Diastereomer-specific bioaccumulation of hexabromocyclododecane (HBCD) in a coastal food web, Western Norway

The present study reports diastereomer-specific accumulation of HBCD from a point source in five marine species representing a typical food web in a Norwegian coastal area. Samples of mussels, polychaetes, crabs and seabird eggs were analyzed for the diastereomers α-, β- and γ-HBCD, as well as lipid content and stable isotopes of nitrogen (¹⁵N/¹⁴N) to estimate trophic level. Accumulated HBCD did not correlate well with lipid content for most of the species, thus wet-weight based concentrations were included in an assessment of biomagnification. In contrast to β- and γ-HBCD, the α-diastereomer increased significantly with trophic level, resulting in magnification factors > 1 in this coastal marine ecosystem. Data for poikilotherms did not show the same positive correlation between the α-diastereomer and trophic position as homeotherms. The apparent biomagnification of the α-HBCD could be due to bioisomerization or diastereomer-specific elimination that differed between poikilotherms and homeotherms.     

Behavior, mass inventories and modeling evaluation of xenobiotic endocrine-disrupting chemicals along an urban receiving wastewater river in Henan Province, China

Historically, the locations of cities mainly depend on the available water source and the urban river not only supplies the fresh water to city but also receives its wastewaters. To analyze the influences of urban zone on its receiving water river, the Jialu River in Henan Province, China, a typical urban river was chosen. Water and sediment samples were collected along the river in 2007 to analyze the concentrations of xenobiotic endocrine-disrupting chemicals (XEDCs) including nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA) in surface water and sediment. The results showed that the concentrations of OP, NP and BPA in surface water were 20.9-63.2 ng L⁻¹ (mean 39.8 ng L⁻¹), 75.2-1520 ng L⁻¹ (mean 645 ng L⁻¹), 410-2990 ng L⁻¹ (mean 1535 ng L⁻¹), respectively. The lowest and highest concentrations of XEDCs in surface water were found in the upper stream and downstream of Zhengzhou urban zone, which was regarded as the major discharge source of these chemicals to this river. The concentrations of OP, NP and BPA in the sediment were 15.9-31.1 ng g⁻¹, 145-349 ng g⁻¹ and 626-3584 ng g⁻¹ with the average concentrations of 21.4 ng g⁻¹, 257 ng g⁻¹ and 2291 ng g⁻¹, respectively. The results of in situ sediment-water partition of XEDCs showed that the partition coefficients (log K_oc′) in the downstream were higher than that in the upstream, which was mainly caused by the retransfer of surface sediment from the upper stream to the downstream. Comparison of measured and theoretical inventories of XEDCs in sediment indicated that the residual time of XEDCs in sediment in the river was about 5 years, which was in the same order of magnitude with its big flood frequency. In order to predict concentration variances of XEDCs in surface water, a fugacity-hydrodynamic model was developed according to the concept of in series completely stirred tank reactors (CSTR). The model results showed that about 29-65% of XEDCs derived from the urban zone (about 2.0 t yr⁻¹) would finally dissipate from aqueous phase in the 170 km downstream of the river. Assuming the discharge amount of XEDCs from the urban zone remaining constant, the predicted concentrations of the total XEDCs in the over 90% river reach would be higher than 1.0 μg L⁻¹ under all normal, high water and low water season in 2007.     

Accumulation of polychlorinated biphenyls and organochlorine pesticide in pet cats and dogs: Assessment of toxicological status

PCB and DDT concentrations were determined in the adipose tissue of cats and dogs from Southern Italy. In cats p,p′-DDE was the most abundant DDT component (95.0%), while in dogs these compounds were absent, except in two specimens. PCB concentrations were higher in cats (199.02 ng g^− 1 lipid weight) than in dogs (41.61 ng g^− 1 lipid weight). Also there were inter-specific differences in the contribution of the different congeners to PCBs, although PCB 138, PCB 153 and PCB 180 were the most representative congeners in both species. Animals from one location, Taranto City, had significantly elevated concentrations of dioxin-like PCBs compared to the other locations. Consequently the estimated mean 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalents (TEQs) of coplanar PCBs were higher in these animals (cats: 0.65 pg g^− 1 lipid weight; dogs 0.29 pg g^− 1 lipid weight) than in the other ones (cats: 0.12 pg g^− 1 lipid weight; dogs: 0.001 pg g^− 1 lipid weight).     

