Biota-sediment Accumulation Factors Research Articles

Congener-specific evaluation of biota-sediment accumulation factor model for HCHs and DDTs under small-scale in situ riverine condition

Purpose The congener-specific biota-sediment accumulation factors (BSAFs) model for hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) was evaluated for four different freshwater fish species (Orienus plagiostomus, Tor putitora, Glyptothorax punjabensis, and Cyprinus carpio) in in situ riverine conditions of Kabul River, Pakistan.

Potential risk reduction of Aroclor 1254 by microbial dechlorination in anaerobic Grasse River sediment microcosms

Aroclor 1254 was the second most produced commercial PCB mixture and is found in soils, sediments and sewage throughout the globe. This commercial PCB mixture is considered particularly toxic because of the relatively high concentrations of congeners with dioxin-like properties. The potential for risk reduction by microbial reductive dechlorination of Aroclor 1254 (A1254) was investigated in sediment microcosms from Grasse River (GR), Massena, NY. The specificity of A1254 dechlorination was doubly- and singly-flanked chlorines in meta positions and to a less extent doubly-flanked para chlorines of 2345-substituted chlorobiphenyl rings. The average dechlorination rate of A1254 was 0.0153 Cl−/biphenyl/day, and dechlorination rates of single congeners ranged between 0.001 and 0.0074 Cl−/biphenyl/day. Potential risk associated with A1254 based on the toxic equivalency factors of the dioxin-like congeners was reduced by 83%. Additional potential risk associated with bioaccumulation in fish was reduced by 35% based on biota-sediment accumulation factor estimates for all detected congeners. Finally, the dechlorination end-products were tri- and tetra-chlorobiphenyls with unflanked chlorines, all of which are susceptible to further degradation by aerobic microorganisms. The combined results indicate that microbial reductive dechlorination has the potential for reducing risk associated with toxicity and bioaccumulation in fish in sites contaminated with A1254.

Bioaccumulation of Polybrominated Diphenyl Ethers by Tubifex Tubifex.

The selective uptake of polybrominated diphenyl ethers (PBDEs) by oligochaetes makes it possible to assess the bioaccumulation of individual congeners in commercial mixtures. Twenty-one congeners from three BDE commercial mixtures (TBDE-71, TBDE-79 and TBDE-83R) and as individual congeners (BDE-77, BDE-126, BDE-198 and BDE-204) were tested on Tubifex tubifex in accordance with the OECD TG 315 "Bioaccumulation in Sediment-Dwelling Benthic Oligochaetes". All the congeners that were spiked in the sediment were detected at the end of the uptake phase and at the end of the experiment. The bioaccumulation factor (BAF), the kinetic bioaccumulation factor (BAFK) and the biotasediment accumulation factor (BSAF) were calculated, and indicate a high bioaccumulation potential for tri- to hexa-BDEs and a lower bioaccumulation potential for hepta- to deca-BDEs. The penta-homologues BDE-99 and BDE-100 showed the highest BSAFs of 4.84 and 5.85 (BAFs of 7.34 and 9.01), while the nona- and deca-BDEs exhibit bioaccumulation in up to one-order-lower concentrations. The change in the bioaccumulation potential between the group of trito hexa-BDEs and hepta- to deca-BDEs correlated with the generally accepted molecular-mass threshold for the molecular transition through biological membranes (700 g/mol).

Effects of multiwalled carbon nanotubes on the bioavailability and toxicity of diphenhydramine to Pimephales promelas in sediment exposures.

Multiwalled carbon nanotubes (MWCNTs) and pharmaceutical compounds are classified by the US Environmental Protection Agency as contaminants of emerging concern, with significant research devoted to determining their potential environmental and toxicological effects. Multiwalled carbon nanotubes are known to have a high adsorptive capacity for organic contaminants, leading to potential uses in water remediation; however, there is concern that co-exposure with MWCNTs may alter the bioavailability of organic compounds. Existing studies investigating MWCNT/organic contaminant co-exposures have shown conflicting results, and no study to date has examined the combined effects of MWCNTs and a common pharmaceutical. In the present study, juvenile fathead minnows (Pimephales promelas) were exposed to sublethal concentrations of the over-the-counter antihistamine diphenhydramine (DPH) in the presence of natural sediment for 10 d, with some treatment groups receiving MWCNTs. Addition of MWCNTs did not have a protective effect on DPH-related growth inhibition, and did not reduce the whole-body burden of DPH in exposed fish. Mass-balance calculations indicated that significant amounts of DPH were adsorbed to MWCNTs, and DPH concentrations in water and sediment were commensurately reduced. Bioconcentration factor and biota-sediment accumulation factor increased in the presence of MWCNTs, indicating that P. promelas accumulates DPH adsorbed to MWCNTs in sediment, likely by co-ingestion of MWCNTs during feeding from the sediment surface. Environ Toxicol Chem 2017;36:320-328. © 2016 SETAC.

