Assessment of Geochemical Mobility of Metals in Surface Sediments of the Santa Rosalia Mining Region,Western Gulf of California

To asses the geomobility of cadmium, copper, iron, manganese, nickel, lead, and zinc in marine sediments near the Santa Rosalía copper smelter, which is located on the eastern coast of the Baja California Peninsula, sequential leaching was applied to sediment samples containing different levels of Cu: (1) uncontaminated or slightly contaminated (<55 mg kg⁻¹ Cu); (2) moderately contaminated (55–500 mg kg⁻¹ Cu); and (3) heavily contaminated (>500 mg kg⁻¹ Cu). Concentrations of Cd, Cu, Fe, Mn, Ni, Pb, and Zn in four fractions of the leachate (mobile fraction F1, relatively mobile fraction F2, associated with organic matter/sulphides fraction F3, and residual fraction F4) were measured by atomic absorption spectrophotometry (AAS). The sediments with Cu concentration <500 mg kg⁻¹ displayed prevalence of mobile acid-leachable fraction F1 and reducible fraction F2 for Cd, Cu, Mn, and Pb, whereas the relative contribution of fraction F3 was relatively low for all of the examined metals. Residual fraction F4 was highest (>65%) for Fe and Ni because both metals are associated with the crystalline matrix of natural sediments. The sediments heavily contaminated with Cu (>500 mg kg⁻¹) had dramatically increased percentages of Cu, Mn, Pb, and Zn, ranging on average from 63 to 81%, in the residual fraction. In the case of Cu, for example, the relative abundances of this element in the different fractions of such sediments followed this sequence: residual fraction F4 (76 ± 5%) >absorbed form and carbonates fraction F1 (15 ± 5%) >Fe and Mn oxyhydroxides fraction F2 (5 ± 2%) >fraction associated with organic matter and sulphides F3 (4.5 ± 3.9%). Copper, Pb, and Zn contents in each geochemical fraction of all samples were compared with sediment-quality guideline values (“effects range low” [ERL] and “effects range medium” [ERM]) to assess their possible negative effects on biota. Copper contents in mobile fractions F1 and F2, which were moderately contaminated with Cu, were higher than ERL but lower than ERM guideline values. For heavily contaminated sediments, Zn contents of mobile fractions F1 and F2 were higher than ERL but lower than ERM guideline values. The Cu content of fraction F1 was higher than ERM guideline values, whereas for fractions F2 and F3 copper content was higher than ERL guidelines but still lower than ERM guideline values.     

Temporal Variation of Metals in Water,Sediment and Tissues of the European Chup (<Emphasis Type="Italic">Squalius cephalus</Emphasis> L.)

The aim of this study was to analyze seasonal variation of levels of Chromium (Cr), Manganese (Mn), Nickel (Ni), Copper (Cu), Zinc (Zn), Cadmium (Cd) and Lead (Pb) in water, sediment and tissues of Squalius cephalus (L., 1758) taken from five different stations chosen at Yamula Dam Lake (Kayseri, Turkey). Concentrations of metals were generally sorted as water<tissue<sediment. The highest concentration of metals in water was observed in the samples taken in the summer (Mn, 1.04 ± 0.15 mg L⁻¹; Ni, 0.42 ± 0.12 mg L⁻¹; Cu, 1.25 ± 0.88 mg L⁻¹; Zn, 3.61 ± 1.53 mg L⁻¹; Pb, 0.58 ± 0.09 mg L⁻¹). While the highest Zn (24.85 ± 21.82 μg g⁻¹) and Pb (10.89 ± 4.2 μg g⁻¹) concentrations in sediment were observed in the winter samples, the highest Mn concentration (167.2 ± 99.37 μg g⁻¹) was observed in the summer. Cd pollution was determined in sediment according to international criteria. The highest metal concentration in tissues was generally observed in the liver and the other tissues; following liver were gills and muscles. In liver tissues, while the highest accumulation of Zn (110.34 ± 13.1) and Mn (22.5 ± 14.85 μg g⁻¹), which are essential for the body, were observed in the winter, Pb (22.58 ± 7.83 μg g⁻¹) and Cd (11.77 ± 7.83 μg g⁻¹), which are toxic, were found to be higher in the summer. Also, concentrations of Mn, Cd and Pb in muscle tissues were found to be above the limits permitted.     

