Food Web Magnification Factors Research Articles

Trophic transfer of polycyclic aromatic hydrocarbons through the food web of the Fildes Peninsula, Antarctica.

The Antarctic ecosystem is characterized by few consumer species and simple trophic levels (TLs), rendering it an ideal setting to investigate the environmental behavior of contaminants. The paper aims to assess the presence, sources and biomagnification behavior of polycyclic aromatic hydrocarbons (PAHs) of the Antarctic food web and is the first study of biomagnifications of PAHs in the Fildes Peninsula in Antarctica. Nine representative species from the Fildes Peninsula in Antarctica were sampled and evaluated for PAH presence. PAH concentrations ranged from 477.41 to 1237.54ng/g lipid weight (lw) in the sampled Antarctic biota, with low molecular weight PAHs (naphthalene, acenaphthylene, acenaphthene, and fluorene) comprising the majority of the PAHs. PAHs concentrations were negatively correlated with TLs. Further, the food web magnification factor (FWMF) of ∑PAHs was 0.63, suggesting biodilution of PAHs along the TLs. Source analyses revealed that the PAHs mainly originated from petroleum contamination and the combustion of fossil fuels.

Trophic structure and biomagnification of cadmium, mercury and selenium in brown smooth hound shark (Mustelus henlei) within a trophic web

Stable isotopic values of carbon (δ13C) and nitrogen (δ15N) were used to characterize the trophic structure and biomagnification of Cadmium (Cd), Mercury (Hg) and Selenium (Se) in a trophic web of 18 taxa namely zooplankton, crustaceans, mollusks, fishes, and Mustelus henlei shark collected off the western coast of Baja California Sur, Mexico. Isotopic results indicated interspecies variations in the trophic web structure with mean δ13C values of – 20.0‰ (zooplankton) < − 18.2 ‰ (M. henlei) < − 14.1 ‰ (Thaisella kiosquiformis, mollusk). In general, δ15N and δ13C values increased from primary consumers (zooplankton) to predators, following the isotopic patterns of other trophic webs. The concentrations of Cd, Hg and Se were relatively less in most of the organisms except mollusks that presented high concentrations of Cd. The biomagnification factors of the trophic web showed biodilution of Cd (Food Web Magnification Factor, FWMFCd = 0.2), biomagnification of Hg (FWMFHg = 3.34) and Se (FWMFSe = 1.45) respectively. However, the concentrations of Se did not increase consistently from the lower trophic levels to the higher ones. This study documents the dynamics of a marine trophic structure and demonstrates that biodilution/biomagnification processes of metal contaminants are largely species specific and are closely related to physical - chemical and food web structure.

Temporal distribution patterns of metals in water, sediment, and components of the trophic structure in a tropical coastal lagoon of the Gulf of Mexico.

Trophic transfer and bioaccumulation of trace metals have a profound impact on the structure and function of coastal areas; however, the metal accumulation patterns in detritus-based food webs and the influence of climatic variability have not been thoroughly investigated. The Tampamachoco Lagoon (Gulf of Mexico) is a coastal system impacted by emissions from a thermoelectric plant. We evaluated the spatial-temporal distribution patterns of Al, Cd, Hg, Cr, Cu, and Pb in water, sediments, and in organisms categorized by trophic levels (TLs), trophic guilds, and habitat preferences. The sediments had the highest concentrations of metals with no significant differences between seasons. The indices of geo-accumulation and potential ecological risk classified sediments as "moderately contaminated", evidencing a threat to human health through consumption of detritivores and filter-feeders. The lowest TLs (filter-feeders and detritivorous) reached the maximum Metal Pollution Index in the rainy season. According to discriminant analyses of metals and species, omnivorous and zoobentivorous organisms were associated with Hg during the rainy and dry seasons; while Al, Cd, and Cu were related to low TLs, and seston was associated with Pb. Food web magnification factor analysis showed that: (a) Pb, Cu, and Cr were biodiluted as trophic levels increased; (b) Cd and Hg showed temporal biomagnification trends; (c) Al, Pb, Cu, and Cd showed significant biodilution from the lowest TL to intermediate TLs; and (d) Hg was transferred from the lowest to intermediate TLs with clear biomagnification effects.

