Uranium contamination of anthropogenic origin has been identified in unconsolidated sediments of a 1.5km portion of the Ashtabula River near its confluence with Lake Erie. Uranium concentrations as high as 188 μg/g dry sediment are present. A small tributary of the Ashtabula River, Fields Brook, is the apparent point of origin of the uranium in the Ashtabula River sediments. {left sup}137Cs dating of a sediment core indicates that the U contamination occurred during the post-1964 time frame. The horizons of elevated U concentration also exhibit > 10× elevations in Zr, Nb, Hf, Ta, and W. {left sup}238U/{left sup}235U isotopic ratios indicate that the uranium is largely but not exclusively of natural composition. Distinct horizons of slightly {left sup}235U -depleted ({left sup}238U/{left sup}235U > 137.88) and slightly {left sup}235U -enriched ({left sup}238U/{left sup}235U < 137.88) uranium are also present. {left sup}210Pb activities and {left sup}232Th/{left sup}230Th isotopic measurements indicate that a significant portion of the uranium contains {left sup}238U daughters in approximate secular equilibrium. It is inferred that at least two distinct sources of anthropogenic U contamination exist: (A) discharges from the processing of enriched and depleted U metal by a DOE contractor facility and (B) U-bearing wastes from the production of TiO{dub}2 from ilmenite and associated minerals. These isotopic methodologies are potentially useful in settings where releases of nonnatural {left sup}238U/{left sup}235U composition materials and/or "naturally occurring radioactive material" (NORM) have taken place.
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