Environmental per- and polyfluoroalkyl substance (PFAS) contamination is a concern at hundreds of Department of Defense (DoD) sites with historical use of aqueous film forming foam (AFFF). Since the major pathways for transport of PFASs in the environment are via stormwater runoff and contaminated groundwater plumes that may feed into nearby lakes and streams, it is critical for DoD to understand the ecological and human health risks associated with the presence of PFASs in aquatic habitats. The overarching goal of this project is to improve the understanding of the pathways and rates of uptake, bioaccumulation and biomagnification of subsurface-derived PFASs within warm water stream ecosystems. Three complementary studies are included in this project consisting of field observations from PFAS-contaminated streams, followed by controlled laboratory and mesocosm studies designed to evaluate environmental factors that may impact PFAS transfer among hypothesized pathways. These studies aim to achieve the following three objectives: 

1. Assess the bioavailability, bioaccumulation and biomagnification of a mixture of PFAS constituents throughout the aquatic food web of a warm water stream contaminated with PFASs attributed to AFFF-impacted groundwaters.
2. Quantify the effect of key physical and geochemical factors on the bioavailability and uptake rates of sediment-derived PFASs from sediment and water to select lower trophic-order organisms.
3. Quantify rates of PFAS transfer along controlled primary and trophic pathways, including uptake, excretion and trophic transfer by select aquatic species representing multiple trophic levels and degrees of sediment association. This includes sediment and water exposure directly to higher trophic-level organisms.

The experimental approach consists of three comparative field and controlled studies investigating the pathways and rates by which subsurface-derived PFASs are taken up by and transferred through warm-water stream food webs. The three studies consist of 1) a comparative field study investigating primary uptake and biomagnification of PFASs through the full food web of a PFAS contaminated stream, 2) a controlled experiment investigating geochemical and physical controls on primary passive vs. active uptake pathways, and 3) a controlled trophic experiment, investigating bioaccumulation and biomagnification along key, defined primary uptake and trophic transfer pathways.

The results produced from this project would be useful in quantitatively predicting and assessing the risks of PFASs to aquatic wildlife and humans at DoD sites where streams and rivers are affected by AFFF-use. In particular, the field component will provide insight into the extent and pathways of PFAS uptake and transfer within aquatic food webs of streams, assisting in identifying trophic levels, habitats and species most threatened by PFASs, potential pathways for human exposure, and inform which individual or mixtures of PFASs are important for ecological risk assessment. The controlled-laboratory experiment will provide estimates of bioconcentration factors and bioacummulation factors of different PFAS under different physical and geochemical factors. The findings from the controlled trophic transfer mesocosm studies (combined with the field study) will generate useful information on the magnitude of how PFASs biomagnify up the food chain to fishes that may be consumed by humans (i.e., via trophic magnification factors, TMFs).

Lewis, A.J., X. Yun, D. Spooner, M. Kurz, E. McKenzie, C. Sales. 2022. Exposure Pathways and Bioaccumulation of Per-and Polyfluoroalkyl Substances in Freshwater Aquatic Ecosystems: Key Considerations. Science of the Total Environment, 822. https://doi.org/10.1016/j.scitotenv.2022.153561