“Development and Field-Testing of Advanced Passive Samplers for PFAS” by Dr. Rainer Lohmann (SERDP Project ER20-1293)
The focus of this project is to develop and validate simple and reliable passive samplers for PFAS in water, which supports the DoD’s need to make informed decisions on the extent and magnitude of per- and polyfluoroalkyl substances (PFAS) contamination. Three different passive sampler types were evaluated to determine dissolved concentrations of PFAS in groundwater, surface water (fresh and salt water), and porewater, while representative sorbents were characterized for PFAS uptake. This presentation will review the benefits and drawbacks of the different passive sampler types and outline planned work, focusing on two of the three passive samplers. One passive sampler is a quickly equilibrating (24 hours) graphene monolith (GM) passive sampler. This sampler was produced, optimized with chemical modification of its surface, and validated for dissolved PFAS in surface water and porewater. A second sampler, a sorbent-filled porous polyethylene tube sampler, remained in the linear uptake phase for several weeks, and its sampling rate was mostly unaffected by differing water flow effects in surface waters. Site managers and risk assessors can utilize these passive samplers to derive representative exposure concentrations for sound risk assessment. The passive samplers can either derive time weighted average PFAS concentrations in water, which is highly relevant for exposure and risk assessment, or deliver equilibrium concentrations to map out pollution hotspots.
“Vertebrae™ Segmented Wells for Monitoring PFAS Mass Flux/Discharge” by by Dr. Craig Divine (SERDP Project ER20-5026)
Contaminant mass flux/discharge is used to characterize sources and transport pathways and quantify groundwater plume behavior. It provides a framework for prioritizing sources, evaluating remedy options, and focusing remedial approaches. Consequently, long-term mass flux/discharge reduction is increasingly a key performance goal for remedial strategies. Methods are therefore needed to reliably measure mass flux/discharge trends over time. The purpose of this field demonstration is to assess the Vertebrae™ well system (VWS) for reliable PFAS mass flux/discharge in groundwater downgradient of a former source area at a PFAS-impacted site. The VWS contains multiple isolated screen segments and functions as a multi-port well installed horizontally. Multiple 500-foot long VWSs were successfully installed in a transect orientation within target high permeability and high concentrations zones. Multiple techniques were compared to measure groundwater flux including active fiber optic distributed temperature sensing, single-well tracer testing, and pneumatic hydraulic testing. Overall, the VWS provided robust and repeatable PFAS mass flux/discharge estimates over time, with variability in magnitude correlated to seasonal groundwater dynamics. The technology is applicable to any type of groundwater contaminant and can support more reliable risk assessment, remedy performance assessment, and optimization activities. Lessons learned and best practices will be shared.
Dr. Rainer Lohmann is a Professor at the University of Rhode Island’s Graduate School of Oceanography in Narragansett, RI. His research focuses on the detection, fate, and transport of anthropogenic pollutants in the environment, often relying on passive samplers in the process. Dr. Lohmann is Director of the NIEHS-funded URI Superfund Research Program Center on the Sources, Transport, Exposure and Effects of PFAS (STEEP), and PI on several SERDP projects focused on assessing PFAS detection tools and bioaccumulation processes. Since 2000, he has published over 180 publications and book chapters. He is a member of the Executive Committee of the U.S. EPA’s Board of Scientific Counselors, and serves as editor of Environmental Toxicology and Chemistry. Dr. Lohmann was awarded a Fulbright Fellowship as part of the Fulbright Arctic Initiative III in 2020, and an Alexander-von-Humboldt Fellowship in 2011. He received a degree in Chemical Engineering from EHICS (Strasburg, France) and a doctoral degree in Environmental Science from Lancaster University (United Kingdom).
Dr. Craig Divine is a National Technical Expert and Senior Vice President at Arcadis. He has 25 years of experience characterizing and remediating PFAS, chlorinated solvents, metals, and petroleum hydrocarbons utilizing a wide range of technologies, including in situ bioremediation, chemical oxidation, air sparging, cosolvent flushing, soil mixing, and dynamic groundwater recirculation. He has co-authored about 50 scientific papers on these topics, and is an Associate Editor for Groundwater Monitoring & Remediation and Remediation Journal. He currently serves as a principal investigator on projects to develop and demonstrate the Sentinel™ passive sampler and HRX Well® technologies for PFAS monitoring and treatment. Dr. Divine received a bachelor's degree in biology from Wheaton College, a master's degree in watershed science from Colorado State University, and a doctoral degree in geochemistry and hydrogeology from the Colorado School of Mines.