Seasonal Variation of Polychlorinated Biphenyls and Organochlorine Pesticide Levels of Sea and Cultured Farm Fish in the Samsun Region of Turkey

The concentrations of selected Organochlorine (OC) pesticides (α-HCH, β-HCH, γ-HCH, HCB, aldrin, 2,4′-DDE, 4,4′-DDE, 2,4′-DDT, 4,4′-DDT) and Polychlorinated Biphenyls (PCBs) (28, 70, 74, 81, 99, 101, 105, 118, 128, 138, 153, 156, 170, 180, 183, 187) were measured in two species of cultured freshwater fish (rainbow trout, Oncornhychus mykiss and catfish, Silurus glanis) and two kinds of sea fish (mullet, Mugil cephalus and salmon, Salmo salar) between March 2008 and June 2009 in order to evaluate the status, seasonal changes and potential sources of pollution in the Samsun region of Turkey. Concentrations of total PCBs ranged from 17.6 to 335 ng/g in rainbow trout, 1,063 to 3,234 ng/g in mullet, 21 to 1,887 ng/g in salmon and 108 to 1,172 ng/g lipid in catfish and total OC pesticide concentrations ranged from 303 to 473, 319 to 6,158, 101 to 249 and 34 to 6,069 ng/g lipid in rainbow trout, mullet, salmon and catfish, respectively. It is concluded that the levels of persistent organic pollutants should be monitored regularly and rigorously by the appropriate government agency, with mandatory public reporting.     

Mercury Distribution in Sediments and Bioaccumulation by Fish in Two Oregon Reservoirs: Point-Source and Nonpoint-Source Impacted Systems

Mercury pollution was compared in two Oregon reservoirs of similar size and age, located within the same ecoregion. Cottage Grove Reservoir was distinguished by a history of mercury mining and processing within its watershed, while Dorena Reservoir was not. Mercury concentrations in sediments of the reservoirs, tributary streams, and three species of fish were measured. Sediment mercury concentrations in the main tributary of Cottage Grove Reservoir, which drains the subbasin where past mercury mining occurred, was tenfold higher than mercury in sediments from other reservoir tributaries. There were no significant differences between sediment mercury concentrations in the tributaries of Dorena Reservoir. The average mercury concentration in the basin sediment of Cottage Grove Reservoir (0.67 ± 0.05 μg/g dry wt) was higher than for Dorena Reservoir (0.12 ± 0.01 μg/g dry wt). At Cottage Grove Reservoir, maximum mercury concentrations were near or exceeded 1 μg/g wet wt for largemouth bass (Micropterus salmonides) and bluegill (Lepomis macrochirus) epaxial muscle. Muscle mercury concentrations in largemouth bass and crappie (Pomoxis nigromaculatus) from Cottage Grove Reservoir were significantly higher than from the same species from Dorena Reservoir. Numbers of bluegill of the same age available from both reservoirs were too small for statistical comparisons. Mercury concentrations in largemouth bass muscle fluctuated annually in both reservoirs. Fish ages were consistently positively correlated with muscle mercury concentrations in only the point-source-impacted reservoir. These results indicated that a point source, Black Butte Mine, contributed amounts of mercury greatly in excess of mobilization from natural deposits, atmospheric deposition, and small-scale uses of the metal as an amalgamating agent in gold mining. Received: 12 September 1996/Accepted: 22 July 1997     

PCBs and Organochlorines in Tissues of Silverside (Odontesthes bonariensis) from a Coastal Lagoon in Argentina

A freshwater fish species, silverside (Odontesthes bonariensis) from Mar Chiquita coastal lagoon, Argentina, was analyzed for concentrations of several organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs) in liver, gonads, mesenteric fat and muscle, and the contents of the digestive tract over several stages of sexual maturation. PCBs and OCs were detected at ng/g concentrations (wet weight) in pooled samples, with levels generally in the order of fat > liver > gonad > muscle, reflecting the differences in tissue lipid content. Lipid-normalized concentrations of the analytes were relatively consistent among tissues, except for significantly higher concentrations of PCBs (e.g., 447.7 ng/g lipid wt) in the ovaries of female silverside. DDT and its metabolites, γ-HCH, and several insecticides from the cyclodiene class, including endosulfan and endosulfan sulfate, were the predominant OCs in fish tissues and the contents of the digestive tract, reflecting recent and past pesticide use in this region. The ratio of OCs to PCBs in all tissues was >1; consistent with contamination of the region with OC pesticides. However, PCBs were dominated by penta- and hexachlorobiphenyls, which is consistent with direct (i.e., nonatmospheric) inputs. Biomagnification of penta- and hexachlorobiphenyl PCB congeners was noted in fish tissues relative to the contents of the digestive tract. Total OC and PCB concentrations in the ovaries and muscle of silverside were below concentrations associated with reproductive impairment in fish or the limits for human consumption, respectively.     