Trace Elements Contamination in Coral Reef Skeleton,Gulf of Mannar,India

Coral samples were collected from Kurusadi, Shingle and Appa islands of Gulf of Mannar for analyzing the trace elements. The mean concentrations in the coral reef skeleton ranges from 0.19 to 0.62  μg g⁻¹ for Fe, from 6.71 to 15.6 μg g⁻¹ for As, from 0.28 to 1.31 μg g⁻¹ for Cd, from 0.56 to 5.29 μg g⁻¹ for Co, from 7.25 to 22.34 μg g⁻¹ for Cr, from 0.63 to 5.08 μg g⁻¹ for Cu, from 98.38 to 138 μg g⁻¹ for Mn, from 0.18 to 2.53 μg g⁻¹ for Ni, from 0.18 to 4.56 μg g⁻¹ for Pb and from 44 to 135.25 μg g⁻¹ for Zn. The factor analysis revealed the source of trace elements accumulation in the coral skeleton particularly Mn from detrital inputs and Cd from anthropogenic sources. This paper also highlights the nature of trace elements available in coral skeleton.     

Vertical Fluxes and Accumulation of Trace Metals in Superficial Sediments of the Río de la Plata Estuary, Argentina

Superficial sediments and settling material collected in Buenos Aires coastal area were analyzed to evaluate the accumulation and sources of trace metals. Residual elements showed homogeneous sedimentary concentrations (Fe: 23,846 ± 4,367; Ni: 10 ± 2.7; Mn: 706 ± 314 μg g⁻¹) whereas anthropogenic metals presented exponentially decreasing offshore gradients (Zn: 98 ± 69; Cr: 28 ± 21; Cu: 19 ± 15; Pb: 18 ± 13 μg g⁻¹). Anthropogenic impact was evaluated through metal-Fe relationships, Fe-normalized enrichment factors and sediment quality guidelines. The slopes of metal-Fe regressions from background sites were comparable to upper crust metal ratios, excepted Cr which is impoverished, and Mn which is diagenetically enriched. Metal-Fe relationships also hold for most 2.5 km offshore sites but with higher slopes denoting human influence, and are completely lost in 1–2.5 km sediments and trap material which plot over the regressions and exceed sediment quality guidelines.     

Metal Concentrations in Two Bioindicator Fish Species, <Emphasis Type="Italic">Merlangius merlangus</Emphasis>, <Emphasis Type="Italic">Mullus Barbatus</Emphasis>, Captured from the West Black Sea Coasts (Bartin) of Turkey

The Black Sea is very vulnerable to originating from land based human activities and its health is equally dependent on the coastal and non-coastal states of its basin. Total concentrations of cadmium, copper, zinc, lead, nickel, aluminum, iron, manganese, boron and chromium concentrations were determined in Merlangius merlangus (whiting) and Mullus barbatus found in Amasra in the West Coast of the Black Sea (Turkey). The metal contents that were measured in head and muscle was expressed in μg g⁻¹ wet weight. On average, while the highest Fe (344.25 μg g⁻¹), Mn (10.35 μg g⁻¹), Cr (0.96 μg g⁻¹) and Al (76.77 μg g⁻¹) concentrations were measured in the heads of M. merlangus and the highest Zn (77.99 μg g⁻¹), Cu(8.53 μg g⁻¹), B (44.83 μg g⁻¹), Ni (1.96 μg g⁻¹), Cd (0.40 μg g⁻¹) and Pb (6.80 μg g⁻¹) concentrations were detected in the muscles of M. merlangus. There were significant differences between metal levels of muscles in these two species. In terms of permissible levels reported by WHO FAO and TSE, there is not any risk for human consumption for both M. merlangus and M. barbatus, for Pb.     