Bioaccumulation of polycyclic aromatic hydrocarbons, polychlorinated biphenyls and hexachlorobenzene by three Arctic benthic species from Kongsfjorden (Svalbard, Norway)

The predicted expansion of oil and gas (O&G) activities in the Arctic urges for a better understanding of impacts of these activities in this region. Here we investigated the influence of location, feeding strategy and animal size on the bioaccumulation of Polycyclic Aromatic Hydrocarbons (PAHs), Polychlorinated Biphenyls (PCBs) and Hexachlorobenzene (HCB) by three Arctic benthic species in Kongsfjorden (Svalbard, Norway). No toxicity was expected based on biota PAH critical body residues. Biota PCB levels were mainly below limit of detection, whereas samples were moderately polluted by HCB. PAH concentrations in biota and Biota Sediment Accumulation Factors (BSAFs) were generally higher in Blomstrandhalvøya than in Ny-Ålesund, which was explained by a higher abundance of black carbon in Ny-Ålesund harbour. BSAFs differed significantly among species and stations. We conclude that contaminant body residues are a less variable and more straightforward monitoring parameter than sediment concentrations or BSAFs in Arctic benthos.

Concentration of polychlorinated biphenyl (PCB) congeners in the muscle of Clarias gariepinus and sediment from inland rivers of southwestern Nigeria and estimated potential human health consequences

ABSTRACTThe distributions of polychlorinated biphenyl (PCB) congeners were determined in sediment and muscle of the African sharptooth catfish (Clarias gariepinus) from the Ogun and Ona rivers, southwest Nigeria. In addition, the effect of PCB congeners on condition factor (CF) and associated human health risk was assessed using muscle levels for a noncarcinogenic hazard quotient (HQ) calculation. Elevated concentrations of high-molecular-weight (HMW) PCB congeners were detected in sediment and fish downstream of discharge points of both rivers. A significant reduction in fish body weight and CF was observed to correlate with high PCB congener concentrations in the Ona River. A principal component (PC) biplot revealed significant site-related PCB congener distribution patterns for HMW PCB in samples from the Ogun River (71.3%), while the Ona River (42.6%) showed significant PCB congener patterns for low-molecular-weight (LMW) congeners. Biota-sediment accumulation factor (BSAF) was higher downstream for both rivers, presenting PCB congener-specific accumulation patterns in the Ona River. Significant decreases in fish body weight, length and CF were observed downstream compared to upstream in the Ona River. The non-carcinogenic HQ of dioxin-like congener 189 downstream in both rivers exceeded the HQ = 1 threshold for children and adults for both the Ogun and Ona rivers. Overall, our results suggest that industrial discharges contribute significantly to PCB inputs into these rivers, with potential for significant health implications for neighboring communities that utilize these rivers for fishing and other domestic purposes.

Assessment of Heavy-Metal Pollution in Sediments and Tilapia Fish Species in Kafue River of Zambia

We report results from an evaluation of the levels of heavy metals, i.e., copper (Cu), cadmium (Cd), lead (Pb), nickel (Ni), manganese (Mn), chromium (Cr), and iron (Fe) in sediment and tilapia fish samples from a wide stretch of the Kafue river of Zambia. In sediment samples, the highest Pb and Fe concentrations were recorded at Hippo Dam, i.e., 36.2±0.1mg/kg dw and 733±37mg/kgdw at Kafue Town, respectively. Other notably high metal concentrations in sediment were Cr at Kafue Bridge (42.5±0.1mg/kgdw [dw]), Cu at Mpongwe (233±5mg/kg dw), and Mn at Kafue Town (133±1mg/kg dw); it was highest at Ithezi Tezhi Dam at 166±1mg/kgd. Three fish species, i.e., three-spot bream Tilapia andersonii, red-breasted bream T. rendalli, and nile tilapia Oreochromis niloticus were evaluated for levels of the seven metals. The concentrations of the metals in these fish species afforded estimation of the biota sediment-accumulation factor, which is the ratio of the concentration of the metal in liver to that in the sediment. The coefficients of condition (K) values, which give an indication of the health of the fish, were also estimated. The K values ranged from 2.5±0.5 to 5.1±0.6 in all of the three fish species. Partial least squares analysis showed that heavy metals are generally sequestered evenly in all of the parts of all of the three fish species except for elevated levels of Mn, Cd, and Pb in the liver samples.

