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The purpose of this study was to simultaneously evaluate several key factors which potentially affect the accumulation of hydrophobic pollutant compounds in sediment by benthic organisms. These factors were: (1) organic carbon content of the sediment; (2) equilibration time of the pollutant with the sediment; and (3) feeding strategies of the organism. [14C-U]2,4,5,2′,4′,5′-hexachlorobiphenyl (HCBP) was equilibrated with sediments from Narragansett Bay, RI containing either 4 or 2% total organic carbon for periods of either one or four weeks. Biological availability of the compound was assessed by following the kinetics of HCBP uptake into either the omnivorous deposit feeding polychaete Nephtys incisa or the deposit feeding bivalve Yoldia limatula exposed to bedded sediment.
In an attempt to normalize bioaccumulation data for differences in the lipophilic reservoirs between sediment and organism, an apparent preference factor (APF) was calculated comparing body burdens normalized to % lipid with sediment concentrations normalized to % total organic carbon (TOC) APF = (HCBPs/$TOC)/(HCBPo/%lipid) For both organisms, APF reached a constant value within 20 days. Length of isotope incubation with sediment had no observable effect on either the rate of approach to a constant APF or the value of APF reached. Even after normalizing with the preference factor calculation, significant differences were still evident between bioaccumulation from the two sediment types and between bioaccumulation from the same sediment by Yoldia and Nephtys. These data indicate that in addition to the influence of sediment TOC and lipid content of the organism, intrinsic properties of sediment and biological properties of the organism influence the transfer and bioaccumulation of hydrophobic compounds.
PCBs, polychaetes, bivalves, bioavailability, preference factors
Assistant professor, Environmental Sciences Program, University of Massachusetts/Boston, Boston, MA
Professor, Environmental Studies, Louisiana State University, Baton Rouge, LA