Bioavailability of tetra- and hexa-chlorobiphenyls to benthic organisms from marine sediments

Benthic animals (Nephtys incisa and Voldia limatula) were exposed to marine sediments which had been spiked with C-14 labelled tetra- (TPCB) or hexa-(HPCB) chlorobiphenyl and equilibrated for periods up to one month. The sediments and organisms were collected at various time intervals and analyzed for their PCB content by liquid scintillation counting following extraction with acetonitrile. The organic carbon content of the sediments and the lipid content of the animals was also determined. Changes in the body burdens of TPCB and HPCB were rapid during the first ten to twenty days of accumulation and tended to level off after thirty days. Accumulation rates were more rapid for the TPCB than for HPCB. Both the rate of accumulation and the apparent steady-state concentrations of PCBs were influenced by the organic carbon content of the sediments. Lipid normalized concentrations of both PCBs appeared to reach steady-state more rapidly than the whole-body concentrations. Preference factors (PF animal/sediment ratios) calculated for these sediments suggest that PF may not be independent of sediment organic carbon content