure 8: Lead Concentrations (mg/kg) in a Marsh Sediment Core “Caeciliengroden ’ (southwest of the Jade Bay) Sediment Core (=2pm). Data source: Schwedhelm/Irion 1985. - 17-

The base of the layer characterized by anthropogenic lead deposition can be dated to have been deposited at the end of 1900s. The level of lead concentration, however, shows that the mixing of anthropogenically contaminated sediments with relatively unpolluted soil layers did not take place until recent decades (Schwedhelm/Irion 1985). These results were affirmed by Meyercordt (1992), who analysed lead concentrations in six sediment cores from salt marshes in the area of the North Frisian Wadden Sea in 1989. The soil layers were dated by radiological analysis, using the 210Pb, 137Cs and 14 C methods.

Since 1870 the lead concentrations have increased significantly above the geological background value. The highest pollution levels - about 60 mg Pb/kg - were measured at a sediment depth which was 10-30 years old, i.e., they were deposited between 1960 and 1980. Lead concentrations in the more recent sediments of the upper soil layers have decreased after this high, which might be caused by the lead emission reduction policies in the 70s (Meyercordt 1992).

Unlike the lead concentrations in the sediment cores of Schwedhelm/Irion (1985), which are quite stable in the anthropogenically contaminated soil layers, lead pollution is continuously increasing in the core samples from the North Sea analysed by the German Federal Office of Navigation and Hydrography (1999) (Figure 9). There may be a number of reasons for this. Important factors for regional differences in pollution levels are the variation of bioturbation, flow and waves.

The cores shown in Figure 9 were analysed in the early 80s, so the decrease in lead concentrations in upper core levels shown by Meyercordt (1992) might not yet have occurred. Indeed, the latter was concluded to have taken place after 1980.

lead concentration (mg/kg) lead concentration (mg/kg) 0 to 20 30 40 50 60 70 80 0 20 40 60 80 100 120

6000 year old/

O, 10

■5 ioo

-100 year old

Sample position: O QA >XTnrtUf

Figure 9: Lead Concentrations (mg/kg) in Sediment Cores (s20pm) from the North Sea. The upper core was taken in the area of Skagerrak, the other from southwest of the North Frisian Isles. Data source: Federal Office of Navigation and Hydrography 1999.

-WrWd*' '?■■- - 18 -

Overall, lead concentrations of about 80 mg/kg in the upper sediment layers of the North Sea coincide well with the results of ARGE-Elbe (1996a) and Koopmann et al. (1994), who analysed sediment cores from the German Wadden Sea. The hypothesis that the sediments of the Wadden Sea were more contaminated with lead than those from the open North Sea could not in general be proved. However, regional differences in lead concentrations were observed, with significantly enhanced lead loads in the river estuaries.

4 CHANGES IN THE LEAD CONCENTRATIONS IN TERRESTRIAL SOILS

Due to the parent material, i.e., rocks or sediments, the lead concentrations in soils vary. These geological background values are increased mainly by atmospheric lead deposition originating from anthropogenic lead emissions. Atmospheric lead deposition is the most important source of lead in the pollution of forests because their rough surface functions as a filter for the contaminated aerosols (Vanmechelen et al. 1997).

Lead is accumulated nearly exclusively in the humus layer of soils, compounded in metal-organic complexes and reduces sharply in deeper layers (Schultz 1987). The ecological impact of lead pollution depends on the lead concentration dissolved in soil water. This is influenced by the total lead load, the lead solibility, the content of organic and inorganic complexation agents and the redox conditions (BMLEF 1997). Lead which is extractable with diluted acids, so-called plant-available lead, constitutes only a small fraction of the total lead in soils. Soil lead is largely unavailable to plants, as evidenced by the experiments of Vanmechelen et al. (1997). The results showed that in spite of several applications of lead in the soil, the increase of lead content of plants was quite small. Overall, lead is strongly retained by organic matter (Vanmechelen et al. 1997).

Tyler (1992) defined values for critical lead concentrations in the humus layer which had harmful impacts on soil organisms. While lead concentrations of about 150 mg Pb/kg might damage invertebrates, harmful effects on the biochemical soil activity, the soil respiration and microflora are not expected until concentrations of more than 500 mg Pb/kg humus are reached.

From 1987-1993 a national forest soil inventory was undertaken in Germany, which was designed to include an investigation of atmospheric heavy metal inputs. The grid size of the sample points was 8*8 km, which guaranteed representative results for the following four site factors: soil type, soil structure, orography and potential, natural vegetation. This does not mean that the values of one sample point were used to represent an area of 64 km2, rather that the analysis was thought to determine regional patterns of chemical soil parameters (BMLEF 1997).

The lead concentration in the humus layer varied between undetectable values and 4211 mg Pb/kg, the median being 94 mg Pb/kg. Overall, at 25 % of the survey plots, the amounts of Pb accumulated in the organic material were higher than the critical value of 150 mg Pb/kg and therefore were potentially toxic for soil organisms. High lead concentrations were found particularly in the main industrial and traditional oremining areas (Nordrhein-Westfalen, Sachsen-Anhalt, the Harz Mountains and the Ore Mountains) and in forests near to large cities (Berlin and Hamburg). Forests in the catchment areas of cities were polluted mainly by local emitters, for example, metal plants and the high amount of -19- automobile exhaust fumes. Regionally enhanced lead loads in Brandenburg, the south of Mecklenburg-Vorpommern and mountain areas such as the Franken Forest or the Thuringian Forest were thought to be caused not by local emitters but mostly by atmospheric long-distance transport of lead emissions (BMLEF 1997).

In 1997 a report of the forest soil conditions in Europe was published by the United Nations Economic Commission of Europe and the European Commission. The results were quite similar to the German soil inventory (Vanmechelen et al. 1997); they were as follows:

- atmospheric deposition has caused high levels of lead in strongly industrialised areas;

- concentrations of lead in humus layers and topsoils showed regional gradients reflecting atmospheric deposition patterns.

- contaminated soils which accumulated more than lOOmg Pb/kg in the organic layer were commonly observed in Central Europe. However, critical concentrations of more than 500mg Pb/kg, defined by Tyler (1992), were exceeded in less than 1 % of the samples.

Regional lead concentration patterns were also discussed by KOnig (1986), who analysed soil samples of agricultural and vegetable gardening land in 1979-1983. Samples were taken in areas of high heavy metal pollution. Compared to control samples with background lead concentrations, the lead loads in soils of oremining areas and floodplains of highly contaminated rivers were the most enhanced. Lead concentrations increased by about 1530 % were found in oremining areas; these were even high above the threshold for lead in sewage sludge (max. 100 ppm Pb) (KOnig 1986).

