Radionuclide Concentrations in soils an Vegetation at Low-Level Radioactive Waste Disposal Area G During 2004

Soil samples were collected at 15 locations and unwashed overstory and understory vegetation samples were collected at nine locations within and around the perimeter of Area G, the primary disposal facility for low-level radioactive solid waste at Los Alamos National Laboratory (LANL). These samples were analyzed for {sup 3}H, {sup 238}Pu, {sup 239,240}Pu, {sup 90}Sr, {sup 241}Am, {sup 137}Cs, {sup 234}U, {sup 235}U, and {sup 238}U. Soil samples collected at Area G contained detectable concentrations of 3H (27%), {sup 239,240}Pu (60%), {sup 238}Pu (40%), and {sup 241}Am (47%) above regional statistical reference levels (RSRLs). In contrast, the levels of {sup 137}Cs, {sup 90}Sr, and U in all of the soil samples at Area G were either nondetectable or within RSRLs. The highest levels of {sup 3}H in soils were detected in the southwestern portion of Area G near the {sup 3}H shafts, whereas the highest concentrations of the Pu isotopes were detected in the northern and northeastern portions. All concentrations of {sup 3}H and Pu in soils, however, were far below LANL screening action levels. As for vegetation, most radionuclides in/on plants were either nondetectable or within RSRLs. The exceptions were {sup 3}H in overstory and some understory vegetation, particularly in the southwestern portion of Area G, which correlated very well with the soils data in that area. Also, there was some foliar contamination from {sup 241}Am and Pu isotopes in/on a few plant samples--the highest concentrations occurring in the northern section of Area G