| Popis: |
Anthropogenic radionuclides have been introduced into the Barnegat Bay environment via global fallout from nuclear weapons testing and by low-level discharges from the Oyster Creek Nuclear Generating Station. A significant portion of these radionuclides have been adsorbed to fine-grained particles and consequently provide excellent tracers for fine-sediment transport and accumulation patterns in the Bay and adjacent shelf environment. Fine-grained particles tagged with reactor nuclides are presently accumulating along the landward shore of Barnegat Bay at rates between I and 7 cm year−1. There is some indication that reactor-tagged sediments are also being transported into the mouths of small tributaries which discharge into the Bay. Reactor-tagged particles that escape from the Bay, through Barnegat Inlet, onto the shelf, are accumulating during the summer with fine-grained material from other sources, in depressions along the shelf bottom. These near-shore mud deposits are apparently resuspended and dispersed by major storms probably on a seasonal basis. By comparing radionuclide ratios in the reactor releases with the ratios observed in the fine-grained sediments in the vicinity of the reactor, it appears that (I) 35% to 50% of the total 137Cs activity in the top 30 cm of the sediments in Oyster Creek is attributable to reactor releases, (2) if transuranic releases have occurred from the Oyster Creek Reactor, the increments of 239,240Pu and 238Pu are not distinguishable from the fallout plutonium burden in the sediments and (3) radiocobalt is removed from the liquid effluent and stored in the sediments at least 20× more effectively than radiocesium. A budget of 60Co, based on inputs from the reactor, storage in the Bay sediments, and outputs through Barnegat Inlet on particles and in the dissolved phase, indicates that 40% of the 60Co released by the Oyster Creek reactor resides in the sediments of Barnegat Bay. The accumulation and dispersal patterns of reactive activation products such as 60Co released during routine nuclear reactor operations provide important clues to the probable transport pathways of a wide variety of pollutants including transuranic nuclides if significant releases of such materials were to occur. |
