Table 1.
Summary of Strategic Environmental Research and Development Program–funded projects related to per‐ and polyfluoroalkyl substance fate and transport
| Project title | Primary objectives | Project a |
|---|---|---|
| Behavior of Perfluoroalkyl Chemicals in Contaminated Groundwater b | The overall goal of this pioneering research was to evaluate the relative importance of key physicochemical and biological parameters in determining the fate and transport of PFAAs in groundwater in the presence of cocontaminants and during remediation of cocontaminants. | ER‐2126 |
| Characterization of the Fate and Biotransformation of Fluorochemicals in AFFF‐Contaminated Groundwater at Fire/Crash Testing Military Sites b | The overall goals of this pioneering research were to identify individual PFAS and their oxidizable precursors in AFFF formulations and AFFF‐contaminated groundwater, sediment, and soil and to carry out biotransformation studies to determine precursor biodegradation pathways in AFFF‐contaminated media. | ER‐2128 |
| Key Fate and Transport Processes Impacting the Mass Discharge, Attenuation, and Treatment of Poly‐ and Perfluoroalkyl Substances and Comingled Chlorinated Solvents or Aromatic Hydrocarbon c | Specific objectives of this project include 1) investigation of the fundamental mechanisms controlling the release of PFAS from complex source zone phases, 2) examination of the coupled diffusion and potential abiotic reactions of PFAS and comingled contaminants in low‐permeability materials, 3) assessment of the biotic transformation of the wide range of PFAS and cocontaminants (chlorinated solvents and BTEX) present in the dissolved plume and the impacts of PFAS on cocontaminant bioremediation, and 4) quantification of the impacts of remedial activities targeting cocontaminants (i.e., BTEX, chlorinated solvents) on the PFAS plume. | ER‐2720 |
| Insights into the Long‐Term Mass Discharge & Transformation of AFFF in the Unsaturated Zone c | Field and laboratory data are being used to elucidate processes affecting PFAS transformation and mass discharge of AFFF from vadose zone sources over time. Efforts employ the use of a highly characterized and instrumented field test cell emplaced within an aged unsaturated zone AFFF source zone. The test cell is used to facilitate enhanced water flushing of the unsaturated zone source, thereby serving as a means to evaluate PFAS discharge, composition, and transformation as a function of time and fractional PFAS removal. Parallel bench‐scale testing is being performed to provide additional mechanistic insight needed to interpret the field results—specifically, to assess soil desorption kinetics, PFAS partitioning to natural colloids, micellar PFAS mass discharge, and PFAA precursor transformation under cyclic aerobic–anaerobic conditions. | ER18‐1204 |
| Establishment of Fate and Transport Mechanics for PFAS under Controlled Aquifer Conditions and Correlation to Existing Data c | The technical objective of this project is to utilize a scaled aquifer, where chemistry and aquifer conditions can be controlled, to determine relevant factors controlling the transport of PFAS in the subsurface. | ER18‐1621 |
| Development and Laboratory Validation of Mathematical Modeling Tools for Prediction of PFAS Transformation, Transport, and Retention in AFFF Source Areas c | This project integrates experimental and modeling data designed to 1) improve understanding of sequestration mechanisms and abiotic/biotic transformations controlling transport and persistence of selected PFAS and 2) develop and validate mathematical models on the processes governing transformation, transport, and retention of PFAS in AFFF source areas. Laboratory experiments on the transport and partitioning experiments and coupled abiotic and biotic transformations will provide data necessary to develop and validate mathematical modeling tools. | ER18‐1149 |
| A Mechanistic Understanding of PFAS in Source Zones: Characterization and Control c | The study is designed to identify fundamental mechanisms controlling the nature and permanence of PFAS interactions with components of source zone soils/sediments under unsaturated and saturated conditions and in the presence of NAPL. Controlled laboratory column experiments will characterize the transport of anionic, cationic, and zwitterionic PFAS and their interactions with organic matter and mineral phases of pristine soils/sediments and with PFAS‐coated soils/sediments. Additional experiments will be done to characterize the number and type of thermodynamically stable phases that form when AFFFs are mixed with common NAPLs, such as JP4 and trichloroethene, and their impact on PFAS transport under saturated conditions. These data will be used then to assess PFAS mobility under unsaturated conditions in the vadose zone to identify the key hydraulic parameters that control PFAS mobility and retention. | ER18‐1259 |
| Evaluating the Importance of Precursor Transport and Transformation for Groundwater Contamination with PFAS c | Mobility of PFAS and PFAA precursors in groundwater is being evaluated through a series of controlled column experiments. Partition coefficients for PFAS, with a focus on geochemical conditions that may affect mobility of PFAS, will be determined. Biotransformation of PFAA precursors will be examined to determine rates and natural factors that can affect conditions. Quantifying these conditions and reaction rates will contribute to the development of a reactive transport model. Passive sampling methods are also being developed that will provide time‐weighted average concentrations of PFAS traveling from the source unsaturated zone to the groundwater and monthly average PFAS concentrations and correlations with seasonal and associated geochemical variations in surface waters. | ER18‐1280 |
