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). CO₃²⁻ remarkably inhibited the U(VI) adsorption, while the adsorption of U(VI) was promoted by PO₄³⁻ and SO₄²⁻. 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所周围环境介质中的行为对于地质处置库的安全评估很重要。但是，U（VI）在自然介质中的环境行为的估计是不够的。这项工作旨在确定U（VI）在西南地区候选极低放射性废物（VLLW）处置场周围的天然土壤上的吸附。结果表明，伪二级动力学和Freundlich模型可以很好地支持U（VI）在土壤上的吸附过程。U（VI）的吸附取决于pH，但与温度无关。高离子强度（NaCl）在低pH（2.0–5.5）下强烈影响吸附过程。CO ₃ ^2-显着抑制了U（VI）的吸附，而PO促进了U（VI）的吸附₄ ³⁻和SO ₄ ²⁻。天然存在的土壤有机物（SOM）对U（VI）具有很高的亲和力，而另外的腐殖酸（HA）的存在强烈抑制了U（VI）的吸附。亚铁的出现可能导致低pH值（pH <4）下U（VI）的还原，从而促进U（VI）的固定化。这些发现将为超低碳废物处置的安全评估以及污染土壤的修复提供一些指导。