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Influence of sediment ingestion and exposure concentration on the bioavailable fraction of sediment‐associated tetrachlorobiphenyl in oligochaetes
Author(s) -
Sormunen Arto J.,
Leppänen Matti T.,
Kukkonen Jussi V. K.
Publication year - 2008
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/07-334.1
Subject(s) - bioavailability , sediment , environmental chemistry , chemistry , bioaccumulation , tenax , extraction (chemistry) , desorption , pore water pressure , chromatography , adsorption , geology , gas chromatography , biology , paleontology , bioinformatics , organic chemistry , geotechnical engineering
The desorption and bioavailability of 3,3′,4,4′‐tetrachlorobiphenyl (PCB 77) were studied in spiked natural sediments at six concentrations. The desorption kinetics were measured in a sediment–water suspension using Tenax® resin extraction, and the bioavailability was measured by exposing Lumbriculus variegatus (Oligochaeta) to PCB 77–spiked sediment in a 14‐d kinetic study. In addition, freely dissolved pore‐water concentrations were measured using the polyoxymethylene solid‐phase extraction method. The present study examined whether bioavailability can be defined more accurately by measuring the size of desorbing fractions and the pore‐water concentrations than by using the standard equilibrium partitioning approach. The importance of ingested sediment in bioaccumulation also was investigated. Our data showed a clear, decreasing trend in the rapid‐desorbing fractions and in the standard biota–sediment accumulation factors (BSAF) with increasing concentration in sediment. Desorbing fractions–refined BSAFs were more uniform across the concentration treatments, and the pore‐water PCB 77 concentration predicted tissue concentrations close to observed values. In the risk assessment process, pore‐water concentration or desorbing fractions would lead to more precise bioavailability estimates compared with those from the traditional equilibrium partitioning approach. The result also showed, however, that sediment‐ingesting worms had access to an additional bioavailable chemical fraction that was especially evident when PCB 77 pore‐water concentrations most likely approached the solubility limit. Thus, feeding may modify the bioavailable fraction that cannot be explained by simple equilibrium partitioning models.