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(IP04) Factors affecting contaminant bioavailability in sediments: considerations for risk evaluation of contaminated sediments.
Hecht, Scott*,1, Gunnarsson, Jonas2, Boese, Bruce3, Lamberson, Janet3, Schaffner, Christian4, Giger, Walter4, Jepson, Paul1, 1 Oregon State University, Corvallis, Oregon, USA2 Stockholm University, Stockholm, Sweden3 U.S. EPA, Newport, Oregon, USA4 Swiss Institiute of Technology (EAWAG), Dubbendorf, Switzerland
ABSTRACT- Sediments act as repositories for many hydrophobic anthropogenic contaminants that are responsible for deleterious ecological impacts and increase risk to human health. Total sediment contaminant concentration often does not correlate to observed toxicity and accumulation by organisms because only a fraction of the total chemical pool is bioavailable. Predictive models often over- or under estimate bioaccumulation by benthic organisms. Equilibrium based accumulation models in particular fail to take into account animal behavior and type of sediment organic carbon that may influence accumulation. We demonstrate that bioaccumulation by benthic amphipods can vary significantly with the above factors, resulting in body burdens that were not accurately predicted by biota-sediment accumulation factors. Two contaminants, hexachlorobiphenyl (PCB congener) and 4-nonylphenol (surfactant breakdown product) were spiked to sandy sediments that were enriched with either labile (Ulva sp.) or refractory (lignin) organic matter. Three species of estuarine amphipod (Eohaustorius estuarius, Grandiderella japonica, and Chorophium salmonis) were exposed to sediment treatments for 16 days. Accumulation kinetics and steady state body burdens were determined. Results support that organism biology and/or type of organic matter influence contaminant bioavailability, therefore these factors should be considered when evaluating risk of contaminated sediments to aquatic systems.
Key words: Contaminated sediment, amphipods, nonylphenol
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