The distribution of Cd, Cu, Pb and Zn in the biota of two freshwater sites with different trace metal inputs

The concentrations of Cd, Cu, Pb, and Zn were determined in the abiotic and biotic components at two sites in the Fox River, Illinois. Analysis of the metals was completed on solutions of wet ashed or dry ashed samples with a single beam atomic absorption spectrophotometer. Despite different inputs of the trace metals there were no significant differences in the concentration of Cu or Zn in the biota between the two sites. This was postulated to be due to physiological control of these metals. However, Cd and Pb concentrations were higher in the biota and substrate at the high input site. No accumulation of Cd or Pb occurred at higher trophic levels. Cu and Zn concentrations were similar for all biota with the exception of crayfish and snails which had higher Cu and Zn concentrations, respectively.     

Heavy Metals (Cd,Cu, Ni,Pb, and Zn) Fractionation in River Sediments,Hamedan, Western Iran

Five heavy metals (Cd, Cu, Ni, Pb, and Zn) in river sediments from Abshineh River, Hamedan, western Iran, were fractionated by a sequential extraction procedure. Cu, Ni, Pb, and Zn existed in sediments mainly in residual fraction (mean 92%, 86%, 77%, and 65%, respectively), whereas Cd occurred mostly as organic matter (mean 41%) and exchangeable (mean 25%) fractions. The mean percent of mobile fraction of Cd, Cu, Ni, Pb, and Zn in contaminated sediments was 25, 13, 4, 24, and 10, respectively, which suggests that the mobility and bioavailability of the five metals in sediments probably decline in the following order: Cd = Pb > Cu > Zn > Ni. The metal levels were also evaluated according to the contamination factor, which revealed significant anthropogenic pollution of Cd and Pb.     

Risk Element (As,Cd, Cu,Pb, and Zn) Contamination of Soils and Edible Vegetables in the Vicinity of Guixi Smelter,South China

Risk element (As, Cd, Cu, Pb, and Zn) contamination in soils and in two edible vegetables (Solanum melongena L. and Capsicum annum L.) was investigated in the vicinity of Guixi Smelter, South China. Soil As concentrations averaged 23.9 mg/kg. Sites near the smelter tailings recorded the highest levels of As and heavy metals in soils. The concentration order of heavy metals in soils was Cd < Pb < Zn < Cu. Cu and Cd in soils were abundant in the exchangeable and bound to carbonate fraction, while Pb and Zn were in the residual fraction, limiting their potential toxicity as pollutants. The proportions of the metals in the mobile fraction followed the order Pb < Zn < Cu < Cd. In Solanum melongena L. and Capsicum annum L., Zn concentration was the highest, followed by Cu, Cd, and Pb, different from that in soils and in the mobile fraction. Concentrations of heavy metals in the labile fractions in soils and in vegetables presented significant correlation (p < 0.05). Both of the two vegetables are not the Cu and Zn accumulators. As for Cd and As, Capsicum annum L. poses a higher risk to animal and human health than Solanum melongena L., with soil-plant transfer coefficients more than three. Root-stem is the main barrier for most of the heavy metals and As in the two vegetables, resulting in higher metal concentrations in roots relative to other plant tissues. The low stem-fruit transfer coefficients for Zn in Solanum melongena L. and for Pb in Capsicum annum L. suggested that very few of them could reach the fruits.     

Partitioning of Zn,Cd, Pb,and Cu in organic-rich soil profiles in the vicinity of a zinc smelter

