Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2025110501
Ultrashort-chain perfluoroalkyl substances (PFAS) exhibit high hydrophilicity, mobility, and root concentration factors, facilitating their transport and accumulation in soil-crop systems and posing phytotoxicity risks. Post-drought rehydration (PDR) is a critical water management strategy to mitigate drought effects in paddy fields. This study investigated the regulation and mechanisms of PDR on ultrashort-chain PFAS transport in paddy soils through sterilized and non-sterilized experiments, employing three-dimensional fluorescence spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray fluorescence spectroscopy, and amplicon sequencing. Results showed that PDR increased the bioavailable fraction of ultrashort-chain PFAS in soil solution while delaying their release into overlying water. Sterilization experiments confirmed that PDR-induced compensatory migration was primarily driven by microbial activity. Geochemical analyses revealed that PDR reduced hydrophilic functional groups (e.g., hydroxyl) on soil particle surfaces and increased cation bridging sites. Microbiological sequencing indicated that PDR activated secondary metabolic pathways, enhancing microbial extracellular polymeric substances (EPS) production, which provided binding sites for ultrashort-chain PFAS. Consequently, EPS competed with soil particles for cation bridging, altering PFAS interfacial partitioning and increasing bioavailable and cation-complexed fractions in soil solution, thereby exacerbating rhizosphere exposure risk to rice. This study elucidates the coupled geochemical and microbiological mechanisms governing ultrashort-chain PFAS mobility under PDR, informing risk assessment and management in paddy agroecosystems.
Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2026011902
The migration of perfluoroalkyl and polyfluoroalkyl substances (PFASs) at the water–soil interface in paddy fields is a critical determinant of their environmental fate and crop safety. This study investigated the influence of low-molecular-weight organic acids (LMWOAs) on PFASs mobility under waterlogged conditions. Four LMWOAs—oxalic, citric, lactic, and acetic acids—were individually enriched in paddy soils, and the migration of 15 PFASs was monitored. Acetic acid enrichment most strongly suppressed PFASs release into overlying water. Mechanistic analyses using X-ray photoelectron spectroscopy, three-dimensional excitation–emission matrix spectroscopy, microbial amplicon sequencing, and metagenomics revealed that acetic acid reshaped the microbial community, enriching sulfate-reducing bacteria and upregulating sulfur reduction genes (SULT1A) and nitrogen transformation genes (nifN, nirI, nthB). This drove sulfate reduction to sulfite and sulfide. ABT modeling identified sulfur metabolism as the dominant factor controlling PFASs immobilization (26.06% contribution). Experiments under varying sulfur redox conditions confirmed that sulfite (SO3^2−) oxidation indirectly altered dissolved organic matter (DOM) composition, weakening PFASs–DOM binding and reducing PFASs in overlying water. These findings demonstrate that LMWOAs accumulation, particularly acetic acid, can effectively impede PFASs migration at the paddy water–soil interface via microbial sulfur cycling and associated DOM structural changes, offering a potential strategy for PFASs remediation in agricultural systems.
Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2026041402
Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants ubiquitously distributed in paddy soils. In paddy management, surface water irrigation introduces quinolone antibiotics (QNs) into the soil, potentially altering PFAS interfacial migration via microbial community shifts. This study investigated the soil-water partitioning of PFAS under irrigation with four QNs (norfloxacin, ciprofloxacin, enrofloxacin, ofloxacin) using UHPLC-MS/MS and soil metagenomics. Results showed that QNs input, especially norfloxacin, significantly promoted the release of short-chain PFAS (e.g., PFBA) from soil to overlying water, while long-chain PFAS remained largely retained in soil. Metagenomic analysis revealed that archaeal and viral communities contributed most to PFAS release. Spearman correlations indicated ammonia-oxidizing archaea (Nitrososphaera) positively correlated with PFBA, whereas Bcep22virus negatively correlated with multiple PFAS. Differential gene expression and co-occurrence networks suggested QNs suppressed key functional genes in archaea and viruses (nitrogen metabolism, secretion systems, outer membrane proteins), reshaping interfacial partitioning and enhancing short-chain PFAS mobility, thereby increasing food security risks.