Formation of perfluorinated surfactants from precursors by indigenous microorganisms in groundwater

•The formation of PFSs from precursors was measured in incubation tests.•Indigenous microorganisms in groundwater biodegraded FOSA to PFOS.•Addition of nutrients and soil promoted the formation of PFOS.•PFSs were formed from precursors in street runoff by microorganisms in groundwater.•PFS precursors were more abundant in street runoff than in wastewater effluent.

The formation of perfluorinated surfactants (PFSs) from their precursors in waters is of concern. In this study, the formation of PFSs through biodegradation of precursors was measured in incubation tests. Indigenous microorganisms in groundwater were able to biodegrade perfluorooctane sulfonamide (FOSA) to yield perfluorooctane sulfonate (PFOS). The addition of nutrients and soil promoted the formation. A 42-d incubation test using sources of groundwater recharge showed that PFOS, perfluorooctanoate, and perfluorononanoate were significantly and remarkably (⩾1.5×) formed from precursors in street runoff through biodegradation, but not in rainwater or wastewater effluent. Significant formation of PFSs from precursors in street runoff was observed.