Nano-zero-valent Iron Promotes Early-Phase PFOA Phytoaccumulation by Enhancing Root Surface Adsorption, ROS/Anion Channel-Mediated Transmembrane Uptake, and Soluble Protein-Facilitated Translocation for Enhanced Phytoremediation

Phytoremediation of perfluorooctanoic acid (PFOA) contaminated soil remains inefficient, stemming from limited root adsorption, transmembrane transport, and root-to-shoot translocation. Nano-zero-valent iron (nZVI) as a slow-release iron supplement to plant could potentiate PFOA phytoremediation markedly without posing growth inhibition as other iron salts. In this study, 100mg/kg nZVI application to perennial ryegrass (Lolium perenne L.) yielded remarkable improvements: root PFOA enrichment increased by 48.2% and shoot translocation by 84.9%, significantly outperforming both Fe2+ and micro-scale ZVI. For the first time, we systematically unraveled the underlying mechanisms across the entire “root surface adsorption-transmembrane transport-upward translocation” pathway: promoting root-surface iron composites that temporarily adsorb PFOA; inducing a transient ROS burst to increase membrane permeability while activating the Ca2+-CDPK-SLAC1 anion channel, enabling the transmembrane transport of the root-accumulated PFOA; and elevating shoot soluble protein levels and transpiration to facilitate upward translocation. Building on the observation that nZVI-enhanced phytoextraction exhibits an early-phase boost followed by time-dependent attenuation, we developed a rapid-cycle cultivation strategy with periodic nZVI replenishment, achieving 71.1% PFOA removal from industrial soil contaminated with 44 PFAS within 45 days, and demonstrated broad-spectrum enhancement across all PFAS. Given the conserved nature of PFAS uptake and translocation mechanisms in higher plants, the framework established in ryegrass suggests broad applicability of this nZVI-assisted strategy across diverse soil-plant systems. Our study elucidates the mechanistic basis for nZVI-mediated regulation of PFOA fate in soil-plant systems, resolving the long-standing inefficiency of PFOA phytoremediation.