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(458) Bioaccumulation of 4-nonylphenol by benthic amphipods from spiked estuarine sediments. Hecht, Scott1, Gunnarsson, Jonas2,3, Boese, Bruce2, Lamberson, Janet2, Schaffner, Christian4, Giger, Walter4, 1 2 3 4 ABSTRACT- Nonylphenol (NP) is a moderately persistent, hydrophobic chemical (Log Kow 4.5) with endocrine disrupting and acute narcotic effects in aquatic biota. It is a metabolite of the widely used surfactants, nonylphenol polyethoxylates. Because of its extensive use, there is concern as to the ultimate fate of NP in benthic systems, particularly, the potential for bioaccumulation by benthic biota via the sediment and the resulting transfer to higher trophic levels. Bioavailability of hydrophobic organic compounds is strongly influenced by the total organic carbon (TOC) content of the sediment. In this study, sediments were spiked with 14C-NP and two types of TOC of different nutritional quality. Bioaccumulation of NP was measured in three amphipod species (Eohaustorius estuarius, Grandidierella japonica, and Corophium salmonis) that have different feeding strategies. Our goals were (1) to determine if amphipods bioaccumulate significant amounts of NP from sediment and (2) to determine if TOC quantity and quality influence NP bioaccumulation. Amphipods were exposed for 16 days to equal concentrations of NP in three treatments: "control" (no additional TOC), "refractory TOC" (sediment enriched with lignin), "labile TOC" (sediment enriched with dried algae (Ulva sp.)). NP concentrations in animals, sediment, porewater and overlying water were quantified with liquid scintillation counting and chemical analysis. NP bioaccumulation was inversely related to TOC quantity, but unrelated to TOC nutritional quality. Accumulation rate and steady-state concentrations of NP were highest in control treatments, and there was no significant difference between refractory and labile TOC treatments. During the experiment, NP concentrations decreased in sediment and increased in porewater and overlying water, especially in controls. Our results indicated that porewater was the major route of NP exposure to amphipods. Bioaccumulation factors and bioconcentration factors (based on porewater) were 150-1000 and 1100-4400 respectively, indicating that amphipods can be major sources of NP to higher trophic levels such as juvenile salmonids. Key words: surfactant, nonylphenol, bioaccumulation, amphipod |
