Influence of soil microbiology on radionuclide transport and uptake into plants

Deep geological repositories (DGR) will be used for the final disposal of highly radioactive waste. For the safety assessment of the DGR, it is important to consider accident scenarios such as the ingress of water, which might lead to a release of radionuclides (RNs) from the repository into the groundwater. RNs in groundwater can migrate to the surface soil where they can interact with indigenous microorganisms and plants, entering the food chain and posing a health risk to humans. The reliable modelling of the RN uptake into plants requires more than just transfer factors. A more detailed process understanding of the RN uptake into plants, including the effects of soil microorganisms, is necessary. RNs may affect the soil microbial community altering the natural community composition and interactions. Root exudates from plants and microorganisms can alter the speciation of RNs, affecting their bioavailability and mobility. We study the impact of soil microorganisms on the RN transport and uptake into plants at the molecular level. The experiments discussed focus on studying the modulation of soil microbial diversity in the presence of RNs and selected root exudates. In addition, radiation-resistant soil microorganisms will be isolated to study their interaction with RNs and their effect on the degradation of root exudates. This will include characterization of the degradation products and their interactions with RNs. These findings will be used to elaborate radioecological models for the assessment of the RN transport and uptake into the food chain.