Variations of lead concentration over time were investigated by Shotyk (1995) in the early 1990s. Peat cores representing vertical profiles were taken, for example, from an ombrotrophic bog at Etang de la Gruyere in the Jura Mountains in western Switzerland, and a blanket bog near Loch Laxford in northwestern Scotland. The different lead loads of the two profiles proved not only that recent rates of atmospheric lead deposition had been several times higher at the Swiss site (about 4 to 5 times), but also that they were significantly higher as long ago as approximately 1000 years before present. The analysis also showed that recent atmospheric inputs of lead have been much greater than the pre­ industrial atmospheric supply, but that they have been decreasing since the early 1990s.

5 LEAD LEVELS IN FRESHWATER AND MARINE BIOTA

5.1 Algae and Protozoa

Foraminifers (Foraminifera) are meiobenthic organisms that accumulate lead mainly in their plasma but also in their shells. Hdbel (1984) compared lead concentrations of fossil foraminifers from the Quaternary period, assuming them to represent background values, to lead loads of samples of North Sea foraminifers from 1984. The results showed an accumulation factor of lead of about 15.5 (Table 6). The lead concentration in foraminifers was positively correlated to the lead loads in the surrounding sediment. In areas of highly contaminated sediment the lead concentrations of -20- foraminifers were also extremely high. Overall, the lead loads in sediments were 10 to 20 times higher than those in foraminifers.

Table 6: Lead Concentration (mg/kg) in Fossil and Recent Foraminifers in 1984.

foraminifers lead (mg/kg) fossils from the Quaternary (assumed to represent the background value) 3.3 German Bight (1984) 50.8 maximum (between Dollart and Leybucht) (1984) 87.5 minimum (1984) 8.3

Data source: adapted from Hobel 1984.

This relationship resulted in regional variations of lead concentration in foraminifers in the German Bight. Due to enhanced lead loads from the rivers Jade, Weser, Eiser and Elbe, high lead levels of above 40 mg/kg were found in Jade Bay, the mouth area of the river Weser, the coastal area between Dollart and Leybucht and northwest, south and southeast of Helgoland. Less-contaminated foraminifers, with lead concentrations lower than 14 mg/kg, were located in the northern part of the German Bight and to the North of the Eastern Frisian Isles (Hobel 1984).

Lead concentrations in plankton, mainly diatoms (Bacillariophyceae), were roughly similar to those in foraminifers. Seasonal patterns of lead loads in plankton were explained by temperature variations (Hobel 1984).

Bladder wrack (Fucus vesiculosus), a macroalga, is one of the bioindicators collected in different areas of the German part of the North Sea within the German Environmental Specimen Banking programme since 1985 (Umweltbundesamt 1998). It is used as an indicator of metal pollution because its metal content is directly related to the dissolved metal concentrations in the water; this is because it incorporates lead directly from the water. Additionally, the sessility of most macroalgae enables them to be associated with local concentrations of lead.

The samples were taken on a bimonthly basis from Koenigshafen (Sylt-Romo Bay) and Eckwarderhoeme (Jade Bay) and analysed as annual homogenates (Umweltprobenbank 1999a). Figure 10 shows that the lead concentrations in bladder wrack from Eckwarderhoeme were significantly higher than in those from Koenigshafen. This was caused not only by the circulation patterns in the German Bight but also by the dissolved lead input from fluvial discharges to JadeBay (Emons 1999).

In the period 1985-1997 the lead concentrations in bladder wrack from Eckwarderhoeme did not decline significantly. Overall, they were comparable to lead levels in marine systems with low levels of lead contamination (Umweltbundesamt 1998). Unfortunately, the four-year time period over which the analysis of lead loads of bladder wrack in Koenigshafen was carried out was too short to prove a systematic decrease in lead concentrations. -21-

According to Emons (1999), the relatively stable lead concentrations in marine and fluvial aquatic systems are a result of local and regional lead emitters, for example, industrial plants and catchment areas. Therefore the decreasing atmospheric lead deposition rarely influenced lead loads in aquatic systems, and the positive impacts of policies reducing lead emissions, such as the s 120 ban of lead additives in gasoline, could not

be shown within this time frame. § 1.00 o 0.90 Regional differences of lead contamination of bladder wrack in the North Sea were also Bladder-Wrack -6- = Eckwarderhoeme studied by Ftirstner and Wittmann (1983). 4 - =Konigshafen The detailed analysis of bladder wrack

populations in coastal waters around Great 1985 89 91 93 95 97 88 90 92 94 96 Britain indicated significantly higher lead year contamination in the eastern Irish Sea and Figure 10: Lead Concentration (pg/g) in North Sea than in other coastal waters Bladder Wrack (Fucus vesiculosus), surrounding Great Britain. 1985-1997. The mean value (ng/g) and the standard deviation are illustrated. Data source: Umweltprobenbank 1999a.

5.2 Mussels

Lead concentrations in marine invertebrates, such as mussels (Bivalvia), depend on the accumulation mechanisms in each species. The accumulation of lead results from the net difference between rates of uptake and excretion, influenced by changes in body tissue. These changes may be increases due to growth, storage of metabolic reserves or gametes, or decreases resulting from, for example, starvation or gamete release. The accumulation of lead involves detoxification and storage, to some degree, either temporary or permanent (Rainbow 1990).

Blue mussels (Mytilus edulis), bivalves, are one of the bioindicators most often used in pollution monitoring programs. Their low biotransformational potential enables them to concentrate pollutants. Moreover, their sessility, longevity and wide geographic distribution are characteristics advantageous to their use as bioindicators of local water quality (Lozan et al. 1994). However, it is not only for these reasons that the effect of lead on bivalves have been emphasized in investigations; it is also because they are consumed by humans and hence represent a potential threat to public health as well as an economic factor (Ftirstner/Wittmann 1983).

Mussels are filtering organisms, that is, they feed on microscopic particles filtered from the water by their gills. Lead is taken in by feeding. They accumulate lead therefore not only from the dissolved -22- fraction, but also from that compounded to suspended matter. The final influence on the lead loads of blue mussels is the lead concentration in phytoplankton (ARGE-Elbe 1988).

