Research Centre for Radwaste and Decommissioning & Williamson Research Centre for Molecular Environmental Science, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Williamson Building, Oxford Road, Manchester M13 9PL, United Kingdom; British Geological Survey, Environmental Science Centre, Nicker Hill, Keyworth, Nottingham NG12 5GG, United Kingdom.
Research Centre for Radwaste and Decommissioning & Williamson Research Centre for Molecular Environmental Science, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Williamson Building, Oxford Road, Manchester M13 9PL, United Kingdom.
Sci Total Environ. 2017 Jan 1;575:485-495. doi: 10.1016/j.scitotenv.2016.08.126. Epub 2016 Oct 14.
Geological disposal of intermediate level radioactive waste in the UK is planned to involve the use of cementitious materials, facilitating the formation of an alkali-disturbed zone within the host rock. The biogeochemical processes that will occur in this environment, and the extent to which they will impact on radionuclide migration, are currently poorly understood. This study investigates the impact of biogeochemical processes on the mobility of the radionuclide technetium, in column experiments designed to be representative of aspects of the alkali-disturbed zone. Results indicate that microbial processes were capable of inhibiting Tc migration through columns, and X-ray radiography demonstrated that extensive physical changes had occurred to the material within columns where microbiological activity had been stimulated. The utilisation of organic acids under highly alkaline conditions, generating H and CO, may represent a mechanism by which microbial processes may alter the hydraulic conductivity of a geological environment. Column sediments were dominated by obligately alkaliphilic H-oxidising bacteria, suggesting that the enrichment of these bacteria may have occurred as a result of H generation during organic acid metabolism. The results from these experiments show that microorganisms are able to carry out a number of processes under highly alkaline conditions that could potentially impact on the properties of the host rock surrounding a geological disposal facility for intermediate level radioactive waste.
英国计划将中水平放射性废物进行地质处置，涉及使用胶凝材料，以促进在宿主岩石内形成一个堿性扰动区。在这种环境中将会发生的生物地球化学过程，以及它们将在何种程度上影响放射性核素迁移，目前还知之甚少。本研究通过旨在代表堿性扰动区某些方面的柱实验，调查了生物地球化学过程对放射性核素锝迁移性的影响。结果表明，微生物过程能够抑制锝通过柱子的迁移，X 射线射线照相术表明，在微生物活性受到刺激的柱子内，材料发生了广泛的物理变化。在高度堿性条件下利用有机酸，产生 H 和 CO，可能代表微生物过程改变地质环境水力传导率的一种机制。柱沉积物主要由专性嗜堿性 H 氧化细菌组成，这表明这些细菌的富集可能是由于有机酸代谢过程中 H 的产生所致。这些实验的结果表明，微生物能够在高度堿性条件下进行多种可能影响中水平放射性废物地质处置设施周围宿主岩石特性的过程。