Distributions of total mercury and methylmercury in surface sediments and fishes in Lake Shihwa, Korea

The concentrations of total mercury (THg) and methylmercury (MeHg) in the sediments of Lake Shihwa, an artificial salt lake in Korea located near two large industrial complexes, were determined to investigate the state of Hg contamination in the lake sediments and the effect of local Hg source. THg and MeHg concentrations in the sediments, monitored for 2 years, ranged from 0.02 to 0.28 µg g^− 1 and ≤ 0.026 to 0.67 ng g^− 1, respectively. The overall distribution of Hg in lake sediments showed higher values near industrial complexes and in the central part of the lake. However, the correlations between Hg and environmental factors, such as organic material (OM) content, and acid volatile sulfide (AVS), were weak and did not clearly explain the variation in Hg distribution. The spatial distribution of sediment Hg and monthly precipitation data during the sampling period showed that the amount of runoff following rain events and water gate operation may be additional important factors regulating Hg level and distribution in lake sediments. The levels of THg in fish species in this lake ranged from 9.8 to 35 ng g^− 1, suggesting that the bioavailability of sediment Hg in the lake may be low. Although the THg concentrations in Lake Shihwa sediment were lower than those in other foreign study sites, they were higher than in neighboring coastal regions, and are constantly increasing. This result indicates that the nearby industrial complexes may be the major source of Hg found in the sediments of Lake Shihwa.     

Analysis of composition, distribution and origin of hexachlorocyclohexane residues in agricultural soils from NW Spain

Concentrations of the isomers of the organochlorine pesticide hexachlorocyclohexane (HCH) were determined in 252 surface soil samples collected within a sampling network covering agricultural areas in Galicia (NW Spain). The concentration of total HCH (sum of α + β + γ + δ) ranged between 4 and 2305 ng g⁻¹ (dry weight), with the α-HCH and γ-HCH isomers predominating (< 1-1404 ng g⁻¹ and < 1-569 ng g⁻¹, respectively). The distribution of the pesticide residues was very heterogeneous, with the largest concentrations present in one of the studied areas (the province of A Coruña). The distribution of HCH was not found to be related to any soil property (organic matter, pH, clays, and metals). Multivariate statistical analysis of the data revealed that three populations of samples with a defined composition of HCH, can be related to the source of HCH: technical HCH (α/γ > 3), lindane (99% γ-HCH), or both. The existence of a third population consisting almost exclusively of α-HCH suggests that background contamination of anthropogenic origin dates from several decades ago. The detailed analysis of these populations enabled the possible temporal scale of the application of these pesticides to be deduced.     

Catchment condition as a major control on the quality of receiving basin sediments (Sydney Harbour, Australia)

The current work aimed to compile existing information to better understand the source, fate and effects of metallic contaminants in one catchment-receiving basin system (Iron Cove) in Sydney Harbour (Australia). Copper, Pb and Zn concentrations of potential source materials, i.e. soils (mean 62, 410 and 340 µg g^− 1, respectively) and road dust (mean 160, 490 and 520 µg g^− 1, respectively) and in materials being transported to the estuary, i.e. in gully pots (mean 110, 200 and 260 µg g^− 1 for Cu, Pb, and Zn, respectively), in bedload (mean 210, 880 and 1700 µg g^− 1, respectively) and particulates in canals draining the catchment (mean 325, 290 and 1865 µg g^− 1, respectively) were highly enriched. Estuarine sediments in the receiving basin are enriched 20 times over pre-anthropogenic concentrations and are toxic to benthic animals at the canal mouths. Stormwater remediation is required to reduce metal loads to the adjacent estuary.     

Mercury in waterways that drain into the Wash, in eastern England

Recent work suggests that concentrations of mercury in the livers of wading birds increase during the winter, when they are feeding in the Wash in eastern England. Sediment samples, and a few samples of water and gastropods, from rivers and drainage ditches south-west of the Wash were therefore analysed for total mercury. No large-scale contamination was found, but appreciable amounts of mercury were found in ditches from two bulb-dipping sites: the highest residue in a sediment was 223 μg g⁻¹ (wet wt). The rate of water flow affects the distribution of mercury from a discrete source. Aquatic gastropods may be useful monitors for detection of intermittent release.We studied both the relationship between depth of sediment sample and amount of mercury, and the effect of drying on the mercury content of sediment samples. Sediments with several μg g⁻¹ mercury lost little or no mercury when air-dried at room temperatures. Optimal depth of sample is governed by conflicting requirements to obtain as high a concentration of mercury as possible for ease of analysis, and to get as consistent samples as possible.     

