Deposition and resuspension of antimony-125 and cesium-137 in the soil-plant system in the environment of a nuclear fuel reprocessing plant

Field studies were conducted during the summer of 1987 to characterize the levels of 125Sb and 137Cs releases and the distribution of the two radionuclides in vegetation and soil at distances of 0.45 and 0.75 km from a nuclear fuel reprocessing plant stack. Samples were collected of sagebrush, wheatgrass, and rabbitbrush and their leaves, stems, roots, and litter were separated. Vegetation samples were dried at 70 degree C for 48 hours, ground, and concentrations of 125Sb and 137Cs were determined by gamma spectrometry. Soil samples were collected from the surface to a depth of 18 cm (at 3 cm increments), dried at 45 degree C, and the concentrations of 125Sb and 137Cs measured in the same manner as for vegetation samples. Results showed that the activity of 125Sb was higher in the leaves than in the stem and roots. Total activity of 125Sb (1041.77 Bq m-2) was distributed as 33.4% in vegetation and 66.6% in soil. Deposition of airborne 125Sb measured through absorption by transplanted vegetation was about one Bq m-2 day-1. The resuspension rate of 125Sb from vegetation determined by an air-flux chamber positioned over sagebrush plants was less than 61 x 10-11 sec-1. Cesium-137 concentrations were lower in the leaves than in the stems and roots indicating slow movement through plant tissues