Plutonium,radiocesium and radiocobalt in sediments of the Hudson River estuary |
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| Authors: | CR Olsen HJ Simpson RM Trier |
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| Institution: | 1. Lamont-Doherty Geological Observatory, Columbia University, Palisades, NY 10964, U.S.A.;2. Department of Geological Sciences, Columbia University, Palisades, NY 10964, U.S.A. |
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| Abstract: | Anthropogenic radionuclides have reached the Hudson estuary as global fallout from nuclear weapons testing and through local releases from commercial nuclear reactors. Significant activities of238Pu and239,240Pu (fallout-derived),134Cs and60Co (reactor-released), and137Cs (derived from both sources), have accumulated in the sediments throughout the estuary, with the primary zone of accumulation near the downstream end of the system in New York harbor. The estuary appears to have trapped nearly all of the239,240Pu delivered as fallout, and consequently, ocean dumping of dredged harbor sediment is currently the primary means for the net transport of these nuclides to coastal waters. In contrast, only 10–30% of the137Cs,134Cs and60Co delivered to the estuary have been retained on the fine particles which accumulate at a rapid rate in the harbor.The primary factors which have governed the distribution of anthropogenic radionuclides in Hudson sediments are: (1) spread of fine particles labeled with both fallout and reactor nuclides throughout the axis of the estuary, (2) differences in timing of the peak fallout years (1962–1964) and years of maximum reactor releases (1971–1972), (3) large variations in sediment accumulation rates, ranging from a few millimeters per year or less to many tens of centimeters per year, (4) appreciable desorption of137Cs and134Cs from particles at higher salinities, and (5) possible enhanced desorption of60Co at higher salinities (relative to134Cs and137Cs) which may be associated with the release of reduced manganese from the harbor sediments. |
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