Ashworth D J, Shaw G
Department of Environmental Science and Technology, Imperial College London, Silwood Park, Ascot, Berkshire SL5 7PY, UK.
J Environ Radioact. 2006;89(1):61-80. doi: 10.1016/j.jenvrad.2006.03.006. Epub 2006 May 22.
A 6-month soil column experiment was conducted to compare the upward migration and plant uptake of radiochlorine and radioiodine from shallow, near-surface contaminated water tables. Both fixed and fluctuating water tables were studied. After 6 months, (36)Cl activity concentrations were relatively uniform throughout the soil profile apart from an accumulation at the soil surface, which was especially marked under a fluctuating water table scenario. In contrast, (125)I (a surrogate for (129)I) tended to accumulate at the boundary between the anoxic conditions at the base of the column and the oxic conditions above, due to its redox-dependent sorption behaviour. The uptake of (36)Cl by perennial ryegrass was much greater than that of (125)I due to its greater migration into the rooting zone and its ready availability in soil solution. In the context of radioactive waste disposal, where these radionuclides may potentially be released into groundwater, (36)Cl would be expected to present a greater potential for contamination of the biosphere than (129)I.
进行了一项为期6个月的土柱实验，以比较放射性氯和放射性碘从浅层近地表受污染地下水位向上迁移及被植物吸收的情况。研究了固定水位和波动水位两种情况。6个月后，除了在土壤表面有累积外，整个土壤剖面中（36）Cl的活度浓度相对均匀，在波动水位情况下这种累积尤为明显。相比之下，由于（125）I（作为（129）I的替代物）的氧化还原依赖性吸附行为，它倾向于在柱体底部的缺氧条件与上方的有氧条件之间的边界处累积。多年生黑麦草对（36）Cl的吸收远大于对（125）I的吸收，这是因为（36）Cl向根区的迁移能力更强且在土壤溶液中易于获取。在放射性废物处置的背景下，这些放射性核素可能会释放到地下水中，预计（36）Cl对生物圈的污染潜力比（129）I更大。