Influence of lake characteristics on the biomagnification of persistent organic pollutants in lake trout food webs

The biomagnification of polychlorinated biphenyls (PCBs) and major organochlorine pesticides (OCPs) was studied using lake trout (Salvelinus namaycush) and other food web organisms collected from 17 lakes in Canada and the northeastern United States between 1998 and 2001. Whole lake trout (n = 357) concentrations of the sum (Sigma) of 57 PCB congeners ranged between 1.67 and 2,890 ng/g wet weight (median 61.5 ng/g wet wt). Slimy sculpin had the highest mean concentrations of SigmaPCB of all forage fish (32-73 ng/g wet wt). Positive relationships between log (lipid wt) concentrations of PCB congener 153, PCB congener 52, p,p'-dichlorodiphenyldichloroethylene, hexachlorobenzene, cis-chlordane, trans-nonachlor, or dieldrin and trophic level (determined using stable nitrogen isotope ratios) were found for most of the 17 food webs, indicating biomagnification of these PCBs and OCPs. The p,p'-dichlorodiphenyldichloroethylene had the highest trophic magnification factors (TMFs) of the 14 individual compounds studied, averaging 4.0 +/- 1.8 across the 17 lakes, followed by trans-nonachlor (3.6 +/- 1.5) and PCB congener 153 (3.4 +/- 1.2). Average TMFs for 14 individual PCBs or OCPs were significantly correlated with log octanol-water partition coefficient, implying that the rate of accumulation along the food web is dependent on hydrophobicity and recalcitrance. Significant correlations (p < 0.05) were found between TMFs of SigmaPCBs, hexachlorobenzene, alpha-hexachlorocyclohexane, and lindane and lake area, latitude, and longitude, but not for 11 other PCBs or OCPs. Overall, the results of the present study show that biomagnification of PCBs and most OCPs, as measured by TMFs, is only weakly influenced by such factors as latitude and longitude. Exceptions are hexachlorocyclohexane isomers and hexachlorobenzene, which had generally greater TMFs in northern lakes, possibly due to lower rates of elimination and biotransformation in the food web.     

Comparison of mercury concentrations in landlocked, resident, and sea-run fish (Salvelinus spp.) from Nunavut, Canada

Mercury concentrations ([Hg]) in Arctic food fish often exceed guidelines for human subsistence consumption. Previous research on two food fish species, Arctic char (Salvelinus alpinus) and lake trout (Salvelinus namaycush), indicates that anadromous fish have lower [Hg] than nonanadromous fish, but there have been no intraregional comparisons. Also, no comparisons of [Hg] among anadromous (sea-run), resident (marine access but do not migrate), and landlocked (no marine access) life history types of Arctic char and lake trout have been published. Using intraregional data from 10 lakes in the West Kitikmeot area of Nunavut, Canada, we found that [Hg] varied significantly among species and life history types. Differences among species-life history types were best explained by age-at-size and C:N ratios (indicator of lipid); [Hg] was significantly and negatively related to both. At a standardized fork length of 500?mm, lake trout had significantly higher [Hg] (mean 0.17?μg/g wet wt) than Arctic char (0.09?μg/g). Anadromous and resident Arctic char had significantly lower [Hg] (each 0.04?μg/g) than landlocked Arctic char (0.19?μg/g). Anadromous lake trout had significantly lower [Hg] (0.12?μg/g) than resident lake trout (0.18?μg/g), but no significant difference in [Hg] was seen between landlocked lake trout (0.21?μg/g) and other life history types. Our results are relevant to human health assessments and consumption guidance and will inform models of Hg accumulation in Arctic fish.     