Distribution, Speciation and Bioaccumulation of Hg and As in Mariculture Sediments from Dongshan Bay, China

ABSTRACTHg and As are the major hazardous pollutants in marine sediments due to their high toxicity to benthonic organisms. Understanding the spatial distribution, speciation and bioaccumulation of these toxic elements in sediments is therefore of high environmental importance for identifying their potential risks. Sediments and bivalves Paphia undulata were collected from the mariculture area of Dongshan Bay, China, for characterizing geochemistry (by using the European Community Bureau of Reference (BCR) sequential extraction procedure) and bioaccumulation of Hg and As [by calculating the biota sediment accumulation factor (BSAF)]. Both elements in sediments were mostly associated with the residual fraction (69.52–95.06% and 88.22–91.12% of the total concentration, respectively), followed by the oxidizable (bound to sulfides and organic matter) fraction (1.25–25.32% and 3.62–6.00%, respectively). However, Hg presented a higher bioaccumulation than As. Correlation analysis indicated that As in residual fraction and Hg in oxidizable fraction exert positive contributions (R = 0.927, P < 0.01 and R = 0.869, P < 0.05, respectively) on their own bioaccumulation factor. This indicated that P. undulata could adsorb both Hg in organic fraction and As in residual fraction from the sediments. Therefore, we should pay more attention to the potential dissolution and release of metals bound to sediments in the digestive tracts of marine organisms.

Distribution and bioaccumulation of butyltins in the edible gastropod Odontocymbiola magellanica

ABSTRACTButyltins (BTs) were found in sediments and body tissues of the edible gastropod Odontocymbiola magellanica, in which imposex has been recorded since 2000. BTs in sediments ranged from < MDL to 174.8 ng (Sn) g−1 for TBT, < MDL to 19.2 ng (Sn) g−1 for DBT, and < MDL to 71.8 ng (Sn) g−1 for MBT. In body tissues BTs varied from < MDL to 147.1, < MDL to 77.0 and < MDL to 345.3 ng (Sn) g−1 for TBT, DBT and MBT, respectively. BT concentrations were higher in gonads and digestive glands than in the albumen gland and foot (edible). The highest concentrations of BTs in both sediments and gastropods were found in the harbour area, decreasing with distance to the harbour and areas with less maritime traffic. The Biota-Sediment Accumulation Factor (BSAF) in the different organs was between 0.02–0.42, 0.09–0.35 and 0.08–5.25 for TBT, DBT and MBT, respectively. There were positive correlations between concentrations of BTs in sediments and gastropod body tissues, suggesting that xenobiotic accumulation in O. magellanica occurs mainly through contaminated sediments, rather than water or the food chain. Considering current sediment quality guidelines, our results indicate that acute toxic effects would be expected from TBT exposure, which represents a serious environmental threat for the benthic community. Although the levels of BTs found in the foot of this edible gastropod did not exceed the recommended Tolerable Daily Intake in polluted areas, they should be monitored to ensure the safety of seafood consumers. The alternative antifouling biocides Irgarol and Diuron were not detected in sediments.

Bioavailability of polycyclic aromatic hydrocarbons (PAHs) to short-neck clam (Paphia undulata) from sediment matrices in mudflat ecosystem of the west coast of Peninsular Malaysia.

