Schwermetallbelastung von Dreissena polymorpha in Donau und Drau und ihre Bedeutung als Bioindikator

Goal and Scope

This study was undertaken to investigate the differences in heavy metal burden between the organisms and environmental compartments and to evaluate the role of Dreissena polymorpha as a bioindicator organism.

Methods

The concentrations of zinc, copper, cadmium and lead in whole soft body and selected tissues of D. polymorpha at two river habitats in Austria were examined using atomic absorption spectroscopy (AAS). Concentrations in organisms were compared to those in sediment and water.

Results and Conclusion

Zebra mussels of the river Drau showed generally higher heavy metal concentrations as compared to mussels of the river Danube and contained elevated zinc and cadmium levels as compared to metal concentrations found in soft tissues of zebra mussels from uncontaminated sites in Germany and The Netherlands. The essential metals zinc and copper were mainly accumulated in gills, foot and byssal gland tissue of the mussel, in contrast to the non-essential metals cadmium and lead which were found predominantly in the midgut gland. The heavy metal concentrations in both, sediments and mussel tissue, were higher than in water samples. There was no correlation between the concentrations in water and in the organisms except for zinc. In contrast, correlations were found between concentrations in sediments and mussel soft tissue.

Recommendation and Perspective

Further investigations should include the examination of sediments and consider the mechanism of food uptake to assess the role of D. polymorpha as a bioindicator organism.     

The common mussel Mytilus edulis as an indicator of pollution by zinc,cadmium, lead and copper. I. Effects of environmental variables on uptake of metals

The net uptake of zinc, cadmium, lead and copper by the common mussel Mytilus edulis (L.) exposed to different conditions was investigated with a view to using this species as an indicator of contamination of the marine environment by these metals. The variables studied were season, position of the mussel in the water column, water salinity, water temperature, and the simultaneous presence of all four metals. Each of these 5 variables affected the net uptake of some or all of the metals studied under some conditions. Seasonal variation in concentrations of zinc, cadmium and copper was found in samples collected at three separate locations. The relationship of seasonal variation to tissue weight and absorption route of the metals is discussed. Near to freshwater inputs of trace metals, the concentrations of zinc, cadmium and lead in mussels were found to vary according to the depth at which the mussels were collected; in summer when freshwater run-off is less, this effect was absent. Low salinities did not affect the net uptake of zinc by mussels, but increased the net uptake of cadmium and decreased that of lead. Low temperatures had no effect on the net uptake of zinc or lead; the net uptake of cadmium was unaffected by low temperatures at high salinities but was decreased by low temperatures at low salinities. The presence of the other metals had no effect on the individual net uptake of either zinc, cadmium or lead. A sampling programme was devised to eliminate the effects of these environmental variables and to allow the use of M. edulis as an indicator of zinc, cadmium and lead in marine and estuarine environments. In contrast to the other metals, the net uptake of copper by the mussel was extremely erratic, and was affected by salinity and temperature changes and by the presence of the other metals and changes in their relative concentrations. The effects of other metals on the net uptake of copper cannot be easily eliminated or allowed for; it is, therefore, suggested that the mussel should not be used as an indicator of copper in the marine environment.     

Toxicity of zinc,cadmium and copper to the shrimp Callianassa australiensis. III. Accumulation of metals

Callianassa australiensis (Dana) that survived 14 d acute lethality studies were analysed to determine the concentrations of zinc, cadmium and copper in the whole shrimp and in various parts of the body. Using regression analysis, the influence of each metal upon the uptake of the others was studied. Zinc and cadmium appeared to enhance the uptake of each other. In a mixture of zinc and copper, the uptake of zinc was enhanced and that of copper was inhibited. In a mixture of cadmium and copper, the uptake of copper was inhibited by the presence of cadmium, but cadmium uptake was unaffected in the presence of copper. In a mixture of all three metals, similar effects were observed except that zinc and copper, occurring together, appeared to have no effect upon cadmium uptake. Additional 14 d experiments with cadmium suggested that accumulation of this metal was a function of metal concentration in the water and of duration of exposure. The whole shrimp cadmium concentration also appeared to be a function of the size of the shrimp. The variation in concentration factors is described and the need for further research on the effects of combinations of metals on various organisms is emphasized.     

