Plutonium and cesium radionuclides in the Hudson River Estuary and other environments. Annual technical progress report, 1 December 1977--30 November 1978

Radionuclide activities were measured in a large number of sediment cores and suspended particle samples throughout the salinity range of the Hudson River estuary. Activities of 137Cs, 134Cs, and 60Co determined by gamma spectrometry and 239,240Pu and 238Pu determined by alpha spectrometry indicate reasonably rapid accumulation rates in the sediments of marginal cove areas, and very rapid deposition in the harbor region adjacent to New York City. General distributions of 137Cs and 239,240Pu are similar in surface sediments and with depth in cores, but there are deviations from the fallout ratio due to (1) addition of reactor 137Cs and (2) loss of 137Cs from the particle phases at higher salinities. Measurable amounts of reactor-derived 134Cs and 60Co are found in nearly all sediment samples containing appreciable 137Cs between 15 Km upstream of Indian Point and 70 Km south of the reactor. Accumulations of 239,240Pu in New York harbor sediments are more than an order of magnitude greater than the fallout delivery rate. Depth profiles of radionuclides and variations of activities with particle size at low salinities in the Hudson indicate the importance of organic phases, including large flocculent particles greater than 180μ, in binding plutonium, and no evidence of significant chemical migration within the sediments. Measurements of water column fallout 239,240Pu in a saline lake with a high carbonate ion concentration yielded activities about two orders of magnitude greater than has been found for fallout plutonium in other continental waters, indicating extensive mobility in some natural water environments