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

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。这些区域包括含水层-为地下淡水提供重要来源;非饱和带-除水外还含有土壤气体;土壤-生长着各种各样的植物;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。与这些隔间相关的过程通常是孤立地研究的。然而，常见的是，在这些隔室之间的界面处，地球化学反应性最高。此外，必须了解跨越边界的物质通量，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界面间的质量通量在地方、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改进的定量概念模型的运输和浅层地下水和土壤中的地球化学反应过程的发展，特别侧重于跨环境界面的传质过程。我的研究计划将通过一系列具体项目朝着这一长期目标取得进展，这些项目的共同点是舱间气体的转移，包括氧气、二氧化碳和甲烷。为此，我们将调查乙醇混合燃料在浅无压含水层的意外泄漏的影响，通过表征土壤气体和表面活性剂气体排放的空间分布和时间演变。我们将研究控制页岩气开采现场的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，气体转移到非饱和区，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排放量来量化硫化物和碳酸盐丰富的矿山废物的温室气体排放量，我们将使用二氧化碳流入量测量来量化真实的时间超镁铁质矿山废物材料的碳封存潜力。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。该代码将用于定量评估生物矿化作用，即植物诱导的矿物捕获的碳固存过程，以及植物与土壤之间的相互作用对作物生产力和矿物风化的影响。总之，这些研究将为最佳环境管理做法提供指导，并将努力打破学科界限。

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.