Further studies of long-term ecological effects of exposure to uranium

Spatial variability in sampling for soil uranium distribution by a polar coordinate system was evaluated in randomly selected soil cores at the Los Alamos Scientific Laboratory. Variations for surface (0- to 2.5-cm-deep) soils were 0.18 at 10 m from the nuclear weapons test detonation point and 0.96 at 50 m. Results were strongly influenced by past uranium dispersal patterns, variable leaching of uranium debris, and surface water runoff. A total surface (0- to 5-cm) soil uranium inventory within a 12.6-ha circle centered on the E-F detonation point was estimated to be 3000 kg when calculated by soil uranium concentration isopleths and 4500 kg when using annuli of a polar coordinate sampling system. Uranium concentrations in tissues of deer mice (Peromyscus maniculatus) and pocket gophers (Thomomys bottae) were sufficiently different to conclude that the greater bioavailability of uranium in the top few millimeters of soil at E-F Site, combined with the difference in grooming and food habits of the animals, resulted in greater contamination of deer mice than of pocket gophers