Polychlorinated biphenyls (PCBs) were measured in the air and water over the Hudson River Estuary during six intensive field campaigns from December 1999 to April 2001. Over-water gas-phase PCB concentrations averaged 1100 pg/m3 and varied with temperature. Dissolved-phase PCB concentrations averaged 1100 pg/L and displayed no seasonal trend. Uncertainty analysis of the results suggests that PCBs with 5 or fewer chlorines exhibited net volatilization. The direction of net air/water exchange could not be determined for PCBs with 6 or more chlorines. Instantaneous net fluxes of PCBs ranged from +0.2 to +630 ng m-2 d-1. Annual fluxes of [summation operator]PCBs were predicted from modeled gas-phase concentrations, measured dissolved-phase concentrations, daily surface water temperatures and wind speeds. The net volatilization flux was +62 μg m-2 yr-1, corresponding to an annual loss of +28 kg/yr of PCBs from the Hudson River Estuary for the year of 2000. Investigation of the air-water exchange of PCBs in the Hudson River Estuary suggests that PCBs with 5 or fewer chlorines undergo net volatilization.

We present direct evidence of the release of synthetic nanoparticles from urban applications into the aquatic environment. We investigated TiO2 particles as these particles are used in large quantities in exterior paints as whitening pigments and are to some extent also present in the nano-size range. TiO2 particles were traced from exterior facade paints to the discharge into surface waters. We used a centrifugation based sample preparation which recovers TiO2 particles between roughly 20 and 300 nm. Analytical electron microscopy revealed that TiO2 particles are detached from new and aged facade paints by natural weather conditions and are then transported by facade runoff and are discharged into natural, receiving waters. Microscopic investigations are confirmed by bulk chemical analysis. By combining results from microscopic investigations with bulk chemical analysis we calculated the number densities of synthetic TiO2 particles in the runoff. The release of synthetic TiO2 particles from exterior applications into the aquatic environment is demonstrated.

Laboratory tests of fipronil and its degradation products have revealed acute lethal toxicity at very low concentrations (LC50) of <0.5 μg/L to selected aquatic macroinvertebrates. In streams draining basins with intensive rice cultivation in southwestern Louisiana, USA, concentrations of fipronil compounds were an order of magnitude larger than the LC50. The abundance (ρ = -0.64; p = 0.015) and taxa richness (r2 = 0.515, p < 0.005) of macroinvertebrate communities declined significantly with increases in concentrations of fipronil compounds and rice-cultivation land-use intensity. Macroinvertebrate community tolerance scores increased linearly (r2 = 0.442, p < 0.005) with increases in the percentage of rice cultivation in the basins, indicating increasingly degraded stream conditions. Similarly, macroinvertebrate community-tolerance scores increased rapidly as fipronil concentrations approached about 1 μg/L. Pesticide toxicity index determinations indicated that aquatic macroinvertebrates respond to a gradient of fipronil compounds in water although stream size and habitat cannot be ruled out as contributing influences. Aquatic macroinvertebrate commmunities in southwestern Louisiana streams respond to a gradient of fipronil compounds in water.

The objective of this study was to investigate the accumulation of selenium in lakes downstream of a uranium mine operation in northern Saskatchewan, Canada. Selenium concentrations in sediment and biota were elevated in exposure areas even though water concentrations were low (<5 μg/L). The pattern (from smallest to largest) of selenium accumulation was: periphyton < plankton and filterer invertebrates < detritivore and predator invertebrates < small bodied (forage) fish and predatory fish. Biomagnification of selenium resulted in an approximately 1.5–6 fold increase in the selenium content between plankton, invertebrates and forage fish. However, no biomagnification was observed between forage fish and predatory fish. Selenium content in organisms from exposure areas exceeded the proposed 3–11 μg/g (dry weight) dietary toxicity threshold for fish, suggesting that the selenium released into these aquatic systems has the potential to bioaccumulate and reach levels that could impair fish reproduction. Selenium bioaccumulation patterns in a north temperate, cold water aquatic ecosystem were similar to those reported from warm water systems.