Residues of Organochlorines in Sediments and Tilapia Collected from Inland Water Systems of Hong Kong

The levels and patterns of organochlorines including DDTs, HCHs, and PCBs were investigated in sediments and tilapia (Tilapia mossambica) collected from inland water systems [Tai Wai (S1), Fo Tan (S2), Siu Lek Yuen (S3), Tai Po (S4), and Tai Wo (S5)] in the New Territories of Hong Kong. Sediment and tilapia samples were also collected from two fish ponds for comparison. The ranges of DDTs, HCHs, and PCBs in river sediments were 2.82–8.63 ng/g (DW), 0.05–2.07 ng/g (DW), and 43–461 ng/g (DW), respectively. All these values were significantly higher (p < 0.05) than the pond sediments. Low chlorinated congeners (especially mono-, tri-, and tetrachlorobiphenyls) were enriched in sediment samples accounting for 70–80% of total PCBs.  The ranges of DDTs, HCHs, and PCBs in tilapia muscle collected from Fo Tan and Tai Wai were 28.2–40.1 ng/g (DW), 2.04–3.76 ng/g (DW) and 267–310 ng/g (DW), respectively. These values were also significantly higher (p < 0.05) than those collected from the fish ponds. Higher chlorinated PCBs (tetra-, penta-, hexa-, and heptachlorobiphenyls) were commonly found in tilapia accounting for almost 60% of the total PCBs. The effect of lipid contents in organochlorines accumulation was not significant (p < 0.05) in general. Received: 24 July 1998/Accepted: 18 November 1998     

Joint toxicity of mercury and selenium in salmonid eggs

Toxic interactions between mercury and selenium in fertilized eggs of rainbow trout (Salmo gairdneri) and lake trout (Salvelinus namaycush) were investigated and compared to the pronounced synergistic effect previously reported in carp (Cyprinus carpio) eggs. Mercury produced concentration-dependent decreases in median survival times and caused decreases in median hatch times. Selenium, at concentrations up to 10 mg Se/L, had no effect on hatching times, and did not produce mortality, and had no effect on mercury toxicity. At concentrations of 100 mg Se/L and higher, an apparent protective effect of selenium on mercury toxicity was observed in lake trout eggs. Requirements for additional research are discussed with emphasis on predictions of region-wide damage to freshwater fish populations due to atmospheric deposition of these chemical elements.     

Current-Use Pesticides and Organochlorine Compounds in Precipitation and Lake Sediment from Two High-Elevation National Parks in the Western United States

Current-use pesticides (CUPs) and banned organochlorine compounds (OCCs) were measured in precipitation (snowpack and rain) and lake sediments from two national parks in the Western United States to determine their occurrence and distribution in high-elevation environments. CUPs frequently detected in snow were endosulfan, dacthal, and chlorothalonil in concentrations ranging from 0.07 to 2.4 ng/L. Of the OCCs, chlordane, hexachlorobenzene, and two polychlorinated biphenyl congeners were detected in only one snow sample each. Pesticides most frequently detected in rain were atrazine, carbaryl, and dacthal in concentrations from 3.0 to 95 ng/L. Estimated annual deposition rates in one of the parks were 8.4 μg/m² for atrazine, 9.9 μg/m² for carbaryl, and 2.6 μg/m² for dacthal, of which >85% occurred during summer. p,p’-DDE and p,p’-DDD were the most frequently detected OCCs in surface sediments from lakes. However, concentrations were low (0.12 to 4.7 μg/kg) and below levels at which harmful effects for benthic organisms are likely to be observed. DDD and DDE concentrations in an age-dated sediment core suggest that atmospheric deposition of DDT and its degradates, and possibly other banned OCCs, to high-elevation areas have been decreasing since the 1970s. Dacthal and endosulfan sulfate were present in low concentrations (0.11 to 1.2 μg/kg) and were the only CUPs detected in surface sediments. Both pesticides were frequently detected in snow, confirming that some CUPs entering high-elevation aquatic environments through atmospheric deposition are accumulating in lake sediments and potentially in aquatic biota as well.     

Polychlorinated Biphenyls and Organochlorine Pesticides in Plasma and the Embryonic Development in Lake Erie Water Snakes (<Emphasis Type="Italic">Nerodia sipedon insularum</Emphasis>) from Pelee Island,Ontario, Canada (1999)

