90Sr and 137Cs in soil and biota of fallout areas in southern Nevada and Utah.

Measurements of 90Sr and 137Cs in soil, vegetation and small mammals were made periodically at sites in southern Nevada and Utah that were contaminated by radioactive fallout from nuclear detonations at the Nevada Test Site (NTS) as well as from global sources. Results from a survey in 1980 indicate that both of these fallout-derived radionuclides have remained primarily within the top 5-cm layer of undisturbed soil in these arid land areas. Trace amounts of 90Sr and 137Cs were measured in soil and biota samples. The 90Sr concentrations in jackrabbit and rodent bone samples in 1980 varied within the range of 2-8 pCi/g ash (equivalent to 0.4-1.6 pCi/g wet bone or 5-20 pCi/g Ca). The 137Cs concentrations in muscle-tissue samples were generally less than 1.5 pCi/g ash (less than 0.045 pCi/g wet muscle). Comparisons of data obtained periodically since the early 1950s show that measured concentrations of 90Sr in bone tissues have been highly variable in trace amounts, and that the concentration attenuation appears to be following radioactive decay of this radionuclide.