Heavy-Metal Concentrations in Soft Tissues of the Burrowing Crab Neohelice granulata in Bahía Blanca Estuary, Argentina

Copper (Cu), cadmium (Cd), and chromium (Cr) in soft tissues of male and female burrowing crab Neohelice granulate, as well as their eggs, were measured in two different locations in the Bahía Blanca estuary, a moderately polluted ecosystem, from October 2008 to August 2009. Differences between sexes, sites, and seasonality were assessed. Furthermore, metal levels in eggs were compared with metal levels in female crabs. The results showed no significant differences for Cu and Cd between sexes (Student t test p > 0.25 for both sites) and sites (two-way analysis of variance: Cu p = 0.82 and Cd p = 0.29). Nevertheless, seasonality was found, with winter having significantly lower concentrations for both metals. The range of Cu concentrations was between 96.92 and 152.18 μg g⁻¹ dry weight (dw), and the range of Cd concentrations was between 6.09 and 10.41 μg g⁻¹ dw. Cr concentrations could not be assessed because most of the values were lower than the detection limit. Although heavy metals in sediments were not measured in this study, a bioaccumulation process may be occurring for Cd because levels found during the entire sampling period were greater than levels in sediment from previous years. For Cu, a regulation process may be occurring considering that this is an essential metal and levels of Cu in N. granulata found in this study were between 1 and 2 orders of magnitude greater than levels in sediments. Finally, Cu and Cd levels in eggs were detectable, but they were lower than levels in female crabs. The importance of these findings is linked to the fact that metal accumulation seems to be occurring before hatch. The presence of heavy metals in soft tissues as well as in eggs of N. granulata is of great importance considering that this is a key species within the Bahía Blanca estuary; therefore, it plays a major role in the transference of pollutants to greater trophic levels.     

Content of Lead and Cadmium in Barred Hogfish, Bodianusscrofa, Island Grouper, Mycteroperca fusca, and Portuguese Dogfish, Centroscymnus coelolepis, from Canary Islands, Spain

Concentration of lead and cadmium has been analyzed in Bodianus scrofa and Mycteroperca fusca captured in the Canary Islands coast. Concentration of Pb ranged from 2.53 to 306.40 and 4.97 to 792.00 μg kg⁻¹ respectively, while that of Cd ranged from 1.75 to 1854.50 and 6.78 to 656.00 μg kg⁻¹. The same metals have been analyzed in muscles, liver and skin of Centroscymnus coelolepis from Canary Islands, with contents of Pb and Cd ranged between 24.18–96.12 μg kg⁻¹ and 32.00–3266.58 μg kg⁻¹ respectively, and in the Azores Archipelago, with concentrations of Pb and Cd ranged as follow: 18.41–38.99 μg kg⁻¹ and 5.23–4179.87 μg kg⁻¹ respectively. Percentage of contribution of both metals to the PTWIs, has also been calculated for both fishes.     

Lead,Zinc, and Cadmium in Vegetable/Crops in a Zinc Smelting Region and its Potential Human Toxicity

Lead, Zn, and Cd in vegetables/crops were investigated in a zinc smelting region in China, and their daily dietary intake by local residents was estimated. It is observed that Pb, Zn, and Cd were in 34.7–91.1, 242–575, and 0.199–2.23 μg g⁻¹ dry weight in vegetables/crops with their greatest concentrations in leafy vegetable. The daily dietary intake of Pb, Zn, and Cd by adult residents reached 3, 646, 59,295, and 186 μg day, respectively, and lettuce and cabbage together contributed 75% of the Pb, 50% of the Zn, and 70% of the Cd.     