Abstract

A five-step sequential extraction procedure was applied to organic-rich soil samples from five soil profiles situated 1–8 km from a zinc smelter. The partitioning of Zn, Cd, Pb, and Cu into five operationally defined fractions (exchangeable, “carbonate’’-bound, reducible, oxidizable, and residual) was studied at different soil depths down to 35cm. In the surface soil (0–1 cm) a major part of Pb and Cu was extracted in the oxidizable fraction, whereas for Zn and Cd slightly more was extracted in the ‘‘carbonate”-fraction than in the other four fractions. Extracted metal proportions in the oxidizable fraction were respectively of the order of 30%, 20%, 50%, and 80% for Zn, Cd, Pb, and Cu in the surface soil for all sites, but these proportions decreased with soil depth. In the surface soil less than 20% of all the elements were extracted in the residual fraction, but the proportions associated with this fraction generally increased with soil depth. In the C-horizon, differences in extracted proportions of Pb and Cu in the residual fraction were probably due to geochemical factors, whereas for Zn the low extracted proportion at a highly contaminated site (20%) may be due to Zn migration to the C-horizon at this site. For Cd the extracted proportions in the C-horizon were lower than for the other elements, generally below 20%, presumably because Cd is weaker in terms of its adsorption to the soil than the other elements studied. Total concentrations of the metals decreased strongly with increasing distance from the smelter, but less systematic differences were observed for their distributions among fractions. Potentially bioavailable metal proportions (exchangeable + “carbonate”-bound fraction) in the surface soil were about 50%, 60%, 20%, and 10% for Zn, Cd, Pb, and Cu, respectively. In C-horizon soil the mobility sequence Cd>Zn>Pb = Cu was generally observed. The present results indicate that the concentrations and chemical fractionation of Zn, Pb, and Cd in these soils represent a considerable risk to natural terrestrial food chains.     

Complexation of a Ligand with a Surfactant Micelle for Soil Heavy Metal Desorption

The ligands iodide (I^?) and thiocyanate (SCN^?), alone or in admixture, in combination with a non-ionic surfactant, Triton X-100, were evaluated as washing agents for heavy metal desorption from a contaminated soil. After seven successive washings, selective sequential extraction (SSE) was performed to determine the heavy metal content that remained associated with each geo-chemical fraction of the soil. The surfactant with 0.336 mol L^?1 of ligand I^? removed 75% Cd and 23% Cu, whereas the mobilization of Zn and Pb were not significant after 7 washings. At a concentration of 0.286 mol L^?1, the ligand SCN^? in the presence of surfactant removed 36% Cd, 44% Cu and 77% Zn. Among the washing agents, the combination of I^? and SCN^? produced the highest desorption efficiencies 95% Cd, 48% Cu, and 3.1% Pb, but not for Zn. The SCN^? ligand extracted the most Zn (77%). The SSE procedure indicated that the I^? removed metals from the exchangeable, carbonate and oxide fractions whereas SCN^? removed metals only from the exchangeable fraction. Both ligands, in the presence of surfactant, removed Cu from all fractions except the exchangeable sites, whereas only SCN^? plus surfactant removed Zn from all fractions. The ligand mixture plus surfactant mobilized only limited quantities of Pb from the oxide and residual fractions.     

强还原过程对设施菜地土壤重金属形态转化的影响

设施菜地由于污水灌溉、粪肥施用等导致重金属污染.本文通过土柱淹水同时添加玉米秸秆培养和后期通水淋洗,研究强还原法对设施土壤重金属(Cd、Cu、Pb和Zn)形态转化的影响.结果表明: 强还原处理使土壤pH显著降低,玉米秸秆处理变化更显著;土壤氧化还原电位(Eh)迅速下降至-280 mV左右.玉米秸秆处理可以促进土壤中Cd、Cu、Pb和Zn活化,第9天土壤中有机物及硫化物结合态和残渣态Cd、Cu、Pb和Zn含量比重下降;至15 d培养结束,土壤中4种重金属含量较对照分别减少18.1%、19.0%、16.1%和15.7%.玉米秸秆处理可以增加土壤中Cd和Zn的溶出量,但是Cu的溶出量减少;胶体结合态Cd和Pb含量较对照增加、Cu较对照显著减少、Zn没有显著变化.强还原可以引起设施土壤重金属活化,提高蔬菜积累重金属的风险,而且其随土壤水分的运移可能导致水体的污染.     

Heavy Metal Accumulation and Distribution in Organs of the Mussel Crenomytilus grayanus from Upwelling Areas of the Sea of Okhotsk and the Sea of Japan

The subcellular and cytosolic distribution of Zn, Fe, Ni, Cu, Mn, Cd, and Pb in the digestive gland and kidney of the mussel Crenomytilus grayanus from upwelling areas of the Sea of Okhotsk and the Sea of Japan was studied. Cd, Zn, Pb, and Ni have accumulated in the kidneys of mussels from these areas. When the concentrations of both essential and toxic metals in the mussel organs had increased significantly, their redistribution into the cytosol took place. Gel chromatography of cytosolic proteins in the kidneys of mussels sampled in the area with a strong stationary upwelling revealed metallothioneins. This is uncommon for bivalve mollusks from unpolluted areas. High molecular weight proteins act as preliminary ligands for Cd.     

