中文摘要：

由于地下水系统中，孔隙介质比表面积大，研究核素运移时应该考虑发生在固一液表面上的化学反应．表面络合理论能很好地描述固-液界面上发生的化学反应，解释固-液界面吸附作用．本文研究了存在表面络合吸附作用情况下地下水中核素U（Ⅵ）的运移情况，并以我国南方某尾矿库为例成功实现了对浅层地下水中核素U（Ⅵ）运移的数值模拟．研究表明，在模拟固-液比相对较大的地下水系统中溶质运移规律时，考虑表面络合作用是必要的；在该研究区内表面络合吸附作用与pH值呈非线性关系，当pH为6～7时，孔隙介质表面对U（Ⅵ）吸附量较大，且pH为6时地下水中U（Ⅵ）浓度达到最低．

英文摘要：

The hydrogeochemical reaction taking place on surface of porous media, which has huge specific surface area, should been taken into account in the simulation of radionuclide migration in groundwater. Surface complexation is one of successful theories to interpret mechanism of adsorption occurring on surface of solid phase and liquid phase. In this paper, the uranium（ Ⅵ ） migration in groundwater of one uranium mill - tailing site in southern China had been simulated using solute reaction - transport numerical model which coupled surface complexation model. The results indicate that surface complexation model is more suitable for simulation in porous media of groundwater system which has great solid -liquid ration. And the results also display that the surface complexation is a nonlinear function of pH, reaching a maximum under neutral pH.