The major objective of this project is the evaluation of the bioaccumulation, biotransformation and biomagnification of per- and polyfluoroalkyl substances (PFAS) in plankton at the base of the marine food web. Specifically, the project team will derive the uptake, transformation, and bioaccumulation of PFAS in marine phytoplankton (trophic level 1), zooplankton (trophic level 2), and fish, with a focus on understanding the uptake of PFAS at the base of marine food webs. This project is based on the notion that a proper understanding of PFAS behavior at the base of the food web is needed before food web modelling should be undertaken.

Prior data implied enhanced bioaccumulation of PFAS in plankton, likely due to transformation of precursor compounds; this project will disentangle the role of biotransformation versus bioaccumulation of terminal perfluoroalkyl acid (PFAA) in plankton, and undertake target laboratory studies with phytoplankton, zooplankton on their own, and combined to decipher the enrichment of PFAAs from one trophic level to the next, before performing extensive field-based studies covering trophic levels from plankton to top predators. The main objectives are:

• Determine the uptake, transformation, and bioconcentration of PFAS in phytoplankton.
• Determine the uptake, transformation, and bioconcentration of PFAS in zooplankton.
• Assess bioaccumulation and magnification of PFAS from phyto- to zooplankton.
• Evaluate bioaccumulation and biomagnification of PFAS from plankton to fish in Narragansett Bay, and at a coastal site impacted by aqueous film-forming foam (AFFF).

The following tasks will be conducted to address the project objectives:

• Establish pure phytoplankton cultures (trophic level 1), and dose with (a) PFAA to determine bioconcentration; (b) precursor compounds to assess metabolism to and accumulation of terminal PFAA; and (c) AFFF to mimic complex exposure.
• Establish a zooplankton culture (trophic level 2), and dose with (a) PFAA to determine bioconcentration; (b) precursor compounds to assess metabolism and accumulation of terminal PFAA; and (c) AFFF to mimic complex exposure.
• Conduct laboratory experiments to determine bioaccumulation and biomagnification in zooplankton being fed PFAS-containing phytoplankton.
• Extend the field assessment of PFAS bioaccumulation and magnification from plankton to fish in Narragansett Bay, collecting water, plankton, and fish.

This work is significant to site managers by (1) improving understanding of the basic nature of bioaccumulation and biomagnification at the bottom of the food web in both laboratory and field; (2) shedding light on the importance of precursor transformation for the presence of terminal PFAA in biota, which needs to be assessed to properly derive the enrichment of PFAS in food webs; and (3) focusing on extractable organofluorine, its potential formation and uptake by biological samples. This will help understand the presence of unaccounted PFAS.