The common mussel Mytilus edulis as an indicator of trace metals in Scandinavian waters. I. Zinc and cadmium

Concentrations of zinc and cadmium in whole soft parts of mussels, Mytilus edulis (L.), collected from 54 locations in Scandinavian waters were determined. Local variations in concentrations of the two metals found in samples taken close to industrial sources of zinc and cadmium confirmed the ability of the mussel to act as an accurate indicator of pollution by these metals over the entire range of salinities in which this species can exist. In addition, offshore samples remote from industrial discharges revealed higher concentrations of zinc and cadmium in mussels from lowsalinity areas (Gulf of Finland, Southern Bothnian Sea, Baltic proper) than in those from high-salinity areas (Kattegat, Eastern Skagerrak). Major decreases in metal concentrations present in the mussel were apparent in the regions of the Sound and the Great Belt, which are areas of rapid salinity change due to mixing of Baltic water with water from Kattegat. Comparison of these results with those reported for zinc and cadmium in water throughout the study area suggested the existence of a higher biological availability of these metals in regions of low salinity; possible reasons for this are discussed. Data from the present survey are also compared to those reported for mussels taken elsewhere. This comparison reveals the Baltic area to be considerably polluted by trace metals; in contrast, the waters of Kattegat and skagerrak are considered to be relatively unpolluted.     

Heavy metals and pesticides in anuran spawn and tadpoles,water, and sediment

High concentrations of metals (cadmium, copper, lead, and zinc) and of lindane were measured in the sediment and in the spawn and tadpoles of Bufo bufo, Rana dalmatina, and Rana ridibunda from two Austrian locations. Residues in spawn suggest maternal transfer. Increase of the metal concentrations from spawn to advanced tadpole stage is explained by the larval microphaguous feeding habits which cause high exposition of the tadpoles to substances concentrating in sediments and suspended particles. Metal and pesticide concentrations in spawn and tadpoles are toxic to various other aquatic organisms and are furthermore considered to be potentially hazardous to the anurans themselves. The results are conform with world‐wide observations of contamination of anuran larvae with heavy metals, and prove the significance of non‐point source chemical exposure due to allochthonous toxicant input by wind load and precipitation.     

Metal levels in some benthic organisms of Haifa Bay,mediterranean (Israel)

Benthic organisms revealed enhanced uptake of mercury from polluted surface sediments (in the vicinity of a chlor‐alkali plant) which were enriched in mercury by up to 148 times relative to sediments from an unpolluted area. There is a strong correlation between the concentrations of mercury in the benthic organisms and sediments. No correlation was found between cadmium, lead, copper and zinc levels in the benthic fauna populations and the concentrations of these metals in the sediments. Ranges of concentrations (μg/g wet wt.) in the whole soft tissues varied: Hg, <0.005–3.31; Cd <0.018–1.99; Pb, <0.025–1.56; Cu, 0.242–28.8; and Zn, 9.75–310.2. The three gastropod molluscs show higher metal concentrations than do the bivalves.     

The effects of exposure to zinc and cadmium separately and jointly on the free amino acid pool of Gammarus pulex (L.)

Effects of the heavy metals zinc and cadmium on the free amino acid (FAA) pool of Gammarus pulex were studied at different metal concentrations and combinations as well as different exposure times. The dominant effect of these two metals was the reduction of most free amino acids and the whole FAA pool, except in the 10‐day low zinc and cadmium concentration exposures which resulted in a rise of free amino acid pool.

Among the free amino acids, the most sensitive to zinc exposure, were alanine, glutamic acid, arginine, and taurine; valine, leucine, asparagine, and isoleucine were among the most sensitive to cadmium. No predictable changes of individual free amino acids were shown in the mixed metals exposures. Elevation of taurine concentration was constant in seven of the eight treatments, it is suggested that this elevation may be related to the hepatopancreatic damage observed and induced synthesis of metallothioneins.     

Concentrations of cadmium,manganese, copper,zinc, and lead in the tissues of the oyster (Crassostrea iredalei) obtained from Setiu Lagoon,Terengganu, Malaysia

Heavy metals pollution in aquatic environments is a major problem contributing to human health issues. The study of these pollutants through bioindicators such as the oyster Crassostrea iredalei is important for (1) determining the levels and sources and (2) regulating the quantity of pollutants. The concentrations of cadmium (Cd), manganese (Mn), copper (Cu), zinc (Zn), and lead (Pb) in tissues of C. iredalei, sediment and surrounding water was measured, and data was analyzed to determine the relationship between sampling periods and between oyster tissue, sediment, and water. The highest concentration of metals in oyster tissue was Zn, followed by Cu, Mn, Cd, and Pb. Concentrations of Cd, Cu, and Zn exceeded the maximum level allowed according to the Malaysian Food Act of 1983, which is equivalent to the WHO recommended levels of heavy metals in organisms used for consumption. The highest metal concentration in sediment was Mn followed by Zn, Pb, Cu, and Cd. Concentrations of heavy metals in surrounding water were Zn, Pb, Cu, Mn, and Cd. There was no correlation between metal concentration in oyster tissue and in sediment for all five metals.     

