Chemical and biological availability of sediment-sorbed benzo[a]pyrene andhexachlorobiphenyl

This study examined the chemical and biological availability of two nonpola r organic compounds, benzo[a]pyrene (BaP) and hexachlorobiphenyl (HCBP), fr om a spiked sediment that was aged for varying amounts of time. Chemical av ailability was evaluated using four different solvent combinations to extra ct chemicals from the sediment. The extractability of BaP and HCBP from sed iment using traditional solvents was then compared to the transfer efficien cy (TE) of a benthic invertebrate (Lumbriculus variegatus) to relate chemic al extractability to bioavailability in the organisms. Results indicated th at water was the solvent that best approximated bioavailability for BaP, wh ereas comparisons for HCBP were inappropriate, because TE values exceeded 1 00%. The inability to obtain a reasonable TE estimate for HCBP was most lik ely due to the fact that the oligochaetes received a major portion of their uptake from interstitial water instead of ingestion of sediment particles, which invalidated an important assumption of the TF, model. Overall, the r esults of this study indicate that exhaustive chemical extractions may be a n inaccurate representation of the bioavailable fractions for some contamin ants.