Tissue distribution, bioaccumulation, and carcinogenic risk of polycyclic aromatic hydrocarbons in aquatic organisms from Lake Chaohu, China

Freshwater products consumed in the diet are among the major sources of exposure of humans to polycyclic aromatic hydrocarbons (PAHs). In this study, eight freshwater organisms and environmental samples were collected from Chaohu Lake, the fifth-largest lake in China. The levels of PAHs in the collected organisms were measured using GC–MS. Tissue distribution characteristics in three fish species were studied. Relationship between residual levels and environment concentrations were analyzed and bioaccumulation effect and influencing factors were identified. Finally, the potential carcinogenic risk of aquatic product intake was estimated. The concentrations of ΣPAHs in aquatic organisms varied from 18.4 to 398 ng/g, with a mean value of 157 ± 125 ng/g. For carp, the highest ΣPAHs level was detected in the brain with concentration of 591 ng/g. For topmouth culter, and bighead fish, the organs with the greatest ΣPAHs concentration were gills (440 ng/g) and muscles (200 ng/g), respectively. Significant correlations were found between the PAH content in environment media including water, SPM, sediment and PAH content in aquatic animals. The calculation of food web magnification factors and risk assessment indicates that although the PAH concentration diluted with the increase of the trophic level, PAHs exposure through the aquatic products intake still poses potential carcinogenic risk. The incremental lifetime cancer risk values were 7.68 × 10−6 and 4.75 × 10−6 in urban and rural populations, respectively.

Evaluation on the biomagnification or biodilution of trace metals in global marine food webs by meta-analysis

The transmission and accumulation of trace metals in marine food webs have a profound influence on the structure and function of marine environment. In order to quantitatively assess the trophic transfer behaviors of eight common metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) in simplified five-trophic level marine food webs, a total of 9929 biological samples from 61 studies published between 2000 and 2019, involving 154 sampling sites of 33 countries/regions, were re-compiled using meta-analysis. Based on concentration-trophic level weighted linear regression and predator/prey comparison, the food web magnification factor (FWMF) and the biomagnification factor (BMF) were calculated, respectively. The results showed dissimilar trophic transfer behaviors of these metals in global marine food webs, in which As and Ni tended to be efficiently biodiluted with increasing trophic levels (FWMFs < 1, p < 0.01), while Hg, Pb and Zn trophically biomagnified (FWMFs > 1, p < 0.05). However, Cd, Cr and Cu presented no biomagnification or biodilution trend (p > 0.05). The values of FWMFs were ranked as: Hg (2.01) > Pb (1.81) > Zn (1.15) > Cu (1.13) > Cr (0.951) > Cd (0.850) > Ni (0.731) > As (0.494). In terms of specific predator-prey relationship, Pb showed significant biodilution from tertiary consumers (TC) to top predators (BMF < 1, p < 0.05), whereas Cd and Cu displayed obvious biomagnification from primary consumers (PC) to secondary consumers (SC) (BMFs >1, p < 0.05). Additionally, when Cu and Zn were transferred from SC to TC, and primary producers to PC, clear biodilution and biomagnification effects were observed, respectively (p < 0.05). Further analysis indicated that the average concentration of Hg in five-trophic level marine food webs of developed countries (0.904 mg kg−1 dw) was more noticeable (p < 0.05) than that of developing countries (0.549 mg kg−1 dw).

