模拟降雨条件下南方某城市土壤中铀的迁移转化机制  

Migration and Transformation Mechanism of Uranium in Soil of a Southern City under Simulated Rainfall Conditions

作　　者：漆文斌 李冠超 杨波 孙功明 高柏[1] 方正 史天成 QI Wenbin;LI Guanchao;YANG Bo;SUN Gongming;GAO Bai;FANG Zheng;SHI Tiancheng(School Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;Radiation Environment Monitoring Center of Guangdong Province Nuclear Industry Geological Bureau,Guangzhou 510800,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,南昌330013 [2]广东省核工业地质局辐射环境监测中心,广州510800

出　　处：《有色金属（冶炼部分）》2024年第5期151-159,共9页Nonferrous Metals（Extractive Metallurgy)

基　　金：广东省地质勘察与城市地质专项项目([2021]638);企事业委托项目。

摘　　要：土壤中放射性核素铀是主要天然辐射贡献者之一,当土壤中铀含量异常时其化学毒性和放射性会对人类健康产生严重威胁。城市是人口高密度区,明确土壤中铀含量水平是城市放射性地质调查重要工作,为城市规划区及潜在规划区提供基础数据支撑。以某城市土壤作为研究对象,通过静态吸附试验和模拟降雨动态淋滤试验方式,对城市放射性地质调查土壤中铀迁移转化机制进行分析研究。结果表明:加Cu离子使土壤铀吸附率下降9.7%;初始铀浓度、吸附时间、粒径大小表明定量土壤中吸附铀酰离子的负点电荷有限;pH为4~6的土壤吸附铀能力最强。SEM分析表明,吸附铀酰后,土壤表面由凹凸不平变为平滑、孔隙度减少及变小。铀在不同pH下的淋洗动力学均符合双常数动力学程,土壤表面对铀的释放表现为一定的微曲线性特征。在pH为4~6自然酸性条件下,当溶液中铀含量大于土壤时,土壤会吸附溶液中铀酰离子;当溶液中铀含量小于土壤时,土壤中铀酰离子易释放到溶液中。该研究为城市放射性地质调查提供了理论依据。Radionuclide uranium in soil is one of the main natural radiation contributors.When the uranium content in soil is abnormal,its chemical toxicity and radioactivity can pose a serious threat to human health.Cities are densely populated areas,so it is important to determine the level of uranium content in soil of urban radioactive geological survey,which can provide basic data support for urban planning areas and potential planning areas.Taking a city soil as the research object,the mechanism of uranium migration and transformation in urban soil during radioactive geological survey was analyzed by static adsorption test and simulated rainfall dynamic elution test.The results show that adding Cu ions can reduces the soil′s adsorption rate by 9.7%.The initial uranium concentration,adsorption time,and particle size indicate that the negative point charge of uranyl ion adsorbed in soil is limited.The soil′s uranium adsorption capacity is strongest at pH values between 4 and 6.SEM analysis reveals that after uranium adsorption,the soil surface changes from uneven and porous to smooth,with reduced and smaller porosity.The leaching kinetics of uranium at different pH values is consistent with bi-constant kinetic model,and the release of uranium from soil surface shows a slight curvilinear characteristic.Under natural acidic conditions with a pH value of 4 to 6,when the content of uranium in the solution is greater than that in the soil,the soil will absorb the uranyl ions from the solution.When the content of uranium in the solution is less than that in the soil,the uranyl ions in the soil are easily released into the solution.This study provides a theoretical basis for urban radioactive geological surveys.

关 键 词：城市土壤 放射性 淋滤试验 铀 迁移 

分 类 号：X53[环境科学与工程—环境工程]