Measurement of surface mercury fluxes at active industrial gold mines in Nevada (USA)

Mercury (Hg) may be naturally associated with the rock units hosting precious and base metal deposits. Active gold mines are known to have point source releases of Hg associated with ore processing facilities. The nonpoint source release of Hg to the air from the large area (hundreds to thousands of hectares) of disturbed and processed material at industrial open pit gold mines has not been quantified. This paper describes the field data collected as part of a project focused on estimating nonpoint source emissions of Hg from two active mines in Nevada, USA. In situ Hg flux data were collected on diel and seasonal time steps using a dynamic flux chamber from representative mine surfaces. Hg fluxes ranged from < 1500 ng m⁻² day⁻¹ for waste rock piles (0.6-3.5 μg g⁻¹) to 684,000 ng m⁻² day⁻¹ for tailings (2.8-58 μg g⁻¹). Releases were positively correlated with material Hg concentrations, surface grain size, and moisture content. Highest Hg releases occurred from materials under active cyanide leaching and from tailings impoundments containing processed high-grade ore. Data collected indicate that as mine sites are reclaimed and material disturbance ceases, emissions will decline. Additionally local cycling of atmospheric Hg (deposition and re-emission) was found to occur.     

Potential source contributions and risk assessment of PAHs in sediments from Taihu Lake, China: comparison of three receptor models

In this work, three receptor models (Principal Component Analysis-Multiple Linear Regression (PCA-MLR) model, Unmix model and Positive Matrix Factorization (PMF) model) were employed to investigate potential source apportionment of PAHs in sediments from Taihu Lake, China. A total of 15 priority PAHs in 29 sediments from Taihu Lake were measured, with ∑PAHs (sum of 15 PAHs) concentrations ranging from 209 to 1003 ng g⁻¹ dw. Source apportionment results derived from three different models were similar, indicating that the highest contribution to ∑PAHs was from vehicular emission (53.6-54.3%), followed by coal combustion (23.8-28.8%) and wood combustion (11.9-16.0%). The contribution of mixed wood and coal combustion source identified by PCA-MLR was 41.3%. For the first time the risk assessment for each identified source category was quantitatively calculated by combining the BaP equivalents (BaPE) values with estimated source contributions. The results showed that vehicular emission posed the highest toxic risk, with BaPE values of 26.9-31.5 ng g⁻¹ dw, and the BaPE values for coal combustion and wood combustion were 6.56-15.6 ng g⁻¹ dw and 2.94-6.11 ng g⁻¹ dw, respectively. The distributions of contribution and BaPE for each identified source category were studied as well, and showed similar trends among the sampling sites, for each source category.     

Biomonitoring of Cd, Cr, Hg and Pb in the Baluarte River basin associated to a mining area (NW Mexico)

With the purpose of knowing seasonal variations of Cd, Cr, Hg and Pb in a river basin with past and present mining activities, elemental concentrations were measured in six fish species and four crustacean species in Baluarte River, from some of the mining sites to the mouth of the river in the Pacific Ocean between May 2005 and March 2006. In fish, highest levels of Cd (0.06 μg g^− 1 dry weight) and Cr (0.01 μg g^− 1) were detected during the dry season in Gobiesox fluviatilis and Agonostomus monticola, respectively; the highest levels of Hg (0.56 μg g^− 1) were detected during the dry season in Guavina guavina and Mugil curema. In relation to Pb, the highest level (1.65 μg g^− 1) was detected in A. monticola during the dry season. In crustaceans, highest levels of Cd (0.05 μg g^− 1) occurred in Macrobrachium occidentale during both seasons; highest concentration of Cr (0.09 μg g^− 1) was also detected in M. occidentale during the dry season. With respect to Hg, highest level (0.20 μg g^− 1) was detected during the rainy season in Macrobrachium americanum; for Pb, the highest concentration (2.4 μg g^− 1) corresponded to Macrobrachium digueti collected in the dry season. Considering average concentrations of trace metals in surficial sediments from all sites, Cd (p < 0.025), Cr (p < 0.10) and Hg (p < 0.15) were significantly higher during the rainy season. Biota sediment accumulation factors above unity were detected mostly in the case of Hg in fish during both seasons. On the basis of the metal levels in fish and crustacean and the provisional tolerable weekly intake of studied elements, people can eat up to 13.99, 0.79 and 2.34 kg of fish in relation to Cd, Hg and Pb, respectively; regarding crustaceans, maximum amounts were 11.33, 2.49 and 2.68 kg of prawns relative to levels of Cd, Hg and Pb, respectively.     

