BIOACCUMULATION OF POLYCHLORINATED-BIPHENYLS FROM SEDIMENTS TO AQUATIC INSECTS AND TREE SWALLOW EGGS AND NESTLINGS IN SAGINAW BAY, MICHIGAN, USA

Sediments in the Saginaw Bay region of the Great Lakes contain concent rations of polychlorinated biphenyls (PCBs) that may adversely affect biotic species in various trophic levels. In this study we collected a nd analyzed sediments, benthic invertebrates, tree swallow eggs, and n estlings to evaluate linkages between PCBs in sediments and at various trophic levels in the Saginaw River, Michigan, USA. Our results indic ate that patterns of relative concentrations of PCB congeners change w ith trophic level, specifically from sediment to invertebrates and fro m tree swallow eggs to nestlings. However, if biota-sediment accumulat ion factor (BSAF) values are based on only the non-and mono-ortho-subs tituted PCB congeners or 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalen ts (TEq), calculated BSAF values are close to those predicted by fugac ity theory. The use of site-specific BSAF values and reference doses f or toxic effects in wildlife can be used to derive sediment quality cr iteria (SQC) that are protective of wildlife at the top of the sedimen t-based food chain. The threshold concentration of TEq in sediments th at would protect sensitive avian species at the same trophic level as tree swallows was calculated to be 1.5 x 10(-1) TEq/g total organic ca rbon. Based on this value and the BSAF determined for tree swallow nes tlings, the hazard quotient for sediments in this area was determined to be 0.7. This indicates that current concentrations of TEq due to PC B congeners in the sediments should be below the threshold for adverse effects on tree swallows. The uncertainty in the concentrations of PC B congeners in the sediments was approximately a factor of 2, which de termined the degree of resolution that could be obtained from the obse rvations made in this study.