Bioaccumulation of PCBs in aquatic biota from a tidal freshwater marsh ecosystem

Water. sediments. and aquatic biota were sampled in a tidal river-marsh on the Potomac River near Washington, DC (USA) to assess baseline concentrations of polychlorinated biphenyls (PCBs) and bioaccumulation in finish species. The mean sediment total-PCB concentration in the wetland was 50 ng/g dry weight. and mean concentrations in biota ranged front 150 ng/g to 450 ng/g wet weight. The highest PUB concentrations were observed in channel catfish. The median biotasediment accumulation factor (BSAF) estimated in all finfish species for total-PCBs was 2.9. However. some of the individual and co-eluting PCB congeners had median BSAFs that were substantially greater (e.g., congener numbers 42. 74, 182/187/128, and 171) or lower (e.g., congener numbers 18/15, 45, 185, and 208) than the total-PCB average. Apparent bioaccumulation factors (biota/water PCB concentration ratios) for PCB congeners showed a parabolic relation with n-octanol/water partition coefficients. confirming some previous investigations. There was no clear trend between apparent bioaccumulation factors and trophic level, Organic-carbon-normalized sediment distribution constants (sediment/water PCB concentration ratios) were linearly related to the apparent bioaccumulation factors for all the finfish species investigated.