Source Document: The Relationship Between Pocket Gophers (Thomomys bottae) andthe Distribution of Buried Radioactive Waste at the Los Alamos National Laboratory

摘要

Material Disposal Area G at the Los Alamos National Laboratory is a low-levelradioactive waste storage facility. The noticeable presence of pocket gopher mounds and cast soil on closed waste burial sites of various types resulted in the need to understand possible interactions between gophers and radioactive waste at Area G. In our study, pocket gophers, mound soil, off-mound surface soil, and vegetation were collected at Area G and at off-site background locations. The samples were analyzed for 241 Am, 238 Pu, 239 Pu, 3 H, and total U. A comparison of radionuclide concentrations in mound soil to surface soil and in gophers to soil and vegetation implied that gopher activity is generally not resulting in the upward transport of radionuclides. Concentrations of 241 Am, 238 Pu, 239 Pu, and 3 H in some of the gopher, soil, and vegetation samples were higher than background at some of the sites, however, gophers at only one site within Area G had 3 H concentrations that resulted in an estimated dose to gophers that could impact their health. Relationships in radionuclide concentrations between the four media (pocket gophers, mound soil, off-mound surface soil, and vegetation) were examined by conducting correlation tests. Correlations were highest for Am 241 and 238 Pu, however, only the 238 Pu relationship may be accurate enough to be used in predicting concentrations. The relationship in radionuclide concentration between pelts and carcasses was highly variablecarcasses, including the gastrointestinal tract, contained between 51% and 575% of the radionuclide concentration on pelts. Data generated by this study are valuable for ecological risk assessments. Further investigation through modeling and monitoring may be necessary to determine if the 3 H shafts are a source of environmental 3 H levels that are of ecological concern. Future research should include modeling the transport of radionuclides through ecological receptors within and around Area G. This should include investigations of transfer to high-level carnivores, especially raptors.