Effect of soil physicochemistry on uranium speciation and availability to plants

Soils have been contaminated by uranium from nuclear weapons production facilities, nuclear testing, nuclear reactor operations, improper waste storage practices and nuclear accidents. Also the mining and processing of materials containing naturally occurring radionuclides has resulted in widescale contamination of uranium among other contaminants. Adequate knowledge of the physicochemical conditions governing the radionuclide availability and speciation in the exposure medium is necessary to assess the transport of radionuclides and the impact of radioactive contamination on man and environment or to propose optimal remediation strategies. Although the geochemical behaviour of uranium has been studied extensively, the bioavailability of this metal has been insufficiently studied in the past. This paper will review some general aspects of uranium behaviour in soils, the approaches to unravel the processes ruling uranium behaviour and the major factors influencing uranium bioavailability.