A Preliminary Study on Metal and Nutrient Concentrations in Running Water Systems in Southern New Caledonia

Metal and nutrient concentrations were measured in five running water sampling sites of New Caledonia. Metal concentrations were homogeneous (Ni; 22.7–50.6 μg L⁻¹) or not (Fe; 37–749 μg L⁻¹). Concentrations of Ni, Cr, Fe were high, including high dissolved fractions (up to 47.8, 70.8 and 417 μg L⁻¹, respectively). Concentrations of anthropogenic metals (Ag, As, Cd, Cu, Pb, Sb, V, Zn) were low (maximum: total Cu, 0.6 μg L⁻¹). The contamination of waters is presumably due to soil weathering and mining activities. Metal concentrations and phosphate depletion (<0.04 μmol L⁻¹) suggest constrained conditions for the development of aquatic life.     

Anthropogenic Contamination of Metals in Sediments of the Santa Rosalía Harbor, Baja California Peninsula

To know the environment impact on a harbor of the Santa Rosalía port on the Baja California peninsula, the concentrations of metals (Cd, Co, Cu, Mn, Pb, U and Zn) in harbor sediments were determined for 13 stations and compared with their average upper Earth´s crust abundance. The mean enrichment factors, calculated using Al as a normalizer, were higher than the unity for Ag, Ba, Bi, Cd, Co, Cu, Mn, Ni, Pb, Sb, U, V and Zn. Concentrations of slightly enriched Cd in the sediments are below the effect range low (ERL) sediment quality guidelines value only at three stations. The levels of Pb in the harbor sediments at four stations (1, 6, 9 and 11) are between the ERL (46.7 mg kg^?1) and the effect range medium (ERM) (218 mg kg^?1), and Pb content in the rest of the sediment samples is higher than the ERM, demonstrating the high extent of the anthropogenic impact of this metal on the sedimentary environment. The total concentrations of the potentially toxic elements Cu (3,390 ± 804 mg kg^?1) and Zn (1,916 ± 749 mg kg^?1) very strongly exceed their ERM, showing a high possibility of toxicological danger for marine biota, living inside or entering the harbor.     

The Extent of Arsenic and of Metal Uptake by Aboveground Tissues of <Emphasis Type="Italic">Pteris vittata</Emphasis> and <Emphasis Type="Italic">Cyperus involucratus</Emphasis> Growing in Copper- and Cobalt-Rich Tailings of the Zambian Copperbelt

The extent of arsenic (As) and metal accumulation in fronds of the As hyperaccumulator Pteris vittata (Chinese brake fern) and in leaves of Cyperus involucratus, which grow on the surface of an old flotation tailings pond in the Zambian Copperbelt province, was studied. The tailings consist of two types of material with distinct chemical composition: (1) reddish-brown tailings rich in As, iron (Fe), and other metals, and (2) grey-green tailings with a lower content of As, Fe, and other metals, apart from manganese (Mn). P. vittata accumulates from 2350 to 5018 μg g⁻¹ As (total dry weight [dw]) in its fronds regardless of different total and plant-available As concentrations in both types of tailings. Concentrations of As in C. involucratus leaves are much lower (0.24–30.3 μg g⁻¹ dw). Contents of copper (Cu) and cobalt (Co) in fronds of P. vittata (151–237 and 18–38 μg g⁻¹ dw, respectively) and in leaves of C. involucratus (96–151 and 9–14 μg g⁻¹ dw, respectively) are high, whereas concentrations of other metals (Fe, Mn, and zinc [Zn]) are low and comparable with contents of the given metals in common plants. Despite great differences in metal concentrations in the two types of deposited materials, concentrations of most metals in plant tissues are very similar. This indicates an exclusion or avoidance mechanism operating when concentrations of the metals in substrate are particularly high. The results of the investigation show that Chinese brake fern is not only a hyperaccumulator of As but has adapted itself to high concentrations of Cu and Co in flotation tailings of the Zambian Copperbelt.     