The Influence of Temperature and Salinity Upon the Acute Toxicity of Heavy Metals to the Banana Prawn (Penaeus merguiensis de Man)

Bioassays were conducted to determine the effects of temperature and salinity on the acute toxicity of mercury, copper, cadmium, zinc, nickel and lead to juvenile banana prawns (Penaeus merguiensis de Man). Tests were conducted at all combinations of 35, 30 and 20°C with 36 and 20° salinity over 96 h. The general rank order of metal toxicity was Hg > (Cu, Cd, Zn) > Ni > Pb. The toxicity of all metals increased with increased temperature. This was most noticeable in the high salinity treatments, particularly for copper and zinc. Salinity appeared to influence the toxicity of all metals tested although significant differences were only found for copper and lead at 20°C. At this temperature prawns were markedly more susceptible to both metals in low salinity sea water. The data are compared with lethal concentrations found for other crustaceans and are discussed in relation to existing water quality criteria.     

Baseline study on Cd,Cu and Pb concentrations in Atlantic neuston organisms

Neuston organisms were caught during two Atlantic expeditions (1982 and 1987) between 48°N and 40° S. About 1200 individuals from 19 taxa were analysed for cadmium, copper and lead. The distribution of metal concentrations was log-normal and thus best described by the median and the percentiles. Fourteen taxa with sample numbers larger than 20 were subjected to a logarithmic regression of weight vs metal concentration. The metal concentrations from populations with significant correlations were then weight-corrected: eight populations for lead, five for cadmium and four for copper. When grouped into ecological categories the pleuston organisms displayed significantly higher cadmium concentrations than the euneuston, which in turn had higher values than the pseudo-and/or facultative neuston. The relative deviation from the median was used in an averaging operation to obtain a broader spatial resolution of the neuston-bound metals, based on 16 taxa which were encountered at ten or more stations. The geographical distribution of cadmium and lead can be interpreted in light of chemical oceanographic knowledge and underlines the importance of organisms in the biogeochemical cycling of metals in the sea.     

An assessment of copper,zinc and cadmium contamination and their ecotoxicological effects in O. mediterranea Costa, 1853 (Amphipoda,Talitridae)

This study was conducted to compare metals bioaccumulation in the Talitrid O. mediterranea collected from the banks of Bizerte lagoon. Individuals were exposed to a series of contaminated soil with different concentrations of cadmium, copper, and zinc. Biological and physiological responses were highlighted. Body metals concentrations were measured in the talitrid using flame atomic emission spectrometry. Results showed that after the second week, the mortality increased especially with cadmium exposure, and a mass gain was obtained between weeks for copper and zinc. Furthermore, the concentration factor indicated that O. mediterranea could be considered as a macroconcentrator of copper and zinc. Histopathological analysis showed that the different metals concentrations induced significant changes in the morphology and in the ultrastructural organisation of hepatopancreatic cells. Significant alterations obtained after metals exposure were the increase in the number of the majority cell organelles. Also, heavy metals were present in the form of numerous granules with different size in the cell surface. Furthermore, metals exposure affected the brush border causing the disruption of microvilli filament. Through these results, O. mediterranea could be a good indicator providing measurable responses. It could be an attractive candidate for the biochemical study of heavy metals toxicity in coastal ecosystems.     

High copper concentrations in squid livers in association with elevated levels of silver,cadmium, and zinc

Livers from 43 Loligo opalescens, 14 Ommastrephes bartrami, and 7 Symplectoteuthis oualaniensis were analyzed for their silver, cadmium, copper, zinc and iron contents. Copper concentrations of up to 15,000 μg/g dry weight were found in L. opalescens in conjunction with significant correlations between this element and Ag, Cd and Zn. The latter elements are known to affect Cu metabolism in terrestrial organisms; however, whether the correlations occurring in marine organisms represent casual, or cause and effect, relationships is as yet unknown.     

