Poly-\nand Perfluoroalkyl Substances in Seawater and\nPlankton from the Northwestern Atlantic Margin

The\nocean is thought to be the terminal sink for poly- and perfluoroalkyl\nsubstances (PFAS) that have been produced and released in large quantities\nfor more than 60 years. Regulatory actions have curbed production\nof legacy compounds such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic\nacid (PFOA), but impacts of regulations on PFAS releases to the marine\nenvironment are poorly understood. Here, we report new data for 21\ntargeted PFAS in seawater and plankton from the coast, shelf, and\nslope of the Northwestern Atlantic Ocean. We find strong inverse correlations\nbetween salinity and concentrations of most PFAS, indicating that\nongoing continental discharges are the major source to the marine\nenvironment. For legacy PFAS such as PFOS and PFOA, a comparison of\ninland and offshore measurements from the same year (2014) suggests\nthat there are ongoing releases to the marine environment from sources\nsuch as submarine groundwater discharges. Vertical transport of most\nPFAS associated with settling particles from the surface (10 m) to\ndeeper waters is small compared to advective transport except for\nperfluorodecanoic acid (PFDA; 35% of vertical flux) and precursor\ncompounds to PFOS (up to 86%). We find higher than expected bioaccumulation\nfactors (BAFs = Cplankton/Cwater) for perfluorinated carboxylic acids (PFCAs) with\nfive and six carbons (log BAF = 2.9–3.4) and linear PFOS (log\nBAF = 2.6–4.3) in marine plankton compared to PFCAs with 7–11\ncarbons. We postulate that this reflects additional contributions\nfrom precursor compounds. Known precursor compounds detected here\nhave among the highest BAFs (log BAF > 3.0) for all PFAS in this\nstudy,\nsuggesting that additional research on the bioaccumulation potential\nof unknown organofluorine compounds is urgently needed.