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 sedime nt 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-wa ter partition coefficients (log K(ow) > 6.0). PCA analysis suggested t hat most PCB congeners had similar distributions in the Lake Erie food web, although congeners with very high Kows and coplanar congeners IU PAC # 77, 126, and 169 were found to have different distributions. Non -parametric statistics were used to determine if significant differenc es in concentration of selected PCB congeners existed among species an d among tissues. Congener 126 was found primarily in benthic fish and top predators, whereas there was no significant differences in the con centrations of congener 77 in fish species of the benthic and pelagic food web. Congener 169 was found at very low concentrations in the foo d web of Lake Erie. There were also significant differences in concent rations of coplanar PCBs among liver, egg, and muscle tissues, but tre nds 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 e vident that the dynamics of individual congeners, in particular the co planar PCBs, need to be accurately assessed in order to predict the en vironmental hazard of PCBs.