Fluorine mass balance exposes intrinsic PFAS and precursor content in geosynthetics used in landfill systems

Per- and polyfluoroalkyl substances (PFAS) are persistent contaminants widely detected in landfill leachates, yet infrastructure materials themselves have not been comprehensively evaluated as potential intrinsic sources of PFAS. This study provides the first integrated fluorine mass-balance assessment of geosynthetics used in landfill liner and cover systems. Twenty-two targeted PFAS were quantified across 26 materials, including polyester and polypropylene geotextiles and a polyethylene coating, alongside total oxidisable precursor (TOP) assays and total fluorine (TF) analysis. Ultra-short-chain PFAS, particularly pentafluoropropionic acid (PFPrA) and trifluoroacetic acid (TFA), were frequently detected. Across material types, the summed targeted PFAS concentrations varied considerably, reaching up to 33.51 μg/g in nonwoven polypropylene geotextiles, compared to a maximum of 2.21 μg/g in nonwoven polyester geotextiles, up to 2.18 μg/g in woven polypropylene geotextiles, and 3.69 μg/g in the polyethylene coating. The polyethylene coating showed the largest response to precursor oxidation among all materials tested, with PFAS concentrations rising nearly tenfold and perfluorobutanesulfonic acid (PFBS) as the dominant post-oxidation compound. Across materials with detectable total fluorine, targeted PFAS accounted for less than 16% of the measured total fluorine, indicating that the majority of fluorinated content is present in non-target or polymeric fluorinated forms not captured by conventional monitoring. These findings demonstrate that certain geosynthetics used in landfill systems contain embedded PFAS and precursor inventories that may influence facility-scale fluorine mass balances, emphasising the importance of material-level PFAS characterisation in regulatory frameworks for waste containment. While the results are specific to the materials analysed herein, they highlight the need for a broader evaluation of infrastructure materials used in waste containment systems.