Zn In Mussels Research Articles

Direct Determination of Cadmium, Lead, and Zinc in Mussels by Two-Stage Probe Atomization (TPA) Graphite Furnace Atomic Absorption Spectrometry (GFAAS)

Seafood consumption may induce health risks due to its contamination by pollutants. In this study, the two-stage probe atomization technique (TPA) was combined with graphite furnace atomic absorption spectrometry (GFAAS) to develop a novel procedure for determining Cd, Pb and Zn in mussels collected in the Sea of Japan (Russia). The application of TPA eliminated organic matrix interferences during GFAAS determination of heavy metals and allowed significant reduction of the sample pretreatment processes. The procedure involved the formation of a suspension of treated lyophilized mussels that were inserted into graphite furnace. The limits of detection using the optimized conditions were 0.8, 10, and 0.4 ng/g for Cd, Pb, and Zn, respectively. Inductively coupled plasma – optical emission spectrometry (ICP-OES) was employed to characterize the accuracy of the developed technique. The concentrations of heavy metals in Crenomytilus Grayanus mussel tissues from Peter the Great bay did not exceed 8.2, 31 and 475 μg/g for Cd, Pb, and Zn and are considered to have no negative effects upon human health.

Biomonitoring of Trace Metals in the Keban Dam Reservoir (Turkey) Using Mussels (Unio elongatulus eucirrus) and Crayfish (Astacus leptodactylus).

Freshwater mussels and crayfish are commonly used as biomonitors of trace metals. In the present study, the concentrations of ten metals were determined in mussels (Unio elongatulus eucirrus) and crayfish (Astacus leptodactylus) collected from the Keban Dam Reservoir in Turkey. The significant spatial differences in concentrations of studied metals except As in mussels were not found. However, Co, Cr, Cu, and Zn concentrations in mussels and As, Co, Cu, Fe, Pb, and Zn concentrations in crayfish showed significant seasonal differences. As, Cd, and Mn levels in mussels were about nine times higher than those in crayfish. The concentrations of Cd, Cr, Cu, Pb, Zn, and inorganic As in crayfish and mussels were lower than maximum permissible levels. When compared with other biomonitoring studies using mussels and crayfish, high concentrations of As, Cd, Co, Cr, and Ni in mussels and Cr and Ni in crayfish were observed due to lithogenic sources and anthropogenic activities in the basin. Bioconcentration factor values of Fe, Mn, Cd, and Zn in mussels and Zn, Cu, Fe, and Co in crayfish were > 1000, which indicates that both U. e. eucirrus and A. leptodactylus have potential to bioaccumulate these metals. Therefore, attention should be paid to mussels and crayfish from ecological and human health perspective, because they are potential vectors of metals to higher trophic levels.

Residual effects of lead and zinc mining on freshwater mussels in the Spring River Basin (Kansas, Missouri, and Oklahoma, USA)

Concentrations of selected trace elements in surface water and fluvial sediment were investigated as possible factors limiting the distribution and abundance of freshwater mussels in the Spring River Basin, a 6600 km(2) watershed overlapping a former Pb and Zn mining and ore processing district in the central USA. Mussel taxa richness surveys and supporting physical habitat assessments were performed in 23 stream reaches dispersed throughout the basin and above and below former mining sites. Quantitative mussel density surveys were performed in the Spring River at one upstream reference location and one downstream location. Concentrations of 16 trace elements in the soft tissues of mussels and Asian clams (Corbicula fluminea) were determined at most survey sites. Comparable analyses were performed on surface water samples collected during base flow and peak flow synoptic surveys and sediment samples collected during base flow periods. Sites on the Spring River immediately upstream of heavily mined areas supported at least 21-25 species of mussels, whereas sites near the lower terminus of the river yielded evidence of 6-8 extant species. Between the upper and lower quantitative survey sites, mean mussel and clam densities declined by 89% and 97%, respectively. Tributary reaches below heavily mined areas lacked evident bivalve communities and contained concentrations of Cd, Pb, and Zn that continually or sporadically exceeded hardness-dependent water quality criteria and consensus-based sediment quality guidelines (probable effect concentrations). In less contaminated stream reaches supporting bivalves, concentrations of Cd, Pb, and Zn in mussels and clams were correlated spatially with the levels occurring in surficial sediment (0.50 < or = tau < or = 0.64, p < or = 0.03). In non-headwater perennial stream reaches, sediment Cd, Pb, and Zn levels were related inversely to mussel taxa richness (-0.80 < or = tau < or = -0.64, p < or = 0.004). Metal contaminant burdens in mussels and clams fluctuated measurably in association with variable stream flow conditions and accompanying changes in surface water and sediment chemistry. Concentrations of Cd, Pb, and Zn in mussels approximately paralleled the levels measured in composite clam samples (0.74 < or = tau < or = 0.79, p<0.001), implying C. fluminea could serve as a possible surrogate for native mussels in future metal bioaccumulation studies. Overall, streams draining heavily mined areas exhibited depauperate (or fully extirpated) mussel assemblages and correspondingly elevated concentrations of Cd, Pb, and Zn in water, sediment, and bivalve tissue. Other evaluated environmental chemistry parameters, and physical habitat conditions assessed at the stream reach scale, demonstrated little general relationship to the degraded status of these assemblages. We conclude that pollution attributable to former mining operations continues to adversely influence environmental quality and impede the recovery of mussel communities in a large portion of the Spring River Basin.

