West Valley Plutonium and Americium-241 in Lake Ontario sediments off the mouth of Niagara River

Abstract

Recently deposited fine-grained sediments in Lake Ontario off the mouth of Niagara River contain highly toxic238Pu,239,240pu, and241Pu (241Am) from global fallout as well as from low level releases of these radionuclides from the West Valley radioactive waste management site. This is demonstrated through sediment core radionuclide inventories, radionuclide activity ratios, and assignment of independently-derived210Pb dates to sediment core segments. Reasonable agreement between measured and calculated inventories, derived using various assumptions and available discharge and environmental monitoring data, suggests that nearly all of the West Valley-delivered239,240Pu and 24241Am resides in the bottom sediments of Lake Ontario, comprising about 36 and 80%, respectively, of the measured (1982) inventories of these radionuclides. The West Valley241Am is largely derived from the decay of241Pu and, assuming negligible further deliveries of241pu (241Am), its growth is expected to continue until about 2040.