摘要
长期暴露在高铀(U)地下水中会对人体健康造成潜在威胁。尽管高U地下水形成的水文地球化学过程已得到广泛研究,目前对含水层沉积物的水文地球化学特征如何控制地下水U迁移和富集仍缺乏深入理解。本文以河套盆地为研究区,采集了山前区和平原区含水层沉积物样品并对其中U的不同赋存形态和含量进行分析。结果表明,山前区沉积物中U含量远高于平原,山前区U主要以铁锰氧化物结合态(F3-U)为主,平原区主要为基质态(F5-U)。沉积物U含量随其粒径减小呈现增大的趋势,其中黏土沉积物中U含量最高。沉积物中各赋存态U含量与Fe、Mn含量均呈正相关关系,表明Fe、Mn对沉积物中U富集有着重要控制作用。地下水中的U主要受到沉积物中可交换态(F1-U)、碳酸盐结合态(F2-U)和铁锰氧化物结合态(F3-U)这三种赋存形态的控制。在山前区,解吸附和氧化溶解作用促进地下水中U的富集;在平原区,含水层中铁锰氧化物还原溶解释放的U在还原环境中被还原为U(IV)再次固定在沉积物中,形成高Fe 2+低U的地下水。本研究将含水层沉积物地球化学特征与地下水U的迁移富集建立联系,揭示了含水层沉积物铀赋存特征对地下水U富集的影响。
Extended exposure to uranium-contaminated groundwater can pose health risks.While the hydrogeochemical processes leading to elevated uranium(U)concentrations in groundwater are well-documented,the mechanisms controlling U enrichment in groundwater remain poorly understood.This study investigated in the Hetao Basin,U forms and contents in aquifer sediments obtained from both the piedmont and plain zones.The results showed that the U contents in piedmont aquifer sediments were significantly higher than those in the plain,and U mainly existed in the form of Fe-Mn oxide binding(F3-U)and matrix state(F5-U)in piedmont and plain aquifer sediments,respectively.The U contents in the aquifer sediments increased as sediment grain size decreased.Both Fe and Mn in the aquifer sediments played a crucial role in U enrichment since positive correlations were observed between U and these elements.In the piedmont zone,U enrichment in groundwater primarily occurs through desorption and oxidative dissolution of U-bearing minerals.In contrast,in the plain zone,U released from Fe and Mn oxides reductive dissolution is reduced to U(IV)and immobilized within the aquifer sediments,which leads to high Fe(II)and low U groundwater.This study establishes critical links between the aquifer sediment geochemistry and the U enrichment in groundwater,providing valuable insights into the processes controlling U mobilization.
作者
章一川
常光明
鲁重生
邢世平
郭华明
ZHANG Yichuan;CHANG Guangming;LU Chongsheng;XING Shiping;GUO Huaming(MOE Key Laboratory of Groundwater Circulation and Environmental Evolution,China University of Geosciences(Beijing),Beijing 100083,China;School of Water Resources and Environment,China University of Geosciences(Beijing),Beijing 100083,China)
出处
《地学前缘》
北大核心
2026年第2期535-547,共13页
Earth Science Frontiers
基金
国家自然科学基金重点项目“碳氮硫循环驱动下地下水典型氧化还原敏感组分转化过程和富集机理(42130509)”。
