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

本论文主要研究了以下五个方面的内容：（1）DNAPL液滴在孔隙中的截留和残留效应参数特征研究（2）提高DNAPL迁移模型对含水层污染源区的预测精度（3）污染层截留和残留参数的识别（4）开发基于DNAPL迁移模型的饱和区和非饱和区数值模拟工具（5）将具有圈闭和剩余参数的模拟工具应用于现场（1）：结果表明，土壤中残留DNAPL的参数与宏观毛管数和键数有关。获得了以下与土壤中污染物的迁移、预测和修复相关的参数。1)胶体在水膜中的扩散是土壤胶体淋溶的一个限制因素，它促进了污染物的迁移。2)大约50%的供应 ...更多信息 胶体被捕获在土壤中。3)胶体的速度比示踪剂（Br-）的速度高3 ~ 4倍。4)胶体对农药的吸附量显著高于土壤对农药的吸附量（3 × 10^3倍）。5)对于气体在土壤中的运移，考虑土壤结构，如空气含量或孔隙尺寸分布的气体运移参数的新的预测模型的开发。这些新模型能够预测气态污染物在土壤中的迁移。(2):将基于侵入逾渗理论的指进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特性的基础上，提高了DNAPL迁移模型的预测精度。(3)通过柱试验，假定污染土壤为非均质，证实了即使在高速条件下，溶解速率也会变低。(4)分别在孔隙、实验室和现场尺度上研究了扩散限制聚集（DLA）或IP理论所代表的随机模型和对流弥散方程的有限差分方法。阐明了差分格式的稳定性以及解与质量平衡的网格依赖性。(5)：将开发的模型应用于现场。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基于小尺度和大尺度水力模型的地下水流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