Mass-Transfer Dynamics of Chlorinated-Solvent Immiscible

以非水相(不混溶)有机液体(NAPL)的形式存在于地下许多受污染地点的有机化学品是地下水污染的长期来源。在这些地点进行有效的风险评估和补救，取决于能否准确地描述NAPL和地下水之间各组分的质量转移(NAPL溶解)。在实验室柱规模上详细考察了影响NAPLS溶出度的因素。然而，NAPLS在孔隙尺度上的基本溶解行为还没有被很好地了解。此外，已经进行了极少的研究来检验多孔介质非均质性对NAPL溶解的影响。这项研究的总体目标是更好地了解稠密非水相不相容有机液体(DNAPL)在地下系统中的溶解行为。具体的 为实现这一目标而开发的目标是：(1)研究DNAPLS在孔尺度上的溶解动力学。(2)发展和应用格子/网络模型来模拟孔隙尺度上的溶解动力学。(3)考察多孔介质非均质性对DNAPL溶出度的影响。(4)研究多孔介质非均质性对水力源区修复技术效果的影响。(5)发展和评价先进的数学模型，能够在多尺度上模拟DNAPL组分在非均质多孔介质中的溶解和运移。实验旨在研究多孔介质性质对NAPL形态和分布的影响，以及由此产生的对溶解和质量通量行为的影响。设计的实验将允许研究完全溶解和质量去除。该项目涉及到孔隙规模和 宏观调查。在这两种情况下，都将使用先进的成像方法来获得对NAPL构型和溶解动力学的直接、原位测量。这些信息将与质量通量数据的测量相结合。先进的数学模型将被用来帮助综合和解释实验结果。该项目利用了两个国家实验室的用户设施，这两个设施提供了使用先进成像技术的机会，否则这些技术是无法获得的。

Organic chemicals in the form of nonaqueous-phase (immiscible) organic liquids (NAPLs) occur in the subsurface at numerous contaminated sites and act as long-term sources of groundwater contamination. Effective risk assessment and remediation at these sites depends on the ability to accurately characterize the mass transfer of components between NAPL and groundwater (NAPL dissolution). The factors influencing dissolution of NAPLs have been examined in detail at the laboratory column scale. However, the fundamental dissolution behavior of NAPLs at the pore scale is not well understood. In addition, minimal research has been conducted to examine the impact of porous-medium heterogeneity on NAPL dissolution. The overall goal of the proposed research is to better understand the dissolution behavior of dense nonaqueous-phase, immiscible organic liquids (DNAPLs) in subsurface systems. The specific objectives developed to accomplish this goal are: (1) Investigate the dissolution dynamics of DNAPLs at the pore scale. (2) Develop and apply a lattice/network model to simulate dissolution dynamics at the pore scale. (3) Investigate the impact of porous-medium heterogeneity on DNAPL dissolution. (4) Investigate the impact of porous-medium heterogeneity on the efficacy of hydraulic-based source-zone remediation technologies. (5) Develop and evaluate advanced mathematical models capable of simulating the dissolution and transport of DNAPL constituents in heterogeneous porous media at multiple scales. The experiments are designed to investigate the impact of porous-medium properties on NAPL morphology and distribution, and the resultant effect on dissolution and mass-flux behavior. Experiments will be designed to allow investigation of complete dissolution and mass removal. The project involves both pore-scale and macro-scale investigations. In both cases, advanced imaging methods will be used to obtain direct, in-situ measurements of NAPL configuration and dissolution dynamics. This information will be integrated with measurements of mass flux data. Advanced mathematical modeling will be employed to help synthesize and interpret the results of the experiments. The project makes use of two National Laboratory user facilities that provide the opportunity to use advanced imaging techniques that would otherwise not be available.