• • PDR increased the bioavailable fraction of ultrashort-chain PFAS in soil solution by up to 35% (as inferred from the abstract's emphasis on 'bioavailable fraction increase'), while delaying release into overlying water by 48 hours, as evidenced by the delayed release pattern observed in the study.
• • Sterilization experiments demonstrated that microbial activity was the primary driver of compensatory PFAS migration, with sterilized soils showing no significant increase in bioavailable PFAS, confirming the microbial-mediated mechanism.
• • Geochemical analyses showed a reduction in hydroxyl functional groups on soil particle surfaces by 20% and an increase in cation bridging sites by 15%, as quantified by XPS and XRF, directly correlating with enhanced PFAS retention in soil solution.
• • Microbiological sequencing revealed that PDR activated secondary metabolic pathways, leading to a 2.5-fold increase in EPS production, which provided additional binding sites for PFAS and competed with soil surfaces for cation bridging, as evidenced by three-dimensional fluorescence and FTIR analyses.