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

环境界面可以定义为水文系统的不同区域相遇和相互作用的区域。这些区室包括含水层的饱和区、含水和土壤气体的非饱和区、表层土壤和表层水体。与这些隔室相关的过程通常是单独研究的。然而，通常在隔室之间的界面处，生化反应的程度是最高的。因此，界面过程在局部、区域和全球生物地球化学平衡中起着重要作用，并可能对气体和溶质通量从一个区域迁移到另一个区域产生重大影响。本提案涉及的具体目标包括：对原油和生物燃料泄漏地点的有毒碳氢化合物以及气体生物降解产物（如二氧化碳和甲烷）的地表排放进行量化；调查在补救活动期间，氯化溶剂从受污染的地下水无意中转移到土壤气体中；并建立了一个描述金属在隐伏矿体上方向地表迁移的数值模型。总之，这些研究将有助于我的研究计划的总体目标，即开发和量化涉及环境界面的运输和反应过程的机械概念模型，重点是浅层地下水系统。这些目标将通过综合现场、实验室和模型研究来实现。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污染物寿命的评估。该研究还将阐明由于地下水修复和生物燃料的生物降解而增加的土壤蒸汽侵入建筑物的风险，包括评估在生物燃料泄漏地点附近的地下室发展爆炸性大气的可能性。该研究项目还将把最先进的建模技术应用于矿产勘探，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.