| Baseline Data Acquisition and Numerical Modeling to Evaluate the Fate and Transport of Per‐ and Polyfluoroalkyl Substances within the Vadose Zone c | Specific objectives of this proof‐of‐concept project include 1) to generate fundamental physicochemical properties data with which to evaluate the significance of air–water interfacial accumulation as a source of retention and as an environmental sink for PFAS, 2) to investigate the potential for interfacial tension‐induced flow and lateral spreading of PFAS in the vadose zone to determine whether these processes could increase the scale of PFAS contamination, and 3) to incorporate these mechanisms into the current version of the commercially available HYDRUS unsaturated flow and transport model. | ER18‐1389 |
| Development and Validation of Novel Techniques to Assess Leaching and Mobility of Per and Polyfluoroalkyl Substances (PFAS) in Impacted Media d | The overarching goal of this project is to develop a framework for evaluation and prediction of the release of PFAS from AFFF‐impacted media. The specific objectives include 1) development of a standard leaching assessment methodology for AFFF‐impacted media; 2) utilization of approaches including HRMS, mid‐infrared spectroscopy, and chemometrics to evaluate and develop a predictive model of PFAS sorption and desorption to AFFF‐impacted media; and 3) comparison of results of laboratory testing to leaching and mobility under field‐relevant conditions to develop an approach for translation of bench‐scale test results to site‐scale implications. | ER20‐1126 |
| Improving Access and Utility of Analytical Data for the Confident Discovery, Identification, and Source‐Attribution of PFAS in Environmental Matrices d | The objective of the proposed research is to develop a data analytics infrastructure to contain PFAS mass spectral information and metadata of detected PFAS. With an open database structure, analytical laboratories will be able to include this database in their nontargeted analytical analysis workflow to identify unknown PFAS. | ER20‐1056 |
| Establishing an Approach to PFAS Forensics and a PFAS Source Materials Forensic Library d | The overall objective of this work is to provide a framework for PFAS forensics in environmental samples. The 3 steps to achieving this objective include 1) establishing a PFAS forensic library of source materials; 2) validating PFAS forensic approaches using environmental samples and determining the extent to which forensic information is preserved in environmental samples, and 3) characterizing changes to select PFAS forensic signatures associated with environmental fate and transport. | ER20‐1121 |
| Machine Learning Pattern Recognition for Forensic Analysis of Detected Per‐ and Polyfluoroalkyl Substances in Environmental Samples d | This 1‐yr project will explore the use of modern machine learning algorithms to evaluate the probability that PFAS in environmental samples come from AFFF sources. The approach will use machine learning to search for recognizable patterns in PFAS‐containing samples, with the objective of assigning probabilities that the contamination originates from specific sources. | ER20‐1205 |
| Ultrahigh‐Resolution Fourier‐Transform Ion Cyclotron Resonance Mass Spectrometry for Fingerprinting, Source Tracking, and Allocation of Per‐ and Polyfluoroalkyl Substances (PFAS) d | The overarching objective of this 1‐yr project is to apply ultrahigh‐resolution Fourier transform ion cyclotron resonance mass spectrometry to identify compounds in AFFFs at the molecular level that can be used to guide the development of novel analytical approaches to identify unique marker compounds for AFFF “fingerprinting” and PFAS source allocation and to catalogue PFAS associated with AFFF releases. | ER20‐1265 |
| A Simple and Robust Forensic Technique for Differentiating PFAS Associated with AFFF from other PFAS Sources d | This project consists of the following 3 specific objectives: 1) expand the total oxidizable precursor assay to obtain more detailed information on polyfluorinated compounds present at contaminated sites to support a proposed forensic tool, 2) identify data that are most useful to the analysis of PFAS source fingerprints, and 3) assess the effect of environmental processes (e.g., biotransformation, sorption) on observed fingerprints at AFFF‐impacted sites. | ER20‐1330 |
| Comprehensive Forensic Approach for Source Allocation of Poly‐ and Perfluoroalkyl Substances d | This project will develop a set of tools for use in forensic PFAS source allocation, including 1) a database of PFAS and other chemical constituents observed in discrete PFAS sources (i.e., landfill leachate, municipal wastewater effluent, chromium plating, etc.), 2) a comprehensive PFAS transformation pathway map to establish the context and linkages between specific PFAS and discrete sources, 3) a multivariate analysis resulting in an LC‐MS/MS‐based “forensic LC‐MS/MS PFAS panel” for use in PFAS source allocation, and 4) a curated HRMS PFAS library to enable more precise source allocations when needed. | ER20‐1375 |
a
Web links to project summaries are provided as available.
b
Completed projects.
c
Ongoing projects.
d
New‐start projects.
AFFF = aqueous film–forming foam; BTEX = benzene, toluene, ethylbenzene, and xylene; HRMS = high‐resolution mass spectrometry; NAPL = nonaqueous phase liquids; PFAA = perfluoroalkyl acid; PFAS = per‐ and polyfluoroalkyl substances.