Troldborg Mads, Binning Philip J, Nielsen Signe, Kjeldsen Peter, Christensen Anders G
Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kgs. Lyngby, Denmark.
J Contam Hydrol. 2009 Feb 27;105(1-2):28-37. doi: 10.1016/j.jconhyd.2008.11.002. Epub 2008 Nov 12.
Risk assessments of sites contaminated with organic contaminants are typically conducted using models that ignore gas phase transport in the unsaturated zone. Here a general approach to developing analytical solutions to multiphase transport is presented. The approach is based on a combined gas and aqueous phase contaminant transport equation. The equation has the same general form as the standard advection-diffusion equation for which many analytical solutions have been derived. Four new analytical solutions are developed using this approach: a three-dimensional solution accounting for infiltration, lateral gas diffusion, sorption and degradation; a simple one-dimensional screening model, and two one-dimensional radial gas diffusion models for use in simulating volatile organic contaminant diffusion in unsaturated soils with an impermeable cover. The models show that both degradation and diffusion are important mechanisms for attenuation of contaminant concentrations at the water table. Finally, model results are compared with field data to illustrate the applicability of the solutions in risk assessment.
对受有机污染物污染场地的风险评估通常使用忽略非饱和带气相传输的模型来进行。本文提出了一种开发多相传输解析解的通用方法。该方法基于气相和水相污染物传输联合方程。该方程具有与标准平流扩散方程相同的一般形式，对于标准平流扩散方程已经推导出了许多解析解。利用这种方法开发了四个新的解析解：一个考虑入渗、横向气体扩散、吸附和降解的三维解；一个简单的一维筛选模型，以及两个用于模拟挥发性有机污染物在有不透水覆盖层的非饱和土壤中扩散的一维径向气体扩散模型。这些模型表明，降解和扩散都是地下水位处污染物浓度衰减的重要机制。最后，将模型结果与现场数据进行比较，以说明这些解在风险评估中的适用性。