Mercury and Other Mining-Related Contaminants in Ospreys Along the Upper Clark Fork River,Montana, USA

We investigated links between mining-related contaminants in river sediment and their occurrence in nestling ospreys (Pandion haliaetus) in the Clark Fork River Basin, Montana, USA. Blood and feather samples from 111 osprey chicks were collected during 4 years from nests along river sections with greatly different sediment concentrations of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn), and mercury (Hg). No significant differences between river sections were found among Zn (3,150 ± 160 μg L⁻¹) and Cd (<5 μg L⁻¹) concentrations in blood. Cu, Pb, and As concentrations in blood were significantly increased in chicks from the most contaminated river sections (mean values of 298, 8.9, and 100 μg L⁻¹, respectively). Cu, Zn, and Pb concentrations increased significantly during a year of above-average river runoff combined with high suspended sediment loads in rivers. Total Hg concentrations in blood and feathers were highly correlated and depended on the geographic locations of the nests. The lowest blood concentrations of Hg were observed in the most upstream river section (mean 151 μg L⁻¹) where total sediment concentrations were increased (0.80 mg kg⁻¹). River sections with intermediate blood concentrations (mean 206 and 303 μg L⁻¹) were associated with low to intermediate sediment concentrations (0.058 and 0.46 mg kg⁻¹). The highest concentrations of Hg in ospreys (mean 548 μg L⁻¹) were observed downstream from a contaminated tributary (1–4 mg kg⁻¹ in sediment). In river sections with lower Hg concentrations in sediment, there was a negative correlation between blood Hg concentration and chick mass, presumably due to high deposition rates into growing feathers. This relationship was absent in sections of high Hg exposure. Osprey blood and feathers are suitable for monitoring Hg in aquatic ecosystems; however, responses of As, Cd, Cu, Pb, and Zn are more subtle.     

Sudden Cadmium Increases in the Digestive Gland of Scallop, Nodipecten nodosus L., Farmed in the Tropics

Cadmium bioaccumulation in Nodipecten nodosus reared on a marine farm in a tropical bay was measured in muscle tissue and the digestive glands in animals ranging from 6 to 16 months. No bioaccumulation tendencies regarding Cd concentration were observed in muscle tissue (below 1 μg g⁻¹), while in the digestive gland concentrations remained below 5 μg g⁻¹ until the organisms reached 10 months, and reached levels above 10 μg g⁻¹ from 12 months onwards (reaching 27 μg g⁻¹). This is the same bioaccumulation pattern noted in animals transplanted to a different Cd exposure. Allometry and environmental factors cannot explain this sudden increase.     

Combined Use of Bioindicators and Passive Samplers for the Assessment of River Water Contamination With Metals

In autumn 2005, the site-specific variability of cytosolic metal and protein concentrations in gills of European chub from the Sava River could be mostly associated with gill mass variability. In spring 2006, the correlations of metals and proteins with gill mass were mainly nonsignificant, and their site-specific variability could be presumably associated with river water pollution. The spring cytosolic concentrations of Zn, Cu, and Mn did not differ significantly between the sites (medians: 8.37–11.34 μg ml⁻¹, 68.2–86.2 ng ml⁻¹, and 55.9–68.6 ng ml⁻¹, respectively). Increased cytosolic Cd concentrations were obtained at Oborovo and Lukavec Posavski (median: 4.01 ng ml⁻¹)—the sites influenced by pollution sources from two major urban areas—compared with the remaining sampling sites (median: 1.93 ng ml⁻¹). Cytosolic Fe concentrations were almost two times higher at Jasenovac (median: 11.98 μg ml⁻¹) compared with the concentrations at Sava-Zagreb (median: 6.72 μg ml⁻¹). Labile Fe concentrations measured in river water with passive samplers indicated that cytosolic Fe concentrations in the spring possibly reflected water-borne Fe uptake. The spring cytosolic protein concentrations decreased from upstream (Otok Samoborski: 27.2 ± 5.6 mg ml⁻¹) toward the downstream sites (Lukavec Posavski: 14.8 ± 2.8 mg ml⁻¹), possibly because of the influence of organic pollution and water toxicity. The spring period seems to be a more appropriate season for the assessment of the river water pollution if chub gills are used as the target organ.     