Ecological drivers of mercury concentrations in fish species in subsistence harvests from Kotzebue Sound, Alaska

The State of Alaska assesses human exposure to mercury (Hg) via fish consumption producing consumption guidelines for fish tailored for children and women of childbearing age. Under these guidelines, unrestricted consumption is suggested for many fish species, while limited consumption is recommended for others. Subsequent questions have arisen regarding ecological drivers influencing [Hg] in fishes consumed by Alaskans. This community-assisted public health study evaluates [Hg] in fishes from Kotzebue Sound to examine factors that may drive observed [Hg]. We examined eight species of subsistence harvested fish (least cisco, chum salmon, Pacific herring, humpback whitefish, sheefish, starry flounder, Pacific tomcod, and fourhorn sculpin) from Kotzebue Sound. We report total Hg concentrations ([THg]) and monomethyl Hg+ concentrations ([MeHg+]) in the context of various factors (such as species, fork length, carbon and nitrogen stable isotope (δ15N or δ13C)) values that may influence [Hg] and [MeHg+]. Across all 297 fish, [THg] ranged from 3.4 ˗ 235.2 ng/g ww. [THg] was positively correlated with fork length in six of eight fish species, as well as with trophic level (indicated by δ15N values) in five species. [MeHg+] was positively correlated with fork length in four species, and with δ15N values over all specimens examined, and specifically for three individual species. In six of the seven species analyzed, %MeHg was >80% of [THg]. This value decreased with fork length in three species, with no relationship for δ15N values in any species. Among top ranked models based on Akaike Information Criterion correction (AICc), fork length was more frequently included as an explanatory factor for [Hg] than δ15N or δ13C values. The food web magnification factor for [THg] was 11.3, and 12.6 for [MeHg+]. Biomagnification is likely driving [THg] and [MeHg+] over the entire food web, while within species, bioaccumulation is likely a stronger driver of [THg] and [MeHg+] than feeding ecology or trophic position. The [THg] for all species fell within the established unrestricted consumption guideline of 200 ng/g weight wet as established by the State of Alaska's fish consumption guidelines for Hg.

Trophic Structure and Biomagnification of Total Mercury in Ray Species Within a Benthic Food Web.

Stable isotopes of C (δ13C) and N (δ15N) were used to explore the trophic structure and evaluate mercury (Hg) biomagnification in the food web of muscle of three commercially important ray species from the Pacific coast of Baja California Sur (PCBCS): the shovelnose guitarfish (Pseudobatos productus), banded guitarfish (Zapteryx exasperata), and bat ray (Myliobatis californica). The food web of these ray species predominately consisted of zooplankton, three species of fish, and five species of invertebrates. Mean δ15N values in all species ranged from 10.54 ± 0.18‰ in zooplankton to 17.84 ± 0.81‰ in the shovelnose guitarfish. Mean δ13C values ranged from - 22.05 ± 0.75‰ in the red crab to - 15.93 ± 0.78‰ in the bat ray. Mean total Hg concentration ([THg]) in all species ranged from 0.0009 ± 0.0002mgkg-1 ww in zooplankton to 0.24 ± 0.19mgkg-1ww in the banded guitarfish. The food web magnification factor was 6.38 and significantly greater than 1.0. The present study describes [THg] biomagnification in the benthic food web of three ray species of the PCBCS. This provides an important baseline knowledge of the biomagnification dynamics and pathways of Hg in this environment for these multiple interacting species.

Mercury speciation, bioavailability, and biomagnification in contaminated streams on the Savannah River Site (SC, USA)

Water, sediment, and biota from two streams on the Savannah River Site were sampled to study mercury (Hg) biogeochemistry. Total and methyl- Hg (MHg) concentrations were measured for all samples, speciation models were used to explore Hg speciation in the water, and Diffusive gradients in thin films (DGT) were applied to indicate the vertical profiles of labile Hg (DGT-Hg). Trophic position (δ15N) was estimated for biota and used to establish MHg biomagnification model. The speciation model indicated Hg methylation in the water occurred on settling particles and the most bioavailable Hg species to bacteria were complexes of inorganic Hg and labile organic ligands. Correspondingly, dissolved organic carbon concentrations were positively related to MHg concentrations in the water. In the sediment, the sharp increase of DGT-Hg around the sediment water interface underscores the importance of this interface, which determines the differences in the accumulation and generation of labile Hg among different waterbodies. The positive correlation between sediment MHg and sulfate concentrations suggested possible methylation reaction by dissimilatory sulfate reducing bacteria in the sediment. The food web magnification factors of MHg were 9.6 (95% CI: 4.0–23.4) and 4.4 (95% CI: 2.5–7.7) for the two streams established with trophic data of biofilm, invertebrates, and fish. Meanwhile, DGT-Hg concentrations in the water were positively correlated to biofilm Hg concentrations, which can be combined with the MHg biomagnification model to generate a modified biomagnification model that estimate MHg bioaccumulation with only labile Hg concentrations in the water. With this approach, Hg accumulation in abiotic and biotic environmental compartments was connected and the different bioaccumulation patterns of Hg in different waterbodies were explained with both geochemical and biological factors.

