非饱和土壤中吸附性溶质运移的基本方程和参数结构

The Basic Equation and Parameter Structure of Adsorbing Solute Transport in Heterogeneous unsaturated soils

本文应用随机场的谱分析方法,研究了吸附性溶质在非饱和、非均匀土体中运动时平均浓度所遵循的基本方程.当非饱和水分运动以重力为主要作用力时,设经对数变换后的土壤饱和渗透系数、吸附系数和α参数均为正态平稳随机场,求得了宏观弥散度的解析表达式.研究结果表明,宏观弥散度由三部分组成,分别来源于非饱和渗透系数的自相关函数、非饱和渗透系数与吸附参数的互相关函数,以及吸附参数的自相关函数.并得到在不同溶质运移阶段,宏观弥散度与各影响因素之间的关系 .

The mean concentration equation of adsorbing solute transport in heterogeneous unsaturated soil was studied based on the spectrum analysis of the spacial random field. A closed expression of the macrodisper-sivity was obtained when unsaturated soil water movement was gravity dominated and the log-transformed conductivity, adsorbing coefficient,and the a parameter were considered as stationary normal spatial random fields. It was shown that macrodispersivtty included three parts , they are the contributions from the covariance of unsaturated conductivity, the cross-covariance of unsaturated conductivity and adsorption coefficient,and the Co-variance of the adsorption coefficient. The macrodispersivity was a linear function of solute travel distance for a short solute transport distance, and a constant for a large solute transport distance.