Since 1985 the German Environmental Specimen Bank has studied changes of lead concentrations of blue mussels at three sample stations in the German Bight, at Koenigshafen (Sylt-Romo-Bay), Eckwarderhoeme (Jade Bay) and Lister Hafen. Due to the choice of samples the influences of sex, age, temporal variation and salinity could be eliminated. Figure 11 shows that in the years 1986-1997 the mean lead concentration of blue mussels at Eckwarderhoeme varied between 2.4 mg/kg 8 I and 3.6 mg/kg, consistently higher than that at -§ Lister Hafen (measured until 1992) and Koenigshafen (measured since 1992). •o 1 A clear trend in lead concentrations could not G be determined at any of the three sampling stations. It was assumed, however, that during 1985-1997 there was a regional assimilation of lead contamination levels in the German i Wadden Sea (Umweltbundesamt 1998). Mussels Over the period 1986-1993 Hablizel and = Eckwarderhoeme Karbe (1994) analysed long-term trends and = Konigshafen regional variability of lead concentrations in -x-= Lister Hafen blue mussels from the Ems, Jade, Weser and 1985 87 89 91 93 95 97 86 88 90 92 94 96 Elbe estuaries. They found high variations of year lead levels in the bivalves, showing either Figure 11: Lead Concentration (pg/g) in Blue decreasing, increasing or fluctuating lead Mussels (My til us edulis) in the German concentrations during the investigated time Wadden Sea, 1985-1997. period. High lead loads in blue mussels were The mean value (pg/g) and the standard deviation are found in the estuaries of the rivers Weser and illustrated. Data source: Umweltprobeabank 1999a. Elbe.

Analyses by the Ministry of Ecology of Low Saxony had similar results: there was no significantly decreasing trend of lead concentrations in blue mussels from the North Sea (Figure 12). Similar findings were obtained in investigations in Schleswig-Holstein between the years 1990 and 1996, where lead concentrations of blue mussels at the sample stations Suedfall, Helgoland and Norderaue were analysed (Ministry of Nature and Environment of Schleswig-Holstein 1999). -23-

The different studies of lead loads in blue mussels over time agree with the results of analyses of contaminated bladder wrack in the North Sea. Lead levels in aquatic systems did not decline in the 80s and 90s despite the policies of reduction in lead emissions. Due to those policies, atmospheric lead concentrations have decreased, but those of marine aquatic systems, which are more influenced by the long-term accumulation of lead in soil and fluvial systems,have not

year * Sample stations: Memmertbalje ( 53°387 6°57.1’); Nordemey West ( 53°41.577°10 ’); Unterweser (53°397 8°18.3’)". Wilhelmshaven Leitdamm (53=30 ’/ 8°10’)

0 Bantsbalje * A Borkum O Cuxhaven Leitdamm + Elmshtim Rinne @ Mellumbalje

oo oo oo oo OO OO ON ON On On On ON on On

* Sample stations: Bantsbalje (53=3477=01 ’); Borkum (53=35.47 6=47.84 ’); Cuxhaven Leitdamm (53=53.057 8=41.03 ’); ElmshOm Rinne (53=29.057 6=54.00 ’); Mellumbalje (53=41.097 8 =08.08’) Figure 12: Lead Concentration (mg/kg) in Blue Mussels (Mytilus edulis) in the North Sea, 1982-1997. Data source: Ministiy of Ecology ofNiedersachsen 1999.

Changes of lead concentrations in mussels in fluvial systems were analysed by ARGE-Elbe in the years 1990 and 1991 (Gaumert 1994). Samples of winkles (Dreissena polymorpha) were taken from -24 - the River Elbe at the Schnackenburg measuring station (km 474.5 from the source). The differences between tissue concentrations of the control sample compared to those of the exposed animals were determined to equate to a net accumulation of lead of about 129 %. Although mussels are sessile filtering organisms, no correlation was found between lead concentrations in water, sediment and winkles. Hence, the bioavailability of lead depended not only on abiotic factors, such as temperature, redox conditions or the presence of complexation agents, but also on the physiology of the winkle. Moreover, the study results confirmed that bioavailability had to be regarded as another important factor in the assessment of river quality and control (Gaumert 1994).

5.3 Fish

Bream (Abramis brama L.), an osteichthye, has frequently been selected as a bioindicator in German monitoring programs. It is a widespread species and due to its stationary way of life it is possible to use the lead concentrations in it to infer those in the surrounded sediment (Thiel 1999).

The intake of lead by bream occurs mainly by feeding and not, as in many other fish species, by filtering water through their gills. Bream feed on macrobenthic organisms in the sediment, such as ostracodes, larvae and pupae of chironomids, nereids and oligochaetes (Debus 1987). Compounded to erythrocytes, lead is distributed by the blood system of the fish. It is accumulated mostly in the bones, but also in the liver, kidneys and gills. Acute damage caused by lead results in inactivity of enzymes (Strait 1992).

Analyses of lead loads in bream from the River Elbe were conducted by the ARGE-Elbe in the years 1979-1980 and 1994 (ARGE-Elbe 1980, 1996b). In 1979/80 the lead concentrations in bream muscles were small. The maximum value of 43 pg Pb/kg fresh weight was far below the German threshold for food (0.50 mg Pb/kg fresh weight of consumable fish parts), defined in 1996 by the “Bundesamt filr gesundheitlichen Verbraucherschutz und Veterinarmedizin“ (BgW 1996). Fish is not banned for human consumption until concentrations of more than twice the 0.50 mg/kg threshold value are reached, which has never occurred in Germany. Overall, lead contamination of fish is believed to be of minor importance (Ballin 1999). A study of lead concentration in bream muscles in 1994 also showed that exceedenceof the lead thresholds of German food law did not occur (ARGE-Elbe 1996b).

In the years 1979-1994 Kruse et al. (1994) analysed the changes of lead concentrations in breams over time (Figure 13). Again, the lead levels in the consumable fish parts were low. Higher lead levels were measured only in the liver and kidneys. Long-term impacts of lead concentration in bream tissue could, however, not be assessed (Kruse et al. 1994).

In the period 1980-1989 comparable results of lead concentrations varying around a constant level were determined in fish from the Bavarian RiverDanube. Overall, lead levels in fish were always the lowest among those of all aquatic organism; Wachs (1992/93) therefore questioned the suitability of fish as a sensitivebioindicator of pollutants. -25 -

In 1991 and 1992 the German Environmental Gluckstadt white (Elbe-km: 675) Agency (Umweltbundesamt 1996) Gorleben black (Elbe-km: 492.2) o 75 % quantile o median A 25 % quantile investigated biological effects of heavy metal 25- • contamination of fish. The analysis focussed • on dab (Limanda limanda L.) in the North Sea | 9 and on flounder (Platichthys flesus L.) in r i 1 estuaries. Like breams, the adult flounder also ▲ ; o has sedentary habits and a widespread r§10 Pp d 6 distribution. During its early years of life, it 8 0 4 h dwells in fluvial freshwater in the most- o A 0 —V------polluted areas. Living close to the sediments, : i 1 • d : A the flounder has more direct contact with the 0 i 7 9 10 10 11 9 10 4 5 sediment than most other fish species 1979 1984 1986 1991 1994 year (Umweltbundesamt 1996). Figure 13: Lead Concentration (mg/kg) in Bream (Abramis brama L.) Muscles in the River Elbe, 1979-1994. Data source: ARGE-EIbe 1999c.

