Plutonium in Lake Ontario

The presence of West Valley-delivered radionuclides in the western basin of Lake Ontario is demonstrated through an analysis of plutoniums and associated radionuclides in a 210Pb-dated sediment core. It is observed that the radionuclide profiles are consistent with the 1970 West Valley peak discharge and not the 1963 fallout peak activity. The drainage basin soils are estimated to annually release only about 0.006% of their fallout 239,240Pu inventory to the receiving waters. Taken together, on a lakewide basis, both releases have made very little contribution to the overall levels of plutoniums in the open waters though surges in West Valley emissions were obviously a significant contributor to western Lake Ontario waters. It appears nuclear reactor operations contribute very little plutonium to the open waters. Their influence on the nearshore zone must await the availability of relevant release and monitoring data.