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

非水相液体在天然多孔介质中的释放是一个普遍存在的环境问题。污染物跨越NAPL-水相边界的转移既决定了地下水污染的程度，也决定了剩余NAPL相在多孔介质中的持久性。先前的研究表明，在水环境中，NAPL-水界面会发生“老化”现象，例如形成类似皮肤的粘性薄膜。然而，令人惊讶的是，人们对控制NAPL在多孔介质中形成这种膜的因素和机理以及这种膜对有机污染物从NAPL到水相的传质的影响知之甚少。在拟议的项目中，我们将解决这些知识差距，以便(I)实现对导致多孔介质中NAPL形成粘性相边界的反应和环境条件的过程的了解(老化)，以及(Ii)开发和更新此类边界层的物理模型，以量化多组分NAPL-水系统中与时间相关的界面现象(传质)。为此，我们将利用模型和真实的NAPL在水和水的多孔介质中进行间歇和渗流实验，并密集使用化学探针技术。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，应用新设计的光谱和电化学工具对界面进行空间高分辨率研究，并为受NAPL污染的多孔介质的反应传输建模做出贡献。

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.