Retardation and mobilization of arsenic at redox fronts under advective flow conditions - a concerted multidisciplinary approach (AdvectAs)

平流条件下氧化还原前沿砷的延迟和动员 - 协调一致的多学科方法 (AdvectAs)

基本信息

批准号：
320059499
负责人：
Professor Dr.-Ing. Olaf A. Cirpka
金额：
--
依托单位：
Lamont-Doherty Earth Observatory
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/320059499?language=en
关键词：
Retardation mobilization arsenic redox fronts

项目摘要

Elevated levels of arsenic (As) in groundwater are a health problem affecting over 100 million people worldwide, particularly in the densely populated river deltas of South and Southeast Asia. Aquifers containing low and high As levels are characterized by highly contrasting redox conditions that are often separated by Fe-dominated transition zones. Such redox fronts play a crucial role with regard to As advection and retention, consequently preventing safe aquifers from contamination with As. However, because of the constantly growing water demand and increasing groundwater abstraction, aquifers being currently not affected by As are at risk of becoming As-polluted in the future.Despite more than a decade of research, it remains largely unknown to which extent sorption of As at Fe-dominated redox fronts delays the contamination of low-As aquifers under enhanced advective flow conditions. Without addressing this key issue in a comprehensive, multidisciplinary manner, it is not possible to make reliable and robust predictions about the time scale over which low-As aquifers are likely to become contaminated by incursion of water from adjacent As-bearing aquifers.We hypothesize that the stability and persistence of the redox transition zones in space and time are largely controlled by the mutual interaction of (a) transport processes, (b) microbial activity and (c) the stability of As host mineral phases (mainly Fe-bearing). We postulate that the abundance and type of Fe phases as well as of As species vary across the transition zones as a result of the availability of electron donors and acceptors, the activity of specific microbial communities, and the overall water exchange and solute transport. Furthermore, we expect that external sources of dissolved organic carbon, e.g. by vertical aquifer-aquitard exchange, foster As mobilization and enrichment in groundwater.The overarching goal of this proposed multidisciplinary research project is to assess potential future As contamination of currently 'safe' groundwaters by understanding and predicting the long-term mobility of As under enhanced hydraulic forcing across Fe-dominated redox transition zones in aquifer systems.The simultaneous characterization of these key processes on As-dynamics and their interactions will be carried out in a test field in Vietnam, which has previously been characterized by our research consortium and is particularly suitable to reach our research goals. Data obtained will be integrated in an advanced reactive transport model that couples physical transport and exchange with the key bio-geochemical reactions. This integrated model will allow to analyze the future evolution of the relevant redox fronts in time and space and the fate of As. To our knowledge, such a comprehensive approach involving all key disciplines has not been carried out up to date and will, thus, significantly enhance our understanding and our ability to predict As mobility in groundwaters.

地下水中砷（AS）的水平升高是一个健康问题，影响了全球超过1亿人，尤其是在人口稠密的南亚和东南亚河流三角洲。含有低和高水平的含水层的特征是高度对比的氧化还原条件，这些氧化还原条件通常由Fe为主导的过渡区隔开。这种氧化还原方面在对流和保留方面起着至关重要的作用，因此阻止了安全的含水层与AS污染。但是，由于水需求不断增长和地下水抽象的增加，目前不受AS的影响的含水层有可能在将来被污染。如果不以全面的多学科方式解决这一关键问题，就不可能对低水平含量的时间尺度做出可靠，可靠的预测，因为该时间尺度可能会因从相邻的含量含水层中吸入水的侵袭而污染了含水。我们假设，我们假设通过空间和持续的空间对态度的稳定性和持久性是由空间对立的，则是lar gral nimobs contiqual nimobs contiqual nim sirobs contiqual in lar fung quarial fung quartiqu sirobs lar fung quariqual n lar fung sirctiate（活性和（c）AS AS宿主矿物相的稳定性（主要是Fe-Bearent）。我们假设，由于电子捐赠者和受体的可用性，特定的微生物群落的活性以及整体水交换和溶质运输，因此在过渡区的丰度和类型的Fe阶段和AS种类都在过渡区域各不相同。此外，我们期望溶解有机碳的外部来源，例如by vertical aquifer-aquitard exchange, foster As mobilization and enrichment in groundwater.The overarching goal of this proposed multidisciplinary research project is to assess potential future As contamination of currently 'safe' groundwaters by understanding and predicting the long-term mobility of As under enhanced hydraulic forcing across Fe-dominated redox transition zones in aquifer systems.The simultaneous characterization of these key processes on As-dynamics他们的互动将在越南的一个测试领域进行，以前以我们的研究联盟为特征，特别适合实现我们的研究目标。获得的数据将集成到高级反应传输模型中，该模型将物理传输并与关键的生物地球化学反应融合在一起。该集成模型将允许分析时间和空间和AS命运的相关氧化还原前沿的未来演变。据我们所知，涉及所有关键学科的这种全面方法尚未得到最新，因此，将大大增强我们的理解和预测作为地下水中流动性的能力。