Trophodynamics and biomagnification of trace metals in aquatic food webs: The case of Rufiji estuary in Tanzania

Transfer of trace metals into fish of commercial value poses a public health concern. Therefore, sediments, invertebrates, and fish from three sampling sites in the Rufiji estuary were analyzed for trace metals to evaluate their concentrations and trophic transfer within estuarine food web. Stable isotopes of carbon and nitrogen were also used to study the trophic relationship between different organisms. Biomagnification of trace metals in organisms from different trophic levels was quantified and evaluated by calculating the bioaccumulation factor and biomagnification factor. Trophic magnification factor for different trace metals was determined from the slope of the regression line between trace metal concentration and the trophic level of functional groups in sampled organisms. The results indicated that As and Zn displayed trophic level-dependent accumulation in the Rufiji food webs. As and Zn increased with the trophic level, whereas Ag, As, Co, Cr, Cu, Mn, Ni, and Pb depicted an opposite trend. Food web magnification factors varied from −0.57 for Ni to 0.39 for Zn, whereas trophic magnification factor varied from 0.27 for Ni to 2.47 for Zn. Zn and Ni bioaccumulate in the food webs as indicated by a slope greater than zero, whereas the remaining trace metals are eliminated from food webs or their trophic transfer is interrupted.

Residues, bioaccumulations and biomagnification of perfluoroalkyl acids (PFAAs) in aquatic animals from Lake Chaohu, China

Residual levels of perfluoroalkyl acids (PFAAs) in seven species of aquatic animals were analyzed by liquid chromatography-mass spectrometry. The distribution, composition, bioaccumulation, and biomagnification of PFAAs and their effect factors were studied. The results showed that: 1) Wet weight concentrations of 17 PFAAs in the aquatic animals ranged from 1.77 to 38.65 ng/g, with a mean value of 12.71 ± 9.21 ng/g. PFOS was the predominant contaminant (4.57 ± 4.57 ng/g, 6.76%–46.25%), followed by PFDA (1.95 ± 1.37 ng/g, 11.68%–21.25%) and PFUdA (1.84 ± 1.21 ng/g, 9.73%–35.34%. 2) PFAA residual levels in Culter erythropterus (30.98 ± 6.65 ng/g) were the highest, followed by Hemibarbus maculatus (16.79 ± 1.88 ng/g), while the PFAA levels in Carassius auratus were the lowest (2.22 ± 0.60 ng/g). 3) Biota-water bioaccumulation factors (BAFs), biota-suspended solid accumulation factors (BSSAFs) and biota-sediment accumulation factors (BSAFs) ranged from 0.35 to 12,370.51, 7.77 to 8452.92 and 9.10 to 6984.61, respectively. Bioaccumulation by shrimp and snails was significantly affected by Kow. 4) Food web magnification factors were greater than 1, indicating that biomagnification of PFAAs occurs across trophic levels. The bioaccumulation and biomagnification of PFAAs were significantly correlated with carbon chain length.

