School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China; Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, China.
J Environ Radioact. 2021 Jul;233:106619. doi: 10.1016/j.jenvrad.2021.106619. Epub 2021 Apr 21.
The behaviors of U(VI) in environmental media around radioactive waste disposal site are important for safety assessment of geological repositories. However, the estimation of environmental behaviors of U(VI) in natural media was insufficient. This work aimed to determine the adsorption of U(VI) on natural soil surrounding a candidate very low-level radioactive waste (VLLW) disposal site in southwest China. Results showed that the adsorption process of U(VI) on soils could be well supported by pseudo-second-order kinetic and Freundlich model. The adsorption of U(VI) was pH-dependent but temperature-independent. High ionic strength (NaCl) strongly affected the adsorption process at low pH (2.0-5.5). CO remarkably inhibited the U(VI) adsorption, while the adsorption of U(VI) was promoted by PO and SO. Naturally occurred soil organic matters (SOMs) showed high affinity for U(VI), while the presence of additional humic acid (HA) strongly inhibited U(VI) adsorption. The occurrence of ferrous iron could result in the reduction of U(VI) at low pH values (pH < 4), leading to the promotion of immobilization of U(VI). These findings would provide some guidance for the safety assessments of the VLLW disposal as well as the remediation of contaminated soil.
U(VI) 在放射性废物处置场周围环境介质中的行为对于地质处置库的安全评估非常重要。然而，对天然介质中 U(VI) 的环境行为的估计还不够。本工作旨在确定中国西南某低放废物处置场附近天然土壤对 U(VI) 的吸附作用。结果表明，U(VI)在土壤上的吸附过程可以很好地用准二级动力学和 Freundlich 模型来支持。U(VI)的吸附过程受 pH 值影响，但不受温度影响。高离子强度（NaCl）在低 pH 值（2.0-5.5）下强烈影响吸附过程。CO 显著抑制 U(VI)的吸附，而 PO 和 SO 则促进 U(VI)的吸附。天然存在的土壤有机质（SOM）对 U(VI)具有高亲和力，而额外添加的腐殖酸（HA）则强烈抑制 U(VI)的吸附。亚铁的存在可能导致低 pH 值（pH < 4）下 U(VI)的还原，从而促进 U(VI)的固定化。这些发现将为低放废物处置的安全评估以及受污染土壤的修复提供一些指导。
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