Tissue distribution of Cd,Cu, Zn,Ni, Cr,Pb and Hg in striated heron,Butorides striatus (Aves: Ardeidae), in a fluvial ecosystem

In this study, the striated heron (Butorides striatus), a species that reproduces in the Middle Paraná River floodplain, was examined for lead, cadmium, chromium, zinc, nickel, mercury and copper concentrations, using liver, kidney, muscle, vertebra and feathers. The results showed low exposure to chromium because all tissue samples had concentrations below the limit of detection. Similar results were obtained for nickel and lead, with the exception of vertebra. This might be associated with either long-term exposure to these metals, or it may be that both nesting and wintering areas are non-polluted. Zinc and copper, both essential metals, were found in all tissues and their concentrations were within the ranges reported in the literature. Mercury was also found in all tissues, but at very low concentrations and even at concentrations below those that produce negative effects in several species of birds (e.g. reproductive success, food intake). Studies of this type are needed to interpret the role of organisms within environments impacted by different human activities.     

Modelling the concentrations of dissolved contaminants (Cd,Cu, Ni,Pb, Zn) in floodplain soils

Central European floodplain soils are often contaminated with potentially toxic metals. The prediction of their aqueous concentrations is a prerequisite for an assessment of environmental concerns. We tested the aqueous concentrations of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) derived from multi-surface adsorption modelling (on hydrous iron, aluminum and manganese oxides, clay and soil organic matter) against those analyzed in situ in the soil solution of four horizons of floodplain soils at the Elbe River, Germany. The input data for the reactive metals were derived from a seven-step sequential extraction scheme or from extraction with 0.43 M nitric acid (HNO₃) and evaluated in four modelling scenarios. In all scenarios, measured and modelled concentrations were positively related, except partially for Pb. Close reproduction of the measured data was obtained using measured data of accompanying cations and anions together with amounts of reactive metals from both the sequential extraction or from 0.43 M HNO₃ extraction, except for Cu, which was often strongly overestimated, and partially Cd. We recommend extraction with 0.43 M HNO₃ to quantify reactive metals in soil because the modelling results were metal-specific with better or equal results using the single extractant, the application of which is also less laborious. Approximations of ion concentrations and water contents yielded similar results. Modelled solid-phase speciation of metals varied with pH and differed from that from sequential extraction. Multi-surface modelling may be an effective tool to predict both aqueous concentrations and solid-phase speciation of metals in soil.     

Soil and plant concentrations of cadmium and zinc in the vicinity of a smelter

Cadmium, zinc and lead concentrations in soils and plants near a smelter at Avonmouth are reported for samples collected in May 1979 and in May 1980. The total metal soil concentrations fall as distance from the smelter increases and decrease rapidly with depth for cadmium and zinc. The concentrations of these two metals are highly correlated at all depths. Near the smelter, where the carbon content and pH values of the soils are lowest, almost all the cadmium, as measured by EDTA extraction, is available. Concentration of metals in plants also decrease with distance from the smelter, with concentrations being lower in samples collected in 1980. This is possibly due to a seasonal variation in biomass, producing a dilution effect. We conclude that uptake of cadmium and that of zinc by grass species have different relationships to the carbon content of the soil.     

Some Preliminary Observations On Zinc and Cadmium Accumulative Capacity in Arum Italicum Mill

Pot and hydroponic trials as well as tests on samples collected in a mining area and in two different urban sites of Tuscany were carried out on Arum italicum Mill (Italian arum) plants. Zinc and cadmium contents were determined by differential pulse anodic stripping voltammetry (DPASV) in different organs of about 180 samples. After 65 days treatment, zinc and cadmium median contents in leaves of plants grown hydroponically in solutions containing both metals at different concentrations fell within the range of 281-2022 and 8.3-45.1 μg g^-1 (dry weight), respectively. Some Italian arum plants were also cultivated in pots in the presence or absence of malate or citrate in order to evaluate the role of these ligands in zinc and cadmium accumulation. Citrate enhanced cadmium uptake compared to malate.     

Patterns of trace-metal distribution in tissues of Pleoticus muelleri (Crustacea: Decapoda: Solenoceridae)

Trace-metal distribution in tissues of the shrimp Pleoticus muelleri Bate from the Patagonian region, Argentina, was related to sex, size and physiological condition. Concentrations of cadmium, copper, manganese and zinc were determined in the digestive gland, male reproductive system and muscle of adult specimens. Significant (p<0.01) sex-dependent differences in mean metal concentrations (g g^-1 wet wt) were found in the following tissues of males and females, respectively: digestive gland, Cu, 82.9 and 30.8; Zn, 32.5 and 44.9; reproductive system, Zn, 12.8 and 38.6; Mn, 1.7 and 3.1; Cd, 0.29 and 0.58. Metal levels of muscle showed no significant differences between sexes. Cadmium was not detected in muscle, suggesting that its incorporation into this tissue was strictly regulated. Metal concentrations in the male reproductive system were in general weakly correlated (0.001<p<0.05) with either body size or the concentration of metals in the digestive gland. The developing ovary incorporated substantial amounts of zinc, while cadmium and copper levels decreased at proportional rates (p<0.001). The patterns of the variations in the concentrations of these metals in the ovary strongly suggested that a regulatory mechanism operated throughout oogenesis. Manganese was not involved in this presumptive mechanism. The results of this study are discussed in terms of concentrations and in absolute amounts for standardized individuals.     

