Biogeochemical processes in groundwater and the vadose zone with an emphasis on gas and solute fluxes across environmental interfaces

环境界面可定义为水文系统不同分区交汇和相互作用的沿着区域。这些分区包括含水层的饱和带、含水层和土壤气的非饱和带、表层土壤和地表水体。与这些隔间相关的过程通常是孤立地研究的。然而，常见的是，生化反应性的程度在隔室之间的界面处最高。因此，界面过程在局部、区域和全球地球化学平衡中起着重要作用，并对从一个区域迁移到另一个区域的气体和溶质通量产生重大影响。本提案中涉及的具体目标包括：对原油和生物燃料泄漏现场有毒碳氢化合物以及二氧化碳和甲烷等气体生物降解产物的过量排放进行量化，调查在补救活动中氯化溶剂从受污染地下水无意中转移到土壤气体的情况，以及建立一个数值模型，描述金属向埋藏矿体上方地表迁移的情况。总之，这些研究将有助于我的研究计划的总体目标，开发和量化的机制概念模型的运输和反应过程涉及环境界面，重点是浅层地下水系统。这些目标将通过综合实地、实验室和建模研究来实现。整个研究计划将带来环境和经济效益。在碳氢化合物和生物燃料泄漏现场，这项工作将有助于改进对污染物寿命的评估。该研究还将揭示由于地下水修复和生物燃料生物降解而导致土壤蒸气侵入建筑物的风险增加，包括评估生物燃料泄漏地点附近地下室形成爆炸性气氛的可能性。该研究计划还将把最先进的建模技术扩展到矿产勘探的应用中，产生可用于定位埋藏矿体的知识。

Environmental interfaces can be defined as regions along which different compartments of the hydrologic system meet and interact. These compartments include the saturated zone of aquifers, the unsaturated zone containing water and soil gas, surficial soils, and surface water bodies. Processes associated with these compartments are often studied in isolation. However, it is common that the degree of biochemical reactivity is highest at the interfaces between the compartments. As a result, processes at interfaces play an important role in local, regional and global biogeochemical balances, and can have significant impacts on gas and solute fluxes migrating from one region to another. Specific objectives addressed in this proposal include the quantification of surficial emissions of toxic hydrocarbons together with gaseous biodegradation products such as carbon dioxide and methane at crude oil and biofuel spill sites, the investigation of the inadvertent transfer of chlorinated solvents from contaminated groundwater to soil gas during remediation activities, and the development of a numerical model that describes the migration of metals towards the ground surface above buried ore bodies. Together, these studies will contribute to the overarching objective of my research program to develop and quantify mechanistic conceptual models for transport and reaction processes involving environmental interfaces, with an emphasis on shallow groundwater systems. These objectives will be achieved through integrated field, laboratory, and modeling studies. The research program as a whole will lead to environmental and economic benefits. At hydrocarbon and biofuel spill sites, the work will allow for an improved assessment of contaminant longevity. The study will also shed light on increased risks for soil vapor intrusion into buildings due to groundwater remediation and biodegradation of biofuels, including an assessment of the potential for development of an explosive atmosphere in basements near biofuel spill sites. The research program will also extend state-of-the-art modeling techniques to applications in mineral exploration, generating knowledge that can be used to locate buried ore bodies.