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Abstract: The use of a silicone rubber passive sampler for the assessment of the availability of lipophilic organic contaminants in sediments is described. The passive sampler accumulated polycyclic aromatic hydrocarbons (PAHs) from sediments with an equilibration time of 20days for most PAHs. The method was used to measure the free dissolved concentrations in pore water of 30 PAHs (parent and alkylated), their water exchangeable concentrations and sediment–water partition coefficients in field sediments from a Scottish sea loch that supports fish farming. Fluoranthene and pyrene dominated the PAH concentration composition in the pore waters. The water exchangeable concentration reflected the pyrogenic pollution pattern found in the sediments and indicated that a proportion of the PAHs were not available for exchange with the aqueous phase. Strong linear relationships between organic carbon normalised sediment–water partition coefficients (logKoc ) and corresponding octanol–water partition coefficients of PAHs were obtained. The logKoc values obtained are on average, 0.6log units higher than literature values commonly used in sediment risk assessments, consequently direct measurements of logKoc in field sediments should be used to improve the reliability of risk assessments. [Copyright &y& Elsevier]

Abstract: This study evaluates the potential of silicone rubber passive sampling devices (SR-PSDs) as a suitable alternative to automatic water samplers (autosamplers) for the preliminary identification of a wide range of organic contaminants in freshwater systems. The field performance of SR-PSDs deployed at three sites on two streams of an agricultural catchment area in North East (NE) Scotland, United Kingdom (UK) was assessed concurrently with composite water samples collected from two of the sites using autosamplers. The analytical suite consisted of selected plant protection products (PPPs; commonly referred to collectively as ‘pesticides’), including 47 pesticides and a separate sub-category of 22 acid/urea herbicides. Of these, a total of 54 substances, comprising 46 pesticides and 8 urea herbicides were detected in at least one of the SR samplers. All but 6 of these SR-PSD detected substances were quantifiable. By comparison, a total of 25 substances comprising 3 pesticides and 22 acid/urea herbicides were detected in the composite water samples, of which only 8 acid/urea herbicides were quantifiable. The larger number and chemical classes of compounds detected and quantified via passive sampling reflect the lower limits of detection achieved by this device when compared to autosamplers. The determination of dissolved concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) added to the information on contaminant pressures at each site, allowing assessment of the reliability of SR-PSDs in freshwater systems and the identification of possible contaminant sources. The study demonstrated the utility of SR-PSDs for detecting and semi-quantifying low concentrations of analytes, including those which hitherto have not been measured in the catchment area and also some pesticides that are no longer approved for agricultural use in the UK and EU. The SR-PSD approach can thus provide a better understanding and clearer picture of the use and presence of organic contaminants within catchments. [Copyright &y& Elsevier]

Abstract: We investigated the feasibility of coupling passive sampling and in vitro bioassay techniques for both chemical and ecotoxicological assessment of complex mixtures of organic contaminants in water. Silicone rubber passive sampling devices (SR-PSDs) were deployed for 8–9weeks in four streams and an estuary of an agricultural catchment in North East (NE) Scotland. Extracts from the SR-PSDs were analysed for freely dissolved hydrophobic organic contaminants (HOCs) and screened for wide range of pesticides. The total concentrations of dissolved PAHs (∑PAH40, parent and branched) in the water column of the catchment varied from 38 to 69ngL−1, whilst PCBs (∑PCB32) ranged 0.02–0.06ngL−1. A number and level of pesticides and acid/urea herbicides of varying hydrophobicity (log K OWs ∼2.25 to ∼5.31) were also detected in the SR extracts, indicating their occurrence in the catchment. The acute toxicity and EROD induction potentials of SR extracts from the study sites were evaluated with rainbow trout liver (Oncorhynchus mykiss; RTL-W1) cell line. Acute cytotoxicity was not observed in cells following 48h exposure to the SR extracts using neutral red uptake assay as endpoint. But, on a sublethal level, for every site, statistically significant EROD activity was observed to some degree following 72h exposure to extracts, indicating the presence of compounds with dioxin-like effect that are bioavailable to aquatic organisms in the water bodies of the catchment. Importantly, only a small fraction of the EROD induction could be attributed to the PAHs and PCBs that were determined. This preliminary study demonstrates that the coupling of silicone rubber passive sampling techniques with in vitro bioassays is feasible and offers a cost effective early warning signal on water quality deterioration. [Copyright &y& Elsevier]

The availability of polycyclic aromatic hydrocarbons (PAHs) from marine sediments to the ragworm (Nereis virens) was studied. Concentrations of PAHs in pore waters were determined using silicone rubber passive samplers. Calculated bioconcentration factors confirmed that partitioning of PAHs between the lipid phase of the polychaetes and pore water is a passive process. Low biota-sediment accumulation factors (BSAF) calculated using total sediment concentration suggested a fraction of the total PAH burden in the sediment may be strongly sorbed to organic carbon and not available to the polychaete. Organic carbon normalised concentrations of the potentially exchangeable fractions of contaminants and freely dissolved concentrations (measured using silicone rubber samplers) provide a better description of the observed bioaccumulation by the ragworms. These data indicate that the concept of availability should be included in environmental risk assessments based upon equilibrium partitioning models, and that silicone rubber samplers can provide the necessary information for these models. [Copyright &y& Elsevier]