The European programme BORIS : Involvement of biological components in the transfer of radioactive nuclides to plants

The ability to predict the consequences of an accidental release of radioactive nuclides relies mainly on the level of understanding of the mechanisms involved in radioactive nuclides interactions with different components of agricultural and natural ecosystems and their formalisation into predictive models. Numerous studies and databases about contaminated agricultural and natural areas have been obtained but their use to enhance our prediction ability has been largely limited by their unresolved variability. Such variability seems to stem from an incomplete knowledge about radioactive nuclide interactions with the soil matrix, soil moisture, biological elements in the soil and additional pollutants, which may be found in such soils. In this project, we investigate mainly the role of the biological elements (plants, mycorrhiza, microbes) in: radioactive nuclide sorption/desorption in soils and radioactive nuclide uptake/re lease by plants. Because of the importance of the chemical nature of the involved radioactive nuclides, we will follow the bioavailability of three radioactive nuclides: caesium, strontium, and technetium. The role of additional non-radioactive pollutants will also be scrutinised as they may interfere with the mechanisms governing radioactive nuclide transfer to plants. Knowledge acquired from the experiments will be incorporated into two mechanistic models BIOPHAST and BIORUR specifically modelling radioactive nuclide sorption/desorption from soil matrices and radioactive nuclide uptake by/release from plants. These mechanistic models will be incorporated into assessment models to enhance their prediction ability. One expects to extract from these experiments scientific bases for the development of bioremediauon methods of radioactive nuclidecontaminated soils.