Evidence of ecological impacts from pesticide runoff has prompted installation of vegetated treatment systems (VTS) along the central coast of California, USA. During five surveys of two on-farm VTS ponds, 88% of inlet and outlet water samples were toxic to Ceriodaphnia dubia. Toxicity identification evaluations (TIEs) indicated water toxicity was caused by diazinon at VTS-1, and chlorpyrifos at VTS-2. Diazinon levels in VTS-1 were variable, but high pulse inflow concentrations were reduced through dilution. At VTS-2, chlorpyrifos concentrations averaged 52% lower at the VTS outlet than at the inlet. Water concentrations of most other pesticides averaged 20–90% lower at VTS outlets. All VTS sediment samples were toxic to amphipods (Hyalella azteca). Sediment TIEs indicated toxicity was caused by cypermethrin and lambda-cyhalothrin at VTS-1, and chlorpyrifos and permethrin at VTS-2. As with water, sediment concentrations were lower at VTS outlets, indicating substantial reductions in farm runoff pesticide concentrations. Toxicity identification evaluations identified key pesticides in agricultural runoff, and their concentrations were reduced by farmer-installed vegetated treatment systems.

Fifty fish samples were collected from the Pearl River estuary (PRE) and Daya Bay, South China and were analyzed for DDTs, HCHs, chlordanes and polybrominated biphenyl ethers (PBDEs). Except the high concentrations of DDT observed in fishes, the concentrations of HCHs, chlordanes and PBDEs were low when compared to other regions. BDE-47 was the predominant PBDE congener and the BDE-209 concentrations were relatively low, despite its high concentration in surface sediments. The absence of significant increase of DDT, HCH, chlordane and PBDE concentrations towards higher δ15N values, as well as the lack of a significant correlation (p < 0.1) between log concentrations (lipid normalized) and δ15N, may indicate a weak biomagnification of these chemicals in the food webs. Good agreement was observed between their concentrations and lipid contents of the organisms. Bioconcentration was suggested to be responsible for the accumulation of OCPs and PBDEs in the lower trophic organisms in the studied subtropical waters. Bioconcentration was suggested to be responsible for the accumulation of OCPs and PBDEs in the lower trophic organisms of subtropical waters.

Metazachlor is a frequently used herbicide with concentrations in surface waters up to 100 μg L-1. A long-term mesocosm study was performed in order to investigate effects on stream and pond communities also regarding recovery. Single metazachlor doses of 5, 20, 80, 200, and 500 μg L-1 were given and the aquatic communities monitored for 140 days. In this paper, special attention is paid to the plankton response and the results of the entire study are summarised. Metazachlor strongly affected the stream and pond mesocosm communities at concentrations higher than 5 μg L-1. Direct negative effects were most prominent for chlorophytes whereas diatoms and cryptophytes seemed insensitive. The effects on zooplankton were caused by changes in habitat structure due to the strong decline of macrophytes. The slow degradation of metazachlor combined with the absence of recovery in both chlorophytes and macrophytes is likely to cause long-lasting effects on aquatic ecosystems. Metazachlor at levels >5 μg L-1 is likely to cause long-lasting effects in macrophyte dominated aquatic communities.

The relative abundance and variation of Cr, Co, Cd and Pb in Ascophyllum nodosum and intertidal surface sediments from six locations around the coast were assessed over six seasons. Higher Cd and Pb levels in Galway Docks and Cork Harbour were attributed to localised inputs of these metals from municipal and domestic waste, while at a reference site (Ballyconneely), high algal Cr concentrations were considered a function of geological setting rather than anthropogenic loading. Little seasonal variation was observed, with the exception of higher Co levels in plants in winter, associated with growth dynamics and increased fluvial inputs. In comparison with previously published data for metals in A. nodosum from the North Atlantic, with the exception of localised hot spots, the Irish coastline is still a relatively pristine environment. A. nodosum may be successfully and easily used as a biomonitor of metal contamination in coastal waters. This paper provides details of an easily applicable, cost-effective and ecologically relevant approach to assessing the degree of metal contamination in coastal environments.

The relationship between the microbial methylation of mercury and the microbial activities in sediments and water collected from the estuary of Bilbao (North of Spain) was studied in three different sampling points and in two different seasons. Three different cultures were prepared with a sediment slurry to distinguish between biotic and abiotic methylation pathways and the variations of the methylmercury concentration and the variations of the population of total number of bacteria (TDC), anaerobic heterotrophic bacteria (AHB), sulphate-reducing bacteria (SRB) and Desulfovibrio were measured. From this work, it can be concluded that the variation of MeHg concentrations is a result of the methylation/demethylation processes in the sediments, and that the abiotic processes have a negligible contribution to those processes. According to the statistical analysis of the results (partial least squares analysis) a significant statistical correlation was established between methylmercury and the SRB counts.The methylation of mercury follows a stationary pattern linked to the variation of sulphate-reducing bacteria.