The highest lead concentrations in dabs from the North Sea were found along the British Coast. They were significantly enhanced compared to lead levels in dabs at the Dutch and German coasts. Flounders from British estuaries were also more contaminated than those living in Dutch and German estuaries. Lead concentrations in flounders from the Wadden Sea were much lower than those of flounders in estuaries. The levels of lead in the flesh of the Wadden Sea fish were more than two orders of magnitude lower than the German threshold for food (0.50 mg Pb/kg fresh weight of consumable fish parts).

In 1990, lead concentrations in North Sea flounders were analysed within the framework of the monitoring programme of the Sea Protection Conventions of Oslo and Paris (OSPARCOM 1992). Flounders living on the Dutch coast showed higher lead concentrations than those from the coast of Schleswig-Holstein and Denmark. The study also confirmed enhanced lead levels in fish in estuaries of rivers such as the Elbe and Weser. Due to regional differences of lead concentrations, Lozan et al. (1994) concluded that lead levels in water, sediment and fish were directly correlated.

Similar to those in macroalgae and mussels, there has been no decrease of lead concentrations in fish during the last twenty years, either in marine or in freshwater environments.

5.4 Mammals

In the period 1989-1991 the lead accumulation in the livers and bones of the common seal (Phoca vitulina) and the harbour porpoise (Phocoena phocoena), two mammals from the North and Baltic seas, were investigated (Kremer 1994). Unlike in the common seal, the lead concentration in the tissues of harbour porpoise increases with age. Lead accumulated particularly in the liver and bones decupled (increased by a factor of ten) within 15 years (Kremer 1994). Differences in lead -26- contamination levels were not identified between the mammals from the North and Baltic seas. Enhanced levels in comparison to the North and Baltic Sea, however, were measured in the animals living in the German Bight, influenced by the rivers Elbe and Weser (Luckas/Harms 1987; Harms 1990).

In agreement with other studies of lead concentrations in the tissues of the common seal, Kremer (1994) concluded that the lead levels were toxicologically harmless. This was confirmed by the study of Hapke (1991), who specified that a weekly intake of 3-4 mg lead produced no toxic effects. Due to the accumulation of lead in bones, however, disorders in bone metabolism could be possible.

Overall, analyses of lead concentrations in mammal bones are thought to be very useful for monitoring long-term lead accumulation, because they are not influenced by temporal point exposure (Kremer 1994).

6 REGIONAL DIFFERENCES AND CHANGES OF LEAD CONCENTRATIONS IN TERRESTRIAL PLANTS AND HUMANS

6.1 Variation Among Plant Species/Organs and Regions

The ability to uptake and accumulate heavy metals varies widely among different species (Ktinig/Kramer 1985). Lead concentrations in plants are strongly influenced by site factors, the time of harvesting, and seasonal variations in heavy metal deposition rates. The study of Chamberlain (1983) showed that plants take in lead mainly from the atmosphere and not from the soil. Therefore, varying lead concentrations in plants are assumed to reflect the differences in seasonal lead deposition from the atmosphere.

According to the analysis of KOnig (1986), who investigated lead loads in agricultural plants in 1979-1983, the adsorption of lead was most important for foliage plants. The lead concentration was positively correlated with leaf area (size), plant age, roughness of the leaf surface, and annual season. Additionally, same species from different sites showed varying lead levels due to the changing solubility of lead under different site conditions.

In 1983-1985 Schultz (1987) investigated eight forest ecosystems in northern Germany. Lead concentrations in needles and leaves were analysed for spruce, pine, oak and beech trees. It was proved that atmospheric lead depositions were accumulated mostly in the top surface of the forests. Spruce populations, for example, filtered more than 50 % of the atmospheric lead deposition accumulated in the top layer. Moreover, it was shown that the lead concentration in leaves and needles had decreased since 1975, when the regulation of reduced lead additives in gasoline was passed in Germany. Therefore, Schultz (1987) concluded that lead emissions from gasoline combustion were not responsible for the forest damage which appeared in the early 80s. In addition, it was determined that the toxicology of lead depended not on the total concentration but on the kind of complexation. This -27- explained why forest plants near to lead emitters were only slightly affected. Lead toxicity to plants was limited by the intercellular lead fraction (Schultz 1987).

In 1987-1993 lead concentrations of needles and leaves were analysed within the framework of the National Forest Soil Report of the German Federal Ministry of Agriculture, Nutrition and Forestry (BMLEF 1997). The results showed that atmospheric lead deposition had predominantly regional effects on forest plants. The mean lead concentrations in annual spruce needles were about 0.8 mg/kg dry weight. The overall value of lead contamination, estimated from the literature to be less than 3.0 mg Pb/kg, was exceeded in only 1 % of the samples. The median lead concentration in annual pine needles, 2.9 mg Pb/kg dry weight, was far below 5.0 mg Pb/kg, reported in the literature as a normal value. This normal value was exceeded in 13 % of the pine samples. Unwashed samples were analysed, however, so it is possible that some or most of the lead was only adsorped to the needle surface, having no toxicological effects on plants (BMLEF 1997).

6.2 Changes of Lead Contents of Plants over Time

Since 1985 the German Environmental Specimen Bank has measured changes in lead concentration in terrestrial ecosystems. One of the sample areas chosen for the analysis of annual spruce (Picea abies) sprouts and poplar (Populus nigra) leaves was in a highly populated area in Saarland. It was chosen because of its coal, mine and steel industries and high population density (Umweltbundesamt 1998).

The results showed a significant decrease in lead concentrations in sprouts and leaves in the years 1985-1994 (Figure 14). This development reflected the changes in atmospheric lead concentrations. Due to the several regulations imposed to reduce lead additives in gasoline that have come into effect since —O— poplar leaves the early 1970s, they have significantly decreased —A" spruce sprouts (Hagner 1999).

The lead levels of the spruce sprouts were much higher than those measured in spruce needles in the National Forest Soil Report (BMLEF 1997). This could be a result of the fact that spruce accumulated lead mainly in their buds and twigs and not in their needles (Schultz 1987).