Distribution,bioavailability, and potential risk assessment of the metals in tributary sediments of Three Gorges Reservoir: The impact of water impoundment

To investigate the impact of water impoundment on the metal contamination in sediments cores from the three tributaries of Three Gorges Reservoir (TGR), the concentrations, distribution, bioavailability, and potential risk of eight trace metals between summer and winter were analyzed using sequential analysis. The mean contents of all studied metals were higher than the geochemical background value, and were higher in summer than in winter. The results of the partitioning study indicated that Cr and Ni prevailed in the residual fraction, while a small proportion was found in the easily soluble fractions. Cu and Zn were distributed mainly in the residual and reducible fraction, while Cd and Pb were predominantly associated with non-residual fractions. These observations suggested that the most easily mobilized metals in the study area were Cd and Pb. The mean enrichment factors (EF) of Cu, Zn, Cd and Hg were higher than 1.5, revealing the potential anthropogenic inputs, whilst the EF of other metals remained within the range of natural variability. The positive correlation between non-residual Cu, Zn and Cd and their EF values further indicated that anthropogenic inputs were the potentially major contributor for the enrichment of Cu, Zn and Cd in TGR sediments. The results evaluated by both potential ecological risk index and modified risk assessment code (mRAC) of all sampling sites demonstrated the relatively high potential risk of sediment contamination effect in TGR.     

Metal composition of human hepatic and renal metallothionein

This article is based on data on the levels of metals (Cd, Zn, Cu) and metallothionein (MT) determined radiochemically with²⁰³Hg in renal cortex and liver of 137 autopsy cases. From this number, for 23 cases, the gel filtration of the cytoplasmic fraction of the organs was performed. The molar content of metals in the MT fraction (Sephadex G-50) amounted to 46.9, 50.2, and 2.0% for Cd, Zn, and Cu in renal cortex, respectively, and to 8.3, 83.6, and 9.1% for Cd, Zn, and Cu in the liver, respectively. In parallel with the increase of Cd and MT in renal cortex, increasing saturation was found of the MT fraction by Cd, occurring at the expense of Zn and Cu. Equimolar amounts of Cd and Zn in the MT fraction are found at Cd level of 0.5 μmol Cd/g wet wt of renal cortex. In the liver, analogous dependency (elevation of %Zn, depression of %Cd and %Cu) were observed in relation to Zn and MT levels in this organ. The basic level of Zn (not bound with MT) was estimated at 0.5 μmol/g for both renal cortex and liver. A deficit of non-MT Zn in kidneys is proposed as an alternative mechanism of toxic Cd action.     

Interaction of platinum with metallothionein-like ligands in the rat kidney after administration of cis-dichlorodiammine platinum II

After the administration of the anticancer drug cis-dichlorodiammine platinum II (cisplatin) to male rats, the Pt in the soluble fraction of the kidney is isolated, by gel filtration, in association with a high molecular weight component and a low molecular weight fraction. At 24 h, Pt is also recovered in a metallothionein-like fraction which elutes from Sephadex G-50 with a lower apparent molecular weight than endogenous (Cu, Zn)-thionein or Cd-thionein isolated from the kidneys of Cd2+-treated rats. None of these low molecular weight metal-binding fractions binds to Octyl Sepharose CL-4B. On DE-52 ion exchange chromatography, Cd-thionein is resolved into two isometallothioneins whereas the low molecular weight Pt-binding fraction is only partially purified and contains at least six components which elute at higher gradient concentrations than metallothionein. Pretreatment with Cd2+ which stimulates the synthesis of renal and hepatic metallothionein has no effect on the uptake and subcellular distribution of Pt in the liver and kidneys. Cisplatin treatment reduces the concentration of Cu and Zn in the renal metallothionein and other soluble protein fractions in the kidney. When administered to Cd2+-pretreated rats, cisplatin promotes the loss of Zn from the soluble protein fractions but causes the redistribution of Cd from the metallothionein to the high molecular weight fraction and fails to inhibit the Cd2+-induced accumulation of Cu in the kidneys and the binding of Cu to the soluble protein fractions. It is suggested that metallothionein probably does not have a significant role in the renal metabolism of Pt following the administration of cisplatin to rats.     