Low concentrations of selenium in stream food webs of eastern Canada

Herbivorous and predatory invertebrates and two species of fish (brook trout and blacknose dace) were collected from 49 streams in New Brunswick, Canada to determine whether concentrations of selenium (Se) in the biota were affected by a point source (a coal-fired power plant), and stream water chemistry (pH, sulphate, conductivity, and total organic carbon), and to determine the trophic transfer of Se through these food webs. Total Se concentrations in the biota were generally low (0.2 to 4.8 μg g^− 1 dry weight) across sites and there was no relationship between distance from the coal-fired power plant and Se concentrations in invertebrates or fishes. Water chemistry was an equally poor predictor of Se concentrations in invertebrates and fish. Trophic position (determined using δ¹⁵N) was a significant predictor of Se concentrations in only five of the stream food webs, and two of these had negative slopes, indicating little or no trophic magnification across most systems; many fishes had lower concentrations than their invertebrate prey and trophic transfer was higher at sites with low invertebrate Se concentrations. Variability in Se concentrations in fishes was explained more by site of capture than microhabitat use within the site (as measured with δ¹³C), suggesting among-site differences in geological sources of Se. Because concentrations were below known toxicity thresholds for fish and other consumers, these results suggest that Se is not an environmental issue in New Brunswick streams that do not receive direct inputs from mining activities.     

Vertical distribution and anaerobic biodegradation of polycyclic aromatic hydrocarbons in mangrove sediments in Hong Kong, South China

The vertical distribution of polycyclic aromatic hydrocarbons (PAHs) at different sediment depths, namely 0-2 cm, 2-4 cm, 4-6 cm, 6-10 cm, 10-15 cm and 15-20 cm, in one of the most contaminated mangrove swamps, Ma Wan, Hong Kong was investigated. It was the first time to study the intrinsic potential of deep sediment to biodegrade PAHs under anaerobic conditions and the abundance of electron acceptors in sediment for anaerobic degradation. Results showed that the total PAHs concentrations (summation of 16 US EPA priority PAHs) increased with sediment depth. The lowest concentration (about 1300 ng g^− 1 freeze-dried sediment) and the highest value (around 5000 ng g^− 1 freeze-dried sediment) were found in the surface layer (0-2 cm) and deeper layer (10-15 cm), respectively. The percentage of high molecular weight (HMW) PAHs (4 to 6 rings) to total PAHs was more than 89% at all sediment depths. The ratio of phenanthrene to anthracene was less than 10 while fluoranthene to pyrene was around 1. Negative redox potentials (Eh) were recorded in all of the sediment samples, ranging from − 170 to − 200 mv, with a sharp decrease at a depth of 6 cm then declined slowly to 20 cm. The results suggested that HMW PAHs originated from diesel-powered fishing vessels and were mainly accumulated in deep anaerobic sediments. Among the electron acceptors commonly used by anaerobic bacteria, sulfate was the most dominant, followed by iron(III), nitrate and manganese(IV) was the least. Their concentrations also decreased with sediment depth. The population size of total anaerobic heterotrophic bacteria increased with sediment depth, reaching the peak number in the middle layer (4-6 cm). In contrast, the aerobic heterotrophic bacterial count decreased with sediment depth. It was the first time to apply a modified electron transport system (ETS) method to evaluate the bacterial activities in the fresh sediment under PAH stress. The vertical drop of the ETS activity suggested that the indigenous bacteria were still active in the anaerobic sediment layer contaminated with PAHs. The biodegradation experiment further proved that the sediment collected at a depth of 10-15 cm harbored anaerobic PAH-degrading bacterial strains (two Sphingomonas, one Microbacterium, one Rhodococcus and two unknown species) with some intrinsic potential to degrade mixed PAHs consisting of fluorene, phenanthrene, fluoranthene and pyrene under low oxygen (2% O₂) and non-oxygen (0% O₂) conditions. This is the first paper to report the anaerobic PAH-degrading bacteria isolated from subsurface mangrove sediment.     

