Diffusive solute transport and reaction processes in natural and contaminated porous media

天然和污染多孔介质中的扩散溶质传输和反应过程

• 批准号: RGPIN-2017-05540
• 负责人: Al, Tom
• 金额: $ 2.33万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=711724
• 关键词: Diffusive; solute; transport; reaction; processes

The research program is focused on diffusion and reaction processes in porous media, primarily shallow groundwater systems, with or without anthropogenic contamination. The long-term objective is to improve understanding of coupled diffusion-reaction processes and their controls on solute mobility in groundwater and surface water systems. The proposed research program will address two objectives: 1. In contaminated fractured rock aquifers where natural attenuation of CrVI or chlorinated solvent contamination can be demonstrated, we will build conceptual models by identifying the reactants, products, mechanisms and relative contributions of specific reactions. The conceptual models will be further developed into a numerical framework with the reactive transport code, MIN3P (Mayer et al. 2001). 2. We will improve the understanding of growth mechanisms and time-series variability of chemical and isotopic compositions in growth bands of Fe-Mn nodules that occur at the water-sediment interface in lakes. Knowledge that anthropogenic contaminants in aquifers may undergo natural attenuation by chemical and biological processes integrates well within a risk-based assessment of options for management of contaminated groundwater systems. In cases where it can be shown that natural attenuation mechanisms are active, and risk to human and ecosystem health are low, regulators may decide that aggressive, disruptive and costly remediation approaches are not necessary. We are working with partners in Boeing Corp. and the US EPA to study diffusion and reaction processes that contribute to natural attenuation of Cr(VI) and chlorinated solvents in the matrix pore space of fractured bedrock aquifers. Our contributions include measurement of diffusion transport rates, and the development of geochemical and mineralogical methods to identify mineral reactants and reaction products that allow us to define attenuation reaction processes. Freshwater Fe-Mn nodules have been observed in lakes at the water-sediment interface. The Fe and Mn is thought to be derived from the underlying sediment porewater. In glaciated terrains the nodules are likely as old as the lakes. We will study their origin by conducting detailed studies of the porewater chemistry and stable isotopic composition. Porewater data from the cores will allow for a quantitative study of the upward transport rates for Fe, Mn and trace elements. The nodules, which grow radially similar to tree rings, will be analyzed to determine their age profiles (210Pb, 226Ra, 14C) along the growth direction. This will allow us to define growth rates and total age. These studies will contribute to the understanding of major and trace-element budgets and fluxes to lakes through time. We aim to construct time series for trace-element fluxes at the regional scale that will be valuable in understanding post-industrialization contaminant dispersion.

该研究计划的重点是在多孔培养基中的扩散和反应过程，主要是浅层地下水系统，无论有没有人为污染。 长期目标是提高对耦合扩散反应过程的理解及其对地下水和地表水系统中溶质迁移率的控制。拟议的研究计划将解决两个目标： 1。在受污染的碎石含水层中，可以证明CRVI或氯化溶剂污染的自然衰减，我们将通过确定特定反应的反应物，产物，机制和相对贡献来建立概念模型。 概念模型将进一步发展为具有反应性传输代码MIN3P的数值框架（Mayer等，2001）。 2。我们将提高人们对湖泊水界面界面的Fe-Mn结节生长带中化学和同位素组成的变化的理解。 知道含水层中的人为污染物可能会通过化学和生物过程自然衰减的知识很好地整合了基于风险的污染地下水系统的选择评估。如果可以证明自然的衰减机制是活跃的，并且对人类和生态系统健康的风险很低，则监管机构可能会决定不需要侵略性，破坏性和昂贵的补救方法。我们正在与波音公司和美国EPA的合作伙伴合作研究扩散和反应过程，这些过程有助于自然衰减Cr（VI）和氯化溶剂，这是裂缝基岩含水层的基质孔隙空间中的。我们的贡献包括测量扩散率的测量以及地球化学和矿物学方法的发展，以鉴定矿物反应物和反应产物，使我们能够定义衰减反应过程。 在水 - 水界面的湖泊中，已经观察到淡水Fe-Mn结节。 FE和MN被认为是源于潜在的沉积物孔道。 在冰川地形中，结节可能与湖泊一样古老。我们将通过对毛水化学和稳定的同位素组成进行详细研究来研究它们的起源。 来自核心的孔隙水数据将允许对Fe，MN和微量元素的向上传输速率进行定量研究。将分析与树环径向相似的结节，以确定其年龄概况（210pb，226ra，14c）沿着生长方向。这将使我们能够定义增长率和总年龄。这些研究将有助于对湖泊的主要和痕量元素预算以及对湖泊的通量理解。 我们的目标是在区域规模上构建痕量元素通量的时间序列，这将在理解后工业化污染物分散体方面有价值。