Understanding radionuclide behaviour at the plant-soil interface to direct bioremediation strategies for contaminated land

植物能有效地从环境中积累生长所需的无机元素。然而，矿物质营养积累机制往往是非选择性的，当这些污染物以较高的浓度存在时，会导致吸收潜在的有毒元素，包括放射性核素。一些植物能够耐受放射性核素污染的环境，要么通过介导化学变化来抑制积累，从而降低放射性核素的生物利用度，同时减少土壤溶液的动员（植物稳定），要么通过提高生物利用度来允许放射性核素的大量积累（植物提取）。然而，对地表下放射性核素对植物和相关微生物存在的反应的许多方面的行为知之甚少。虽然很明显，植物能够积累广泛的放射性核素，但缺乏对植物对选定放射性核素影响的详细生物地球化学分析。因此，该项目的目的是了解选定的放射性核素（包括Sr-90、Cs-137、U和Pu的同位素）在植物和相关微生物存在下的地下形态，以及放射性核素生物积累和生物稳定的机制，以便为污染管理途径和生物修复潜力提供信息。通过结合环境放射化学和土壤-植物生态学方法，该项目将与Sellafield有限公司合作，生成放射性核素污染土壤的土壤-植物微生物组的详细特征，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可利用性。这些方法将有助于量化地表以下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可利用性的变化如何与动员和转移到植被中相关。

Plants efficiently accumulate inorganic elements from their environment, which they need for growth. However, mineral nutrient accumulation mechanisms are often non-selective, causing uptake of potentially toxic elements, including radionuclides, when these contaminants are present at elevated concentrations. Some plants are able to tolerate radionuclide contaminated environments, either by inhibiting accumulation by mediating chemical changes that reduce radionuclide bioavailability and also reduce mobilisation through the soil solution (phytostabilisation), or by enhancing bioavailability to allow bulk accumulation of radionuclides (phytoextraction). However, many aspects of sub-surface radionuclide behaviour in response to plant and associated microbial presence are poorly understood. While it is clear that plants are able to accumulate a wide range of radionuclides, a detailed biogeochemical analysis of the influence of plants to selected radionuclides is lacking. The aim of this project is therefore to understand sub-surface speciation of selected radionuclides (including Sr-90, Cs-137, isotopes of U and Pu) in response to the presence of plants and associated microorganisms, and the mechanisms of radionuclide bio-accumulation and bio-stabilisation, in order to inform contamination management pathways and bioremediation potential. By combining environmental radiochemistry and soil-plant ecology approaches, this project, in collaboration with Sellafield Ltd, 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 sub-surface soil radionuclide contamination, and in particular how changes in radionuclide bioavailability correlate with mobilisation and transfer into vegetation.