Trophic magnification of Dechlorane Plus in the marine food webs of Fildes Peninsula in Antarctica

The food web composition, assimilation efficiency of Dechlorane Plus (DP) in food web components, and even extrinsic conditions can affect the trophic biomagnification potentials of DP isomers in food webs. Antarctica ecological system is characterized by the presence of few consumers and simple trophic levels (TLs), which are crucial in discussing the behavior of contaminants. To assess the biomagnification potential of DP in the Antarctic food web, nine representative species were sampled and analyzed from the Fildes Peninsula. Results showed the DP concentrations ranged from 0.25ngg−1 to 6.81ngg−1 lipid weight in Antarctic biota and the concentrations of anti-DP and syn-DP showed significantly positive correlations with TLs (p<0.05, ra=0.85; rs=0.81, respectively), suggesting that syn-DP and anti-DP underwent biomagnification and the biomagnification ability of anti-DP was higher than that of syn-DP. The anti-DP fraction (anti-DP/∑DP) (ƒanti=0.23–0.53) of the organisms was lower than that of commercial products (ƒanti=0.68), demonstrating ƒanti was changed during long-range atmospheric transport or stereoselection enrichment through the food web. Furthermore, based on food web magnification factors (FWMF) comparison between DP and polychlorinated biphenyls (PCBs), the biomagnification potential of DP was found to be similar to that of highly chlorinated PCBs.

Linking mercury, carbon, and nitrogen stable isotopes in Tibetan biota: Implications for using mercury stable isotopes as source tracers.

Tibetan Plateau is located at a mountain region isolated from direct anthropogenic sources. Mercury concentrations and stable isotopes of carbon, nitrogen, and mercury were analyzed in sediment and biota for Nam Co and Yamdrok Lake. Biotic mercury concentrations and high food web magnification factors suggested that Tibetan Plateau is no longer a pristine site. The primary source of methylmercury was microbial production in local sediment despite the lack of direct methylmercury input. Strong ultraviolet intensity led to extensive photochemical reactions and up to 65% of methylmercury in water was photo-demethylated before entering the food webs. Biota displayed very high Δ199Hg signatures, with some highest value (8.6%) ever in living organisms. The δ202Hg and Δ199Hg in sediment and biotic samples increased with trophic positions (δ15N) and %methylmercury. Fish total length closely correlated to δ13C and Δ199Hg values due to dissimilar carbon sources and methylmercury pools in different living waters. This is the first mercury isotope study on high altitude lake ecosystems that demonstrated specific isotope fractionations of mercury under extreme environmental conditions.

Aquatic biota as potential biological indicators of the contamination, bioaccumulation and health risks caused by organochlorine pesticides in a large, shallow Chinese lake (Lake Chaohu)

Aquatic biota have long been recognized as bioindicators of the contamination caused by hydrophobic organic contaminants (HOCs) in aquatic environments. The primary purpose of the present study is to identify which species of aquatic biota are the most sensitive to organochlorine pesticides (OCPs) in Lake Chaohu and can therefore serve as indicators of the lake's health and assist in the assessment of OCPs risks to human health. OCP levels in eight species of aquatic biota were measured using GC–MS, and the relationships between the biota and OCP levels in the water and suspended solids were studied. DDTs pose potential human health risks and were the predominant OCP components found in the aquatic biota. DDT had the highest mean bioaccumulation factor (BAF) and biota suspended solids accumulation factor (BSSAF) of all of the studied OCP components. The food web magnification factors (FWMF) for p, p′-DDT were greater than 1, implying that biomagnification occurred. This finding indicates that DDTs still pose a serious threat to the ecosystem and human health in Lake Chaohu, even though the agricultural application of DDT powder has been officially banned since 1983. There were significant positive relationships between OCPs levels in Culter erythropterus and those in both water and suspended solids, as well as between OCPs levels in Protosalanx hyalocranius and those in suspended solids. This finding suggests that C. erythropterus and P. hyalocranius are the most sensitive aquatic biota to OCPs and may serve as the most effective bioindicators for monitoring OCP contamination in the water and suspended solids of Lake Chaohu. Megalobrama amblycephala, which contained the highest wet weight mean OCP concentration, is the most sensitive OCP indicator and can be used to assess the human carcinogenic risk of OCPs in Lake Chaohu.

