The influence of environmental processes coupled to their attending changes in physical and chemical factors to modulate the fate, transport, and bioavailability of legacy chemicals has long been recognized as important by the scientific community; such information is critically needed for per- and polyfluoroalkyl substances (PFAS) mitigation in aquatic systems. A better understanding of the environmental factors that govern the ultimate movement of chemicals between abiotic and biotic compartments—generally termed the biogeochemistry of the system—is essential. While the consideration of biogeochemistry for linking chemical concentrations in biota to their environment has been applied to other chemicals such as polychlorinated biphenyls (PCBs) and metals, this type of information and conceptual understanding is lacking for PFAS. 

This project will develop an improved understanding of PFAS bioaccumulation in site-related biota and will produce a protocol for the collection and analysis of bioaccumulation of PFAS into fish in surface waters. The study design uses a protocol for evaluating and estimating bioaccumulation initially developed on the Berry’s Creek Study Area (BCSA), an Environmental Protection Agency (EPA) Superfund site. This protocol was a factor in moving the remedial work at the BCSA site into an adaptive management framework. The ability to link observed concentrations of PFAS in site-associated biota to their environment is critical to selecting remedial actions, establishing cleanup levels, and determining the remedial effectiveness for installations impacted by PFAS.

Due to the unique chemical properties of PFAS, the evaluation of PFAS bioaccumulation and toxicity requires consideration of both phase distribution and speciation. PFAS will accumulate and affect organisms differently depending on the bioavailability of each species and their toxic potential. The current approach to estimate bioaccumulation is to calculate a ratio between concentrations measured in biota to those in the relevant abiotic media (soil, sediment, surface water). These ratios or bioaccumulation factors are then used in risk calculations and—for some sites—to derive cleanup levels. Given the complexities of PFAS chemistries, including aqueous film-forming foam (AFFF) mixtures, potential degradation and transformation products, and site-specific environmental conditions, this simple ratio-based approach is insufficient for understanding the link between the underlying geochemical conditions that influence PFAS mobility across environmental media and biota.

To address these issues, work is needed to:

• Implement a field process that provides a consistent selection of measurements and generates spatially coherent results.
• Determine bioaccumulation on a chemical- and species-specific basis, using a statistical framework without the assumptions inherent in a simple ratio-based approach.
• Follow a protocol for analyzing results that integrates site-specific geochemistry and abiotic factors that modulate and/or drive PFAS bioaccumulation in aquatic ecological receptors.

This demonstration will provide both practical and conceptual benefits. The final product will be a guide for conducting field studies and a protocol for estimating bioaccumulation of PFAS in fish that provides a framework for integrating site-specific geochemistry. The clear procedure presented in this document will ensure consistency in study measures, data analysis, and, most importantly, a means to account for site-specific conditions. Successful completion of this demonstration will ultimately lead to more cost effective PFAS management, directly benefiting the warfighter and installation communities. (Anticipated Project Completion - 2027)