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

了解镭(Ra)和铀(U)等放射性核素的行为和环境影响，对于这些放射性核素浓度升高的场所的管理和风险建模至关重要。土壤微生物对生态系统功能至关重要，已被证明影响放射性核素的行为，包括将放射性核素动员到植被中，并可能进入食物链。例如，已有证据表明，细菌将U(VI)还原为U(IV)，而在与丛枝菌根真菌共生的植物中，已观察到U从根到冠的转移减少。然而，对于原核和真核微生物群落在调节放射性核素生物利用度方面所发挥的生化功能，以及这些微生物活动与非生物化学反应的重要性，我们的认识仍然存在许多空白。此外，目前还不清楚土壤中放射性核素浓度的升高是否会影响土壤微生物群落的原核生物和真菌群落，以及这些群落可能如何与植物根相关地发生变化。此外，在放射性核素丰富的环境中，原核生物和真核生物群落之间是否存在特定的相互作用也不清楚。通过结合环境放射化学和功能基因组学方法，该项目将对放射性核素污染土壤的土壤-植物微生物群进行详细的描述，以便更准确地了解放射性核素的行为及其如何决定放射性核素的生物有效性。这些方法将有助于量化表层土壤放射性核素污染的更广泛的生态后果，特别是放射性核素生物有效性的变化如何与向地上食物链的转移相关。

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.