Survival of manure-borne E. coli in streambed sediment: Effects of temperature and sediment properties

Escherichia coli bacteria are commonly used as indicator organisms to designate of impaired surface waters and to guide the design of management practices to prevent fecal contamination of water. Stream sediments are known to serve as a reservoir and potential source of fecal bacteria (E. coli) for stream water. In agricultural watersheds, substantial numbers of E. coli may reach surface waters, and subsequently be deposited into sediments, along with fecal material in runoff from land-applied manures, grazing lands, or wildlife excreta. The objectives of this work were (a) to test the hypothesis that E. coli survival in streambed sediment in the presence of manure material will be affected by sediment texture and organic carbon content and (b) to evaluate applicability of the exponential die-off equation to the E. coli survival data in the presence of manure material. Experiments were conducted at three temperatures (4 °C, 14 °C, and 24 °C) in flow-through chambers using sediment from three locations at the Beaverdam Creek Tributary in Beltsville, Maryland mixed with dairy manure slurry in the proportion of 1000:1. Indigenous E. coli populations in sediments ranged from ca. 10¹ to 10³ MPN g⁻¹ while approx 10³ manure-borne E. coli MPN g⁻¹ were added. E. coli survived in sediments much longer than in the overlaying water. The exponential inactivation model gave an excellent approximation of data after 6-16 days from the beginning of the experiment. Slower inactivation was observed with the increase in organic carbon content in sediments with identical granulometric composition. The increase in the content of fine particles and organic carbon in sediments led not only to the slower inactivation but also to lower sensitivity of the inactivation to temperature. Streambed sediment properties have to be documented to better evaluate the role of sediments as reservoirs of E. coli that can affect microbiological stream water quality during high flow events.     

Bacterial community dynamics in horizontal flow constructed wetlands with different plants for high salinity industrial wastewater polishing

This study is focused on the diversity of bacterial communities from two series of horizontal subsurface flow constructed wetlands (CW) polishing high salinity tannery wastewater. Each series was planted with Arundo donax or Sarcocornia sp. in a substrate composed by expanded clay and sand. Chemical and biochemical oxygen demand removal efficiencies were similar in each series, varying between 58 and 67% (inlet COD 218 ± 28 mg L⁻¹) and 60 and 77% (inlet BOD₅ 37 ± 6 mg L⁻¹), respectively. High numbers of culturable bacteria were obtained from substrate and root samples - 5.75 × 10⁶-3.95 × 10⁸ CFU g⁻¹ recovered on marine agar and 1.72 × 10⁷-8.46 × 10⁸ CFU g⁻¹ on nutrient agar. Fifty bacterial isolates were retrieved from the CW, related phylogenetically to Firmicutes, Actinobacteria, Bacteroidetes, α-, β-, and γ-Proteobacteria. Changes in the bacterial communities, from roots and substrate of each series, related to the plant species, hydraulic loading rates and along CW operation were examined using denaturating gradient gel electrophoresis (DGGE). The clustering analysis suggested that a diverse and distinct bacterial community inhabits each series, which was related to the type of plant present in each CW.     

Nitrous oxide production kinetics during nitrate reduction in river sediments

A significant amount of nitrogen entering river basins is denitrified in riparian zones. The aim of this study was to evaluate the influence of nitrate and carbon concentrations on the kinetic parameters of nitrate reduction as well as nitrous oxide emissions in river sediments in a tributary of the Marne (the Seine basin, France). In order to determine these rates, we used flow-through reactors (FTRs) and slurry incubations; flow-through reactors allow determination of rates on intact sediment slices under controlled conditions compared to sediment homogenization in the often used slurry technique. Maximum nitrate reduction rates (R_m) ranged between 3.0 and 7.1 μg N g⁻¹ h⁻¹, and affinity constant (K_m) ranged from 7.4 to 30.7 mg N-NO₃⁻ L⁻¹. These values were higher in slurry incubations with an R_m of 37.9 μg N g⁻¹ h⁻¹ and a K_m of 104 mg N-NO₃⁻ L⁻¹. Nitrous oxide production rates did not follow Michaelis-Menten kinetics, and we deduced a rate constant with an average of 0.7 and 5.4 ng N g⁻¹ h⁻¹ for FTR and slurry experiments respectively. The addition of carbon (as acetate) showed that carbon was not limiting nitrate reduction rates in these sediments. Similar rates were obtained for FTR and slurries with carbon addition, confirming the hypothesis that homogenization increases rates due to release of and increasing access to carbon in slurries. Nitrous oxide production rates in FTR with carbon additions were low and represented less than 0.01% of the nitrate reduction rates and were even negligible in slurries. Maximum nitrate reduction rates revealed seasonality with high potential rates in fall and winter and low rates in late spring and summer. Under optimal conditions (anoxia, non-limiting nitrate and carbon), nitrous oxide emission rates were low, but significant (0.01% of the nitrate reduction rates).     