Studies of peripheral benzodiazepine receptors in mussels: comparison between a polluted and a nonpolluted site

The aim of this study was to investigate the peripheral benzodiazepine receptors in soft tissue membranes of the mussel Mytilus galloprovincialis from both polluted and nonpolluted seawater populations, using a radioligand specific for this receptor, [ 3 H] PK11195. Mussels were dissected into four body parts—mantle, gills, digestive gland, and muscles—to determine the distribution of tissue-specific peripheral benzodiazepine receptors (PBRs). The specific binding was saturable and reversible. A statistically significant increase (muscle, 537% and mantle, 201%, as absolute percentages) in the maximal number of binding sites ( B max) was found in mussels from the polluted site, compared with mussels from the nonpolluted site. By contrast, the value of the dissociation constant ( K d) at equilibrium does not show a statistically significant variation between the two groups. In competitive experiments of the compounds clonazepam, flumazenil, flunitrazepam, Ro5-4864, PK11195, and protoporphyrin IX, only PK11195 and protoporphyrin IX displaced [ 3 H] PK11195 specifically bound to soft tissue membranes, revealing that the binding sites of peripheral benzodiazepine receptors of mussels have pharmacological properties comparable to those of low vertebrates such as trout. M. galloprovincialis was also tested as an indicator of heavy metal exposure, and metal accumulation in the digestive gland was measured by atomic absorption spectrophotometry (AAS). The contents of Pb, Mn, and Zn in mussels collected off the polluted site were higher than those in mussels from the nonpolluted site. These data suggest that PBRs are present in the soft tissues of the mussel M. galloprovincialis. Here we report preliminary evidence of biochemical alterations in mussels from the polluted site.

Effects of calcium and metabolic inhibitors on trace element uptake in two marine bivalves

The influx of five trace elements (Ag, Cd, Co, Se and Zn) from the dissolved phase into the mussel, Mytilus edulis, and the clam, Macoma balthica, was determined at varying Ca concentrations and in the presence of different metabolic inhibitors. In both bivalves, varying the Ca concentration (but at a constant salinity) did not significantly influence the influx of any of the metals. Influx of Ag, Cd and Zn in mussels was significantly inhibited by verapamil (a Ca channel blocker), whereas trace metal uptake in clams was generally unaffected by this compound. Metabolic inhibitors (ouabain, which inhibits Na +/K +ATPase, and 2,4-dinitrophenol which uncouples oxidative phosphorylation) did not influence trace element influx in mussels. N-Ethylmaleimide, which specifically binds to sulfhydryl groups, reduced the influx of Ag, Cd and Zn, implying that the transport of these metals is carrier-mediated by proteins or other SH-containing compounds. There was no evidence of Cd and Zn interaction in their uptake in mussels. The calculated absorption efficiencies of trace elements from the dissolved phases were highest for Ag, followed by Zn>Cd>Co>Se, and were 2.2 to 3.0 times higher in M. edulis than in M. balthica for Ag, Cd and Zn. While metal transport in mussels appears to be a carrier-mediated process for metals that associate with proteins, the Ca channel may also be involved in the transport of Ag and Zn in mussels, but not in clams. Co is primarily taken up in these animals by passive diffusion.

Mussels as bioindicators of trace metal pollution in the Danube Delta of Romania

Specimens of mussels species Anodonta anatina, Unio pictorum, U. tumidus and surfical sediment samples were collected in the summers of 1994 and 1995 from twelve lakes in the Danube Delta, Romania. Whole mussel tissues were analyzed for metals (Ag, As, Cd, Co, Cu, Cr, Ni, Pb, Se and Zn), and sediment samples were subjected to weak acid extraction and to a sequential extraction procedure, and analyzed for Cr, Cu, Ni and Zn. Total mean Cu and Ag concentrations were statistically greater in Unio species than in Anodonta species, but other metal levels did not significantly differ between mussel species. There was a ten fold variation for Cd and Pb and five fold variation for Zn, Ag and Co concentrations in mussels among lakes. Mean concentrations of As, Cu, Se and Zn in mussel tissues varied two fold among lakes. Zn, Co and Cd concentrations in mussels were significantly negatively correlated with distance gradients from the origin of the Delta and with distance from main channels of the Danube. Other metal concentrations in mussels did not correlate with either distance gradient. Trace metal levels in mussel tissues were correlated with those in weak acid and in sequential extractions of sediment. Zn concentrations in the carbonate fraction was the best predictor of Zn concentrations in mussels. Cu and Ni levels in the organic matter and sulfide fraction were the best estimators of Cu and Ni concentrations in mussels.

