腐殖酸作为环境中普遍存在的天然有机物，对于放射性核素在环境介质中的吸附种态、微观结构和作用机制具有重要影响,关系到核素在环境中的溶解性、生物毒性、吸附及扩散迁移过程。本课题将采用静态吸附法,研究不同实验条件(如pH值、离子浓度和腐殖酸浓度)下,腐殖酸对核素[Sr(II)和Eu(III)]在钙基膨润土上吸附性能的影响；并采用时间衰减荧光光谱法(TRLFS)和同步辐射X射线吸收光谱(XAFS/EXAFS)从原子分子水平上研究核素、腐殖酸与钙基膨润土相互作用的局域原子结构、吸附配位数、以及原子间距等微观结构信息；利用吸附模型对吸附实验数据进行理论解释和数值模拟,推测腐殖酸、核素和膨润土的作用机制。

Humic substances (HSs) are the major components of aquatic.organic colloids and ubiquitous in the natural environment. HSs have marked influence on the adsorption species, micro-structure, interaction mechanism of radionuclides on environmental medium, and thereby can control/affect the dissolubility, biological toxicity, sorption, and migration of radionuclides on the environment. In this proposal,the effects of HSs on Sr(II) and Eu(III) sorption behavior on Ca-bentonite as a function of pH, ion and HS concentrations are investigrated using batch experiments. Time resolved laser fluorescence spectroscopy and extended X-ray absorption fine structure techniques are used to obtained the interaction micro-structure information(such as local atom structure,coordination numbers,atomic distences,etc.) between nuclides, HSs,and Ca-bentonite in the atom/molecular level.Sorption experimental data are explained theoretically and simulated numerically by using sorption models, and the interaction mechanism between nuclides, HSs, and Ca-bentonite will be presumed.