VOCs在土壤孔隙中扩散模型的适用性

为研究污染物在土壤多孔介质中迁移性质，建立了一种可快速测定非保守性污染物在土壤孔隙中有效扩散系数的新方法，采用了土柱扩散实验研究挥发性有机物(VOCs)在土壤中的有效扩散系数．根据多孔介质为干燥和含水体系将挥发性有机物分为保守性和非保守性两种类型的扩散组分，建立了不同的迁移模型方程进行过程描述，并提出了迁移方程的一维解析解，对三氯乙烯和苯在砂土体系的研究表明，利用土柱扩散实验测定挥发性有机物的有效扩散系数的方法可靠，同时表明采用经验扩散模型描述非保守性组分的扩散时应考虑适用范围，孔隙中气相体积含率低时，Millington模型和Collin模型适用性较好，且Collin模型更优一些，当气相体积含率很高时，则应考虑应用Marshall模型和Penmen模型。

Applicability of Diffusion Models for VOCs in Porous Soils

This paper presents a fast measuring method to obtain effective diffusion coefficients of volatile organic compounds (VOCs) in porous medium, which are quite uncommon in literatures. A soil column method for that is designed to investigate effective diffusion coefficients of VOCs in soils. Respective transport equations are also put forward for VOCs with conservative or non-conservative property in pore-diffusion on the basis of the porous medium being non-hydrous or hydrous. The study on diffusion of trichlorethylene (TCE) and benzene in column of sand-soil shows that the experimental method above is reliable in determining effective diffusion coefficients. According to the analysis on laboratory data, a range of application should be specified if using any empirical model to obtain the effective diffusion coefficients of VOCs with conservative property. Millington model and Collin model are applicable to the case of low air-saturation, and Collin model appears more accurate. However, Marshall model and Penmen model should mainly be taken into account when the air-saturation is high in soil.