中文摘要：

在综合分析核工业南方某矿长期观测数据的基础上，对矿区实际情况进行概化，建立了溶质的反应-输运耦合模型，利用溶质反应．输运模拟软件PHREEQC-Ⅱ以U（Ⅵ）为目标对尾矿库区地下水中核素迁移进行了数值模拟。研究了在弥散度、扩散系数、pH值、混合比以及阻滞系数等参数不同取值时U（Ⅵ）在地下水中的迁移规律，并就参数对模拟的影响进行了分析。模拟结果与现场实际情况基本吻合，为矿区环境评价及退役环境治理提供科学依据，也可为类似模拟研究提供参考。

英文摘要：

Based on the analysis of the historical data of the uranium mill-tailing site in southern China, the actual conditions are generalized, and a coupled reaction-transport numerical model is set up to simulate the representative radionuclide-uranium （ Ⅵ） adopting the PHREEQC- Ⅱ code. This work is carded out with the various parameters such as dispersion coefficient, the diffuse coefficient, pH, the mix-ratio, and the retardation coefficient. The sensitivities for the parameters are also analyzed in this paper. The results of this simulation accord with the actual information observed on site. So the simulation, which can be a reference for analogical research, can provide theoretical base for environment assessment and treatment after the decommission of uranium mill-tailing sites.