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

环境界面可以被定义为水文系统的不同隔间相遇并相互作用的区域。这些隔层包括含水层饱和带、含水和土壤气体的非饱和带、地表土壤和地表水体。与这些隔室相关的过程通常是孤立地研究的。然而，通常在隔室之间的界面上生化反应程度最高。因此，界面过程在局部、区域和全球生物地球化学平衡中发挥着重要作用，并可能对从一个区域向另一个区域迁移的气体和溶质通量产生重大影响。该提案涉及的具体目标包括：对原油和生物燃料泄漏地点有毒碳氢化合物以及二氧化碳和甲烷等气态生物降解产物的地表排放量进行量化；调查修复活动期间受污染的地下水向土壤气体无意中转移氯化溶剂的情况；开发描述金属向埋藏矿体上方地面迁移的数值模型。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实地研究、实验室研究和模型研究来实现。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，这项工作将允许改进对污染物寿命的评估。这项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气侵入建筑物的风险，包括评估生物燃料泄漏地点附近地下室发展爆炸性大气的可能性。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.