The potential use of metallothionein in the clam Ruditapes decussatus as a biomarker of in situ metal exposure

This work aimed to validate the relationship between metallothioneins (MTs) and metals (Cd, Cu and Zn) in field conditions. Specimens of the marine bivalve Ruditapes decussatus (Linné, 1758) from Gargour were transferred in two sites: Gargour and Sidi Mansour, both situated along the south-eastern coast of Tunisia. The bivalves were removed from pairs of cages at day 0 (date of transplantation), day 62 and day 132. Metals (Cd, Cu and Zn) and MTs were determined in the subcellular fractions of the digestive gland. In Gargour, metal and MT levels increased significantly after 62 days of transplantation. However, they showed modest and non-significant variations in Sidi Mansour. Zn was mainly associated with the insoluble fraction, whereas Cd and Cu percentages in the soluble and the insoluble fractions were equivalent. Simple correlation analysis showed a positive and significant relationship between MTs and each metal. If all metals were taken together, multiple correlations showed that MTs were significantly correlated with Cd and Zn, with an important coefficient for Cd, but no significant relationship was observed for Cu. Gel filtration chromatography showed that in the heat stable fraction, the only cytosolic SH rich compounds have an apparent low molecular mass (about 15 kDa), which could correspond to metallothioneins. In the digestive gland of R. decussatus MTs responded to moderate increases of metal contamination, without interference with other factors, and could be a promising biochemical indicator of metal exposure.     

Assessment of Heavy Metal Pollution in Water and Sediments from the Ghalechay River,Baychebagh Copper Mine Area,Iran

The concentrations of selected heavy metals in sediments and waters in Baychebagh copper mine were determined using ICP-OES. Except for Co, the average concentrations of Cd, Cu, Pb, and Zn in sediments from the Ghalechay River in the district exceed the world-average shale and continental upper crust value. Enrichment factors for Pb, Cu, and Cd were significantly enriched in sediments, indicating environmental contamination. Geoaccumulation index calculated for different sampling stations indicates that the sediments are unpolluted with respect to Co and Zn while unpolluted to moderately polluted with Cu and highly polluted with Pb and Cd. The Sediment Quality Guidelines (SQGs) suggest that Cd and Pb may pose the highest risk for the environment. Sequential extraction analyses of sediments revealed that Cu, Co, Pb, and Zn bound to extractable, carbonate, reducible and oxidizable fractions are lower than residual fraction. About 10% of the total Pb was associated with the exchangeable fraction, indicating remobilization, while Cd (89%), Pb (73%) Co (58%), Cu (76%), and Zn (68%) closely associated with the residual and oxidizable fractions, resulting in their environmental immobility. The residual forms are not expected to be released under normal conditions in the river and could be considered an inert phase.     

Assessment of Heavy Metal Enrichment,Bioavailability, and Controlling Factors in Sediments of Taihu Lake,China

Heavy metal distribution, bioavailability, and ecological risk in the surface sediment of Taihu Lake were evaluated. Samples were collected from eight representative sites in September 2011 and February 2012. In the surface sediment, average metal contents were in the order of Cr > Zn > Ni > Pb > Cu. Spatially, Zhushan Bay maintained higher Cu, Ni, and Zn contents and Xiaomeikou maintained higher Cr and Pb contents than other sites. Spatial and temporal variation were observed in the bioavailable metals determined by acid-soluble fraction of BCR extraction. The labile metals in Zhushan Bay and Xiaomeikou were quantified by diffusive gradients in thin films (DGT) and DGT-labile concentrations of Zn, Ni, Cu, Pb, and Cd were in descending order, indicating the inconsistence of labile concentrations of different heavy metals with the total metal contents and that the toxic effect of Cd in sediment should be given attention. The ecological risk assessed by Hakanson potential ecological risk index showed that Zhushan Bay suffered the most serious pollution and should be given special attention. Bioavailability of metals should be taken into account during risk assessment for more accurate estimation.     

