Mobility and bioavailability of radionuclides in soils

Abstract

It is crucial to understand the behaviour of radionuclides in the environment, their potential mobility and bioavailability related to their long-term persistence and their radiological hazard and potential impact on human health. Such key information is used to support decision-making. The environmental behaviour of radionuclides depends on ecosystem characteristics. A given soil's capacity to immobilise radionuclides has proved to be the main factor responsible for their resulting activity concentrations in plants. The mobility and bioavailability of radionuclides in soils is complex, depending on clay-sized soil fraction, clay mineralogy, organic matter, cation exchange capacity, pH and quantities of competing cations. Moreover, various plant species have different behaviours regarding radionuclide absorption from soils. This chapter is intended to provide comprehensive up-to-date background information concerning the mobility and bioavailability of selected key artificial and natural radionuclides (e.g. 137Cs, 90Sr, 239,240Pu, 241Am, 238U, 226Ra, 232Th) in different soil types under various environmental conditions.