Influence of root morphology and salinity on PFAS uptake by ten Australian wetland plant species.

Constructed Floating Wetlands (CFWs) show promise as nature-based technology for attenuating per- and polyfluoroalkyl substances (PFAS) in surface water. However, few studies have investigated plant morphological and physiological characteristics that promote PFAS uptake. This study assessed ten wetland plant species exposed to PFAS-spiked stormwater (PFBS, PFPeA, PFHxS, PFOA, PFOS, 30 µg/L each), for 28 days, under two salinity conditions (200 and 1000 mg/L). At low salinity, all species accumulated PFAS, with variation according to species. T. triandra, P. labillardieri, and S. validus were most effective for short-chain compounds (5740-6610 ng PFBS, and 4330-5290 ng PFPeA), whereas E. acuta, C. fascicularis, P. labillardieri, and B. caldwellii accumulated more long-chain compounds (2040-2390 ng PFHxS, 6100-6590 ng PFOS, and 2320-2830 ng PFOA). Plants with thin, branched roots showed greater PFAS accumulation. Bioaccumulation data highlighted that PFAS carbon chain length influenced PFAS partitioning, with PFOS showing limited shoot translocation compared with PFBS and PFPeA (translocation factors: 0.2-2.8 vs 0.4-34.0 vs 0.5-24.6). Elevated salinity significantly suppressed the uptake and translocation of short-chain PFAS (particularly PFPeA), while long-chain compounds were less affected. Results suggest that species selection for CFW must consider plant morphology and site-specific water parameters for optimum removal of complex PFAS mixtures.