title: Direct evidence of sequestration in sediments affecting the bioavailability of hydrophobic organic chemicals to benthic deposit-feeders.
abstract: In contrast to equilibrium partitioning model (EqP) calculations, biota to sediment accumulation factors (BSAF) of hydrophobic organic compounds for deposit-feeders are highly variable. Recent literature suggests that this variability can be attributed to differences in sequestration or the presence of slowly desorbing fractions in the sediment. In the present study, we investigated whether the observed relationship between bioavailability and sequestration is causal. We determined BSAF values and sequestration status, measured as the distribution over rapidly and slowly desorbing fractions, of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in a manipulated sediment as well as in the original, unmanipulated sediment The manipulation, 48 h suspending with Tenax, resulted in reduction of the rapidly desorbing fraction, while other factors such as contact time and sediment properties remained constant. Contrary to expectations based on EqP, BSAF values did not remain constant but were reduced by a factor of 2-27, proportional to the reduction in rapidly desorbing fractions. The results provide direct evidence of a causal relationship between sequestration and bioavailability to deposit-feeders. Furthermore, the present study demonstrates the need to modify traditional use of the equilibrium partitioning model to account for variation in the sequestration status of HOC in sediments.
authors.affiliation: Institute for Risk Assessment Sciences, University of Utrecht, The Netherlands.
authors.forename: Rik
authors.initials: R
authors.lastname: Kraaij
authors.forename: Willem
authors.initials: W
authors.lastname: Seinen
authors.forename: Johannes
authors.initials: J
authors.lastname: Tolls
authors.forename: Gerard
authors.initials: G
authors.lastname: Cornelissen
authors.forename: Angelique C
authors.initials: AC
authors.lastname: Belfroid
mesh_terms: D000818:Animals; D001682:Biological Availability; D019015:Geologic Sediments / Q000737:chemistry*; D007448:Invertebrates; D011078:Polychlorinated Biphenyls / Q000737:chemistry / Q000493:pharmacokinetics*; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry / Q000493:pharmacokinetics*; D012995:Solubility; D014018:Tissue Distribution
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D011078:Polychlorinated Biphenyls