Soil microbiome function controlling radionuclide bioavailability and soil-to-plant transfer

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Understanding the behaviour and environmental impacts of radionuclides such as radium (Ra) and uranium (U) is of critical importance for the management and risk modelling of sites with elevated concentrations of these radionuclides. Soil microorganisms, which are vital to ecosystem functioning, have been shown to affect radionuclide behaviour including the mobilisation of radionuclides into vegetation, and potentially into food chains. For example, bacterial reduction of U(VI) to U(IV) has been evidenced, whilst decreased root-to-shoot transfer of U has been observed in plants symbiotically associated with arbuscular mycorrhizal fungi. However, there are still many gaps in our knowledge of the biochemical functions that prokaryotic and eukaryotic microbial communities play with regard to modulating radionuclide bioavailablity, and the importance of these microbial activities alongside abiotic chemical reactions. Moreover, it is not clear whether elevated soil concentrations of radionuclides are affecting the prokaryotic and fungal communities of soil microbiomes, and how these communities may alter in association with plant roots. Furthermore, it is also unclear whether specific interactions exist between prokaryotic and eukaryotic communities in radionuclide enriched environments. By combining environmental radiochemistry and functional genomics approaches, this project will generate a detailed characterisation of the soil-plant microbiome of radionuclide contaminated soils in order to gain a more accurate understanding of radionuclide behaviour and how this determines radionuclide bioavailability. These approaches will aid quantification of the broader ecological consequences of surface soil radionuclide contamination, and in particular how changes in radionuclide bioavailability correlate with transfer into above-ground food chains.