The bioaccumulation and bioavailability of polycyclic aromatic hydrocarbons (PAHs) were characterized in sediment and Paphia undulata (short-neck clam) from six mudflat areas in the west coasts of Peninsular Malaysia. The concentrations of total PAHs varied from 357.1 to 6257.1 and 179.9±7.6 to 1657.5±53.9ngg -1 dry weight in sediment and short-neck clam samples, respectively. PAHs can be classified as moderate to very high level of pollution in sediments and moderate to high level of pollution in short-neck clams. The diagnostic ratios of individual PAHs and principal component analysis indicate both petrogenic and pyrogenic sources with significant dominance of pyrogenic source. The first PAHs biota-sediment accumulation factors and relative biota-sediment accumulation factors data for short-neck clam were obtained in this study, indicating a preferential accumulation of lower molecular weight PAHs. Evaluation of PAH levels in sediments and short-neck clams indicates that short-neck clam could be introduced as a good biomonitor in mudflats. The results also demonstrated that under environmental conditions, the sedimentary load of hydrocarbons appears to be one of the factors controlling their bioavailability to biota.

Levels and distribution of polybrominated diphenyl ethers in the aquatic and terrestrial environment around a wastewater treatment plant.

The distribution and fate of polybrominated diphenyl ethers (PBDEs) in a riparian ecosystem nearby a wastewater treatment plant effluent were investigated. Different aqueous and terrestrial samples such as soil, sediment, plants, and invertebrates were collected and analyzed for tri- to heptabrominated PBDEs. Furthermore, the food web structure was elucidated using stable carbon and nitrogen isotopes. The highest PBDE levels were found for sediment- and soil-dwelling invertebrates, such as earthworms (Σ13 PBDEs 144ng/g lipid weight), Tubifex tubifex (77ng/g lw), and scarab larvae (49ng/g lw). Differences in congener composition profiles among the different matrices show that the environmental distribution and fate of PBDEs in ecosystems can be very complex. Among the analyzed PBDEs in this ecosystem, the tetra-brominated BDE-47 was the dominant PBDE congener and followed by the penta-brominated BDE-99. A potential trend of increasing BDE-47/99 ratio with the increase of δ(15)N was observed for species with similar energy sources (δ(13)C), indicating a higher bioaccumulation potential for BDE-47 in this ecosystem. A significant correlation was also found between PBDEs and polychlorinated biphenyls (PCBs), indicating similar sources and fate between the two compound groups in this area. The biota-soil or biota-sediment accumulation factors (BSAFs) were somewhat different among the PBDE congeners and species, but were generally highest for those with log Kow values around 6.5-7.

Trait-based modelling of bioaccumulation by freshwater benthic invertebrates

Understanding the role of species traits in chemical exposure is crucial for bioaccumulation and toxicity assessment of chemicals. We measured and modelled bioaccumulation of polychlorinated biphenyls (PCBs) in Chironomus riparius, Hyalella azteca, Lumbriculus variegatus and Sphaerium corneum. We used a battery test procedure with multiple enclosures in one aquarium, which maximized uniformity of exposure for the different species, such that the remaining variability was due mostly to species traits. The relative importance of uptake from either pore water or sediment ingestion was manipulated by using 28 d aged standard OECD sediment with low (1%) and medium (5%) OM content and 13 months aged sediment with medium OM (5%) content. Survival was ≥76% and wet weight increased for all species. Reproduction of H. azteca and weight gain of H. azteca and S. corneum were significantly higher in the medium OM aged sediments than in other sediments, perhaps due to a more developed microbial community (i.e., increase in food resources). Biota-sediment accumulation factors (BSAF) ranged from 3 to 114, depending on species and PCB congener, with C. riparius (3–10)<S. corneum (10–17)≤L. variegatus (7–61)≤H. Azteca (5–114), thus challenging the presumed value of 1–2 typically employed in ecological risk assessment schemes. BSAFs for freshwater taxonomic groups were compared with their marine counterparts and showed overlapping values. The dynamic bioaccumulation model with species-specific bioaccumulation parameters fitted well to the experimental data and showed that bioaccumulation parameters were depended on species traits. Enclosure-based battery tests and mechanistic BSAF models are expected to improve the quality of the exposure assessment in whole sediment toxicity tests.