Decreasing lead concentrations in poplar leaves and pine needles during the last two decades were Figure 14: Lead Concentrations (pg/g) in confirmed by a study of urban ecosystems in Spain. Spruce (Picea abies) Sprouts and Poplar The lead levels declined over this period and were (Populus nigra) Leaves in Urban Areas in positively correlated with automobile density (Toro Saarland, 1985-1996. etal. 1995). Data source: Umweltprobenbank 1999b. -28-

6.3 Blood Lead Levels in Humans

In 1979 and 1981 the blood lead levels of about 5000 adult and child probationers in the European Union were analysed (Wagner et al. 1987). The results showed a decreasing trend in blood lead levels in the population between those two years. To prove that trend, an investigation of school children (6-12 years old) in Berlin in the year 1976 was repeated in 1985. During those 9 years the blood lead levels decreased significantly. The mean value declined from 12.5 pg Pb/100 ml blood to 7.3 pg Pb/100 ml blood (Wagner et al. 1987).

Moreover, these three analyses determined that the contamination level of the German population was much lower than that of the United States, despite the fact that the German probationers of all age groups lived mainly in densely populated areas. Due to that trend of declining blood lead levels in the population Wagner et al. (1987), concluded that the lead reduction policies in Europe had been successful.

An “Environmental Survey” of the adult population of western Germany was conducted for the first time in 1985/86 (WaBoLu 1989); it was repeated in 1990/91 (before reunification) and again in 1991/92 (after reunification), when the investigation was extended to the former East Germany. The geometric mean values of lead in the blood of adults (25-69 years old) of East and West Germany were the same, equal to 45 pg/1. Men, but not women, in the east had a blood-lead level (59 pg/1) significantly higher than men in the west (54 pg/1). The lead content in blood of the adult population in Germany was similar to that found in Sweden (Svensson et al. 1987) and Switzerland (Probst-Hensch et al. 1993). A temporal comparison of the body burden of the West German population in 1985/86 and 1990/91 showed a significant reduction in the blood-lead level of about 27 %, i.e., an average of 17 pg/1 (WaBoLu 1996).

In the study the following factors were defined which influenced the blood-lead level in humans:

- In general, the blood-lead levels of men were higher than those of women. This was thought to be caused by a higher content of haemoglobin in men’s blood which resulted in a higher bonding capacity of lead (Schweinsberg/Karsa 1990).

- The lead content in blood increased significantly with age (WaBoLu 1996).

- The population living in overcrowded areas were more contaminated than that in the countryside. This was confirmed by the large-scale NHANES studies II (1976-80) and III (1988-91) of the United Nations (Pirkle et al. 1994). The finding was explained by a large amount of traffic and industrial lead deposition in large cities.

- Dry deposition of lead and leaded water pipes in houses positively increased blood lead levels (WaBoLu 1996).

- The blood-lead level of smokers was enhanced due to lead contamination in tobacco.

- Alcohol consumption increased the lead content in blood. This might be a result of an enhanced metabolism or the lead contamination of beer and wine (Hense et al. 1992). -29-

According to the evaluation categories defined by the German "Human-Biomonitoring" Commission, at least in 1996, the blood-lead levels of 99 % of the children, 98 % of the women of childbearing age and 98 % of other adults analysed in the “Environmental Survey" were harmless to health. There was no need for action due to the lead content in the blood of any group of the population. The experts of the German "Human-Biomonitoring” Commission stated that measures should be taken when the blood lead level of children and women of childbearing age exceeded 150 pg/1, or in other adults 250 pg/1 (WaBoLu 1996).

Decreasing blood-lead levels were confirmed by several studies in Germany. Figure 15 shows a comparison of analyses done in the years 1979-1997 (Heinzow 1998).

A significant decline in blood-lead levels was determined for every group of the sampled populations. According to the categories 1 and 2 defined by the German "Human-Biomonitoring” Commission, blood-lead levels in the investigated period were never high enough to cause acute health hazards. The regulations reducing lead additives in gasoline seemed to had been based instead on the idea of precaution (Hagner 1999).

* As the arithmetic mean is not available, the median is shown. In comparsion with other studies, the median is up to 10% higher than the arilhmetric mean.

The year the samples were taken is within 2 years of the year shown in the figure. The thresholds of categories 1 and 2 were redefined by the German “Human-Biomonitoring ” Commision, most recently in 1996. Category 1: normal burden, category 2: no health dangers are expected, but controls are recommended. For people with blood-lead levels above category 2, health dangers cannot be precluded, controls are recommended (Heinzow 1998, Human-Biomonitoring-Kommission 1996).

Figure 15: Blood-Lead Levels (pg/1) from Various Studies in Germany, 1979-1997.

Data source: Heinzow 1998. -30-

7 SUMMARY

Since 1979 several studies have analysed the longitudinal distribution of lead concentrations in the suspended matter and sediments of the River Elbe. Despite the regulations reducing lead emissions especially from automobiles, the lead content in suspended matter did not decrease during the 1980s and 1990s. This was explained by the high impact of lead discharges from soil eroded from the catchment area, tributaries and local emitters. Atmospheric lead deposition was of minor importance. Moreover, suspended matter was permanently deposited and resuspended so that younger and older surface sediments were mixed. Regional differences in lead concentration in fluvial suspended matter were mainly caused by the tide, runoff and flow velocity as well as local emissions.

Lead contamination of surface sediments in the estuaries was determined by upstream discharges, marine particles from the North Sea, resuspension and local lead emissions. Analyses of long-term lead pollution, in studies of subaqueous and floodplain sediment cores, showed that the anthropogenic lead pollution in the Elbe area was of recent origin. High lead concentrations were measured in cores from western Germany caused by high lead discharges from the former East Germany.

In the North Sea lead loads were caused mainly by atmospheric lead deposition and fluvial discharges. The estuaries of the rivers Weser, Elbe and Eider were, as confirmed by several studies, to be the most-polluted areas. However, lead loads in the open North Sea were too low to cause any damage to organisms. Analyses of sediment cores from the Wadden Sea showed highly enhanced lead concentrations in recent sediment layers. Due to flow, waves, bioturbation and meandering Wadden channels the contamination level in Wadden sediment cores was quite stable until deeper layers with geological background values were reached.

In terrestrial soils lead was accumulated mostly in the humus layer, compounded in metal-organic complexes. A country-wide investigation of lead concentrations in forest soils in Germany in 1987-1993 revealed that 25 % of the samples exceeded the critical value of 150 mg Pb/kg thought to be potentially toxic for soil organisms. High lead levels were found in industrial and oremining areas as well as in the environs of large cities. Moreover, long-range lead transport resulted in enhanced lead concentrations in mountain areas. On the European level lead contamination patterns were quite similar to the German results.