From three locations along a 34-km shoreline of Pelee Island, Ontario, 30 gravid female Lake Erie water snakes (Nerodia sipedon insularum) were sampled to determine the organochlorine (OC) contaminant levels in plasma and the number of live and dead embryos present in the body cavity. Plasma was analyzed for 59 polychlorinated biphenyl (PCB) congeners and 14 organochlorine pesticides. Concentrations of pesticides were low (≤0.1 ng/g wet wt) in all snakes, but there was significant variation in mean PCB concentrations in plasma from among the sampling locations on Pelee Island. Snakes (n = 5) from the West shore and dock area of the island had significantly higher PCB concentrations (90.4 ± 15.0 ng/g wet wt) in plasma than those from Lighthouse Point (n = 5; 34.4 ± 13 ng/g wet wt) and the south shore of the island (n = 5; 29.4 ± 16.3 ng/g wet wt). Body mass of the female snakes ranged from 252 to 880 g, and mean masses were not significantly different among sample sites. The number of live embryos found ranged from 13 to 46 female snakes and no dead embryos were detected. There were significant positive correlations among body mass, snout–vent length, and number of young per female. There were no significant correlations among body mass, snout–vent length, number of young per female, or per-gram body mass of female snakes and contaminant concentrations in plasma. It was concluded that an interim estimate of a no-effect level on embryonic survival in N. sipedon insularum may be a maximum average concentration of 90.4 ng/g wet wt PCBs and a maximum average concentration of 3.6 ng/g wet wt p,p′-dichloro-diphenyl-dichloroethylene in plasma.     

Bioaccumulation and Biomagnification of Organochlorines in a Marine Food Web at a Pristine Site in Iceland

Organochlorine (OC) bioaccumulation and biomagnification were studied in a marine food web at a pristine site in Iceland. The species studied were the gastropod and grazer chink shell (Lacuna vincta), the filter feeding bivalve blue mussel (Mytilus edulis), the predators butterfish (Pholis gunnellus), and the seabird black guillemot (Cepphus grylle), all sampled and analysed in 1996–1997. Individual OC levels were generally low in chink shell and blue mussels, somewhat elevated in the fish, and an order of a magnitude higher in the top predator black guillemot, except for ΣHCH (hexachlorocyclohexane isomers) and Σchlordane levels, which were similar in all organisms, ranging from 10 to 36 ng/g lipid weight (lw). In the molluscs and fish, mean concentrations of ΣPCB (polychlorinated biphenyl) ranged from 111 to 377 ng/g lw, ΣDDT (dichlorodiphenyltrichloroethane) ranged from 19 to 65 ng/g lw, and HCB (hexachlorobenzene) ranged from 21 to 30 ng/g lw. The levels of same OCs in the black guillemot were on average 2352, 361, and 283 ng/g lw, respectively. The OC tissue concentrations in blue mussel and black guillemot are comparable to levels in Arctic and sub-Arctic regions, but OC levels in blue mussel tissue were an order of magnitude lower than found in the North Sea and the Baltic Sea. The relative composition of OCs were generally similar among species with the PCB congeners emerging as the most abundant compounds with levels an order of magnitude higher than the other compounds in all species. Food web magnification factors (FWMFs) were determined for the OCs by using trophic levels determined from δ¹⁵N. FWMFs >1, indicating biomagnification, were found for ΣPCB, penta- or higher chlorinated PCBs (e.g., PCB 101, 118, 138, 153, 180), β-HCH, HCB, ΣDDT, p,p-DDE, and transnonachlor. The highest FWMF was observed for PCB 180 at FWMF = 5.8.     

Distribution of Total Mercury and Methyl Mercury in Water, Sediment, and Fish from South Florida Estuaries

Concentrations of total mercury and methyl mercury were determined in sediment and fish collected from estuarine waters of Florida to understand their distribution and partitioning. Total mercury concentrations in sediments ranged from 1 to 219 ng/g dry wt. Methyl mercury accounted for, on average, 0.77% of total mercury in sediment. Methyl mercury concentrations were not correlated with total mercury or organic carbon content in sediments. The concentrations of total mercury in fish muscle were between 0.03 and 2.22 (mean: 0.31) μg/g, wet wt, with methyl mercury contributing 83% of total mercury. Methyl mercury concentrations in fish muscle were directly proportional to total mercury concentrations. The relationship of total and methyl mercury concentrations in fish to those of sediments from corresponding locations was fish-species dependent, in addition to several abiotic factors. Among fish species analyzed, hardhead catfish, gafftopsail catfish, and sand seatrout contained the highest concentrations of mercury. Filtered water samples from canals and creeks that discharge into the Florida Bay showed mercury concentrations of 3–7.4 ng/L, with methyl mercury accounting for <0.03–52% of the total mercury. Consumption of fish containing 0.31 μg mercury/g wet wt, the mean concentration found in this study, at rates greater than 70 g/day, was estimated to be hazardous to human health. Received: 3 July 1997/Accepted: 2 September 1997     

