Legacy and Emerging Per- and Polyfluoroalkyl Substances in a Subtropical Marine Food Web: Suspect Screening, Isomer Profile, and Identification of Analytical Interference

The ban/elimination of legacy per- and polyfluoroalkylsubstances(PFASs) has led to a dramatic increase in the production and use ofvarious emerging PFASs over the past decade. However, trophodynamicsof many emerging PFASs in aquatic food webs remain poorly understood.In this study, samples of seawaters and marine organisms including15 fish species, 21 crustacean species, and two cetacean species werecollected from the northern South China Sea (SCS) to investigate thetrophic biomagnification potential of legacy and emerging PFASs. Bis-(trifluoromethylsulfonyl)-imidewas found in seawater via suspect screening (concentration up to 1.50ng/L) but not in the biota, indicating its negligible bioaccumulationpotential. A chlorinated perfluorooctane sulfonate (PFOS) analyticalinterfering compound was identified with a predicted formula of C14H23O5SCl6 (-) (most abundant at m/z = 514.9373).Significant trophic magnification was observed for 22 PFASs, and thetrophic magnification factors of cis- and trans-perfluoroethylcyclohexane sulfonate isomers (1.92and 2.25, respectively) were reported for the first time. Perfluorohexanoicacid was trophic-magnified, possibly attributed to the PFAS precursordegradation. The hazard index of PFOS was close to 1, implying a potentialhuman health risk via dietary exposure to PFASs in seafood on thepremise of continuous PFAS discharge to the SCS. Trophodynamics of perfluoroethylcyclohexanesulfonate isomersin a marine food web are reported for the first time. We found that6:2 and 8:2 chlorinated polyfluorinated ether sulfonates exhibitedhigher trophic magnification factors than all perfluorooctane sulfonate(PFOS) isomers. A chlorinated PFOS analytical interference compoundwas identified.