title: Measuring bioavailability of polychlorinated biphenyls in soil to earthworms using selective supercritical fluid extraction.
abstract: If the release mechanisms during selective chemical extraction of persistent organic pollutants (POP) mimic release mechanisms in natural systems during biological uptake, then a selective non-exhaustive extraction could give a quantitative measure of the bioavailable POP fraction. Supercritical fluid extraction (SFE) is suggested as a possible technique to estimate the amount of bioavailable polychlorinated biphenyls (PCBs) at contaminated sites and hence serve as a new tool in risk assessment. The uptake of PCBs by earthworm (Eisenia foetida) was investigated. PCB contaminated soil was pre-extracted with selective non-exhaustive SFE (50 degrees C, 350 bar, 1h), which removed on average 70% of the individual PCBs. Earthworms were placed in this pre-extracted soil, as well as in untreated soil. After 10 days, the PCB uptake by earthworms in the two systems was compared. The bioaccumulation factor (BAF) was 83% lower in the pre-extracted system than in the untreated system, demonstrating that SFE extracts primarily bioavailable contaminants. From the data, the bioavailable fraction could also be calculated to be 75%, which is very close to the 70% removed by SFE under the applied conditions. This suggests that the chemical methodology is capable of measuring the bioavailable fraction very accurately in this system.
authors.affiliation: Department of Mathematics and Natural Science, Kristianstad University, SE-291 88 Kristianstad, Sweden.
authors.forename: Pär
authors.initials: P
authors.lastname: Hallgren
authors.forename: Rikard
authors.initials: R
authors.lastname: Westbom
authors.forename: Tobias
authors.initials: T
authors.lastname: Nilsson
authors.forename: Sune
authors.initials: S
authors.lastname: Sporring
authors.forename: Erland
authors.initials: E
authors.lastname: Björklund
mesh_terms: D000818:Animals; D001682:Biological Availability; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D009835:Oligochaeta / Q000378:metabolism*; D011078:Polychlorinated Biphenyls / Q000032:analysis / Q000493:pharmacokinetics*; D012989:Soil Pollutants / Q000032:analysis / Q000493:pharmacokinetics*
chemical_list: D012989:Soil Pollutants; D011078:Polychlorinated Biphenyls