Lead contents of fluvial and marine bioindicators have been discussed for benthic organisms, mussels, fish and marine mammals. Compared to fossil foraminifers the lead concentration of recent organisms from the North Sea was enhanced by a factor of 15.5. Due to fluvial lead discharges, the highest lead contents were found in the German Bight. Lead concentrations of bladder wrack did not decline during the period 1985-1997. Studies of changes in lead contents of mussels in the last two decades also showed no trend of decreasing lead concentrations. While atmospheric lead concentrations declined in that time period, they did not decline in marine and freshwater organisms. The latter were more strongly influenced by the long-term accumulation of lead in soil and fluvial systems. Due to abiotic and biotic factors, the lead concentration in fish from the River Elbe and the North Sea varied widely over time but did not decrease. Overall, the lead content in fish flesh from the River Elbe was always far below the German threshold for human consumption. In general, lead concentrations in fish and -31- marine mammals living in the estuaries were higher than those of the Wadden or open sea, although differences occurred between Dutch, German and British coastal zones.

In contrast to freshwater and marine organisms, lead contents of terrestrial plants, such as trees, did indeed decrease in the 1980s and 1990s. Although the adoption and intake of lead was heavily influenced by species, site factors and seasonal lead deposition, declining lead concentrations in leaves, needles and sprouts were confirmed by different studies. Lead contents were positively correlated with decreasing atmospheric lead deposition, because plants take in lead mainly from the atmosphere and not from the soil. In contrast to terrestrial plants, marine and freshwater organisms or abiotic systems are mainly influenced by the long-term accumulation of lead in soil and fluvial systems.

Blood-lead levels in humans showed a similar trend. Studies of lead concentrations in different groups of the German population revealed decreasing blood-lead contents since 1979. Numerous factors influence the blood-lead level in humans, such as age, sex, area of residence, leaded water pipes or consumption of cigarettes and alcohol. Overall, the results showed that human lead contamination in Germany was alwaysbelow levels thought to damage human health.

ACKNOWLEDGEMENTS: I would like to thank the following people for their helpful suggestions and the information they provided: H. Emons, U. Ballin, U. Fdrstner, B.G.J. Heinzow, K.-H. van Bemem, A. Prange, W. Puls, H. Schleichert, M. Spott, M. Thiel, B. Gardeike, M. Costa-Cabral, J. Jones, F. Feser and H. von Storch.

8 REFERENCES

[1] Ackermann, F.: Dynamik der Schwermetallbelastung in feinkdmigen Sedimenten und Schwebstoffen im Tidebereich von Ems, Weser und Elbe. Bundesanstalt for Gewasserkunde, Koblenz 1998 [2] ARGE-Elbe: Data Source of Lead Concentration (mg/kg) in Suspended Matter (s20pm) and Monthly Mean Runoff (m3/sec) from the River Elbe, Hamburg 1999a [3] ARGE-Elbe: Data Source of Lead Concentration (mg/kg) in Deposited Sediment (s20pm) from the River Elbe, Hamburg 1999b [4] ARGE-Elbe: Data Source of Lead Concentration in Bream Muscles (adults) in the River Elbe 1979-1994. Hamburg 1999c [5] ARGE-Elbe: Entwicklung der Metallgehalte in Sedimenten der Tideelbe 1979-1994, Hamburg 1996a [6] ARGE-Elbe: Schadstoffe in Elbefischen - Belastung und Vermarktungsfahigkeit - von der Grenze bis zur See. Hamburg 1996b [7] ARGE-Elbe: Schwermetalldaten der Elbe - von Schnackenburg bis zur See 1984-1988. Hamburg 1988

■*w>Tti.v>v: i%y.> -32-

[8] ARGE-Elbe: Schwermetalldaten der Elbe. Bericht iiber die Ergebnisse der Schwer- metalluntersuchungen im Elbabschnitt von Schnackenburg bis zur Nordsee 1979/1980. Hamburg 1980 [9] Ballin, U.: Staatliches Veterinarantersuchungsamt far Fische und Fischwaren, Cuxhaven, personal communication, November 5,1999 [10] BgVV (Bundesamt far gesundheitlichen Verbraucherschutz und Veterinarmedizin): Richtwerte des BgW. Bundesgesundheitsblatt, Nr. 39, Mai 1996 [11] BMLEF (Bundesministerium far Landwirtschaft, Ernahrung und Forsten): Deutscher Waldbodenbericht 1996. Ergebnisse der bundesweiten Bodenzustandserhebung im Wald von 1987-1933. Bonn 1997 [12] Chamberlain, A.C.: Fallout of Lead and Uptake by Crops. Atmospheric Environment, No. 17/4,1983 [13] Debus, L.: NahrungsOkologische Untersuchungen an juvenilen Bleien und Ploetz. Dissertation, Uni Rostock, 1987 [14] Emons, H.: Umweltprobenbank, Forschungszentrum Jalich, personal communication, November 5,1999 [15] Federal Office of Navigation and Hydrography: Data source of Lead Concentration in Sediment Cores from the North Sea. Hamburg 1999 [16] Fdrstner, U.; Wittmann, G.T.W.: Metal Pollution in the Aquatic Environment. Berlin 1983 [17] Fdrstner, U.; Midler, G.: Schwermetalle in Fliissen und Seen als Ausdruck der Um- weltverschmutzung. Berlin 1974 [18] Fdrstner, U.; Reineck, H.E.: Die Anreicherung von Spurenelementen in den rezenten Sedimenten eines Profilkemes der Deutschen Bucht. Senckenbergiana Marit., Nr. 6/1974 [19] Gadow, S.; Schafer, A.: Die Sedimente der Deutschen Bucht: KomgrdBen, Tonminerale und Schwermetalle. Senckenbergiana Marit., No. 5/1973 [20] Gaumert, T.: Schadstoffilberwachung der Elbe mit der Dreikantmuschel Dreissena polymorpha - Aktives Biomonitoring. In: Karbe, L.; Madler, K.; Westendorf, J. (eds.): Biologische Effekte von Schadstoffen und toxisches Potential von Wasser und Sediment in Elbe und Nordsee, Hamburg 1994 [21] Guhr, H.: Sources of Heavy Metal Pollution in the Drainage Area of the River Elbe in the Former GDR. In: Wilken, R.-D.; Fdrstner, U.; Kndchel, A.: Heavy Metals in the Environment Proceedings of the International Conference, Vol. 2, Hamburg 1995 [22] Hablizel, H.; Karbe, L.: Langzeit-Trends und saisonale Varianz der Schwermetall- Kontamination von Miesmuscheln: Ems-, Jade-, Weser- und Elbeastuar. In: Karbe, L.; Madler, K.; Westendorf, J. (eds.): Biologische Effekte von Schadstoffen und toxisches Potential von Wasser und Sediment in Elbe und Nordsee, Hamburg 1994 [23] Hagner, C.: Historical Review of European Gasoline Lead Content Regulations and their Impact on German Industrial Markets. GKSS Research Center, Report no. 99/E/30, Geesthacht 1999 [24] Hapke, H.J.: Metal Accumulation in the Food Chain and Load of Feed and Food. In: Merian, E. (ed.): Metals and their Compounds in the Environment. Weinheim 1991 [25] Harms, U.: Schwermetalle Cadmium, Blei und Quecksilber in Fischen. In: Lozan, J.L.: Lenz, W.; Rachor, E.; Watermann, B.; von Westemhagen, H. (eds.): Wamsignale aus den Nordsee. Hamburg 1990 -33-

[26] Heinzow, B.G.J.; Sieg, I.; Sabbioni, E.; Hoffmann, B.; Schacke, G.; Schulz, C.; Krause, C.: Trace Element Reference Values in Tissues from Inhabitants of the European Union. Review of Trace Elements in Blood, Serum and Urine and Critical Evaluation of Reference Values for the German Population. Untersuchungsstelle fur Umwelttoxikologie des Landes Schleswig- Holstein, Kiel 1998 [27] Hense, H.-W.; Filipiak, B.; Novak, L.; Stoeppler, M.: Nonoccupational Determinants of Blood Lead Concentrations in a General Population. International Journal of Epidemiology, No. 21/1992 [28] HObel, C.: Zum Schwermetallgehalt im Okosystem der Deutschen Bucht, mit besonderer Berilcksichtigung rezentmariner, benthischer Foraminiferen, Dissertation, Clausthal 1984 [29] Human-Biomonitoring Kommission: 5. Sitzung der Kommission “Human-Biomonitoring” (HBM) des Umweltbundesamtes am 18/19.5.1995 im Institut for Wasser-, Boden- und Lufthygiene, Berlin 1996 [30] Kapitza, H.; Eppel, P.: A Case Study in Atmospheric Lead Pollution of Northern-German Coastal Regions. GKSS Research Center, Geesthacht 28.6.1999 [31] KOnig, W.: Ursachen und EinfluBfaktoren far die Schwermetallgehalte von Boden und Kulturpflanzen - dargestellt anhand von Ergebnissen einer Erhebungsuntersuchung in Nordrhein-Westfalen. Forschung und Beratung Reihe C, Heft 43, MOnster-Hiltrup 1986 [32] KOnig, W.; Kramer, F.: Schwermetallbelastung von Boden und Kulturpflanzen in Nordrhein- Westfalen. Schriftenreihe der LOLF Nordrhein-Westfalen, Band 10, Bonn 1985 [33] Koopman, C; Faller, J.; Bemem, K.-H. van; Prange, A.; Muller, A.: Schadstoffkartierung in Sedimenten des deutschen Wattenmeeres - Juni 1989-Juni 1992. GKSS Research Center, Report no. 94/E/6, Geesthacht 1994 [34] Kremer, H.: Verteilungsmuster der Schwermetalle Blei, Cadmium und Quecksilber in Weich- und Hartgeweben mariner Saugetiere aus deutschen Kustengewassern. Schriften der Bimdesforschungsanstalt fUr Fischerei Nr. 21, Hamburg 1994 [35] Kruse, R.; Ballin, U.; Krhger, K.-E.: Trendstudie zur langfristigen Schadstoffkontamination von Elbfischen zwischen 1979 und 1994. In: Guhr, H.; Prange, A.; Puncochar, P.; Wilken, R.- D.; Bttttner, B. (eds.): Die Elbe im Spannnungsfeld zwischen Okologie und Okonomie, 6. Magdeburger Gewasserschutzseminar, Leipzig 1994 [36] Laane, R.W.P.M.: Background Concentrations of Natural Compounds in Rivers, Sea Water, Atmosphere and Mussels. Ministry of Transport, Public Works and Water Management, Report DGW-92.003, The Hague 1992 [37] Lozan, J.L.; Kausch, H. (eds.): Wamsignale aus FlOssen und Astuaren. Berlin 1996 [38] Lozan, J.L; Rachor, E.; Reise, K.; von Westemhagen, H.; Lenz, W. (eds.): Wamsignale aus dem Wattenmeer. Berlin 1994 [39] Luckas, B.; Harms, U.: Characteristic Levels of Chlorinated Hydrocarbons and Trace Metals in Fish from Coastal Waters of North and Baltic Sea. International Journal of Environmental Analytic Chemistiy, No. 29,1987 [40] Meyercordt, J.: Untersuchungen zum langjahrigen Verlauf von Schwermetalldepositionen in ausgewdhlten schleswig-holsteinischen Salzmarschen auf der Basis von Radionuklid- messungen. GKSS 92/E/107, GKSS-Forschungszentrum, Geesthacht 1992