The distribution of cadmium,copper, lead,zinc and calcium in the tissues of the earthworm Lumbricus rubellus sampled from one uncontaminated and four polluted soils

Summary The tissue distribution of Cu, Cd, Pb, Zn, and Ca in the earthworm Lumbricus rubellus living in non-polluted and heavy-metal polluted soils was investigated. Cd, Pb and Zn were primarily accumulated within the posterior alimentary canal. As the whole-worm Pb burden increased, the proportion of the metal accumulated within this tissue fraction increased. A similar pattern was found for Zn. By contrast, 70%–76% of the Cd burden was found in the posterior alimentary canal, irrespective of the whole-worm Cd content. The accumulation of Cd, Pb and Zn primarily in the posterior alimentary canal prevents dissemination of large concentrations of these metals into other earthworm tissues, and may thus represent a dextoxification strategy based on accumulative immobilisation. Cu was distributed fairly evenly in the tissue fractions investigated. There was no evidence of sequestration of this metal. The apparent lack of a detoxification strategy may contribute to the well-known susceptibility of earthworms to low environmental Cu concentrations. Indeed, earthworms from the site of highest soil Cu (Ecton) were markedly smaller than those from the other sites sampled. The highest Ca concentrations were found in the anterior alimentary canal, and were related to calciferous gland activity. A large proportion of Ca was also stored as a physiologically available pool in the posterior alimentary canal. Despite huge variations in soil Ca concentrations, the body wall Ca levels were fairly similar in L. rubellus from all the study sites. Thus, L. rubellus may become physiologically adapted to soils of exceptionally low Ca concentration. The observations are discussed in the context of the merits of analysing specific tissues, rather than whole organisms, for the purpose of monitoring metal bioaccumulation.     

华南地区典型燃煤电厂周边土壤重金属分布、风险评估及来源分析

为了解华南地区典型燃煤电厂周边表层土壤重金属空间分布特征,对韶关市燃煤电厂周边20处农田表层土壤中7种重金属(镍(Ni)、铜(Cu)、锌(Zn)、镉(Cd)、铅(Pb)、铬(Cr)及砷(As))的总量进行检测,并分析了其相应的空间分布规律,同时评估了周边土壤重金属的生态风险并分析其来源。结果表明:该燃煤电厂周边土壤中重金属Ni、Cu、Zn、Cd、Pb、Cr及As的平均含量分别是17.79、19.59、159.08、3.14、111.01、96.61 mg/kg和21.48 mg/kg,Cd、Pb污染情况突出,重金属Zn、Cd、Pb、Cr的分布与盛行风向密切相关。综合污染指数法表明,Cd、Pb及Zn处于重污染状态;潜在生态风险指数法表明,Cd处于严重潜在生态风险状态;地累积指数法表明,Ni、Cu整体处于无污染状态,Cd整体处于高污染状态。多种统计方法表明,Zn、Cd、Pb及Cr受燃煤电厂影响明显,Cu、As的来源不仅受燃煤电厂等工业的影响,还与该地区农业灌溉用水密切相关,Ni的分布最为均匀,受自然因素影响明显。     

Solid-Phase Chemical Fractionation of Selected Trace Metals in Some Northern Kentucky Soils

The fractionation and distribution with depth of Cd, Cr, Cu, Ni, Pb, and Zn in 26 soils of Northern Kentucky were determined through a sequential extraction procedure in response to environmental concerns about increasing anthropogenic inputs in a fast-paced, urbanizing area. The selected sites have not received any biosolid- or industrial-waste applications. Average total concentrations per metal in soil profiles derived from alluvial, glacial till, and residual materials ranged from 0.43 to 56.00 mg kg^?1 in the sequence Zn > Ni > Pb > Cr > Cu > Cd, suggesting relatively small anthropogenic inputs. The distribution of Cu, Cr, Ni, and Zn increased with soil depth, whereas Cd and Pb remained stable, indicating a strong geological or pedogenic influence. Residual forms were most important for the retention of Cu, Zn, and Ni. Cadmium and Pb exhibited a strong affinity for the Fe-Mn oxide fraction, while Cr showed the strongest association with the organic fraction. In terms of metal mobility and toxicity potential inferred from metal concentrations in labile fractions, Cd posed the greatest risk, followed by Cr ～ Pb > Ni > Zn > Cu. Soil pH, OM, and clay content were the most important parameters explaining the partitioning of metals in labile and residual fractions, emphasizing the importance of metal fractionation in soil management decisions. Alluvial soils generally contained the highest total and labile metal concentrations, suggesting potential metal enrichment through anthropogenic additions and depositional processes. These environments exhibit the highest risk for metal mobilization due to drastic changes in redox conditions, which can destabilize existing metal retention pools.     