Uptake, metabolism and sub-lethal effects of BDE-47 in two estuarine invertebrates with different trophic positions

Two microcosm types -sediment-biota and biota-biota- were constructed to simulate different pathways of BDE-47 uptake, metabolism and oxidative stress effects in two key estuarine invertebrates (polychaete Laeonereis acuta and crab Cyrtograpsus angulatus). In the sediment-biota experiment, both species were exposed to spiked sediments; an environmentally reported and a high concentration of BDE-47 for 2 weeks. In the biota-biota experiment, crabs were fed with polychaetes pre-exposed to BDE-47 in the sediment-biota experiment. The sediment-biota experiment first revealed that polychaetes significantly accumulated BDE-47 (biota-sediment accumulation factor >2; p < 0.05) to a much greater extent than the crab organs (muscle, hepatopancreas, gills) at both sediment concentrations. For oxidative stress responses, polychaete and crab tissues exposed to spiked sediment showed a significant increase (p < 0.05) of only glutathione S-transferase (GST) activity with respect to controls in both BDE-47 concentrations. No lipid peroxidation (TBARS) or total antioxidant capacity (ACAP) changes were evident in the species or organs exposed to either BDE-47 sediment concentration. The biota-biota experiment showed that feeding crabs with pre-exposed polychaetes caused BDE-47 accumulation in organs as well as significant amounts of BDE-47 eliminated through feces (p < 0.05). Unlike the sediment-biota exposure, crabs fed with pre-exposed BDE-47 polychaetes showed the most conspicuous oxidative stress responses. Significant changes in GST and ACAP in both hepatopancreas and gills, in addition to enhanced TBARS levels in the hepatopancreas with respect to controls (p < 0.05), revealed that BDE-47 assimilated by invertebrates represents a potential source of toxicity to their predators. No methoxylated metabolites (MeO-PBDEs) were detected during BDE-47 metabolism in the invertebrates in either of the two different exposure types. In contrast, hydroxylated metabolites (OH-PBDEs) were detected in polychaetes and crab organs/feces in both experiments. Our results demonstrate that PBDE hydroxylation is one of the main biotransformation routes of BDE-47 in estuarine animals, which could be associated with the oxidative stress responses found.

Assessment of the bioaccumulation and biodegradation of butyltin compounds by Thalamita crenata in Kaohsiung Harbor, Taiwan

Butyltin compounds (BTs) are considered as endocrine disruptors or environmental hormones. It has been applied as an antifouling paint in marine vessel, and extensively in commercial, industrial and agricultural applications. In order to investigate the decomposition and accumulation of BTs in benthic crustacean, concentrations of BTs including TBT (tributyltin) and its metabolic products, i.e. MBT (monobutyltin) and DBT (dibutyltin), accumulated in Thalamita crenata in Kaohsiung Harbor, Taiwan were analyzed. The analysis results indicate different concentrations of BTs contained in hepatopanceas and muscle for the crustacean trapped at different locations. Additionally, concentration and composition of BTs found in the crustacean hepatopanceas and muscle also show differences. Hepatopancreas has higher concentrations of BTs than muscle; the BTs contained in hepatopancreas are mostly metabolic products of BTs, whereas the muscle contain higher concentrations of TBT. By the estimates of BDI (butyltin degradation index) and BSAF (biota-sediment accumulation factors), T. crenata shows slow degradation ability of TBT and relatively strong TBT accumulation. The sources of BTs accumulated in T. crenata include harbor sediment and the food that contains BTs.

No such thing as a free meal: organotin transfer across the freshwater–terrestrial interface

Summary Emergent aquatic insects can represent an important subsidy to terrestrial ecosystems but may also transport accumulated contaminants across ecosystem boundaries when larvae develop in contaminated sediments. We sampled tetragnathid spiders (terrestrial predators), larval chironomids (spider prey of aquatic origin) and terrestrial insects (terrestrial prey) from two contaminated and two control sites in the Norfolk Broads (U.K.) to determine whether the organotin compound tributyltin (TBT) is transferred by emergent aquatic insects. TBT, a biocide in antifoulant paints, was prohibited in the U.K. in 1987 and globally since 2008 but persists in sediments for decades. Combining stable‐isotope analyses commonly used in ecology with ecotoxicological methods enabled us to test whether aquatic subsidies could transport organotin to terrestrial predators. Stable‐isotope mixing models (δ15N and δ13C) indicated that chironomids contributed 31–98% to spider biomass. Subsequent organotin analyses revealed consistent, low‐level butyltin (dibutyltin; DBT) contamination of chironomids from the most contaminated site but not from the other three sites. Spiders from the most contaminated site had DBT concentrations similar to those of their chironomid prey. To assess bioaccumulation, we used δ15N values as a proxy for trophic position of sediments, chironomids and spiders, and correlated these values with the respective DBT concentrations. Notwithstanding indications of 15N‐enrichment along this short food chain, chironomid DBT concentrations were significantly greater than those of their spider predators. Biota sediment accumulation factors (sediments to chironomids) and biomagnification factors (chironomids to spiders) were below the thresholds defining the occurrence of bioaccumulation and biomagnification. Although biomagnification was not detected, it is of concern that butyltins are still present in freshwater food webs c. 25 years since last known TBT use in the U.K., and continue to be transferred to terrestrial consumers.