- -34 -

[41] Miehlich, G.: Auen und Marschen als Senken fur belastete Sedimente der Elbe. In: Guhr, H.; Prange, A.; Puncochar, P.; Wilken, R.-D.; Btittner, B. (eds.): Die Elbe im Spannnungsfeld zwischen Okologie und Okonomie, 6. Magdeburger Gewasserschutzseminar, Leipzig 1994 [42] Ministry of Ecology of Niedersachsen: Data Source of Lead Concentration in Blue Mussels in the North Sea 1982-1997, Hannover 1999 [43] Ministry of Nature and Environment of Schleswig-Holstein: Data Source of Lead Concentration in Blue Mussels in the North Sea 1990-1996, Kiel 1999 [44] Muller, G.; Furrer, R.: Schwermetalle in den Sedimenten der Elbe und ihrer Zuflusse. In: Guhr, H.; Prange, A.; Puncochar, P.; Wilken, R.-D.; Btittner, B. (eds.): Die Elbe im Spannnungsfeld zwischen Okologie und Okonomie, 6. Magdeburger Gewasserschutzseminar, Leipzig 1994 [45] OSPARCOM: Assessment of Temporal Trend Monitoring Data 1983-1988: Trace Metals and Organic Contaminants in Biota. In: OSPARCOM: Monitoring and Assessment, Part C: Results of the Monitoring of Organisms. London 1992 [46] Pirkle, J.L.; Brody, D.J.; Gunter, E.W.; Kramer, R.A.; Paschal, D.C.; Flegal, K.M.; Matte, T.D.: The Decline in Blood Lead Levels in the United States. The National Health and Nutrition Examination Surveys (NHANES). JAMA 272, No. 4/1994 [47] Postma, H.: Hydrographic of the Wadden Sea: Movements and Properties of Water and Particular Matter. Wadden Sea Working Group, Report 2, Amsterdam 1982 [48] Prange, A. et al.: Erfassung und Beurteilung der Belastung der Elbe mit Schadstoffen. Teilprojekt 2: Schwermetalle - Schwermetallspezies. Geogene Hintergrundwerte und zeitliche Belastungsentwicklung. GKSS Research Center, Abschlufibericht far das BMBF- Forschungsvorhaben: 02-WT 9355/4, Geesthacht 1997 [49] Prange, A.: GKSS-Forschungszentrum, Geesthacht, personal communication, November 16, 1999 [50] Probst-Hensch, N.; Braun-Fahrlaender, C.; Bodenmann, A.; Ackermann-Liebrich, U.: Alcohol Consumption and other Lifestyle Factors: Avoidable Sources of Excess Lead Exposure. Soziale Praventivmedizin, No. 38/1993 [51] Rainbow, P.S.: Heavy Metal Levels in Marine Invertebrates. In: Furness, R.W.; Rainbow, P.S. (eds.): Heavy Metals in the Marine Environment, Florida 1990 [52] RSU (Rat der Sachverstandigen fur Umweltfragen): Umweltprobleme der Nordsee. Sondergutachten 1980, Stuttgart 1980 [53] Schleichert, H.: Bundesanstalt fur GewSsserkunde, Koblenz, personal communication, September 30,1999 ' [54] Schultz, R.: Vergleichende Betrachtung des Schwermetallhaushalts verschiedener WaldOko- systeme Norddeutschlands. Berichte des Forschungszentrums Waldokosysteme/Waldsterben, Reihe A, Bd. 32, Kassel 1987 [55] Schwedhelm, E.; Irion, G.: Schwermetalle und Nahrelemente in den Sedimenten der deutschen Nordseewatten. Senckenbergische Naturforschende Gesellschaft, Frankfurt 1985 [56] Schwedhelm, E.; Irion, G.: Heavy Metal Distribution in Tidal Flat Sediments of the German Part of the North Sea. In: CEP Consultants Ltd.: Heavy Metals in the Environment. International Conference in Heidelberg 1983, Edinburgh 1983 [57] Schweinsberg, F.; Karsa, L. von: Heavy Metal Concentrations in Humans. Compendium of Biochemical Physiology, No. 95C/1990 -35 -

[58] Shotyk, W.: Atmospheric Deposition of Lead Recorded in Peat Bog Profiles from the Jura Mountains, Switzerland, and Northwestern Scotland. In: Wilken, R-D.; FOrstner, U.; Kntichel, A.: Heavy Metals in the Environment. Proceedings of the International Conference, Vol. 1, Hamburg 1995 [59] Spott, M.: Sektion Gewasserforschung (Inland Water Research), Umweltforschungszentrum Leipzig, personal communication, September 30,1999 [60] Svensson, B.G.; Bjtirnham, A.; Schiltz, A.; Lettevall, U.; Nilsson, A.; Skerfving, S.: Acidic Deposition and Human Exposure to Toxic Metals. Science of Total Environment, No. 67/1987 [61] Streit, B.: Lexikon der Okotoxikologie. Weinheim 1992 [62] Thiel, M.: Institut ftlr Hydrobiologie und Fischereiwissenschaften, Hamburg, personal communication, October 29,1999 [63] Toro, C.; Arunachalam, J.; Marin, C.; Vinagre, F.; Ostapczuk, P.: Poplar Leaves and Pine Needles as Biomonitors for Air Pollution. In: Wilken, R-D.; FOrstner, U.; Kndchel, A.: Heavy Metals in the Environment. Proceedings of the International Conference, Vol. 1, Hamburg 1995 [64] Tyler, G.: Critical Concentrations of Heavy Metals in the Mor Horizon of Swedish Forests. SNV-Report 4078, Solna 1992 [65] Umweltbundesamt (ed.): Umweltprobenbank des Bundes. Ergebnisse aus den Jahren 1994 und 1995. Umweltbundesamt-Texte 14/98, Berlin 1998 [66] Umweltbundesamt: Erprobung von Zielvorgaben fur gefahrliche Stoffe an ausgewahlten FlieBgewSssern - Vergleich von Belastungsdaten und Zielvorgaben for Schwermetalle 1991-1994. Umweltbundesamt Texte 14/97, Berlin 1997 [67] Umweltbundesamt: Fischkrankheiten in der Nordsee. Umweltbundesamt-Texte 57/96, Berlin 1996 [68] Umweltprobenbank: Data Source of Lead Concentration (pg/g) in Blue Mussels and Bladder Wrack in the German Wadden Sea 1985-1997, Jtilich 1999a [69] Umweltprobenbank: Data Source of Lead Concentration (pg/g) in Spruce Needles (Picea abies) and Poplar Leaves (Populus nigra) in Urban Areas in Saarland 1985-1996, JOlich 1999b [70] Vanmechelen, L.; Groenemans, R; van Ranst, E.: Forest Soil Condition in Europe. Results of a Large-Scale Soil Survey. A Report of the United Nations Economic Commission for Europe and the European Commission, Brussels 1997 [71] Vesely, J.: Expert arguments about the long-term lead concentration in the sediments of the upper River Elbe, Prague 1999 [72] Vink, R; Behrendt, H.; Salomons, W.: Development of the Heavy Metal Pollution Trends in Several European Rivers: an Analysis of Point and Diffuse Sources. Water Science Technology, Vol. 339, No. 12 [73] WaBoLu (Institut ftir Wasser-, Boden- und Lufthygiene): Umwelt-Survey 1990/92 Band la: Studienbeschreibung und Human-Biomonitoring. Deskription der Spurenelementgehalte in Blut und Urin der BevOlkerung in der Bundesrepublik Deutschland. WaBoLu Berichte 1/96, Umweltbundesamt, Berlin 1996 [74] WaBoLu (Institut ftir Wasser-, Boden- und Lufthygiene): Umwelt-Survey I: Studien­ beschreibung und Humanbiologisches Monitoring. WaBoLu-Berichte 5/1989, Bundesgesundheitsamt, Berlin 1989 -36-

[75] Wachs, B.: Akkumulation von Blei, Chrom und Nickel in FluBfischen. Zeitschrift fur angewandte Zoologie, 79. Jahrgang, Berlin 1992/93 [76] Wagner, H.M.; Englert, N.; Krause, C.: Nachweis einer tendenziellen Abnahme der Bleibelastung bei der BevOlkerung der Bundesrepublik Deutschland. In: Lahmann, E.; Jander, K. (eds.): Schwermetalle in der Umwelt. Umwelthygienische und gesundheitliche Aspekte. Stuttgart 1987