Determination of Metal Levels in Thirteen Fish Species from Lakshadweep Sea

A bio-monitoring study was performed to investigate the concentration of certain metals (cadmium, cobalt, copper, iron, magnesium, manganese, nickel, lead and zinc) in gill, skin and muscle of thirteen demersal fish species of Agatti Coast of Lakshadweep Sea. All the metal concentrations in gill are higher than skin and muscle. Concentrations of toxic metals such as Cd (0.61 ± 0.67 μg g⁻¹ in Gerres longirostris), Mn (0.83 ± 1.21 μg g⁻¹ in Lutjanus fulvus) and Ni (0.56 ± 0.83 μg g⁻¹ in L. bengalensis) were well above the permissible limits suggested by World Health Organization and Food and Agricultural Organizations.     

Solubility of Trace Elements and Heavy Metals from Stabilized Sewage Sludge by Fly Ash

Stabilized sewage sludge (SS) by fly ash (FA) and alkaline mine tailing as artificial soil, to be applied on the ecological rehabilitation at mining junkyard, offers a potential viable utilization of the industrial by-product, as well as solves the shortage of soil resource in mine area. In this study, trace element and heavy metal soil solution concentrations arising from fly ash, sewage sludge, mine tailing, and artificial soil mixtures were investigated in a laboratory incubation. It was found that total Cd, Pb, and Zn contents in artificial soils were significantly lower than the control standards for pollutants in sludges from agricultural use (GB 4284-84). Soil solution Cd and Pb concentrations were obviously reduced by mixing sewage sludge with alkaline fly ash. Initial soil solution Cd, Pb, and Zn concentrations in artificial soils were 1.773–14.672, 4.05–24.95, and 133–608 μg L⁻¹, respectively, and after 35-days incubation, soil solution Cd, Pb, and Zn concentrations gradually decreased and were approaching control levels by the end of the experiment, and finial soil solution were decreased to 0.037–0.365, 2.12–7.34, and 29–509 μg L⁻¹, respectively.     

Intercomparison Studies on Distribution and Coassociations of Heavy Metals in Liver, Kidney, and Muscle of Harbor Porpoise, Phocoena phocoena, from Southern Baltic Sea and Coastal Waters of Denmark and Greenland

The concentrations of selected metals such as Cd, Pb, Cu, Zn, Cr, Ni, Mn, and Fe were determined in liver, kidney, and muscle of harbor porpoise (Phocoena phocoena) from three geographical regions, i.e., the Baltic Sea and Danish and Greenland coastal waters. The concentrations of Cd in liver and kidney increased with age of the specimens analyzed. Significant interspatial variations in both hepatic and renal levels of Cd were also observed. Average hepatic levels of Cd in Baltic, Danish, and Greenland specimens were (age range) 0.05–0.09, 0.12–0.25, and 20.6–51.6 μg g⁻¹ dry weight, respectively. Such values for renal Cd were as follows: 0.55–0.71, 0.14–1.84, and 0.55–94.3 μg g⁻¹ dry weight. In contrast to Cd, concentrations of Cu in the liver and kidney of specimens from Baltic, Danish, and Greenland areas did not indicate such great interspatial variability. The average hepatic values amounted to (age range) 14.1–15.5, 22.1–63.6, and 16.3–25.9 μg g⁻¹ dry weight, and kidney contained on the average 7.83–8.80, 11.7–16.2, and 11.1–15.7 μg Cu g⁻¹ dry weight, respectively. The higher levels of hepatic and renal Cd in Greenland specimens than in Baltic ones could be explained by different food composition in the area studied. Baltic porpoises mainly feed on fish (cod, plaice) containing extremely low levels of muscle Cd, but an important diet component of Greenlandic individuals is squid, characterized by elevated levels of Cd. Received: 22 May 2001/Accepted: 11 November 2001     

