当前位置: X-MOL 学术Environ. Sci. Technol. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Oxidative Uranium Release from Anoxic Sediments under Diffusion-Limited Conditions
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2017-09-25 00:00:00 , DOI: 10.1021/acs.est.7b02241
Sharon E. Bone 1 , Melanie R. Cahill 2 , Morris E. Jones 2 , Scott Fendorf 2 , James Davis 3 , Kenneth H. Williams 4 , John R. Bargar 1
Affiliation  

Uranium (U) contamination occurs as a result of mining and ore processing; often in alluvial aquifers that contain organic-rich, reduced sediments that accumulate tetravalent U, U(IV). Uranium(IV) is sparingly soluble, but may be mobilized upon exposure to nitrate (NO3) and oxygen (O2), which become elevated in groundwater due to seasonal fluctuations in the water table. The extent to which oxidative U mobilization can occur depends upon the transport properties of the sediments, the rate of U(IV) oxidation, and the availability of inorganic reductants and organic electron donors that consume oxidants. We investigated the processes governing U release upon exposure of reduced sediments to artificial groundwater containing O2 or NO3 under diffusion-limited conditions. Little U was mobilized during the 85-day reaction, despite rapid diffusion of groundwater within the sediments and the presence of nonuraninite U(IV) species. The production of ferrous iron and sulfide in conjunction with rapid oxidant consumption suggested that the sediments harbored large concentrations of bioavailable organic carbon that fueled anaerobic microbial respiration and stabilized U(IV). Our results suggest that seasonal influxes of O2 and NO3 may cause only localized mobilization of U without leading to export of U from the reducing sediments when ample organic carbon is present.

中文翻译:

扩散受限条件下缺氧沉积物中氧化铀的释放

铀和铀的污染是采矿和矿石加工的结果。通常在冲积含水层中含有富含有机物的,减少的沉积物,这些沉积物会积聚四价U,U(IV)。铀(IV)是微溶的,但也可以在暴露动员硝酸盐(NO 3 - )和氧(O 2),这成为地下水由于在地下水位季节性波动升高。氧化性U动员发生的程度取决于沉积物的传输特性,U(IV)氧化的速率以及消耗氧化剂的无机还原剂和有机电子给体的可用性。我们研究了在减少的沉积物暴露于含有O 2或NO 3的人造地下水中控制U释放的过程在扩散受限的条件下。尽管地下水在沉积物中的快速扩散和非铀矿U(IV)物种的存在,在85天的反应过程中几乎没有动员铀。铁和硫化亚铁的生产以及快速的氧化剂消耗表明,沉积物中含有高浓度的可生物利用的有机碳,可为厌氧微生物的呼吸提供动力并稳定U(IV)。我们的结果表明的O-季节性涌入2和NO 3 -可能导致仅局部U形动员而不会导致至U的从还原沉积物出口时足够的有机碳的存在。
更新日期:2017-09-25
down
wechat
bug