中文摘要：

为了获取关键核素在北山花岗岩中的有效扩散系数，依据^125I^-在甘肃北山深部花岗岩中的一维扩散曲线，用参数拟合方法得到了^125I^-在北山花岗岩中的有效扩散系数，并依据扩散方程讨论了衰变和吸附对扩散曲线的影响。研究结果表明，衰变常量和吸附速率常数对一维扩散曲线的影响各不相同，衰变常量的大小影响扩散曲线的形状，吸附速率常数的大小则影响扩散曲线的走势，不同核素的扩散曲线可有很大的差别。

英文摘要：

Geological disposal of high-level radioactive wastes is one of the important issues in many countries, in terms of science ＆ technology, economy, politics, environmental protection and sustainable development of nuclear energy. China plans to construct a geological repository in the middle of the 21st century in order to safely dispose of the wastes from weapon production and fast development of nuclear energy. Currently, the host rock of the potential geological repository has not been determined yet, while the research activities at Beishan, Gansu province indicate that granite is one of the preferable host rocks for potential China＇s geological repository, and basic research in the Beishan granite is necessary. The diffusion curves of key radionuclides in Beishan granite are the most important basis to obtain the effective diffusion coefficients. Based on the one-dimensional through-diffusion experiment for ^125I^- in deep granite from Beishan, Gansu province, the effective diffusion coefficient of ^125I^- in Beishan granite was obtained with least square fitting method, and the influence of radioactive decay and sorption on the shapes of diffusion curve was discussed. The analysis indicates that the influence of radioactive decay and sorption on the shapes of diffusion curve is different. The half life, T1/2 mainly influences the shape of the diffusion curve, while the sorption constant k mainly influences the development of the curve. Therefore, with limited experimental time, the diffusion curves of different radionuclides could be quite different.