Mass transfer, aging and reactions at NAPL interfaces in porous media

非水相液体向天然多孔介质中的释放是一个普遍存在的环境问题。跨非水相污染物-水相边界的污染物转移决定了地下水污染的程度以及多孔介质中残留非水相的持久性。先前的研究表明，NAPL-水界面在水性环境中会出现“老化”现象，例如，形成皮肤状粘性膜。然而，令人惊讶的是，很少有人知道的因素和机制，控制这种膜的形成NAPLs在水性多孔介质中，以及有关的影响，这种膜的有机污染物的传质从NAPL的水相。在拟议的项目中，我们将解决这些知识差距，以便（i）实现基于过程的理解，导致在多孔介质中形成NAPL的粘性相边界（老化）的反应和环境条件，并（ii）开发和验证这种边界层的物理模型，以量化多组分NAPL-水系统（传质）中的时间依赖性界面现象。为此，我们将在水和含水多孔介质中用模型和真实的NAPL进行批量和流通实验，并大量使用化学探针技术。我们将利用化学和流变学分析，微观过程建模，并与研究小组内的合作伙伴合作，我们将应用光谱和电化学工具的新设计，用于界面的空间高分辨率研究，并有助于NAPL污染的多孔介质的反应传输建模。

Release of non-aqueous phase liquids (NAPLs) into natural porous media is a widespread environmental problem. Transfer of pollutants across the NAPL-water phase boundary determines both the extent of groundwater contamination as well as the persistence of residual NAPL phases in porous media. Previous research has shown that NAPL-water interfaces are subject to "aging" phenomena in aqueous environments, e.g., development of skin-like viscous films. However, surprisingly litte is known about the factors and mechanisms that control such film formation of NAPLs in aqueous porous media and about the effects of such films on mass transfer of organic contaminants from the NAPL to the aqueus phase. In the proposed project we will address these knowledge gaps in order to (i) achieve a process based understanding of reactions and environmental conditions leading to the formation of viscous phase boundaries of NAPLs in porous media (aging) and to (ii) develop and vali-date a physical model of such boundary layers to quantify time-dependent interfacial phenomena in multi-component NAPL-water systems (mass transfer). To this end we will carry out batch and flow-through experiments with model and real NAPLs in water and aqueous porous media and make intense use of chemical probe techniques. We will utilize chemical and rheological analysis, microscopic process modeling and, in cooperation with partners within the research group, we will apply new designs of spectroscopic and electrochemical tools for spatially highly resolved investigations of the interface as well as contribute to reactive transport modeling at NAPL-contaminated porous media.