Determination of Trace Elements Level of Pikeperch Collected from the Caspian Sea

Toxic and essential elements levels (chromium, copper, iron, manganese, nickel, lead, cadmium, and zinc) have been determined in the brain, heart, liver, gill, gonads, spleen, bile and muscle of S. lucioperca, collected from the Caspian Sea by employing Flame- Atomic absorption spectrometry. Results indicated that nearly all of the toxic metals concentrations (nickel, lead and cadmium) in tissues were higher than limits for fish suggested by Food and Agricultural Organization, World Health Organization and European Union. Lead was higher in spleen than other tissues. Levels of essential metals (iron, copper, zinc and manganese) were below the limits suggested by European Union and Food and Agricultural Organization/World Health Organization and Turkish Food Codex for fish. Iron distribution pattern in tissues was in the following order: heart (88.67 ± 2.74 μg g⁻¹ wet wt) > spleen (70.96 ± 2.05 μg g⁻¹ wet wt) > bile (29.35 ± 0.94 μg g⁻¹ wet wt) > brain (14.29 ± 0.51 μg g⁻¹ wet wt) > liver (8.57 ± 0.29 μg g⁻¹ wet wt) > gill (3.20 ± 0.14 μg g⁻¹ wet wt) > red (2.79 ± 0.11 μg g⁻¹ wet wt) and white muscles (2.79 ± 0.09 μg g⁻¹ wet wt) > gonads (2.57 ± 0.07 μg g⁻¹ wet wt).     

Geographic distribution of arsenic and trace metals in lotic ecosystems of the Pampa Plain, Argentina

In this paper, the geographic distribution of arsenic and other trace elements in surface waters of 39 lotic ecosystems of central Argentina was evaluated. Manganese and arsenic were the most conspicuous elements, being present in 82% and 59% of the sampled ecosystems of this region, respectively. As concentration averaged 113.69 μg L⁻¹ varying between 55 and 198 μg L⁻¹, other trace elements were hardly detected or not detected at all. It was remarkable the absence of detectable concentrations of anthropogenically derived metals as lead (Pb) and cadmium (Cd).     

Heavy Metal Levels in Suspended Sediments, Crassostrea gigas, and the Risk to Humans

Wild Pacific oyster (Crassostrea gigas) and sediment, both resuspended and suspended (RSS) samples (<53 μm), were collected over an 8-month period from a coastal estuary in Baynes Sound, BC, Canada. Stable isotope analysis (δ¹³C, δ¹⁵N) was used to determine, first, if RSS sediments was an important dietary source to C. gigas and, second, if so, whether it served as a significant dietary exposure route for Cd, Cu, Pb, and Zn. Although RSS sediments were high in trace metals such as Cd, Pb, Zn, and notably Cu, stable isotope signatures for oyster tissues did not correspond to those of RSS sediments. These results indicate that RSS sediments are not a significant source of metal to the oysters. In addition, we compared the potential risk to humans ingesting C. gigas with levels of Cd, Cu, Pb, and Zn from this study to the current Agency for Toxic Substances and Disease Registry (ATSDR) chronic oral minimal risk levels (MRLs) using current Canadian consumption guidelines of three oysters/week. Cu, Pb, and Zn levels were below MRL levels, with Cd exceeding the recommended 0.2 μg/kg/day MRL level fourfold. Total daily intake levels (TDI) for Cd were additionally calculated and either reached or exceeded the Food and Agriculture Organization/World Health Organization (FAP/WHO) reference dose of 1 μg/kg/day for Cd consumption in Canadians. Our results indicate that the current Canadian Cd consumption guidelines do not protect individuals consuming the maximum recommended levels of wild oysters.