(EGB) Understanding and Modeling Hydrogeological, Microbiological, and Geochemical Processes that Control Groundwater Redox Zonation

(EGB) 控制地下水氧化还原分区的水文地质、微生物和地球化学过程的理解和建模

• 批准号: 9708487
• 负责人: David Long
• 金额: $ 46.6万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-15 至 2002-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9708487&HistoricalAwards=false
• 关键词: EGB; Understanding; Modeling; Hydrogeological; Microbiological

9708487 Long One of the most fundamental issues in aquifer biogeochemistry concerns the mechanisms by which solute transport and geochemical processes combine with microbiological activity to influence spatial and temporal variations in redox zonation. We will examine these mechanisms in a shallow sandy aquifer contaminated with petroleum hydrocarbons, which has exhibited redox zonation that varies on seasonal time scales. The dynamic nature of redox zonation at this site allows us to examine the interaction among hydrogeological, geochemical, and microbiological processes, and test hypotheses regarding the (1) reactions that govern groundwater evolution from zone to zone and (2) factors which control the spatial and temporal dimensions of redox zones. By coupling information gained from the three disciplines, through field and laboratory research, a three-dimensional, transient reactive flow and transport model for the evolution of redox zonation will be constructed. The goals of this interdisciplinary study are to (1) quantitatively assess hydrogeologic, geochemical and microbiological constraints that influence redox processes within a given zone; (2) use these constraints to identify sets of reactions that describe the evolution of groundwater from one zone to another; and (3) integrate the reaction sets with a dynamic flow and transport model to simulate past observations regarding the dimensions of various redox zones at the site, as well as compare the predicted and observed outcome of groundwater hydrologic events such as prolonged periods of high or low water table. These goals will be achieved through field sampling (seasonal and event), laboratory analysis and experimentation, in-situ hydrolgeological, microbiological, and geochemical analyses, and hydrogeochemical modeling. Unique aspects of the methods include: (1) combining geophysical and hydrolgeological data to estimate aquifer properties; (2) using 16S rRNA nucleic acid probe hybridization to determine microbial abu ndance, fatty acid methyl ester profiles and 16S rDNA restriction analysis (ARDRA) to determine community structure; (3) estimating redox state from H2 gas concentrations; (4) assessing minerals-microbial interactions using in-situ samplers and experiments; and (5) combing geochemical and microbiological reaction sets in a reactive flow and transport model to quantitatively account for observed water chemistry at the study site. This approach will benefit each discipline through improved understanding of the interaction among physical, chemical and biological processes that lead to redox zonation in both pristine and contaminated aquifers, and will provide fundamental information valuable to the design of appropriate sampling, monitoring and remediation methodologies. This proposal was submitted in response to the Environmental Geochemistry and Biogeochemistry solicitation NSF 96-152, and is being funded jointly by the Divisions of Earth Sciences and Environmental Biology.

9708487长期是含水层生物地球化学中最基本的问题之一，它涉及溶质传输和地球化学过程与微生物活性相结合以影响氧化还原分区中空间和时间变化的机制。 我们将在被石油烃污染的浅沙含水层中检查这些机制，该含石油碳氢化合物表现出随季节性时间尺度而变化的氧化还原分区。 该站点氧化还原分区的动态性质使我们能够检查水文地质，地球化学和微生物过程之间的相互作用，以及关于控制地下水从区域到区域演化的（1）反应的假设，以及（2）控制氧化还原Zones的空间和时间尺寸的因素。 通过从三个学科中获得的耦合信息，通过现场和实验室研究，将构建一个三维的，瞬态的反应性流量和转运模型，以构建氧化还原分区进化的过程。 这项跨学科研究的目标是（1）定量评估影响给定区域内氧化还原过程的水文地质，地球化学和微生物限制； （2）使用这些约束来识别描述地下水从一个区域发展到另一个区域的演变的一组反应； （3）将反应集与动态流和传输模型整合在一起，以模拟现场各种氧化还原区域的尺寸的过去观察结果，并比较地下水水文事件的预测和观察到的结果，例如长时间或低水位表的长时间。 这些目标将通过现场采样（季节性和事件），实验室分析和实验，原位水解学，微生物学和地球化学分析以及水力地球化学建模实现。 这些方法的独特方面包括：（1）将地球物理和水解学数据结合到估计含水层的特性； （2）使用16S rRNA核酸探针杂交来确定微生物缩写，脂肪酸甲基酯谱和16S rDNA限制分析（ARDRA）来确定社区结构； （3）从H2气体浓度估算氧化还原状态； （4）使用原位采样器和实验评估矿物 - 微生物相互作用； （5）在反应性流量和传输模型中梳理地球化学和微生物反应集，以定量考虑研究地点观察到的水化学。 这种方法将通过改善对物理，化学和生物学过程之间的相互作用的了解，从而使每个学科受益，从而导致原始和受污染的含水层的氧化还原分区，并提供对适当采样，监测和补救方法的设计有价值的基本信息。 该提案是根据环境地球化学和生物地球化学招标NSF 96-152提交的，并由地球科学和环境生物学的分裂共同资助。