The U.S. Department of Defense (DoD) aims to address widespread contamination by per- and polyfluoroalkyl substances (PFAS) due to the previous use of PFAS-containing aqueous film forming foams (AFFFs). The goal of this project is to develop and validate a robust, modular suite of quantitative passive sampling tools for a range of PFAS, including but not limited to, the 24 US Environmental Protection Agency analytes. Reliable, validated passive samplers and associated predictive uptake models for PFAS will:

• Provide a cost-effective quantitative technique that allows sensitive, time integrative monitoring of a wide range of PFAS, thereby facilitating study of their fate and transport, including transformation of perfluoroalkyl acid (PFAA) precursors in aqueous environments.
• Yield representative spatial and temporal contamination information enabling reliable prediction of plume movement and exposure risks for PFAS in dynamic systems and facilitating effective remediation and treatment.

Expected outcomes of this project include a suite of innovative, validated passive sampling technologies relevant to a wide range of chemicals and environments, together with best practice guidelines and interpretation tools for sampling of current and emerging PFAS of concern.

The project team hypothesize that AFFFs and industrial sources of PFAS contain complex mixtures of PFAS with a range of physico-chemical properties. The diversity of PFAS mixtures necessitates the use of diverse sorbent phases for passive samplers (e.g. hydrophilic-lipophilic balanced, ionic) and a comprehensive understanding of specific PFAS-sorbent interactions/kinetics. Furthermore, the project team hypothesize that environmental factors and co-contaminants influence PFAS uptake and accumulation in passive sampler sorbents. The three-year project will examine these hypotheses through assessing PFAS-sampler interactions using a systematic modular approach. A range of passive sampling components (e.g. sorbent phases, diffusive material) will be assessed for their effectiveness in the uptake of nonionic, anionic, and zwitterionic PFAS.

The project team will conduct initial laboratory sorption and diffusion studies to establish the necessary data (partition and diffusion constants, rate constants) to model PFAS uptake behavior. This will be followed by in-field calibration and validation trials of passive samplers in environmentally-relevant surface, (fresh, marine) and ground and waste water to characterize impacts of water quality and conditions (e.g. pH, dissolved organic matter, salinity, flowrate, temperature, co-contaminants). A recently piloted prototype PFAS passive sampler developed by the project team and calibrated for priority PFAS in groundwater at Department of Defence sites in Australia forms the basis of the experimental design.

This project aims to advance PFAS passive sampling methodology from a prototype research technology to a cost-effective, easy to use tool that is appropriate for AFFF-contaminated and other sites; produces results that are accurate, reproducible, and adaptable to new site conditions/new PFAS of concern; and can be standardized for use by a range of stakeholders. There is a critical need for improved sampling and analysis of PFAS. It also enables more cost effective management of such sites by facilitating a reliable and comprehensive assessment of the extent of PFAS contamination. A key component of this project will be to establish best practice sampler handling, deployment and storage protocols and guidance to ensure robust application of the developed technology.