The contribution of metal/shell-weight index in target-tissues to metal body burden in sentinel marine molluscs. 2. Mytilus galloprovincialis

The tissue distribution of Zn in mussels collected from a Zn-polluted site and the changes in the pattern of distribution for Zn and Cu in response to experimental exposures to Cu, Zn and Cd, as well as the tissue distribution of Cd have been studied. The organs of mussels were accurately separated avoiding mixtures except the kidney area that was included within the remainder tissues. Mussels exposed to intermediate dose (ID)-Cd showed the highest Cd burden first in gills and then more or less equally distributed between the various tissues examined with a dominance of the digestive gland. Mussels exposed to high dose (HD)-Cd, showed Cd equally distributed through all the organs at both exposure times. Below 0.8 μg Cd/l seawater, the gills of Zn-polluted mussels were able to either protect against Cd entry or mobilise uptaken Cd towards other tissues. On the other hand, Zn- and Cu-burdens did not rise in gill tissue, although in depurating mussels Zn-levels were higher than in any other exposure group. Similar conclusions were obtained for the digestive gland. However, the accumulative capacity of the digestive gland tissue for Cd was not exhausted and Cu burdens were depressed on exposure to Cd. Interactions between metals in the various organs studied could be explained by redistribution of haemocytes or brown cells and by enhanced release of metal-bearing digestive lysosomes in response to metal exposure. It is suggested that (a) the pattern of metal accumulation and tissue distribution as well as a part of the interactions between Cu, Zn and Cd cannot be explained solely by the availability of metallothioneins in specific organs; and (b) the specific cell type in which these ligands occur as well as the relative abundance and distribution of these cells are relevant factors controlling metal burdens in organs of mussels. Therefore, in addition to the chemical and the biochemical approaches, investigations on tissue sections are required to better understand these phenomena. Meanwhile, the digestive gland of mussels could be used as the target organ to monitor metal pollution, including essential and non-essential metals, on the basis of metal/shell-weight indices.

Kinetic determinations of trace element bioaccumulation in the mussel Mytilus edulis

Laboratory experiments employing radiotracer methodology were conducted to determine the assimilation efficiencies from ingested natural seston, the influx rates from the dissolved phase and the efflux rates of 6 trace elements (Ag, Am, Cd, Co. Se and Zn) in the mussel Mytilus edulis. A kinetic model was then employed to predict trace element concentration in mussel tissues in 2 locations for which mussel and environmental data are well described: South San Francisco Bay (California, USA) and Long Island Sound [New York, USA). Assimilation efficiencies from natural seston ranged from 5 to 18: for Ag, 0.6 to 1% for Am, 8 to 20% for Cd, 12 to 16% for CO, 28 to 34% for Se, and 32 to 41 ':, for Zn. Differences in chlorophyll a concentration in ingested natural seston did not have significant impact on the assimilation of Am, CO, Se and Zn. The influx rate of elements from the dissolved phase increased with the dissolved concentration, conforming to Freundlich adsorption isotherms. The calculated dissolved uptake rate constant was greatest for Ag, followed by Zn > Am -; Cd > CO > Se. The estimated absorption efficiency from the d~ssolved phase was 1.53 % for Ag, 0.34 % for Am, 0.31 X for Cd, 0.11 % for CO, 0.03' for Se and 0.89% for Zn. Salinity had an inverse effect on the influx rate from the dissolved phase and dissolved organic carbon concentration had no significant effect on trace element uptake. The calculated efflux rate constants for all elements ranged from 1.0 to 3.0% d-' The route of trace element uptake (food vs dissolved) and the duration of exposure to dissolved trace elements (12 h vs 6 d) did not significantly influence trace element efflux rates. A model which used the experimentally determined influx and efflux rates for each of the trace elements, following exposure from ingested food and from water, predicted concentrations of Ag. Cd, Se and Zn in mussels that were directly comparable to actual tissue concentrations independently measured in the 2 reference sites in national monitoring programs. Sensitivity analysis indicated that the total suspended solids load, which can affect mussel feeding activity, assimilation, and trace element concentration in the dissolved and particulate phases, can significantly influence metal bioaccumulation for particlereactive elements such as Ag and Am. For all metals, concentrations in mussels are proportionately related to total metal load in the water column and their assimilation efficiency from ingested particles. Further, the model predicted that over 96% of Se in mussels is obtained from ingested food, under conditions typical of coastal waters. For Ag, Am, Cd, CO and Zn, the relative contribution from the dissolved phase decreases significantly with increasing trace element parhtion coefficients for suspended particles and the assimilation efficiency in mussels of ingested trace elements, values range between 33 and 67% for Ag, 5 and 1 7 % for Am, 47 and 82% for Cd, 4 and 30% for CO, and 17 and 51 ?h for Zn.