Contaminant transport and remediation in dynamic gas-and-groundwater systems

地下水是一种重要的自然资源，但它是一种受到污染威胁的资源。保护和管理地下水，有赖于调查和监测策略的制定和实施，以及修复技术的设计和运作。这些都是基于我们对地下污染物运输的理解。虽然地下水系统通常被描述为仅由矿物颗粒之间的水组成，但情况并非总是如此。气体与水一起存在于许多地下水系统的孔隙中，这些气体影响污染物的输送方式。例如，气体可以通过自然机制产生，例如地下水位的上升和下降捕获空气或微生物产生气体。它们也可以通过修复技术产生，或者通过不适当密封或损坏的油气井从较深的区域转移到较浅的区域。然而，尽管地下水中广泛存在气体，但它们对污染物迁移和修复的影响往往是孤立地研究的，只考虑单一污染物或技术。识别共同行为的工作很少，导致对数据的误解、概念模型的不完整以及错过了应用程序之间知识转移的机会。该研究计划将对多种天然气和地下水应用进行协调调查，具体研究任务集中在加拿大最紧迫的三个环境问题上：1)危险工业化学品的可持续修复，通常被称为非水相液体（NAPLs）；2)全氟烷基和多氟烷基物质（PFAS）的运输，这是一种新兴污染物，对水资源构成全球威胁，极难降解，浓度极低时对人类健康有害；3)甲烷从油气井泄漏到浅层含水层，这在加拿大处理废弃井相关挑战时尤为重要。为了应对每一种污染物而保护地下水的相关成本都以数十亿美元计，而且它们都受到地下水中存在的气体的影响。总之，这些研究任务的结果将用于开发一个广泛、全面的框架，以描述和评估污染物运输和修复中的气体基过程。研究任务将由5名研究生（3名博士和2名硕士）组成的团队领导。实验将使用中等规模的物理模型来瞄准耦合流动和传质过程，并将与先进的数值模拟相结合，以产生新的知识，以建立改进的调查和监测策略，并开发新的或优化的修复技术来管理和保护加拿大的地下水。

Groundwater is a critical natural resource, but it is a resource that is threatened by contamination. The protection and management of our groundwater relies on the development and implementation of investigation and monitoring strategies, as well as the design and operation of remediation technologies. Each of these are based on our understanding of contaminant transport in the subsurface. Although groundwater systems are often depicted as being composed of only water between mineral grains, that is not always the case. Gases exist alongside water in the pores of many groundwater systems, and these gases affect how contaminants are transported. For example, gases can be created by natural mechanisms, such as the trapping of air by the rise and fall of the water table or the generation of gases by microorganisms. They can also be created by remediation technologies, or be transferred from deeper to shallower zones through improperly sealed or damaged oil and gas wells. However, despite the widespread occurrence of gases in groundwater, their effects on contaminant transport and remediation have often been studied in isolation, considering only a single contaminant or technology. There has been little work to identify common behaviour, resulting in misinterpretation of data, incomplete conceptual models and missed opportunities for knowledge transfer between applications. This research program will conduct a coordinated investigation of multiple gas-and-groundwater applications, with specific research tasks focused on three of the most pressing environmental concerns in Canada: 1) the sustainable remediation of hazardous industrial chemicals commonly referred to as non-aqueous phase liquids (NAPLs); 2) the transport of per- and polyfluoroalkyl substances (PFAS), an emerging contaminant and global threat to water resources that is extremely resistant to degradation and hazardous to human health at very low concentrations; and 3) methane leaking from oil and gas wells into shallow aquifers, which is of particular importance as Canada tackles challenges associated with abandoned wells. The costs associated with protecting groundwater in response to each of these contaminants are measured in the billions of dollars, and they are all affected by the presence of gases in groundwater. Together, results from these research tasks will be used to develop a broad, comprehensive framework to describe and evaluate gas-based processes in contaminant transport and remediation. The research tasks will be led by a team of five graduate students (three Doctoral and two Master's). Experiments will use intermediate-scale physical models to target coupled flow and mass transfer processes, and will be combined with advanced numerical modelling to generate new knowledge to establish improved investigation and monitoring strategies, and to develop new or optimized remediation technologies to manage and protect groundwater in Canada.