Mercury and selenium biomagnification in a Brazilian coastal food web using nitrogen stable isotope analysis: A case study in an area under the influence of the Paraiba do Sul River plume

Mercury (Hg), selenium (Se) and nitrogen (δ15N) stable isotope were assessed in a tropical food web of Rio de Janeiro’s north coast. Isotopic data on muscle suggest a difference related to this parameter along the food web; where top-predators (cetacean and voracious fish) displayed heavier δ15N over the entire food web. Both top-predators presented similar δ15N values. Cetacean displayed higher Hg and lower Se than voracious fish. Five trophic positions (TP) were found in relation to primary consumer as baseline, ranging from 2.0 to 4.0. Positive relationships were found between trace-element and δ15N. The slope of regression equations (0.11 for Se and 0.21 for Hg) and food web magnification factors (2.4 for Se and 5.4 for Hg) showed that Hg presented higher rate of increase over the food web. Simultaneous measurements of trace-elements and ecological tracers emphasize the importance of TP into the trophic structure and distribution of Hg and Se throughout the food web.

An Ecologically Framed Mercury Survey of Finfish of the Lower Chesapeake Bay

Total mercury (THg) and methylmercury (MHg) concentrations and determents of mercury (Hg) accumulation were examined for muscle tissues of 10 finfish from the lower Chesapeake Bay (LCB) and its tributaries. There was no suggestion of potential human harm from Hg due to LCB fish consumption: None of the sampled fish had THg concentrations approaching the United States Environmental Protection Agency human health screening value. Hg concentrations in different fish species generally increased with the increasing stable isotope of nitrogen 15 (δ(15)N) but not the stable isotope of carbon 13 (δ(13)C), thus suggesting that trophic position but not dietary carbon source is a dominant determinant. An MHg biomagnification model was built to estimate a food web magnification factor of approximately 10-fold increase per trophic level. Based on otolith strontium-to-calcium ratios, Atlantic croaker inhabiting less saline waters might accumulate more Hg than those inhabiting more saline waters. The SAS mixed procedure identified significant positive intraspecies relationships between MHg concentration and δ(13)C for summer flounder, weakfish, American eel, Atlantic croaker, and spot.

Biomagnification of mercury through the benthic food webs of a temperate estuary: Masan Bay, Korea

The authors examined food web magnification factors of total mercury (THg) and methylmercury (MeHg) for the benthic organisms in Masan Bay, a semiclosed, temperate estuary located on the southeastern coast of Korea. For benthic invertebrates, concentrations of THg and MeHg (%MeHg) ranged from 9.57 to 195 and 2.56 to 111 ng/g dry weight (12.2-85.6%), respectively. Benthic fish THg and MeHg (%MeHg) concentrations ranged widely from 10.8 to 618 and 2.90 to 529 ng/g dry weight (22.9-93.9%), respectively. The linear regression slopes of log [Hg] relative to δ(15)N (i.e., food web magnification factors) found for the Masan Bay benthic organisms were 0.119 for THg and 0.168 for MeHg. These values are similar to the food web magnification factors of benthic organisms and lower than those of pelagic organisms of various coastal marine environments. It suggests that pelagic organisms might be at greater risk of THg and MeHg accumulation than benthic biota.

Floodplain methylmercury biomagnification factor higher than that of the contiguous river (South River, Virginia USA)

Mercury biomagnification on the South River floodplain (Virginia, USA) was modeled at two locations along a river reach previously modeled for methylmercury movement through the aquatic trophic web. This provided an opportunity to compare biomagnification in adjoining trophic webs. Like the aquatic modeling results, methylmercury-based models provided better prediction than those for total mercury. Total mercury Food Web Magnification Factors (FWMF, fold per trophic level) for the two locations were 4.9 and 9.5. Methylmercury FWMF for the floodplain locations were higher (9.3 and 25.1) than that of the adjacent river (4.6). Previous speculation was not resolved regarding whether the high mercury concentrations observed in floodplain birds was materially influenced by river prey consumption by riparian spiders and subsequent spider movement into the trophic web of the adjacent floodplains. Results were consistent with a gradual methylmercury concentration increase from contaminated floodplain soil, to arthropod prey, and finally, to avian predators.

