Development of an integrated numerical tool to predict fate and transport of contaminants in groundwater based on a DNAPL migration model wi10008881th entrapment and residual effect of droplets

本研究主要围绕以下5个方面展开研究：(1)孔隙中DNAPL液滴截留效应参数特征研究(2)提高含水层中污染源区DNAPL迁移模型预测精度(3)污染层中截留参数识别(4)基于饱和和非饱和区域DNAPL迁移模型的数值模拟工具开发(5)带夹持和残留参数的模拟工具在现场的应用(1)：土壤中残留DNAPL的参数与宏观毛细管数和键数有关。获得了以下与土壤中污染物的迁移、预测和修复有关的参数。1)胶体在水膜中的扩散是土壤胶体淋溶的限制因素，它促进了污染物的运移。更多的胶体在土壤中被捕获。3)胶体的速度比示踪剂（Br-）快3 ~ 4倍。4)农药在胶体上的吸附显著高于在土壤上的吸附（3 × 10^3倍）。5)针对土壤中的气体输运，建立了考虑土壤结构（如空气含量或孔隙大小分布）的气体输运参数预测模型。这些新模型能够预测土壤中气态污染物的迁移。(2)：将基于入侵渗透（IP）理论的指法模型与本研究建立的DNAPL液滴随机游走模型进行了比较，并在了解参数λ特征的基础上提高了DNAPL迁移模型的预测精度。(3)：采用非均质污染土的柱形实验，证实了在高速条件下溶出速率较低。(4)分别在空间、实验室和现场尺度上研究了以扩散有限聚集（Diffusion Limited Aggregation， DLA）或IP理论为代表的随机模型和对流色散方程的有限差分法。阐明了差分格式的稳定性以及溶液和质量平衡的网格依赖性。(5)将所建立的模型应用于现场。从保护和利用地下水健康环境的角度出发，建立了地下水资源管理框架。阐明了数值方法及其在小型和大型水工模型地下水流动分析中的应用存在的问题。少

The following five major subjects were investigated in this research(1) Study on characteristics of parameters governing the entrapment and residual effect of DNAPL droplets in pores(2) Improvement of prediction accuracy of the DNAPL migration model for contaminant source area in aquifer(3) Identification of the entrapment and residual parameters in contaminated layers(4) Development of a numerical simulation tool based on the DNAPL migration model for both saturated and unsaturated areas(5) Application of the simulation tool with the entrapment and residual parameters to field sites(1) : It was shown that a parameter for residual DNAPL in soil was related to a macroscopic capillary number and a bond number. The following parameters associated with transport, prediction and remediation of contaminants in soils were obtained. 1) Colloid diffusion in water films was a limiting factor in leaching of soil colloids, which enhance the transport of contaminants. 2) Around 50% of the supplied … More colloids were captured in soil. 3) The velocity of colloids was three to four times higher than that of tracer (Br-). 4) The adsorption of pesticides onto colloids was significantly higher (3x10^3 times higher) than that onto soil. 5) For the gas transport in soils, new prediction models for gas transport parameters that consider soil structure such as air content or pore size distribution were developed. These new models enabled to predict the transport of gaseous contaminants in soils.(2) : The fingering model based on Invasion Percolation (IP) theory and the random walk model of the DNAPL liquid drop developed in this study were compared and the prediction accuracy of the DNAPL migration model was improved based on the understanding of characteristic of parameter λ.(3): It was confirmed that the dissolution rate became low even in high velocity condition based on column experiments assuming heterogeneous contaminated soil.(4): The stochastic model represented by Diffusion Limited Aggregation (DLA) or IP theory and the finite difference method for convection dispersion equation were investigated at void, laboratory and field scale, respectively. The stability of difference scheme and the grid dependency of solution and mass-balance were clarified.(5): The application of the developed model to field sites was conducted. From the view point of conservation and utilization of healthy groundwater environment, a framework of the groundwater resource management was established. The problems with the numerical methods and its application to groundwater flow analysis based on small- and large-scale hydraulic models were clarified. Less