Australia-wide assessment of perfluoroalkyl substances (PFASs) in landfill leachates

•Spatio-temporal sampling of leachate was undertaken at 27 Australian landfills.•PFASs were detected in all landfills of various ages and waste types.•Five PFASs were detected at all sites, with PFHxA at highest concentrations.•Concentrations of several PFASs increased significantly with decreasing landfill age.•Increasing PFASs concentrations were associated with increasing pH and TOC. Leachate from 27 landfills was analysed for nine perfluoroalkyl substances (PFASs). Five PFASs were detected ubiquitously, with perfluorohexanoate (PFHxA) the predominant PFAS (mean 1700ng/L; range 73–25,000ng/L). Despite the complexity of landfill-specific factors, some general trends in PFAS concentrations were observed. Mean concentrations of eight PFASs were higher in operating landfills (or landfill cells) accepting primarily municipal waste, compared to closed municipal landfills. Landfills accepting primarily construction and demolition wastes produced leachate that had higher mean PFAS concentrations than municipal landfills. Younger landfills appeared to have a higher burden of waste containing PFASs (or their precursors), as significant relationships (p