CAREER: Transport of perfluoroalkyl substances (PFAS) in partially and fully saturated porous media - evaluating the interactions of solution chemistry and organic matter quality

聚和全氟烷基物质（PFAS）是人造化学品。PFAS由于其稳定性和其他有价值的化学性质而被用于各种产品中。然而，PFAS的这种稳定性也使得PFAS难以在环境中生物降解。此外，它们的特性也对人类健康和环境构成威胁。据估计，超过600万美国人在供水中暴露于PFAS，PFAS被认为是国家面临的环境污染中最重要的问题之一。这种担忧源于研究表明，一些PFAS可以进入并留在人体内，可能导致癌症和其他健康问题。这一知识导致了许多努力来处理水源，以在发现时去除PFAS。抽取和处理地下水是这些常用的处理方法之一。虽然这种方法对某些污染物有效，但PFAS在地下水中的运动很难预测，因为我们还不完全了解PFAS与土壤中天然有机质（NOM）之间的相互作用。这个职业项目的目标是通过调查NOM和PFAS的相互作用来解决这一知识差距。这将通过一系列具有良好特征的模型系统的实验来实现。了解这一过程将使我们能够改善地下水处理系统，以保护人类健康。这项工作将用于通过宣传教育公众，以提高对PFAS挑战和解决这些问题的努力的认识。这些努力将提高国家的科学素养，同时对公众进行重要健康问题的教育。这项职业提案的目标是确定PFAS与土壤中有机质相互作用的机制。这将使用一系列传统和新颖的分析方法来实现，以评估有机物，阳离子和PFAS如何通过一个框架，包括溶液相络合和积累在空气-水和固体-水界面相互作用。从这项研究中获得的机制的见解可以解释以前观察到的吸附分布和速率常数值的变化。拟议的工作将结合联合收割机批，静态柱，和流通柱实验，以评估PFAS运输从近地表源通过包气带和饱和地下水。一个理想化的多孔介质系统将使用聚合物涂层珠，其中的聚合物将被用作均匀的定义明确的土壤有机质代理。机制的见解将通过使用有机物代理阐明化学部分如何影响PFAS有机物的相互作用。PFAS与溶解有机物的络合和阳离子结合常数将基于尺寸排阻色谱中的共洗脱来确定。将使用液滴接触角结合在排水和二次吸胀模式下操作的堆叠多环静态柱来评估空气-水界面累积。最后，将使用连续流出物分析（通过高分辨率质谱法）完成PFAS在流通柱中的运输，以定量柱流出物中的PFAS浓度。该项目包括一个多组成部分的推广工作：1）教育活动将侧重于推广到初中和高中学生，2）从一系列学科的本科生的研究机会，和3）在研究生的多学科思维的发展。这些努力将通过提高科学素养和增强国家的STEM劳动力来造福国家。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Poly and perfluoroalkyl substances (PFAS) are man-made chemicals. PFAS have been used in a variety of products due to their stability and other valuable chemical properties. However, PFAS this stability also makes PFAS difficult to biodegrade in the environment. In addition, their properties also pose a threat to human health and the environment. It is estimated that over six million Americans have been exposed to PFAS in the water supply, and PFAS is considered one of the most important issues in environmental contamination facing the Nation. This concern results from studies that have shown that some PFAS can enter and remain in the human body, potentially causing cancer and other health problems. This knowledge has led to many efforts to treat water sources to remove PFAS when discovered. Pumping and treatment of groundwater is one of these commonly used treatment approaches. While this approach has worked for some pollutants, the PFAS movement in groundwater is difficult to predict because we do not fully understand the interactions between PFAS and natural organic matter (NOM) present in soil. The goal of this CAREER project is to address this knowledge gap by investigating the interactions of NOM and PFAS. This will be achieved through a series of experiments with well characterized model systems. Understanding this process will allow us to improve groundwater treatment systems to protect human health. This work will be used to educate the public through outreach to increase awareness of PFAS challenges and efforts to address these concerns. These efforts will increase the scientific literacy of the Nation while educating the public on important health issues.The goal of this CAREER proposal is to identify the mechanisms of PFAS interactions with organic matter in soils. This will be achieved using a range of conventional and novel analytical approaches to assess how organic matter, cations, and PFAS interact through a framework including solution phase complexation and accumulation at air-water and solid-water interfaces. Mechanistic insights gained from this research could explain previously observed variability in sorption distributions and rate constant values. The proposed work will combine batch, static column, and flow-through column experiments to assess PFAS transport from a near surface sources through the vadose zone and saturated groundwater. An idealized porous media system will be created using polymer-coated beads, where the polymers will be employed as homogeneous well-defined soil organic matter proxies. Mechanistic insights will be enabled through the use of organic matter proxies to elucidate how chemical moieties affect PFAS-organic matter interactions. PFAS complexation by dissolved organic matter and cation binding constants will be determined based on co-elution in size exclusion chromatography. Air-water interfacial accumulation will be evaluated using droplet contact angle coupled with stacked multi-ring static columns operated in drainage and secondary imbibition modes. Finally, PFAS transport in flow-through columns will be completed using continuous effluent analysis by high resolution mass spectrometry to quantify PFAS concentrations in the column effluent. The project includes a multi-component outreach effort: 1) educational activities will focus on outreach to middle and high school students, 2) research opportunities for undergraduate students from a range of disciplines, and 3) development of multi-disciplinary thinking in graduate students. These efforts will benefit the Nation through increased scientific literacy and enhancement of the Nation’s STEM workforce.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.