The uptake and distribution of buried radionuclides by pocket gophers (Thomomys bottae)

Material Disposal Area G (Area G) at the Los Alamos National Laboratory is a low-level radioactive waste disposal facility. The noticeably high activity of pocket gophers on closed waste burial sites of various types at Area G resulted in the need to understand possible interactions between gophers and radioactive waste. Fossorial animals can influence the fate of contaminants by directly burrowing into waste trenches, pushing contaminated soil to the surface, or through indirect mechanisms such as consumption of contaminant-laden vegetation or the ingestion of soil. In our study, pocket gophers, mound soil, surface soil, and vegetation were collected at Area G and at offsite reference locations. The samples were analyzed for 241Am, 238Pu, 239Pu, 3H, and total U. It did not appear that gophers were responsible for any upward transport of radionuclides. Concentrations of 241Am, 238Pu, 239Pu, and 3H in some gophers, soil, and vegetation were higher than at reference sites; however, only 3H in gopher carcasses at only one of five sites within Area G was higher than a conservative ecological screening level.