Metal accumulation in benthic invertebrates and sediments at the Kaohsiung Ocean Disposal Site, Taiwan

The distribution of metals (Hg, Pb, Cd, Cr, Cu, Zn, and Ni) in the sediments and in benthic invertebrates (arthropod, echinoderm, and mollusc) from the Kaohsiung Ocean Disposal Site (KODS) during 2014 was studied in terms of biota-sediment accumulation factor (BSAF). The mean concentration of metals in the sediments varied in the following order: Zn >> Cr > Cu > Ni > Pb > Hg > Cd. Results showed that the metal concentration in the sediments from the KODS was in agreement with that of other Asia harbors; there was no drastically high metal level in the Kaohsiung area. Results also showed that arthropod Acanthephyra species had accumulated high metal concentrations (e.g. 0.53, 3.02, 6.80, 53.24, 162.2, and 1.42 μg g−1 of Hg, Pb, Cd, Cu, Zn, and Ni, respectively), whereas mollusc Fusinus hyphalus had the lowest metal concentration. A positive correlation (p < 0.01) was observed between the concentration of Cr in the sediments and in arthropods. For all benthic invertebrates investigated, the BSAF of Cd and Hg were higher than 1.0. Especially the BSAF of Cd was remarkably high, e.g. for arthropods (30.0), echinoderms (38.7), and molluscs (42.2); whereas the BSAF of Pb, Cr, and Ni were low (BSAF << 1.0). According to the above results, benthic invertebrate of arthropods had a large metal accumulation capacity and thus could be suggested as the bioindicator of metal contamination of marine systems in further studies.

ALTINYAZI BARAJ GÖLÜ’NDE (EDİRNE-TÜRKİYE) YAŞAYAN BAZI BALIK TÜRLERİNDE AĞIR METAL BİRİKİMLERİNİN İNCELENMESİ

In this study, heavy metal accumulations of the Altınyazı Dam Lake (Edirne/Turkey) water, sediments and the various tissues (gill, muscle, liver, kidneys) of some fish species (Cyprinus carpio, Carassius carassius, Blicca bjoerkna, Perca fluviatilis, Sander lucioperca) were investigated. Heavy metal analyses (Cd, Cr, Zn, Cu, Fe, Mn, Pb) were performed with PERKIN ELMER AAnalyst 800 Atomic Absorption Spectrofotometer. Only Fe was determined in water, the other metals were below detection limit. All heavy metals were determined in sediment with concentrations Fe&gt; Mn&gt; Cr&gt; Pb&gt; Zn&gt; Cu&gt; Cd. No significant difference in metal concentration in sediment was determined (p&gt;0.05) except Fe (p&lt;0.05). The levels of metals in water and sediment were under the acceptable levels. The levels of Cr, Zn, Cu, Fe, Mn in fish tissues were determined under acceptable limits. However, the levels of Cd and Pb in fish tissues were determined over acceptable limits. Accumulation levels of Cr, Zn, Fe and Pb in C.carpio were found to be different than the other species (p&lt;0.05). Biota-sediment accumulation factors of (BSAF) of some elements were below 1 in some tissues. BSAF of Cd were markedly above 1 in all species, though Pb and Zn were above 1 in C.carpio.

Potential ecological risk of heavy metal contamination in sediments and macrobenthos in coastal wetlands induced by freshwater releases: A case study in the Yellow River Delta, China

We investigated the nine heavy metal contents in the sediments and macrobenthos of the Yellow River Delta Wetlands using three experimental areas that received freshwater releases and one reference area that did not. Heavy metal contents, the single-factor contamination index (SFCI), the metal contamination index (MCI), and the biota-sediment accumulation factor (BSAF) were used to evaluate the potential ecological risk and bioaccumulation. We found that As exceeded the national standard value by more than 50%, and that the ranges of SFCI for each metal were generally larger in autumn than in spring. MCI showed no clear pattern, but the BSAF results suggest that Cd bioaccumulates from sediments to macrobenthos. Pollution-resistant species such as Corophium sinense, Chironomus sp., and Einfeldia sp. became dominant in the areas receiving freshwater releases, and provide direct evidence of ecological risk in the wetlands. Our results provide preliminary information to guide managers for ecological risk assessments.

