考虑弥散尺度效应的两点吸附溶质运移模型及半解析解

Semi-analytical solution for two-site adsorption solute transport model with scale-dependent dispersion

该文考虑弥散尺度效应,建立了有限土柱中溶质运移的两点吸附降解模型。采用Laplace变换和数值反演方法求得了模型的半解析解,并应用试验资料对模型进行了验证。应用半解析解模拟分析了弥散尺度效应、平衡吸附点位所占比例及边界条件对溶质运移过程的影响。结果表明:弥散尺度效应越强土壤溶质运移锋面越远,分布范围越广,溶质浓度峰值越小。平衡吸附点位所占比例越小溶质运移锋面越远,但对溶质分布范围与浓度峰值影响不大。当经验常数a为1.0 m-1时,有限土柱和半无限土柱中溶质浓度几乎一致,出口附近处有限土柱中浓度模拟结果较高;当经验常数a小于1.0 m-1时,模拟结果恰好相反。

A scale-dependent dispersion solute transport model with the equilibrium/non-equilibrium two-site adsorption and microbiological degradation in a finite column was developed. The semi-analytical solutions for solute transport were obtained by using Laplace transformation technique and numerical inversion method and validated with laboratory experimental data. The effects of the empirical constant （a） represented the scale-dependent dispersion, the proportion （f） of equilibrium sites to total sites and the outlet boundary condition of the model on the solute transport were analyzed. The results indicated that the solute front increased with the increase of a or the decrease of f. The spreading of the solute increase and the peak concentrations decrease with the increase of a, had little change with f. The concentrations calculated by the solutions for semi-infinite domains were similar to the concentrations by the solutions for infinite domains at places close to the inlet boundaries, but always lower at places close to the outlet boundaries when the empirical constant α was 1.0 m^-1. It＇s just opposite when α was less than 1.0 m^-1.