Contribution to the ecotoxicological study of cadmium,copper and zinc in the mussel Mytilus edulis

A regulation of internal levels of some essential metals has been observed in various animals, whereas the bioaccumulation of several non-essential metals parallels their overloads in water. In the mussel Mytilus edulis L., we have attempted to determine if such a phenomenon exists by comparing the patterns of accumulation of copper and zinc vs cadmium. With this aim, mussels collected in the Bay of Bourgneuf (France) in November 1983 were exposed to these metals for 16 d. At external levels of zinc as high as 100 gl^-1, mussels were able to maintain a normal concentration in all groups of organs for 4 d. The ability of mussels to limit the bioaccumulation of copper and zinc varied from organ to organ, and decreased with higher levels of contamination and longer periods of exposure. In contrast, at the lowest experimental concentration and the lowest period of exposure, a significant increase of cadmium in mussel tissues was generally observed. Even at the highest sub-lethal doses, the levels of copper and zinc in mussel tissues were not much higher than the natural levels (contaminated:background ratios= 2.3 to 6.1), whereas the bioaccumulation of cadmium was less well restricted (contaminated:background ratios=136 to 192). The use of mussels as a bioindicator of pollution seems doubtful for essential metals, particularly as regards short-term pollution, since the levels of these trace elements in the organisms are largely independent of their concentration in the ambient seawater.     

Bioaccumulation of heavy metals by bivalves from Lim Fjord (North Adriatic Sea)

Trace metal concentrations (Zn, Cd, Pb and Cu) were studied in two different bivalve species of the same age, the mussel Mytilus galloprovincialis, Lmk., and the oyster Ostrea edulis, Linnaeus, which had been grown in the water of Lim Fjord, North West Yugoslavia (Peninsula Istria), i.e. under the same physicochemical conditions. The study offers a realistic view on the metal accumulation ability of oysters and mussels. The distribution of trace metals over the different organs and the edible parts of the mussels and oysters, collected in June 1979, was determined and is discussed in detail. The results are supported by the determination of the trace metal levels in the dissolved state and in the suspended material in the ambient sea water of the bivalves. Concentration factors for zinc, cadmium, lead and copper in the mussels of: 95 000, 9 100, 1 500 and 4 000; and in the oysters of: 95 500, 30 400, 3 400 and 64 500 were found, respectively. The values were evaluated comparing the metal concentration in the bivalve soft part and the dissolved trace metal levels in the adjacent water.     

海河流域沉积物中典型重金属的生态风险评估及验证

沉积物重金属污染及其生态风险评估日益受到关注,而沉积物质量基准是开展生态风险评估的有力工具。本研究通过物种敏感度分布法(species sensitivity distributions, SSD)和急慢性毒性比(acute to chronic ratios, ACR)推导了镍、铜、锌、镉和铅的沉积物质量基准(sediment quality guideline, SQG)。在获得合理的重金属沉积物慢性毒性数据的基础上,采用S-Logistic模型拟合镍、铜、镉和铅的慢性SSD曲线,采用S-Gompertz模型拟合锌的慢性SSD曲线。得到镍、铜、锌、镉和铅沉积物质量基准低值(sediment quality guideline low value, SQGlow)分别为18.6、69.9、107、1.26和38.4 mg·kg~(-1),应用ACRs,得到相应的沉积物质量基准高值(sediment quality guideline high value, SQGhigh)分别为167、226、556、10.1和384 mg·kg~(-1)。与加拿大和澳大利亚重金属沉积物基准值具有一定的可比性。选择花翅摇蚊(Chironomus kiiensis)、伸展摇蚊(Chironomus tentans)和霍甫水丝蚓(Limnodrilus hoffmeisteri)3种底栖生物作为受试生物,验证基准值对海河流域沉积物重金属毒性的预测能力。结果表明,利用SQGs预测沉积物毒性的总准确率为76.2%,3种底栖生物验证准确率从高至低为:花翅摇蚊>伸展摇蚊>霍甫水丝蚓。