POLYCHLORINATED-BIPHENYLS IN DATED SEDIMENTS OF MILWAUKEE-HARBOR, WISCONSIN, USA

A sediment core from Milwaukee Harbor was dated by the Pb-210 and Cs-137 methods and analyzed for polychlorinated biphenyls (PCBs). The mass sedimentation rate of 1. 10 g cm** minus **2 year** minus **1 was significantly higher than for Lake Michigan. The Cs-137 inventory of 162. 9 dpm cm** minus **2 was 11. 7 times higher than that calculated from atmospheric deposition data. There was a significant degree of PCB pollution in the sediments, as evidenced by the fact that the PCB flux was 596 times higher than the average atmospheric input to Lake Michigan. The vertical distribution of PCBs in the relatively undisturbed core followed the available national sales records (1957-74) remarkably well. In addition, there was a sharp drop in layers from the late 1970s which would be expected in view of the recent curtailment of PCB usage and production. Study conclusions are discussed.