中文摘要：

环境放射化学种态分析软件利用实验测定的感兴趣元素的热力学数据,根据所研究体系的组分及相应的分析浓度,从数据库中搜索由这些组分经化学反应可能生成的物种及相应的平衡常数,计算各种元素可能存在的化学种态和平衡浓度,从而得到相应元素在所研究体系中的化学种态分布。本工作利用北京大学编写的环境放射化学种态分析软件CHEMSPEC计算了在氧化性条件下,镎（Ⅵ）在北山五一井水中的溶解度,并分析了pH值、阴离子浓度等因素对溶解度的影响。计算结果表明,地下水的酸度、碳酸根离子浓度对溶解度有显著影响,而硫酸根离子浓度、氯离子浓度的影响可忽略。镎（Ⅵ）在北山五一井水中的溶解度变化范围是1.1×10-5~4.4×10-3mol/L。最大值4.4×10-3mol/L可考虑用于预测镎在北山地下水中的扩散和迁移行为。

英文摘要：

An Environmental Radiochemical Speciation Analysis Code（ERSAC） using the thermodynamic data of elements in water solution,based on the concentration of a radionuclide in a waster system,seeking the possible species of the radionuclide produced by various chemical reactions in the water system and the related equilibrium coefficients of different species,calculates the possible species of the radionuclide and their equilibrium concentrations and provides a speciation profile of the radionuclide in the water system.This paper presents the calculation result of the solubility of neptunium（Ⅵ） in Beishan well 51# groundwater and the influences of pH and groundwater compositions on the solubility using an environmental radiochemical speciation analysis code CHEMSPEC which is developed by the Nuclear Environmental Chemistry Group of Peking University.Our calculation indicates that pH and total carbonate concentration do affect the solubility of neptunium while the sulfate concentration and chloride concentration don＇t.The solubility range of neptunium（Ⅵ） in Beishan well 51# groundwater is from 1.1×10-5 to 4.4×10-3 mol/L.