title: Generation of Perfluoroalkyl Acids from Aerobic Biotransformation of Quaternary Ammonium Polyfluoroalkyl Surfactants.
abstract: The aerobic biotransformation over 180 days of two cationic quaternary ammonium compounds (QACs) with perfluoroalkyl chains was determined in soil microcosms, and biotransformation pathways were proposed. This is the first time that polyfluoroalkyl cationic surfactants used in aqueous film-forming foam (AFFF) formulations were studied for their environmental fate. The biotransformation of perfluorooctaneamido quaternary ammonium salt (PFOAAmS) was characterized by a DT50 value (time necessary to consume half of the initial mass) of 142 days and significant generation of perfluoroalkyl carboxylic acid (PFOA) at a yield of 30 mol % by day 180. The biotransformation of perfluorooctane sulfonamide quaternary ammonium salt (PFOSAmS) was very slow with unobservable change of the spiked mass; yet the generation of perfluorooctanesulfonate (PFOS) at a yield of 0.3 mol % confirmed the biotransformation of PFOSAmS. Three novel biotransformation intermediates were identified for PFOAAmS and three products including perfluorooctane sulfonamide (FOSA) for PFOSAmS through high-resolution mass spectrometry (MS) analysis and t-MS(2) fragmentation. The significantly slower PFOSAmS biotransformation is hypothesized to be due to its stronger sorption to soil owing to a longer perfluoroalkyl chain and a bulkier sulfonyl group, when compared to PFOAAmS. This study has demonstrated that despite overall high stability of QACs and their biocide nature, the ones with perfluoroalkyl chains can be substantially biotransformed into perfluoroalkyl acids in aerobic soil.
authors.affiliation: Department of Civil Engineering, McGill University , Montreal, Quebec H3A 0C3, Canada.
authors.forename: Sandra
authors.initials: S
authors.lastname: Mejia-Avendaño
authors.affiliation: Department of Chemistry, Université de Montréal , Montreal H3C 3J7, Canada.
authors.forename: Sung
authors.initials: S
authors.lastname: Vo Duy
authors.affiliation: Department of Chemistry, Université de Montréal , Montreal H3C 3J7, Canada.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Sauvé
authors.affiliation: Department of Civil Engineering, McGill University , Montreal, Quebec H3A 0C3, Canada.
authors.forename: Jinxia
authors.initials: J
authors.lastname: Liu
mesh_terms: D064751:Ammonium Compounds; D001711:Biotransformation; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D064751:Ammonium Compounds; D012987:Soil; D013501:Surface-Active Agents