Biogeochemical processes and reactive transport across environmental interfaces: From groundwater to soil

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。这些隔室包括含水层——提供新鲜地下水的重要来源，不饱和带——除了水之外还含有土壤气体，土壤——容纳各种各样的植物，以及大气边界层——由我们呼吸的空气组成，含有氧气和二氧化碳。与这些隔室相关的过程通常是单独研究的。然而，通常在这些隔室之间的界面处生物地球化学反应性最高。此外，重要的是要了解跨越边界的质量通量，例如土壤和大气之间的温室气体交换。这些区域内的过程和跨界面的质量通量在当地、区域和全球生物地球化学平衡中发挥重要作用，影响水质、作物生产力和大气温室气体浓度。我的研究计划的总体目标是开发改进的定量概念模型，用于浅层地下水和土壤中的运输和生物地球化学反应过程，特别关注跨环境界面的传质过程。我的研究计划将通过一系列具体的项目来实现这一长期目标，这些项目都有一个共同点，就是在舱室之间转移气体，包括氧气、二氧化碳和甲烷。为此，我们将通过表征土壤气体和地表气体排放的空间分布和时间演变来研究乙醇混合燃料在浅层无约束含水层中意外泄漏的影响。我们将研究控制页岩气采掘点幕式甲烷气体迁移的过程，并将开发和评估数值模拟工具，以表征含水层中的气体迁移、气体向不饱和带的转移以及地下水位和地表之间甲烷的命运。我们将研究是否可以使用二氧化碳流出量来量化富含硫化物和碳酸盐的矿山废物的温室气体排放，我们将使用二氧化碳流入量测量来实时量化超基性矿山废物材料的碳固存潜力。此外，我们将致力于开发一个适合模拟植物-土壤相互作用的综合数值模型。该准则将用于定量评估生物矿化，即植物引起的矿物捕获所产生的碳固存过程，以及植物与土壤之间对作物生产力和矿物风化的影响的相互作用。综合起来，这些研究将为最佳环境管理做法提供指导，并将努力打破跨学科的界限。

Environmental interfaces can be defined as regions along which different compartments of the hydrologic system meet and interact. These compartments include aquifers - providing an important source for fresh groundwater, the unsaturated zone - containing soil gas in addition to water, soils - hosting a wide variety of plants, and the atmospheric boundary layer - consisting of the air we breathe and containing oxygen and carbon dioxide. Processes associated with these compartments are often studied in isolation. However, it is common that biogeochemical reactivity is highest at the interfaces between these compartments. In addition, it is important to understand mass fluxes across the boundaries, for example the exchange of greenhouse gases between soils and the atmosphere. Processes within these compartments and mass fluxes across interfaces play an important role in local, regional and global biogeochemical balances, affecting water quality, crop productivity, and atmospheric greenhouse gas concentrations. The overarching objective of my research program is the development of improved quantitative conceptual models for transport and biogeochemical reaction processes in shallow groundwater and soils, with a specific focus on mass transfer processes across environmental interfaces. My research program will make headway towards this long-term objective through a series of specific projects that all have in common the transfer of gases between compartments, including oxygen, carbon dioxide and methane. To this end, we will investigate the effect of accidental spills of ethanol-blended fuels in shallow unconfined aquifers by characterizing the spatial distribution and temporal evolution of soil gas and surficial gas emissions. We will investigate processes that control episodic methane gas migration at shale gas extraction sites and will develop and evaluate numerical modeling tools to characterize gas migration in aquifers, gas transfer to the unsaturated zone, and the fate of methane between water table and the ground surface. We will investigate whether we can use carbon dioxide effluxes to quantify greenhouse gas emissions from sulfide- and carbonate-rich mine waste and we will use carbon dioxide influx measurements to quantify in real time the carbon sequestration potential of ultra-mafic mine waste materials. In addition, we will work towards the development of an integrated numerical model suitable for simulating plant-soil interactions. This code will be applied to quantitatively assess bio-mineralization, i.e. the process of carbon sequestration by mineral trapping induced by plants, and interactions between plants and soil with effects on crop productivity and mineral weathering. Taken together, these studies will provide guidance towards best environmental management practices and will work towards breaking down interdisciplinary boundaries.