中文摘要：

对宏观弥散度和阻滞系数的取值进行了理论分析,运用PHREEQCⅡ软件,以我国南方某铀水冶尾矿库为例,探讨了宏观弥散度和阻滞系数对地下水中核素迁移模拟的影响.研究表明：宏观弥散度和阻滞系数对大时空的核素迁移模拟影响显著.在其他条件相同的情况下,弥散度增大,受污染地下水中总U浓度开始降低的距离将缩短,但反而迁移得更远;随着阻滞系数的增大,同距离处234U的浓度将显著下降,但其迁移距离变短.要得到可靠的宏观弥散度和阻滞系数,可利用宏观参数与介质统计特性的关系求解介质宏观弥散参数,阻滞系数可由现场实验或实验室土柱实验直接测得.

英文摘要：

Based on the theoretical analysis of the values of the macrodispersivity and retardation coefficient, the radionuclide migration in groundwater at an uranium mill-tailing site in southern China was simulated with hydrogeochemical program PHREEQC-Ⅱ . In the simulation, the effect of macrodispersivity and retardation coefficient was especially taken into account. The results showed that the effect of the macrodispersivity and retar- dation coefficient in radionuclide migration was remarkable. Under the same conditions, the distance of total U concentration reduction was shorter when the macrodispersivity coefficient increased, and its transport distance was longer. As the retardation coefficient increased, the 234U concentration decreased visibly, but its transport distance was shorter. The relationship between the macroparameters and the statistical characteristic of the medium and the acquisitive statistical parameters of the medium could be used to analyze and solve the macroscopical dispersivity parameter. Moreover, the retardation coefficient Rd should be set by in-site experiments or direct measurement through soil column experiment in the laboratory.