Trace Organic Contaminants in Sediment and Water from Ulsan Bay and Its Vicinity, Korea

Sediment and water samples collected from 32 locations in Ulsan Bay and adjacent inland areas were analyzed for polycyclic aromatic hydrocabons (PAHs), nonylphenol (NP), octylphenol (OP), bisphenol A (BPA), organochlorine (OC) pesticides (HCB, HCHs, CHLs, and DDTs), and polychlorinated biphenyls (PCBs) to characterize their spatial distribution and contamination status. PAHs were detected in nearly all sediment and water extracts from Ulsan Bay and its inland locations. The sedimentary PAH concentrations ranged from 17 to 3,100 ng/g on a dry weight basis (DW), which were predominated by two- and three-ring aromatic hydrocarbons in river and/or stream, and four- to six-ring compounds in Ulsan Bay sediment. Concentrations of PAHs in pore water samples were generally two or three orders magnitude less than those of corresponding sediment samples. Maximum concentrations of NP, OP, and BPA in sediments were 1,040, 120, and 54 ng/g DW, respectively. Concentrations of OP and BPA were, on average, 5- to 13-fold less than those of NP. PCB concentrations in sediment ranged from 1.4 to 77 ng/g DW, which were predominated by lower chlorinated congeners such as di- through pentachlorinated biphenyls. Among different OC pesticides analyzed, concentrations of DDTs were the greatest, ranging from 0.02 to 41.9 ng/g DW. NP concentrations were greater at inner locations proximal to municipal wastewater discharges into rivers and/or streams, whereas the concentrations of PCBs and PAHs were great near the sites of high industrial activities. Sediment-pore water partitioning coefficients correlated with those of reported K _oc or K _ow values for selected PAHs in Ulsan Bay, but these varied by an order of magnitude for stream and/or river sediments. Received: 11 June 2000/Accepted: 28 August 2000     

Distribution of Mercury in Several Environmental Compartments in an Aquatic Ecosystem Impacted by Gold Mining in Northern Colombia

Mercury (Hg) used in gold amalgamation is a major source of contamination in developing countries. Water, sediments, plankton, fish, and human samples from Grande Marsh, a Hg-polluted marsh located in the south of Bolívar, municipality of Montecristo, Colombia, were collected during both the rainy and the dry seasons (2003–2006), at three different sampling sites, and analyzed for total Hg (T-Hg) content. Water, sediment, seston, phytoplankton, and zooplankton T-Hg concentrations were 0.33 ± 0.03 μg/L, 0.71 ± 0.03, 1.20 ± 0.06, 0.52 ± 0.03, and 0.94 ± 0.05 μg/g dry weight (wt), respectively. T-Hg levels in these compartments were highly pair-correlated (p < 0.05), and for all of them, except sediments, greater values were found during the dry season. Significant differences were observed for T-Hg concentrations in fish according to their trophic position. Average highest T-Hg values were found in carnivorous species such as Caquetaia kraussi (1.09 ± 0.17 μg/g fresh wt), Hoplias malabaricus (0.58 ± 0.05 μg/g fresh wt), and Plagioscion surinamensis (0.53 ± 0.07 μg/g fresh wt), whereas the lowest were detected in noncarnivorous species such as Prochilodus magdalenae (0.157 ± 0.01 μg/g fresh wt). In those fish species where seasonal comparisons were possible, specimens captured during the dry season had greater T-Hg levels in muscle. Although the T-Hg mean level for all fish samples (0.407 ± 0.360 μg/g fresh wt) did not exceed the recommended limit ingestion level, risk assessment based on the hazard index suggested that a fish intake of 0.12 kg per day (a small carnivorous specimen) could increase the potential health effects related to Hg exposure in the local human population, whose hair T-Hg median value was 4.7 μg/g, and presented a low but significant correlation with fish consumption (r = 0.250, p = 0.016). In short, Hg pollution from gold mining around Grande Marsh has permeated the food web, and currently levels in fish represent a serious concern for human health.     

