Reactive transport in the dynamic capillary fringe

动态毛细管边缘的反应运输

• 批准号: 43741628
• 负责人: Professor Dr. Peter Grathwohl
• 金额: --
• 依托单位: Arbeitsgruppe Hydrogeochemie
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/43741628?language=en
• 关键词: Reactive; transport; dynamic; capillary; fringe

Transport of volatile organic contaminants (VOC) and soil gases (e.g. O2, CO2) across the capillary fringe (CF) depends on the morphology and the dynamics of the groundwater table. It is widely hypothesized that the CF is a highly bioactive region, where biodegradation of organic compounds or pollutants takes place. Overall biodegradation rates depend for example on the supply of electron acceptors such as oxygen, which is limited by diffusion and dispersion in the CF. The work in the first phase of the research unit focused on tracer techniques (dye tracers) and mass transfer of oxygen by transverse hydrodynamic dispersion as well as gas partitioning between the aqueous and the gaseous phase due to air entrapment. Overall objectives were the quantification of the basic mass transfer parameters in the CF and the investigation of the impact of transient conditions and heterogeneities. In the second period, the investigations will be extended to abiotic, rapid model reactions (e.g. consumption of oxygen by reducing species in groundwater). Goals of this proposal are• to quantify the basic mass transfer parameters in the CF for reactive systems under transient conditions and• to investigate the impact of coarse-grained inclusions (heterogeneities) in the porous medium packing on overall mass transfer and reaction rates.Flow-through experiments and numerical modeling (in collaboration with SP 2, Bastian/Ippisch) will be carried out in order to study example reactions in homogeneous and complex heterogeneous porous media by high-resolution spatial and temporal analysis.

挥发性有机污染物(VOC)和土壤气体(如O2、CO2)在毛细管边缘(CF)的传输取决于地下水位的形态和动态。人们普遍认为，碳纤维是一个高度生物活性的区域，在那里发生有机化合物或污染物的生物降解。总的生物降解率取决于电子受体的供应，例如氧气，而氧气的供应受到CF中扩散和分散的限制。研究单位第一阶段的工作重点是示踪技术(染料示踪剂)和横向流体动力弥散对氧的传质，以及由于空气滞留在水相和气相之间的气体分配。总体目标是对循环床中的基本传质参数进行量化，并调查瞬变条件和非均质性的影响。在第二阶段，研究将扩展到非生物的快速模型反应(例如，通过减少地下水中的物种来消耗氧气)。该方案的目标是：·在非稳态条件下，定量反应体系循环流动过程中的基本传质参数；·研究多孔介质填料中粗晶夹杂(非均相)对总传质和反应速率的影响。将开展流动实验和数值模拟(与SP2，Bastian/Ippisch合作)，以高分辨率的时空分析来研究均相和复杂多相多孔介质中的典型反应。