裂隙地下水残留DNAPL的溶解-界面退化响应机制研究

DNAPL (Dense Non-Aqueous Phase Liquid) contamination in fractured groundwater has attracted much attention because of its hard-decomposition, high residual saturation, and slight solution in groundwater. This study of this project will be started from the interface degradation phenomenon between water and DNAPL in the process of DNAPL volume diminution induced by DNAPL dissolution. Finally, the mechanism of the nonlinear residual DNAPL dissolution rate will be studied in detail. For this purpose, the interfacial area between water and DNAPL will be obtained quantitatively by the revised interfacial portioning tracer test. The quantitative relationship between the residual DNAPL saturation and “water-DNAPL” interfacial area will be analyzed. The interaction effect between the form and area of “water-DNAPL” interface and residual DNAPL dissolution rate will be studied by using micro-simulation method. The mechanism of the nonlinear residual DNAPL dissolution rate will be studied in detail. The coupled influences of factors (aperture distribution, flow velocity, and “water-DNAPL” interfacial area) on the residual DNAPL dissolution rate will be discussed by the sensitivity analysis. After that, the time prediction model of residual DNAPL dissolution based on the “water-DNAPL” interface degradation will be developed in a single rough fracture. The results of this project have the theoretical and practical value for controlling and remediating the residual DNAPL contamination in fractured groundwater.

裂隙地下水中重非水相液体（DNAPL，Dense Non-aqueous phase liquid）污染物，因其不易分解、高残留和微溶解等特性受到人们的高度重视。本项目从溶解过程中DNAPL相体积不断减小引起的“水-DNAPL”界面退化现象出发，拟揭示残留DNAPL溶解速率的非性线变化机制。为此，通过对界面追踪实验的修正，实现定量获取“水-DNAPL”界面面积，分析DNAPL残留量与“水-DNAPL”界面面积的定量关系，利用微观数值模拟，研究“水-DNAPL”界面形态和面积对残留DNAPL溶解速率的相互影响机制，基于实验和数值模拟数据的敏感性分析，探讨多因素对残留DNAPL溶解速率的耦合影响，并建立基于“水-DNAPL”界面退化的粗糙单裂隙残留DNAPL溶解时间预测模型。项目研究成果对裂隙地下水残留DNAPL污染的控制、治理具有重要的理论意义和实用价值。

裂隙地下水中重非水相液体（DNAPL，Dense Non-aqueous phase liquid）污染物，因其 不易分解、高残留和微溶解等特性受到人们的高度重视。本项目从溶解过程中DNAPL相体积不断减小引起的“水-DNAPL”界面退化现象出发，拟揭示残留DNAPL溶解速率的非性线变化机制 。为此，通过对界面追踪实验的修正，实现定量获取“水-DNAPL”界面面积，分析DNAPL残留量与“水-DNAPL”界面面积的定量关系，利用微观数值模拟，研究“水-DNAPL”界面形态和面积对残留DNAPL溶解速率的相互影响机制，基于实验和数值模拟数据的敏感性分析，探讨多因素对残留DNAPL溶解速率的耦合影响，并建立基于“水-DNAPL”界面退化的粗糙单裂隙残留DNA PL溶解时间预测模型。在项目执行期间，通过开展合作与研究，主要完成了1）地下介质结构对污染物运移的影响规律研究；2）地下水水流状态对污染物运移的影响规律研究；3）地下水污染物运移过程中传质系数的定量研究；4）地下水污染物运移纵向扩散系数无量纲数Pe的关系研究。项目完成了SDBS界面追踪实验，完成水动力条件对SDB S界面捕捉能力实验研究，开发模拟残留DNAPL溶解过程中“水-DNAPL”界面动态特征的计算程序，揭示了残留DNAPL溶解与“水-DNAPL”界面形态和界面面积的相互影响机制。项目截止至2019年12月31日，发表论文8篇，其中第一作者SCI论文7篇，申请国家发明专利5项，授权3项，登记软件著作权1项。获甘肃省水利科技进步一等奖1项。基本完成了项目设立的总体的目标和任务。