复合衬层中变系数有机污染物迁移规律分析

土工膜和下伏压实黏土组成的复合衬层已被广泛用作填埋场的防渗屏障系统。有机污染物在复合衬层中迁移时，其主要运移机制是扩散作用。假设有机污染物在土工膜中稳态扩散，并假设在下伏衬层中扩散系数为迁移距离的线性函数，且考虑降解作用的影响，建立了有机污染物在复合衬层中的一维扩散模型，针对零浓度下边界条件，获得了模型解析解。基于该解析解，分析讨论了相关参数的敏感性。结果表明，相关参数对计算结果影响很大，降解半衰期对污染物运移同样存在较大影响。该解析模型仅适用于有机污染物在两层复合衬垫中的迁移问题，可为填埋场的初步设计提供参考

Analysis of organic contaminant transport through composite liners with variable coefficient

The composite liners (a geomembrane in intimate contact with a mineral liner) have been widely used as the barrier system for landfills. Diffusion is the predominant mechanism controlling organic contaminant transport within the composite liner. Steady-state diffusion of the organic compounds through the geomembrane was assumed in the models. The diffusion coefficient of the organic compounds through the soil liner was assumed a linear function of distance; and the effect of contaminant degradation was considered. An analytical solution for zero concentration on the bottom boundary was presented. Based on the proposed model, the sensitivity of the relevant parameters was discussed and analyzed. The results show that the relevant parameters have a great impact on the calculation results; and the contaminant half-life also has a great influence on pollutant migration. The proposed analytical solutions can only be used to calculate the organic contaminant through two-layered composite liners, and can be used for preliminary design of landfill composite liners.