title: Selective supercritical fluid extraction as a tool for determining the PCB fraction accessible for uptake by chironomid larve in a limnic sediment.
abstract: Selective supercritical fluid extraction (SFE) at 40 degrees C, 400 bar and 60 min was used to selectively remove bioavailable PCBs from a naturally contaminated limnic sediment. The extraction decreased the sediment concentrations of the nine studied PCBs by 54% (on average). Chironomid larvae were thereafter cultured in pre-extracted sediment as well as in untreated sediment to study the differences in uptake of PCBs in the two cultures. While the prevailing equilibrium partitioning (EqP) theory predicts a 54% decrease in PCB uptake by the chironomids in the pre-extracted sediment, with a maintained biota-to-sediment accumulation factor (BSAF), a decrease in PCB uptake by 91% was observed. For all investigated PCBs the BSAFs were on average 81% lower in the cultures with pre-extracted sediment than in the untreated systems. The data allowed for a calculation of the bioavailable fraction, which was estimated to 60%. This is very close to the 54% removed by selective SFE, demonstrating the possibility of using SFE as a tool to determine the bioavailable PCB fraction in a polluted sediment.
authors.affiliation: Department of Analytical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
authors.forename: Tobias
authors.initials: T
authors.lastname: Nilsson
authors.forename: Erland
authors.initials: E
authors.lastname: Björklund
mesh_terms: D000465:Algorithms; D000818:Animals; D002683:Chironomidae / Q000737:chemistry*; D019015:Geologic Sediments / Q000032:analysis; D007814:Larva; D011078:Polychlorinated Biphenyls / Q000032:analysis* / Q000378:metabolism; D013548:Sweden; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls