Submarine Groundwater Discharge: A Major and Overlooked Source of Per- and Polyfluoroalkyl Substances to Coastal Oceans

The quantification of 78 PFAS in 12 classes was conducted using an ultra-high performance liquid chromatography coupled with a triple quadrupole mass spectrometry (UPLC-MS/MS, Triple Quad™ 6500 plus, AB SCIEX, MA, USA). The 12 classes included two legacy PFAS classes: (i) perfluorocarboxylic acids (PFCA) and (ii) perfluorosulfonic acids (PFSA), alongside ten novel classes: (iii) fluorotelomer sulfonates (FTSA), (iv) fluorotelomer acids (FTCA & FTUCA), (v) perfluoroalkane sulfonamides and their derivatives (FASA & derivatives), (vi) fluorinated phosphonic and phosphinic derivatives (PFPA & PFPiA), (vii) perfluoroalkyl ether carboxylic acids (PFECA), (viii) perfluoroalkyl ether sulfonic acids (PFESA), (ix) aqueous film forming foam compounds (AFFF-related PFAS), (x) omega monochlorine-substituted PFCA and PFSA (Cl-PFAS), (xi) omega monohydrogen-substituted PFCA (H-PFCA), and (xii) perfluorodicarboxylic acids (PFdiCA). Detailed chemical information, the solid-phase extraction (SPE) methodology and instrument methods are provided in the Supporting Information.