Relationships among plutonium contents of soil, vegetation and animals collected on and adjacent to an integrated nuclear complex in the humid southeastern United States of America

Twenty-three representative sampling locations on and adjacent to the Savannah River Plant (SRP) site were selected to obtain information on plutonium movement in the food chain under southeastern US environmental conditions. Soil, a resuspendible fraction of the soil, honeysuckle (Lonicera japonica), and camphor weed (Heterotheca subaxillaris) were collected at each location. Grasshoppers and cotton rats (Sigmodon hispidus) were collected at some locations. The plutonium concentrations in soil at the selected locations ranged from 1.5 to 171fCi/g and alpha percentages of 238Pu ranged from 2 to 66. The concentration of plutonium in the vegetation and on the leaves ranged from 0.17 to 76.1fCi/g and the alpha percentages of 238Pu from 3 to 61. The concentration of plutonium in cotton rats and grasshoppers ranged from 0.07 to 3.58fCi/g and the alpha percentages of 238Pu ranged from 22 to 80. The average ratio of plutonium concentration of vegetation to that of the surrounding soil was 10-1; the corresponding ratio for cotton rats and soil was 10-2. These ratios appear to be independent of the plutonium concentration in the soil. Deposition on the surfaces of leaves and stems was the principal mechanism of plutonium contamination of vegetation. Comparisons among the plutonium values of the vegetation, soil and resuspendible fraction suggest the use of a proposed resuspendible measurement technique as a monitoring method to indicate subtle changes in the plutonium concentration of the soil surface that are not detectable by routine soil sampling. Although the 238Pu data in the various ecosystem components were not conclusive, they do support evidence presented in other studies that there is an apparent increase in the biological availability of 238Pu relative to that of sup(239,240)Pu in the environment. The plutonium concentrations of all ecosystem components decreased as the distance from the reprocessing plants increased. (author)