40K, 137Cs and 226Ra Soil and Plant Content in Seminatural Grasslands of Central Argentina

JURI AYUB J.; VELASCO H.; RIZZOTTO M.; QUINTANA, E; AGUIAR, J.

AIP CONFERENCE PROCEEDINGS

American Institute of Physics

Lugar: New York; Año: 2008 vol. 1034 p. 273 - 276

0094-243X

Activity concentrations of gamma emitting radionuclides have been determined in soil and plant samples, collected in permanent grassland in central Argentina. Two near areas (A1and A2) under field conditions with soil undisturbed at least in the last four decades were selected. The soil is a sandy type with low clay content. The dominant vegetation in these areas consists of herbaceous gramineous, which is used for the feeding of cattle. The 40K inventories are similar in both areas and range from 143 kBq·m-2 to 197 kBq·m-2. For 137Cs the inventories are 0.56±0.06 kBq·m-2 and 0.52±0.2 kBq·m-2, for A1 and A2, respectively. Nevertheless, 137Cs activity concentration has a maximum for layers 5-10 cm depth in A1 and 10-15 cm depth in A2. For deeper layers (>10 cm) both areas show similar activity concentrations. The diffusion coefficient (Ds) and convection velocity (vs) are estimated with a convection-diffusion model.