Target, Nontarget, and Suspect Screening and Temporal Trends of Per- and Polyfluoroalkyl Substances in Marine Mammals from the South China Sea

Per- and polyfluoroalkyl substances (PFASs) have been manufactured and widely used for over 60 years. Currently, there are thousands of marketed PFASs, but only dozens of them are routinely monitored. This work involved target, nontarget, and suspect screening of PFASs in the liver of Indo-Pacific humpback dolphin (Sousa chinensis) and finless porpoise (Neophocaena phocaenoides), two resident marine mammals in the South China Sea, stranded between 2012 and 2018. Among the 21 target PFASs, perfluorooctane sulfonate and 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFESA) predominated in the samples, accounting for 46 and 30% of the total PFASs, respectively. Significantly higher total target PFAS concentrations (p < 0.05) were found in dolphin liver samples [3.23 X 10(3) +/- 2.63 X 10(3) ng/g dry weight (dw)] than in porpoise liver samples (2.63 x 10(3) +/- 1.10 x 10(3) ng/g dw). Significant increasing temporal trends (p < 0.05) were found in the concentrations of two emerging PFASs, perfluoroethylcyclohexane sulfonate and 2,3,3,3-tetrafluoro-2-propanoate in porpoises, indicating increasing pollution by these emerging PFASs. Forty-four PFASs from 9 classes were additionally identified by nontarget and suspect screening, among which 15 compounds were reported for the first time in marine mammals. A primary risk assessment showed that the emerging PFAS 6:2 Cl-PFESA could have possible adverse effects in terms of reproductive injury potential on most of the investigated cetaceans.

Automated summary

The study conducted target, nontarget, and suspect screening of PFASs in the liver of Indo-Pacific humpback dolphins and finless porpoises stranded in the South China Sea between 2012 and 2018. Perfluorooctane sulfonate and 6:2 Cl-PFESA were the predominant PFASs found, with significantly higher concentrations in dolphin liver samples than porpoise liver samples. Temporal trends indicated increasing pollution by emerging PFASs, and a risk assessment highlighted potential reproductive injury from the emerging PFAS 6:2 Cl-PFESA in cetaceans.