Mixed contaminants in soil and groundwater - some fundamental problems and their relevance to remediation and treatment

混合污染物是土壤修复和地下水处理面临的重大挑战。这一建议解决了研究土壤和地下水中混合污染物影响的迫切需要。拟议的工作将超越单一类别的污染物（例如铅、铜、锌；石油碳氢化合物、溴化或氟化化合物）。目前对这些污染物的理解存在重大差距，包括污染物以混合物形式存在时在土壤中的命运和迁移，以及转化机制，特别是在低流动性区域，处理技术之间的潜在协同作用，以及混合污染物在羽流中的迁移。我的研究主要集中在了解污染物的命运和运输过程，以帮助改善环境保护和管理实践，以防止污染物的扩散，减少不利的健康和生态风险。饮用水中的许多全氟烷基和多氟烷基物质都与特定来源有关，例如工业场所、军事消防训练区和废水处理厂。必须认识到，几乎所有受pfas污染的场地在地下水中都含有一种以上的污染物，通常是混合的，包括燃料成分，如石油产品、氯化溶剂和非氯化化合物，例如在消防训练演习期间同时释放到地下。尽管两种或两种以上污染物普遍共存，但迄今为止，关于全氟磺酸在共污染物和共污染物修复中的命运和迁移的详细研究在很大程度上是缺失的。拟议的工作将寻求深入了解控制PFAS影响的基本命运和运输过程，以及混合多环芳烃（PAHs）和地下水中的1,4-二恶烷。我们将特别关注源区多氟烷基向更有问题的全氟烷基物质的释放和转化，以及通常采用的补救技术的成功程度，这些技术往往基于单一污染物。具体的短期目标是：(1)研究控制PFASs从复杂土壤介质中吸附和释放的基本机制；(2)研究PFASs及其混合污染物在低渗透土壤中的扩散和潜在的非生物反应；确定多环芳烃、1,4-二恶烷和降解副产物对一维渗流土壤柱中全氟辛烷及其降解产物突破的影响。提高对这些混合污染物系统的基本命运和运输过程的洞察力的最终目标是促进发展和优化处理策略，以管理存在混合共污染物的pfas站点。

Mixed contaminants pose major challenges in soil remediation and groundwater treatment. This proposal addresses the urgent need to study the effects of mixed contaminants in soil and groundwater. The proposed work will go beyond single classes of contaminants (e.g. lead, copper, zinc; petroleum hydrocarbon, brominated or fluorinated compounds). Significant gaps in current understanding of these contaminants include contaminant fate and transport in soil when present in mixtures, and transformation mechanisms, particularly in low-mobility zones, potential synergies among treatment technologies, and transport of mixed contaminants in plumes.My research is primarily focused on understanding fate and transport processes of contaminants, to help improve environmental protection and management practice, with the goals of preventing the spread of contaminants, and reducing adverse health and ecological risks. Many of the perfluoroalkyl and polyfluoroalkyl substances (PFASs) in drinking water are linked to specific sources, such as industrial sites, military fire-training areas and wastewater treatment plants. It is important to recognize that almost all PFAS-contaminated sites contain more than one contaminant in groundwater, often in commingled plumes, including fuel components such as petroleum products, chlorinated solvents and non-chlorinated compounds, e.g. simultaneously released to the sub-surface during fire-fighting training exercises. Despite this common co-existence of two or more contaminants, detailed study of the fate and transport of PFASs in relation to co-contaminants and co-contaminant remediation is largely missing to date. The proposed work will seek to provide insight into the fundamental fate and transport processes that control the impact of PFAS, as well as comingled polycyclic aromatic hydrocarbons (PAHs) and 1,4-dioxane, in groundwater. We will particularly focus on the release and transformation of polyfluoroalkyl to the more problematic perfluoroalkyl substances in source zones, as well as the degree of success of commonly employed remediation technologies, which tend to be based on single contaminants. The specific short-term objectives are to: (1) investigate the fundamental mechanisms controlling sorption and release of PFASs from complex soil media; (2) examine the diffusion and potential abiotic reactions of PFASs and comingled contaminants in low-permeability soils; and determine the effects of PAHs, 1,4-dioxane and degradation byproducts on breakthrough of PFASs and their degradation products in one-dimensional flow-through soil columns. The ultimate goal of improved insight into the fundamental fate and transport processes in these mixed contaminant systems is to facilitate the development and optimization of treatment strategies for management of PFAS-sites in which there are comingled co-contaminants.