Linking Redox-Cycling to Hydrogeology: Sedimentological Controls on the Capacity of Aquifers to Reduce Nitrate and other Dissolved Electron Acceptors

将氧化还原循环与水文地质学联系起来：沉积学控制含水层减少硝酸盐和其他溶解电子受体的能力

• 批准号: 497727419
• 负责人: Professor Dr.-Ing. Olaf A. Cirpka
• 金额: --
• 依托单位: Department für Funktionelle und Evolutionäre Ökologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/497727419?language=en
• 关键词: Linking; Redox; Cycling; Hydrogeology; Sedimentological

The physical and chemical make-up of sedimentary aquifers is determined by the geology of the host rock and the local depositional environment at the time of their formation. The latter yields a characteristic constellation of structural elements differing both in grain-size distribution (and thus hydraulic conductivity) and content of redox-active minerals and organic matter. This spatially variable and hierarchically organized distribution controls groundwater flow and solute reactive transport in sedimentary aquifers. The presence of reactive organic or mineral phases determines the potential reactivity for nitrate and other dissolved electron acceptors, but for the reactions to occur the electron bearing sediments must be conduits for flow, that is, that they must have a sufficiently high hydraulic conductivity to allow water borne solutes to reach the reactive solid phases. The dependence on matrix-reactivity is a key reason for sustained nitrate contamination in aquifers, despite denitrification being a high-energy-yielding reaction, and the subsurface harboring the necessary microbial capacity to catalyze it. The proposed project aims at quantitatively linking aquifer hydraulic and biogeochemical properties with the “reactivity” of aquifer sediments, and their ability to reduce nitrate via denitrification. Via a coupled hydrogeological, sedimentological and microbiological field-site investigations, flow-through column experiments with field-collected cores and data-informed reactive transport modelling at the laboratory and aquifer scales, we aim to yield a unique dataset that will enable reliable estimates of site- and facies-specific reactivity estimates to feed larger scale (denitrification) predictive models. The project will rely on Direct-Push field investigations at five sites across a spectrum of hydraulic conductivity, nitrate contamination, and organic matter / redox-active mineral content in Germany and Austria for core-logging and sediment sample extraction. Field surveys will inform biogeochemical flow through experiments that will monitor denitrification and denitrifying microbial activity in sediments. A detailed sedimentological characterization of field collected cores will help elucidate the reactive potential of sedimentological facies and build site-specific conceptual sedimentological models. Reactive transport models will help quantifying reaction-rate coefficients that will ultimately yield estimates of overall sediment reactivity. The latter will feed into aquifer scale virtual floodplain aquifer models based on the concept of “cumulative relative reactivity” to solve for reactive transport. We expect this project to advance our understanding of fundamental sedimentological controls on matrix-mediated redox reactions and microbial activity in aquifers, and yield aquifer-scale models that can predict denitrification as a function of an aquifer’s sedimentological setting.

沉积含水层的物理和化学构成由宿主岩石的地质和局部沉积环境确定。后者产生的结构元​​素的特征性星座在晶粒大小的分布（以及水解电导率）和氧化还原活性矿物质和有机物的含量中都有区分。在存在反应性有机或矿物相的存在下，这种空间可变和层次有组织的分布控制可在存在反应性有机或矿物相的情况下进行地下水流动和反应性转运，这决定了硝酸盐和其他溶解的电子受体的潜在反应性，但是要使对电子轴承沉积物发生的反应发生，必须有足够的流ph，即具有足够的水水水力导通态，以至于水力ph。对基质反应性的依赖性是含水层中持续硝酸盐污染的关键原因，二磷酸盐反应是一种高能量产量的反应，并且具有具有催化其催化的微生物能力的地下。拟议的项目旨在定量地将含水层的水解和生物地球化学特性与含水层沉积物的“反应性”联系起来，以及它们通过反硝化减少硝酸盐的能力。通过耦合的水文地质，沉积学和微生物学场地研究，在实验室和含水层尺度上，通过现场收集的核心和数据信息的反应性传输模型进行流动柱实验，我们旨在产生独特的数据集，该数据集将实现一个可靠的反应性估计和设施的反应性估计，以喂养大尺度（DENITREVIDIAL）（DENITREVIDIAL）（DENITREVISITIVE）。该项目将依靠在德国和奥地利的多种液压电导率，硝酸盐污染以及有机物 /氧化还原活性矿物质含量的五个地点进行直接涌入现场调查，以用于核心和沉积物样品提取。现场调查将通过实验来告知生物地球化学流，该实验将监测沉积物中的微生物活性。对现场收集的核心的详细沉积学表征将有助于阐明沉积设施的反应性潜力，并建立特定地点的概念沉积学模型。反应转运模型将有助于量化反应速率系数，最终将产生总体沉积物反应性的估计。后者将基于“累积相对反应性”的概念以求解反应性传输的概念，以含水层尺度的虚拟洪泛区含水层模型为食。我们希望该项目能够提高我们对含水层基质介导的氧化还原反应和微生物活性的基本沉积学控制的理解，并产生含水层尺度模型，这些模型可以预测硝化作用是含水层的沉积层的函数。