Contrasting macrophyte responses to PFAS-contaminated landfill leachates: implications for bioaccumulation and phytotoxicity

We investigated the phytotoxic response and bioaccumulation potential of three aquatic macrophytes, Carex elata, Phragmites australis, and Typha latifolia, for the treatment of landfill leachates containing perfluoroalkyl acids (PFAAs). The plants were cultivated in mesocosms (0.56 × 0.35 × 0.31 m) and fed with three types of landfill leachates characterized by increasing salinity (1,200–19,000 μS cm−1), elevated Na+, Cl−, and NH4+ concentrations, and total PFAAs in the range 200–830,000 ng L−1. Over a 9-month exposure period, the leachate's physicochemical characteristics were monitored, and the plant physiological status was assessed through a hyperspectral spectroradiometer. At harvest, aboveground and belowground tissues were analyzed for 14 PFAAs using UHPLC-MS/MS, and uptake and translocation were quantified through bioconcentration and total removal parameters. Results showed that plant growth was not affected by increasing PFAAs; however, elevated salinity constrained vegetation development. None of the macrophytes exhibited complete senescence, indicating adaptation to extreme conditions. Species-specific stress responses were observed: Carex demonstrated high tolerance and remediation capacity, maintaining robust performance under both high PFAAs loads and extreme physicochemical stress, and Typha exhibited physiological stress, including early spectral alterations prior to structural decline. Results demonstrated the feasibility of phytoremediation for PFAA-contaminated landfill leachates and highlighted Carex as a promising candidate for treatment wetland systems.