Poly- and Perfluoroalkyl Substances in Seawater and Plankton from the Northwestern Atlantic Margin
By Xianming Zhang, Rainer Lohmann, and Elsie M. Sunderland
Environ Sci Technol.
December 3, 2019
The ocean is thought to be the terminal sink for poly- and perfluoroalkyl substances (PFAS) that have been produced and released in large quantities for more than 60 years. Regulatory actions have curbed production of legacy compounds such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), but impacts of regulations on PFAS releases to the marine environment are poorly understood. Here, we report new data for 21 targeted PFAS in seawater and plankton from the coast, shelf, and slope of the Northwestern Atlantic Ocean. We find strong inverse correlations between salinity and concentrations of most PFAS, indicating that ongoing continental discharges are the major source to the marine environment. For legacy PFAS such as PFOS and PFOA, a comparison of inland and offshore measurements from the same year (2014) suggests that there are ongoing releases to the marine environment from sources such as submarine groundwater discharges. Vertical transport of most PFAS associated with settling particles from the surface (10 m) to deeper waters is small compared to advective transport except for perfluorodecanoic acid (PFDA; 35% of vertical flux) and precursor compounds to PFOS (up to 86%). We find higher than expected bioaccumulation factors (BAFs = Cplankton/Cwater) for perfluorinated carboxylic acids (PFCAs) with five and six carbons (log BAF = 2.9-3.4) and linear PFOS (log BAF = 2.6-4.3) in marine plankton compared to PFCAs with 7-11 carbons. We postulate that this reflects additional contributions from precursor compounds. Known precursor compounds detected here have among the highest BAFs (log BAF > 3.0) for all PFAS in this study, suggesting that additional research on the bioaccumulation potential of unknown organofluorine compounds is urgently needed.