Polychlorinated Biphenyls and Metals in Marine Species from French Frigate Shoals, North Pacific Ocean

Polychlorinated biphenyls (PCBs) and metals were analyzed in coral (Porites lobata), fish (Stegastes fasciolatus), crab (Grapsus tenuicrustatus), and sediment samples collected from Tern Island, and the reference samples from Trig and La Perouse Islands. All three islands are part of French Frigate Shoals, a national wildlife refuge in the North Pacific Ocean. Average concentrations of total PCBs ranged from 154 to 274 ng/g in the sediments, from 120 to 267 ng/g in the corals, from 387 to 4,500 ng/g in the crabs, and 1,340 to 46,000 ng/g, dry weight, in the fishes. High concentrations in marine species indicate there is PCB source(s) in French Frigate Shoals, especially Tern Island. Tetra- and pentachlorobiphenyls were 64–66% of the total PCB levels in the sediments, and they accounted for 57–65% of total PCBs in the corals. Penta- and hexachlorobiphenyls were 76–84% of total PCBs in the fishes, and they accounted for 79–85% in the crab samples. The sediment and coral were predominated by lower chlorinated PCB congeners, whereas the fish and crab bioaccumulated mainly higher chlorinated congeners. Selenium concentrations (16–23 μg/g) in sediments were much higher than some reported baseline values (0.4–2.5 μg/g). The average concentrations of arsenic, cadmium, lead, and selenium in the coral and fish were about equal to or less than those in the sediments. Concentrations of arsenic and cadmium in the crabs (49–51 and 3–4 μg/g, respectively) were approximately twofold of those in the sediments. Received: 19 April 1999/Accepted: 2 November 1999     

Polychlorinated Dibenzo-p-Dioxins, Dibenzofurans, and Dioxin-Like Polychlorinated Biphenyls in Sediment and Mussel Samples from Kentucky Lake, USA

Sediment and mussel tissues from the Kentucky Dam Tailwater (KDTW) and Ledbetter Embayment (LE) of Kentucky Lake, Kentucky, USA, were analyzed to examine the presence of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and non-, mono-, and di-ortho-chlorine-substituted polychlorinated biphenyls. Concentrations of target compounds varied with locations and sample matrices. In general, KDTW sediment samples contained slightly higher amounts of PCDD/DFs (average: 1100, range: 120-2400) than the LE sediments (average: 920, range: 580-1300) on a pg/g dry wt (dw) basis. Dioxin-like PCBs in KDTW were (average: 550, range: 70–2,000) higher than in LE (average: 320, range: 44-1000) on a ng/g dw basis. In contrast, mussel tissues had greater concentrations of PCDD/DFs in LE (average: 6500, range: 2200–13,000) than in KDTW (average: 3500, range: 2500-4800). Dioxin-like PCBs were slightly higher in KDTW (average: 76, range: 18–100) than in LE (average: 49, range: 24–96) on a ng/g fat wt basis. Biota sediment accumulation factors (BSAFs) were calculated using tissue concentrations and sediment concentrations based on dry weight. PCDD/DFs BSAF was in the range of 0.21-25 in LE and 0.093-13 in KDTW. 1,2,3,7,8,9-HxCDF in LE and 2,3,7,8-TCDF in KDTW had a greater BSAF, while BSAF for dioxin-like PCBs ranged from 0.84 to 13 in LE and from 2.3 to 12 in KDTW in which PCB-169 had the greatest BSAF in LE and PCB-167 in KDTW. Toxic equivalency (TEQ) was greatest in mussel from LE (mean: 193 pgTEQ/g fat wt) followed by mussel from KDTW (32 pgTEQ/g fat wt), sediment in KDTW (13 pgTEQ/g dry wt), and sediment in LE (7.6 pgTEQ/g dry wt). In general, PCDD/DF had a greater contribution to toxicity in mussels, while dioxin-like PCBs had a greater contribution to toxicity in sediment at both locations.     

Environmental Contaminants in Fish and Their Associated Risk to Piscivorous Wildlife in the Yukon River Basin, Alaska