Ion exchange systems in proton-metal reactions with algal cell walls

Abstract: Algal cell walls contain acidic polysaccharides, e.g. alginic acid in many marine species, and in pectin fresh-water species. At neutral pH these provide anionic sites which bind ionically to metals, and acidification releases metals when covalent bonds to H are made. Added Cu releases an equivalent amount of Ca, Mg, H from Vaucheria , and protonated amines also displace metals. Interestingly, diamines, which function as efficient growth promoters, are sorbed more strongly than monoamines based on Langmuir adsorption constants. Sorption of Pb and Cd on Rhizoclonium from the solid hydroxides releases Na, Ca, Mg from the alga and OH from the hydroxide in essentially stoichiometric amounts. Sorbed heavy, metals can be removed by precipitation of the sulfide (Cd), hydroxide (Cm AI, and Pb), or as an EDTA complex (Pb) in ion exchange processes. Values of ion exchange constants for displacement of Ca by Mg, Zn, Cd, Pb, and Cu on Vaucheria are independent of pH and increase with the (charge)²/radius of metal ions, as also observed for K and AI. These results indicate a non-cooperative behavior of anionic sites which interact with these metals by electrostatic attractions. Rates of metal desorption and ion exchange constants with alginates as model systems were also investigated.     

Metals in squid,Loligo forbesi,adults, eggs and hatchlings. No evidence for a role for Cu- or Zn-metallothionein

An adult squid Loligo forbesi had the following metals in its liver/digestive gland: Mn, Fe, Ni, Zn, Cu, As, Cd, Ba and Pb in the range of 1-110 ppm wet wt. Adult mantle muscle, adult eyes, eggs and hatchlings contained a lesser number of these metals at concentrations above 1 ppm. Chromatographic analysis of non-heat-treated cytosols (in the presence of 5 mM 2-mercaptoethanol) gave no evidence for the presence of copper- or zinc-containing fractions with the molecular weights of mollusc metallothioneins in any of the above tissues. Copper and Zn were bound to either the particulate fraction or to very low molecular weight species.     

Concentration and Distribution of Six Trace Metals in Northern Kentucky Soils

Concentration and distribution of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) were determined in 26 soil profiles (n = 78) of northern Kentucky in response to environmental concerns about increasing anthropogenic inputs in a fast-paced urbanizing area. The selected sites represent alluvial, glacial till or residual soils that have not received any biosolid- or industrial-waste applications. Mean concentrations of Zn (53.8 mg kg^?1) and Ni (25.9 mg kg^?1) were the highest in the soil profile, whereas Cd (0.21 mg kg^?1) was present only in trace amounts. All metals were within the low to middle range of baseline concentrations reported for US soils, suggesting minimal anthropogenic inputs. The distribution of Cu, Cr, Ni, and Zn increased with soil depth, whereas Cd and Pb concentrations were unaffected throughout the soil profile. Alluvial soils had the highest overall metal accumulations, particularly in surface soil horizons, indicating potential metal enrichment through depositional processes. The presence of a fragipan horizon or depth to bedrock did not significantly affect metal retention. Single correlation and multiple regression analyses indicated OM and pH as the most influential soil parameters for metal retention, followed by cation exchange capacity (CEC) and CEC/clay. Single correlations among metals suggested strong covariance of Zn with most metals throughout the soil profile, but weaker for Pb and Ni.     

Total metal burdens in the freshwater amphipod Gammarus fasciatus: contribution of various body parts and influence of gut contents

1. The distribution of trace metals among body parts of the freshwater amphipod Gammarus fasciatus was investigated and the effect of depuration on the total body burden was assessed.
2. Concentrations of Cr, Fe, Mn and Ni were one order of magnitude higher in the gut contents than in the various body parts, accounting for 40–72% of the total body burdens of amphipods. Depuration caused a decrease of total metal concentrations of 35–88%.
3. Levels of Cd and Cu were higher in the hepatopancreas than in other body parts, whereas levels of Zn were relatively constant throughout the body. For Cd, Cu and Zn, depuration had no effect on mean body concentrations.
4. For Pb, an important fraction of the total body burden was associated with the exoskeleton; depuration caused a decrease in Pb body concentrations.
5. Regression between amphipod metal concentrations before and after depuration is a potential tool for correcting for the effect of gut contents. This correcting method was found to be promising for Cd, Cu, Mn and Zn, with R ² varying between 0.66 and 0.98. It was less efficient for Cr, Fe and Pb, and was useless for Ni.