Effects of combined sewer overflows and storm water drains on metal bioavailability in small urban streams (Prague metropolitan area, Czech Republic)

The aims of the study were to evaluate the effect of combined sewer overflows (CSO) and storm water drains (SWD) on metal bioavailability in small urban streams in Prague and to evaluate levels of metals in water, sediment, and macroinvertebrates. The following working hypotheses were adopted: (a) sites dominantly affected by SWD are less polluted by metals, and (b) sites dominantly affected by SWD have higher bioavailability of metals. Physical and chemical parameters (pH, conductivity, NO3-N, NH4-N, COD, alkalinity, and water hardness) and concentrations of the metals Cu, Zn, Pb, Ni, and Cr were determined in samples of water and sediment at five to six sites on four target streams—Zatisský Creek, Kosikovský Creek, Botic Creek, and Rokytka Creek—three to five times per year during the period 2002–2004. The sites from all studied creeks were categorized into five groups according to the prevailing type of urban drainage impact. Macroinvertebrates were sampled and analyzed for metals at each site for a period of 1 month. The concentration patterns of metals were interpreted by partition coefficient (Kd), hazard quotient (HQ), cumulative criterion unit (CCU), and biota sediment accumulation factor (BSAF). Concentrations of metals in water as well as in sediment at sites receiving water from SWD were lower than at sites where creeks receive water from CSO, except for Pb. Concentrations of Cu, Zn, and Pb in sediment were higher at sites affected by CSO. Concentrations of metals in aquatic macroinvertebrates, expressed as BSAF, indicated higher values at sites affected by SWD. Frequencies of high BSAF (>1) were lower in CSO compared to SWD. This finding was explained by (a) a decrease of pH on SWD sites compared to the increase of pH on CSO sites during rain events, (b) a greater resuspension of sediment at SWD sites during rain events, and (c) an abundance of organic matter in CSO available for sorption of metals and a corresponding reduction of their bioavailability. In the study area, the type of urban drainage affects the bioavailability of metals—while SWD increase metal bioavailability, CSO cause its decrease. The sediments in SWD sites do not indicate risk to the benthic community according to the applied environmental quality standards. Water and sediment in creeks affected by SWD are less polluted by metals. Both working hypotheses were therefore supported.

Bioaccumulation and distribution of organochlorine residues across the food web in Lagos Lagoon, Nigeria

Eighteen organochlorine pesticide (OCP) residues were measured in the water, sediment, plankton, benthic invertebrates and fish in various sections of the Lagos Lagoon in 2014 to investigate their bioaccumulation and distribution in the food web. The analysis was done using gas chromatography with an electron capture detector. The concentrations of OCPs in water and sediment ranged from 0.00 to 2.24 µg kg−1 and 0.00 to 1 673.57 µg kg−1, respectively. The sediment had the highest deposition of OCPs, with a total concentration of 2 953.84 µg kg−1. Lindane and heptachlor epoxide had the highest mean concentrations in the sediment, 1 673.57 µg kg−1 and 1 122.74 µg kg−1, respectively, while other OCPs were also found in the biota. Bentho-pelagic fishes had the highest biota-sediment accumulation factor (BSAF) in nine OCP residues, ranging from 1 to 32, and benthic invertebrates had the highest BSAF in three OCP residues, ranging from 1 to 91. The trend in total concentration of OCPs in the lagoon was sediment > Melicertus kerathurus > Eleotris soaresi > Pomadasys jubelini > Tilapia guineensis > Callinectes amnicola > plankton>water. The transfer of organochlorine residues in the food chain and its distribution in the trophic levels was influenced by habitat, environmental conditions, feeding habit and biochemical composition of individual populations. The total residual concentration of OCPs in shellfish and fish ranged between 0.16 ppm and 0.69 ppm. This concentration is quite high compared to the Federal Ministry of Environment limit of <0.01 ppm, and can be harmful if the trend is not checked. Continuous monitoring procedures need to be put in place for environmental safety.