Distribution of a tetrabrominated diphenyl ether and its metabolites in soft-bottom sediment and macrofauna species

Sediment spiked with C-14-2,2', 4,4'-tetrabrominated diphenyl ether (BDE-47) was added as a single pulse, at a low or a high concentration, to intact soft-bottom sediments in a box-cosm system. The vertical distribution of the pollutant and the bioaccumulation in 39 different taxa of macrofauna were analysed after 10, 20 and 29 wk exposure. Throughout the experimental period, 90 % of the recovered BDE-47-derived radioactivity in the sediment was found within the upper 5 cm. The BSAF (biota-sediment accumulation factor) in the different taxa after 29 wk exposure varied between 0.4 and 16.3. The correlation between bioaccumulation and lipid content of all individual specimens in each box-cosm was significantly positive and explained between 11 and 64 % of the variation. When the fauna was divided into groups with different feeding strategies, it was found that the mean BSAF was significantly higher for the surface deposit-feeders than for the suspension-feeders, subsurface feeders and the predators. The difference increased with time and was larger after 29 wk exposure than after 10 wk. We also tested whether there was a correlation between N-15 enrichment, i.e. trophic position, in the analysed species and bioaccumulation, but no such correlation was found. Water-soluble metabolites of BDE-47 were detected in 15 of the 39 macrofaunal species. There was no observable correlation between the presence of metabolites in the macrofauna and bioaccumulation of the pollutant.