Characterizing bioaccumulation and translocation of perfluoroalkane sulfonic acids and novel alternatives p-perfluorous nonenoxybenzene sulfonate and polyfluorinated ether sulfonate in different ryegrass cultivars: Implications for phytoremediation screening.

The hazardous perfluoroalkane sulfonic acids (PFSAs) are being replaced by novel alternatives, and ryegrass demonstrates a promising potential for phytoremediation. This study explored the differential uptake, translocation and distribution patterns of different chain-length PFSAs as well as alternative sodium p-perfluorous nonenoxybenzene sulfonate (OBS) and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFAES), collectively designated as per- and polyfluoroalkyl substances (PFAS), in ten Italian ryegrass cultivars, and identified the roles of specific PFAS functional groups and plant protein in ryegrass bioaccumulation. Long-chain PFSAs showed high contamination loads in whole ryegrass plants, with majority in roots (e.g., approximately 87.5 % for perfluorooctane sulfonate, PFOS); whereas short-chain homologues exhibited lower pollution burdens and were readily translocated to ryegrass leaves (e.g., about 96.4 % for perfluorobutane sulfonate, PFBS). For PFAS with similar fluorocarbon chain lengths, OBS showed the highest ryegrass contamination loads (146 ng average) and root bioaccumulation factors (2.94 average), followed by 6:2 Cl-PFAES and PFOS. The aromatic ring of OBS, chlorine atom of 6:2 Cl-PFAES, and more CF units of PFOS contribute to their retention in ryegrass roots, thus retarding migration to leaves; these PFAS functional groups may augment the effect of plant protein on the bioaccumulation. A molecular indicator (named HE) of PFAS considering interaction mechanisms with protein was proposed to assess protein effects on the bioaccumulation of different PFAS in ryegrass. Protein loads can be used to predict phytoremediation potentials of PFAS by ryegrass. These findings may advance the understanding of novel PFAS accumulation in plants and inform plant screening for PFAS phytoremediation.