Organochlorine chemical residues and elemental contaminants were measured in northern pike (Esox lucius), longnose sucker (Catostomus catostomus), and burbot (Lota lota) from 10 sites in the Yukon River Basin (YRB) during 2002. Contaminant concentrations were compared to historical YRB data and to toxicity thresholds for fish and piscivorous wildlife from the scientific literature. A risk analysis was conducted to screen for potential hazards to piscivorous wildlife for contaminants that exceeded literature-based toxicity thresholds. Concentrations of total DDT (sum of p,p′-homologs; 1.09–13.6 ng/g), total chlordane (0.67–7.5 ng/g), dieldrin (<0.16–0.6 ng/g), toxaphene (<11–34 ng/g), total PCBs (<20–87 ng/g), TCDD-EQ (≤1.7 pg/g), arsenic (0.03–1.95 μg/g), cadmium (<0.02–0.12 μg/g), copper (0.41–1.49 μg/g), and lead (<0.21–0.27 μg/g) did not exceed toxicity thresholds for growth and reproduction in YRB fish. Concentrations of mercury (0.08–0.65 μg/g), selenium (0.23–0.85 μg/g), and zinc (11–56 μg/g) exceeded toxicity thresholds in one or more samples and were included in the risk analysis for piscivorous wildlife. No effect hazard concentrations (NEHCs) and low effect hazard concentrations (LEHCs), derived from literature-based toxicity reference values and avian and mammalian life history parameters, were calculated for mercury, selenium, and zinc. Mercury concentrations in YRB fish exceeded the NEHCs for all bird and small mammal models, which indicated that mercury concentrations in fish may represent a risk to piscivorous wildlife throughout the YRB. Low risk to piscivorous wildlife was associated with selenium and zinc concentrations in YRB fish. Selenium and zinc concentrations exceeded the NEHCs and LEHCs for only the small bird model. These results indicate that mercury should continue to be monitored and assessed in Alaskan fish and wildlife.     

Rock-Shells (Thais clavigera) as an Indicator of As, Cu, and Zn Contamination on the Putai Coast of the Black-Foot Disease Area in Taiwan

This study presents the distribution of arsenic (As), copper (Cu), and zinc (Zn) in various seafoods—oysters (Crassostrea gigas), false fusus (Hemifuscus tuba), venus clams (Cyclina sineasis), green mussels (Perna viridis), blood clams (Arca granosa), flounders (Psettodes erumei), and rock-shells (Thais clavigera) collected from the Putai coast of the black-foot disease (BFD) area in Taiwan. Special attention is paid to evaluate the relationships among As, Cu, and Zn and effect of body size on metal concentration in Thais clavigera. Maximum Zn and Cu geometric mean (GM) concentrations (GM = 615 and 376 μg/g, dry wt, respectively) are found in oysters (Crassostrea gigas), and the values are much higher than those of the other organisms by about 1.7–208 and 1.8–375 times, respectively. Similarly, Thais clavigera has a high capacity for accumulating Cu and Zn collected from the same location. One interesting point is that relatively high As concentrations (GM = 65.7 μg/g, dry wt) in Thais clavigera are found as compared with those in other organisms (range from GM = 2.37 to 40.2 μg/g, dry wt). The As concentrations are significantly higher in Thais clavigera (1.62–27.7 times) than those in other organisms (p < 0.05), except for the false fusus (Hamifuscus tuba). A linear regression analysis shows a significant increase in Zn concentration with increasing Cu concentration in Thais clavigera. On the other hand, the As concentration is correlated with Cu and Zn concentrations (r = 0.77 and 0.77, respectively; p < 0.05) in Thais clavigera. Double logarithmic plots of metal content and concentration against dry-body weight and shell length show linear relationships. The result indicates that large individuals have higher contents of Cu, Zn and As, and have slopes of 1.58, 1.38, and 1.34, respectively. In addition, metal concentrations against shell length for all animal sizes also indicate that Cu, Zn and As have slopes of 1.92, 1.18, and 1.11, respectively. In conclusion, Thais clavigera has a high capactiy for accumulating As, Cu, and Zn and is a potential bioindicator for monitoring As, Cu and Zn. Received: 8 February 1996/Revised: 15 June 1996     

Concentrations of Metals in Water,Sediment, Biofilm,Benthic Macroinvertebrates,and Fish in the Boulder River Watershed,Montana, and the Role of Colloids in Metal Uptake

To characterize the partitioning of metals in a stream ecosystem, concentrations of trace metals including As, Cd, Cu, Pb, and Zn were measured in water, colloids, sediment, biofilm (also referred to as aufwuchs), macroinvertebrates, and fish collected from the Boulder River watershed, Montana. Median concentrations of Cd, Cu, and Zn in water throughout the watershed exceeded the U.S. EPA acute and chronic criteria for protection of aquatic life. Concentrations of As, Cd, Cu, Pb, and Zn in sediment were sufficient in the tributaries to cause invertebrate toxicity. The concentrations of As, Cu, Cd, Pb, and Zn in invertebrates from lower Cataract Creek (63, 339, 59, 34, and 2,410 μg/g dry wt, respectively) were greater than the concentrations in invertebrates from the Clark Fork River watershed, Montana (19, 174, 2.3, 15, and 648 μg/g, respectively), that were associated with reduced survival, growth, and health of cutthroat trout fed diets composed of those invertebrates. Colloids and biofilm seem to play a critical role in the pathway of metals into the food chain and concentrations of As, Cu, Pb, and Zn in these two components are significantly correlated. We suggest that transfer of metals associated with Fe colloids to biological components of biofilm is an important pathway where metals associated with abiotic components are first available to biotic components. The significant correlations suggest that Cd, Cu, and Zn may move independently to biota (biofilm, invertebrates, or fish tissues) from water and sediment. The possibility exists that Cd, Cu, and Zn concentrations increase in fish tissues as a result of direct contact with water and sediment and indirect exposure through the food chain. However, uptake through the food chain to fish may be more important for As. Although As concentrations in colloids and biofilm were significantly correlated with As water concentrations, As concentrations in fish tissues were not correlated with water. The pathway for Pb into biological components seems to begin with sediment because concentrations of Pb in water were not significantly correlated with any other component and because concentrations of Pb in the water were often below detection limits.     

Contaminant residues in fish and sediments from lakes in the Atchafalaya River Basin (Louisiana)

Conversion of bottomland hardwood forests agricultural land has reduced habitat and water quality in many lakes in the floodplain of the lower Mississippi River. The objectives of this study were to ascertain current contaminant residue concentrations in fish and sediment from lakes in the Atchafalaya River Basin and to determine the influence of overflow and agricultural land use on contaminant levels. Fish and sediment samples were collected from eight lakes that differed in overflow (no overflow, headwater overflow, backwater overflow) and land-use characteristics (presence or absence of agricultural land). Residue analysis of 24 sediment and 82 fish samples collected from the study lakes showed that contaminant residues were uniformly low. Total DDT concentrations, consisting mainly of DDE, were found in 98% of the fish samples and generally were the highest residues though they rarely exceeded 0.50 g/g. Dieldrin, -BHC and -BHC, in concentrations rarely exceeding 0.05 g/g, were detected in about 50% of the fish samples. Total organochlorine pesticide and PCB residues were less than 2.00 g/g in all fish from all lakes, except for a 3.46 g/g total in spotted gar (Lepisosteus oculatus) from one lake. Sediments were free from pesticide residues except for occasional traces (0.01 g/g) of -BHC. Metal residue concentrations in fish and sediment samples were typical of uncontaminated areas. Lake systems in the Atchafalaya River Basin appeared to be relatively uncontaminated by agricultural pesticides, but metal and organic residues in fish were similar from lakes with the same land-use and overflow characteristics.     

Uptake of 109Cd from Natural Sediments by the Blue Mussel Mytilus trossulus in Relation to Sediment Nutritional and Geochemical Composition

The objective of this study was to determine if trace metal bioavailability from suspended particulate matter (SPM) and recently deposited lake sediment (LS) to the filter-feeding bivalve Mytilus trossulus was dependent on the nutritional content and/or the geochemistry of the sediment. For SPM these characteristics are seasonally dependent; for LS they are dependent on lake chemistry and trophic status. To meet this objective, SPM was sampled from the Fraser River estuary, British Columbia, Canada, during Winter (March), spring (April, May), and summer (June, July) months. Deposited LS was sampled from an acidic dystrophic and a circumneutral, oligotrophic lake. Sediments were labeled with ¹⁰⁹Cd, fed to M. trossulus and the amount of ¹⁰⁹Cd accumulated over a 4-h feeding period assessed. Simultaneous extraction (separation of the sediment into easily reducible, reducible, and organic sediment components) of the radiolabeled sediments indicated that ¹⁰⁹Cd associated with the inorganic, not the organic portion of sediment. The amount of ¹⁰⁹Cd accumulated by the mussel over the 4-h feeding period was dependent on sediment %carbon (%C) and %nitrogen (%N) content (R² = 0.75 and 0.52, respectively, for SPM and R² = 0.76 and 0.64 for LS, respectively), and not on sediment concentrations of easily reducible manganese or reducible iron. These findings suggest that mussels obtain ¹⁰⁹Cd from the inorganic portion of sediment as a consequence of digestive processes that are selecting for the carbon and nitrogen component of sediment. Hence, accumulation of cadmium from sediment will be dependent on sediment %C, and to a lesser extent %N content; however, amounts that the organism will be exposed to will depend on concentrations present on the inorganic component. Predictive models of metal accumulation by filter-feeding organisms need to consider the role of both sediment components for predicting amounts of metal that the organisms will bioaccumulate. Received: 18 June 1998/Accepted: 21 October 1998