Internal loading of phosphorus in a sedimentation pond of a treatment wetland: effect of a phytoplankton crash

Sedimentation ponds are widely believed to act as a primary removal process for phosphorus (P) in nutrient treatment wetlands. High frequency in-situ P, ammonium (NH₄⁺) and dissolved oxygen measurements, alongside occasional water quality measurements, assessed changes in nutrient concentrations and productivity in the sedimentation pond of a treatment wetland between March and June. Diffusive equilibrium in thin films (DET) probes were used to measure in-situ nutrient and chemistry pore-water profiles. Diffusive fluxes across the sediment-water interface were calculated from the pore-water profiles, and dissolved oxygen was used to calculate rates of primary productivity and respiration. The sedimentation pond was a net sink for total P (TP), soluble reactive P (SRP) and NH₄⁺ in March, but became subject to a net internal loading of TP, SRP and NH₄⁺ in May, with SRP concentrations increasing by up to 41 μM (1300 μl^− 1). Reductions in chlorophyll a and dissolved oxygen concentrations also occurred at this time. The sediment changed from a small net sink of SRP in March (average diffusive flux: − 8.2 μmol m^− 2 day^− 1) to a net source of SRP in June (average diffusive flux: + 1324 μmol m^− 2 day^− 1). A diurnal pattern in water column P concentrations, with maxima in the early hours of the morning, and minima in the afternoon, occurred during May. The diurnal pattern and release of SRP from the sediment were attributed to microbial degradation of diatom biomass, causing reduction of the dissolved oxygen concentration and leading to redox-dependent release of P from the sediment. In June, 2.7 mol-P day^− 1 were removed by photosynthesis and 23 mol-P day^− 1 were supplied by respiration in the lake volume. SRP was also released through microbial respiration within the water column, including the decomposition of algal matter. It is imperative that consideration to internal recycling is given when maintaining sedimentation ponds, and before the installation of new ponds designed to treat nutrient waste.     

Time-dependent variation of mercury in a stream sediment and the effect upon mercury content in Gammarus pulex (L.)

A 3-month investigation has been carried out in a stream environment, on the fluctuation of the level of mercury within the sediment and the Gammarus pulex population. A positive correlation is found between the organic content and the mercury content (μg g⁻¹ dry wt) of the samples. The mean mercury concentration in the organic fraction can be read from the regression line. Of the units: μg g⁻¹ dry wt, μg g⁻¹ ashfree dry wt and μg cm⁻³, the values expressed g⁻¹ ashfree dry wt are considered to be of greatest validity for comparing different localities, and for establishing the pollution level in a stream sediment. Within the investigation period a very high fluctuation is found in the mercury content of analyzed Gammarus pulex. The phenomenon may be explained through fluctuations in the methylating processes within the sediment. No positive correlation is found between mercury in Gammarus pulex and in sediement taken from identical sample locations.     

Bioaccumulation of polybrominated diphenyl ethers and hexabromocyclododecane in the northwest Atlantic marine food web

Seven species of teleost fishes comprising major prey of northwest Atlantic harbor seals were analyzed for polybrominated diphenyl ethers (PBDEs). PBDE concentrations in whole fish samples (n = 87) were compared with those measured previously in harbor seal blubber to evaluate the transfer of PBDEs from prey to predator. Hexabromocyclododecane (HBCD) concentrations were measured in three fish species to provide an initial estimation of HBCD contamination in this ecosystem. HBCD was detected in 87% of the fish samples at concentrations ranging from 2.4 to 38.1 ng/g, lw (overall mean 17.2 ± 10.2 ng/g, lw). ∑PBDE concentrations in fish ranged from 17.9 to 94 ng/g, lw (overall mean 62 ± 34 ng/g, lw). ∑PBDE concentrations in the harbor seals were two orders of magnitude higher than levels in the fish. Biomagnification factors (BMFs) from fish to seals averaged from 17 to 76, indicating that tetra- to hexa-BDEs are highly biomagnified in this marine food web. BDE-47 was the dominant congener in all samples, suggesting exposure to the penta-BDE mixture. The presence of higher brominated congeners including BDE-209 at measurable levels in fish and seal tissue, along with the very high biomagnification of BDE-153, as well as − 155, and − 154, suggests recent exposure to the octa- and deca-BDE formulations in this US coastal marine food web, as well as the additional contribution of BDE-209 debromination in fish to the loading of persistent PBDEs in the seals. This is the first study to report the occurrence of BDE-209 and other higher BDEs in commercially important marine fishes from the northwest Atlantic.     

