Dispersal of radioactivity by wildlife from contaminated sites in a forested landscape

Abstract

Oak Ridge National Laboratory (ORNL) is located within the Valley and Ridge Physiographic Province of eastern Tennessee (USA). Wildlife populations have access to some radioactively contaminated sites at ORNL. Contaminated animals or animal nests within the Laboratory's boundaries have been found to contain 90Sr or 137Cs on the order of 10 −2–10 4 Bqg −1 and trace amounts of other radionuclides (including transuranic elements). Animals that are capable of flight and animals with behavior patterns or developmental life stages involving contact with sediments in radioactive ponds, like benthic invertebrates, present the greatest potential for dispersal of radioactivity. The emigration of frogs and turtles from waste ponds also presents a potential for dispersal of radioactivity but over distances < 5 km. Mud-dauber wasps ( Hymenoptera) and swallows ( Hirundinidae) may transport radioactive mud for nest building, but also over relatively short distances (0.2–1 km). Movement by small mammals is limited by several factors, including physical barriers and smaller home ranges. Larger animals, like white-tailed deer ( Odocoileus virginianus), are potential vectors of radioactivity due to their greater body size, longer life expectancy, and larger home range. Larger animals contain greater amounts of total radioactivity than smaller animals, but tissue concentrations of 137Cs generally decline with body size.