title: Comparative sorption and desorption of benzo[a]pyrene and 3,4,3',4'-tetrachlorobiphenyl in natural lake water containing dissolved organic matter.
abstract: The sorption and desorption of two model compounds, benzo[a]pyrene (BaP) and 3,4,3',4'-tetrachlorobiphenyl (TCBP), were studied in natural lake water with high dissolved organic matter (DOM) content using the equilibrium dialysis and Tenax extraction methods. The sorption of TCBP was lower and reached steady value more slowly than did BaP. Tenax extraction revealed at least two differently desorbing fractions for both model compounds, which also supported the conclusion that DOM-HOC associations may involve several mechanisms. The rapidly desorbing fraction may be attributed to freely dissolved and loosely sorbed compound, whereas the more strongly sorbed fraction may indicate the presence of specific binding sites. The data indicated that the association between hydrophobic organic contaminants (HOC) and DOM is not simply absorption that is solely driven by the lipophilicity of the sorbates. Although contact time had a rather negligible effect on the sorption of BaP, the proportion of desorption resistant fraction increased with time, whereas the desorption of TCBP was less affected by contact time. Steric factors may be the cause of the lower sorption and smaller desorption resistant fraction of TCBP. The results indicate potential differences in the behavior of PAHs and PCBs in the aquatic environment.
authors.affiliation: Laboratory of Aquatic Ecology and Ecotoxicology, Department of Biology, University of Joensuu, PO Box 111, FIN-80101 Joensuu, Finland. jarkko.akkanen@joensuu.fi
authors.forename: Jarkko
authors.initials: J
authors.lastname: Akkanen
authors.forename: Anita
authors.initials: A
authors.lastname: Tuikka
authors.forename: Jussi V K
authors.initials: JV
authors.lastname: Kukkonen
mesh_terms: D000327:Adsorption; D001564:Benzo(a)pyrene / Q000737:chemistry*; D002250:Carbon Radioisotopes / Q000737:chemistry; D005387:Finland; D005618:Fresh Water / Q000737:chemistry*; D006812:Humic Substances / Q000032:analysis; D007700:Kinetics; D009930:Organic Chemicals / Q000737:chemistry*; D011078:Polychlorinated Biphenyls / Q000737:chemistry*
chemical_list: D002250:Carbon Radioisotopes; D006812:Humic Substances; D009930:Organic Chemicals; D001564:Benzo(a)pyrene; D011078:Polychlorinated Biphenyls; C028451:3,4,3',4'-tetrachlorobiphenyl