Biostrome communities and mercury and selenium bioaccumulation in the Great Salt Lake (Utah, USA)

The Great Salt Lake has a salinity near 150 g/L and is habitat for over 200 species of migratory birds. The diet of many of these birds is dependent on the food web of carbonaceous biostromes (stromatolites) that cover 260 km² of the lake's littoral zone. We investigated the biostrome community to understand their production processes and to assess whether they are a potential vector for bioconcentration of high mercury and selenium levels in the lake. The periphyton community of the biostromes was > 99% colonial cyanobacteria. Periphyton chlorophyll levels averaged 900 mg m⁻² or nine times that of the lake's phytoplankton. Lake-wide estimates of chlorophyll suggest that their production is about 30% of that of the phytoplankton. Brine fly (Ephydra gracilis) larval densities on the biostromes increased from 7000 m⁻² in June to 20000 m⁻² in December. Pupation and adult emergence halted in October and larvae of various instars overwintered at temperatures < 5 °C. Mean total dissolved and dissolved methyl mercury concentrations in water were 5.0 and 1.2 ηg L⁻¹. Total mercury concentrations in the periphyton, fly larvae, pupae, and adults were, respectively, 152, 189, 379 and 659 ηg g⁻¹ dry weight, suggesting that bioconcentration is only moderate in the short food web and through fly developmental stages. However, common goldeneye ducks (Bucephala clangula) that feed primarily on brine fly larvae at the Great Salt Lake had concentrations near 8000 ηg Hg g⁻¹ dry weight in muscle tissue. Data from a previous study indicated that selenium concentrations in periphyton, brine fly larvae and goldeneye liver tissue were high (1700, 1200 and 24,000 ηg g⁻¹, respectively) and Hg:Se molar ratios were < 1.0 in all tissues, suggesting that the high mercury concentration in the ducks may be partially detoxified by combining with selenium. The study demonstrated that the high mercury levels in the Great Salt Lake are routed through the biostrome community resulting in invertebrate prey that may provide health risks for birds and humans that consume them.     

Significance and interspecific variability of accumulated trace metal concentrations in Antarctic benthic polychaetes

Trace metals were analysed in polychaetes collected on Polarstern cruise ANT XXI/2 (2003/04) to the Weddell Sea. Pb concentrations were largely less than 1.3 mg kg⁻¹ DW in all samples analysed. Statistical results indicate that the accumulated Cd, Cu and Zn concentrations are related to the feeding guild to which the animals are belonging. Relatively low Cd and Cu concentrations are found in macrophagous carnivores and relatively high concentrations in microphagous detritus feeders. The relationship between Zn concentrations and the feeding guilds of polychaetes is reverse. Cd concentrations range from (median values and interquantile ranges in brackets) 2.6 (1.5-3.2) mg kg⁻¹ DW in the carnivorous Trypanosyllis gigantea to 133 (37-176) mg kg⁻¹ in the microphagous detritus feeder Lanicides bilobata; Cu concentrations from 16 (11-19) mg kg⁻¹ in the carnivorous Antarctinoe spicoides to 40 (23-68) mg kg⁻¹ in the microphagous detritus feeder Phyllocomus crocea and Zn from 89 (69-97) mg kg⁻¹ in the microphagous detritus feeder Isocirrus yungi to 396 (372-404) mg kg⁻¹ in the carnivorous Aglaophamus trissophyllus. Ni is ranging from 3.7 (1.8-6.0) mg kg⁻¹ in Polyeunoa laevis to 34 (20-41) mg kg⁻¹ in A. spicoides, but no significant differences are obvious regarding the feeding guilds. Since information on metals in Antarctic polychaetes is almost completely lacking, our results suggest further studies to clarify the role of feeding in the bioaccumulation of metals in this ecologically important taxonomic group.