Mercury speciation and biomagnification in the food web of Caddo Lake, Texas and Louisiana, USA, a subtropical freshwater ecosystem

We studied the biomagnification of total mercury and methylmercury in a subtropical freshwater lake, Caddo Lake, Texas and Louisiana, USA. The present study is unique in that it not only included invertebrates (seven species) and fish (six species) but also an amphibian (one species), reptiles (three species), and mammals (three species). Nonfish vertebrates such as those included in the present study are often not included in assessments of trophic transfer of Hg. Mean trophic position (determined using stable isotopes of nitrogen) ranged from 2.0 (indicative of a primary consumer) to 3.8 (indicative of a tertiary consumer). Mean total Hg concentrations ranged from 36 to 3,292 ng/g dry weight in muscle and whole body and from 150 to 30,171 ng/g dry weight in liver. Most of the Hg in muscle and whole-body tissue was found as methylmercury, and at least 50% of the Hg found in liver was in the inorganic form (with the exception of largemouth bass, Micropterus salmoides). Mercury concentrations were positively correlated with trophic position, indicating that biomagnification occurs in the food web of Caddo Lake. The food web magnification factors (FWMFs; slope of the relationship between mean Hg concentration and trophic position) for both total Hg and methylmercury were similar to those observed in other studies. Because most of the total Hg in consumers was methylmercury, the FWMF for methylmercury was not significantly different from the FWMF for total Hg. Some vertebrates examined in the present study had low Hg concentrations in their tissues similar to those observed in invertebrates, whereas others had concentrations of Hg in their tissues that in previous studies have been associated with negative health consequences in fish.

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 Sigma HCH (hexachlorocyclohexane isomers) and Sigma chlordane 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 Sigma PCB (polychlorinated biphenyl) ranged from 111 to 377 ng/g lw, Sigma DDT (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 delta(15)N. FWMFs >1, indicating biomagnification, were found for Sigma PCB, penta- or higher chlorinated PCBs (e.g., PCB 101, 118, 138, 153, 180), beta-HCH, HCB, Sigma DDT, p,p-DDE, and transnonachlor. The highest FWMF was observed for PCB 180 at FWMF = 5.8.

Pesticide contamination profiles of water, sediment and aquatic organisms in the effluent of Gaobeidian wastewater treatment plant

Organochlorine pesticides (OCPs, including DDT, HCH and HCB) and six indicator polychlorinated biphenyls (PCB 28, 52, 101, 138, 153, and 180) were measured in water, sediment, zooplankton, fish and Chinese softshell turtle ( Pelodiscus sinensis) from Gaobeidian Lake, which is located in the effluent of Gaobeidian wastewater treatment plant (WWTP) in Beijing, China. DDTs were dominant except for in water. In water, the concentrations of DDTs (6.22 ng l −1) and HCHs (18.0 ng l −1) were less than the limits (l000 ng l −1 for DDTs and 5000 ng l −1 for HCHs). However, PCBs concentration (20.8 ng l −1) exceeded the limit (14 ng l −1) suggested by the United States Environmental Protection Agency (USEPA). The high ratio of p, p′-DDT/DDTs (0.80) in water suggested that DDTs had recently been discharged into the ambient environment despite a longtime ban in China. For fish and Pelodiscus sinensis, the accumulation patterns of OCPs and PCBs were different in muscle and liver. And HCB and PCB 153 were significant different in different species ( p < 0.05). PCBs were dominated by PCB 52 in zooplankton, but by PCB 138 and 153 in Pelodiscus sinensis. The highest food web magnification factor (FWMF) was 4.83 for p, p′-DDT and the second highest was 4.36 for PCB 101 in Gaobeidian Lake. As compared with the other studies, biomagnification in the present study was not obvious. Trophic levels and age were two important factors that might contribute to the bioaccumulation in the present study.