THE DISTRIBUTION OF 42 PCBS, INCLUDING 3 COPLANAR CONGENERS, IN THE FOOD-WEB OF THE WESTERN BASIN OF LAKE ERIE

Non-ortho substituted PCBs, IUPAC numbers 77, 126, and 169, along with 39 other PCB congeners were quantified in samples of Lake Erie sediment and biota during the summer of 1991. Many PCB congeners were found at elevated levels, and biomagnification was apparent in all congeners but was more predominant in congeners with relatively high octanol-water partition coefficients (log K(ow) > 6.0). PCA analysis suggested that most PCB congeners had similar distributions in the Lake Erie food web, although congeners with very high Kows and coplanar congeners IUPAC # 77, 126, and 169 were found to have different distributions. Non-parametric statistics were used to determine if significant differences in concentration of selected PCB congeners existed among species and among tissues. Congener 126 was found primarily in benthic fish and top predators, whereas there was no significant differences in the concentrations of congener 77 in fish species of the benthic and pelagic food web. Congener 169 was found at very low concentrations in the food web of Lake Erie. There were also significant differences in concentrations of coplanar PCBs among liver, egg, and muscle tissues, but trends were not consistent among all the species examined. As significant differences were observed in the distribution of PCB congeners in the Lake Erie food web ''total PCB'' might not be an adequate estimation of the toxicological hazards associated with PCB accumulation. It is evident that the dynamics of individual congeners, in particular the coplanar PCBs, need to be accurately assessed in order to predict the environmental hazard of PCBs.