Transformation of uranium species in soil during redox oscillations. (October 2018)

• Record Type: Journal Article
• Authors: Fu, Haiying; Zhang, Hui; Sui, Yang; Hu, Nan; Ding, Dexin; Ye, Yongjun; Li, Guangyue; Wang, Yongdong; Dai, Zhongran
• Is Part Of: Chemosphere. Volume 208(2018)
• Page Start: 846
• Page End: 853
• Publication Date: 2018-10
• Subjects: Redox cycling -- Uranium speciation -- Stable U(IV) -- Chemical extraction -- Paddy soil; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2018.06.059
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Redox oscillation is commonly found in near-surface environment, where soils are often polluted with many redox active contaminants, including uranium (U). In order to investigate the transformation of U species in near-surface soil under redox oscillations conditions, redox oscillations and reduction experiments were performed, biogeochemical parameters and native microbial community composition were monitored, main elements on the surface of solid-phase were analyzed by XPS, and labile U(IV) species and stable U(IV) species in solid-phase were provisionally defined using an anoxic 1 M sodium bicarbonate extraction. It was found that redox oscillations slightly increased the water-soluble U but significantly increased the stable U(IV) species ( P < 0.05) in soil. In reduction experiment, there was upper limit value for percentage of stable U(IV) species, and the labile U(IV) species could not transform to stable U(IV) species in a short period of time under reduction conditions. The redox transition of Fe enriched on the surface of soil and the conversion of microbial community composition played a major role in speciation transformation of U under redox oscillations conditions. In addition, sequential extraction revealed that the increase of stable U(IV) species content reflected the U speciation transition from acetate extract to more recalcitrant hydroxylamine extract. The finding provides a potential method for improving the stability of U when bio-reduction is used to remediate the U-contaminated soils. Graphical abstract: Image 1 Highlights: U species transformation in soil under redox oscillations conditions was examined. Water-soluble U slightly increased during redox oscillations. Content of stable U(IV) species significantly increased during redox oscillations. U species transformation depended on the transition of Fe and microbial community.