长寿命放射性核素在矿物表面的微观吸附形态，对评估放射性核素在环境中的扩散和迁移行为具有重要的意义。本项目拟采用静态法研究放射性Cs(I)、Sr(II)、Am(III)在高岭石/水界面的吸附特性；利用X射线吸收光谱（XAFS）研究放射性元素在高岭石/水界面的结合形态、局域原子结构；结合密度泛函理论（DFT）计算，在分子水平上获得Cs(I)、Sr(II)、Am(III)在高岭石(001),(010)和(110)面上的微观吸附构型。基于光谱与理论计算结果，运用络合模型对实验数据进行数值模拟计算，阐明放射性核素在矿物中的化学形态及其分布，揭示Cs(I)、Sr(II)和Am(III)与矿物的表界面作用机理，研究结果对分析和评价放射性核素在环境中的化学行为具有重要的科学意义。

The study of the sorption speciation of long-lived radionuclide on mineral surface is important for assessment the mobility of radionuclide in the environment. In this proposal, we will study the sorption property of radioactive Cs(I), Sr(II), Am(III) on kaolinite/water interface over a representative range of relevant conditions by batch technique. X-ray absorption fine structure (XAFS) spectroscopy technique will be applied to study the structural information for the sorption complexes at kaolinite/water interface. Density functional theory (DFT) calculations based on structural constraints for the EXAFS analysis will be performed to study the structure of Cs(I), Sr(II), Am(III) in bulk solution and on the (001), (010) and (110) kaolinite surfaces. Combination of spectroscopy and DFT methods can elucidate the structures of surface complexes at molecular level and thereby to indentify the sorption speciation. Surface complexation models will be completed to simulate the experimental data of Cs(I), Sr(II), Am(III) with kaolinite according to the above structural investigation. The project aims to clarify the the distribution and the chemical speciation of radionuclides in the environment, reveal the mechanism of the interactions between Cs(I), Sr(II), Am(III) and the mineral surface/interface.The results are of great important to evaluate the physicochemical behavior of radionuclides in the natural environment.