C.R. Olsen

Polychlorinated biphenyls in sediments of the tidal Hudson River, New York.

As a result of PCB discharges from two manufacturing facilities located some 60 km upstream of Troy, N.Y., PCBs in sediments of the Hudson River were measured. The sediments contain PCB concentrations of approximately 10 ppm, some one to two orders of magnitude higher than levels previously recorded. A first-order PCB budget for Hudson River sediment samples and regional levels of PCB contamination prior to the large point-source discharges are examined. (5 graphs, 1 map, 23 references, 6 tables)

Sources of heavy metals in sediments of the Hudson river Estuary

Abstract Sediments in the Hudson Estuary contain zinc, copper and lead from metal pollutants discharged to the harbor in the New York City area, from dispersed sources of contamination introduced upstream, and from natural weathering processes. The magnitude of the contribution from each of these three sources to particular sites can be estimated on the basis of total metal abundances, relative proportions of several metals, and other sediment properties. The pattern of recent heavy-metal contamination in Hudson sediments closely follows the distribution in sediments of 137Cs which was derived over the past two decades from global fallout and local releases from a commercial nuclear reactor. Several simple empirical corrections related to grain size and mineralogy variations are suggested for comparing heavy-metal contamination levels of sandy continental shelf sediments with fine-grained estuarine and coastal sediments. Iron has little variation in Hudson sediments while manganese is greater in surface sediment of some low-salinity and fresh-water areas than deeper in the sediments, and generally less in the high-salinity area of rapid sediment deposition in New York harbor. Much of the pollutant Cu added to the harbor appears to be rapidly deposited in the sediments.

Radionuclides in Mono Lake, California

Several radioisotopes of the naturally occurring uranium and thorium decay series, in addition to fallout plutonium, have unusually high concentrations in the water column of Mono Lake, a natural alkaline, saline lake. Complexing by carbonate ions appears to be responsible for the enhanced solubility of actinide elements with oxidation states of IV to VI. In contrast, fallout strontium-90 has been largely removed from the water, probably as a result of coprecipitation with calcium carbonate. The daughter/parent activity ratios of thorium, radium, and uranium isotopes suggest that thorium is removed from the water column to the sediments on time scales substantially longer than a month and that the desorption of thorium from the sediments to the water column requires less than a few years.

Plutonium, radiocesium and radiocobalt in sediments of the Hudson River estuary

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 of 238 Pu and 239,240 Pu (fallout-derived), 134 Cs and 60 Co (reactor-released), and 137 Cs (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 the 239,240 Pu 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 the 137 Cs, 134 Cs and 60 Co 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 of 137 Cs and 134 Cs from particles at higher salinities, and (5) possible enhanced desorption of 60 Co at higher salinities (relative to 134 Cs and 137 Cs) which may be associated with the release of reduced manganese from the harbor sediments.

Fallout plutonium in an alkaline, saline lake

Plutonium isotopes, derived from global fallout following atmospheric testing of nuclear weapons, have been measured in the water and sediments of a natural alkaline, saline lake. The activities of fallout plutonium in the water column are about two orders of magnitude greater than in most freshwater lakes, where these nuclides are found predominantly in the sediments.

Reactor-released radionuclides and fine-grained sediment transport and accumulation patterns in Barnegat Bay, New Jersey and adjacent shelf waters*

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.