Decipher hydrological-ROS-mineral-microbe geochemical interaction and groundwater table fluctuation governing chain-length dependent PFAS evolution.

In the actual complex heterogeneous media (e.g., multi-layered medium with soil lenses) under fluctuating unsaturated conditions (e.g., groundwater table fluctuation (GTF)), the hydrological-reactive oxygen species (ROS)-mineral-microbe interaction mechanism and evolution difference between long-chain PFOA and short-chain GenX are not well quantitatively documented. This study integrates real-time molecular probes, large language models (LLM), ROS identification systems, and high-throughput sequencing to decipher the hydrological-ROS-mineral-microbe geochemical interaction governing GenX and PFOA transformation. A multi-model framework (pp-QSPR model, Hydrus inversion modeling, and COMSOL forward modeling) precisely quantifies differential plume evolution of PFOA versus GenX in heterogeneous aquifers with soil lenses and dynamic water tables. Key findings as follows: microbe active-FexSy geochemical interaction induced ·OH, O2·, and ¹O₂ generation, with unsaturated conditions favoring O2·⁻ and ¹O₂ dominance. The unsaturation enhanced Fe²⁺ release and a greater cooperation role of Fe2+, ·OH, O2·⁻, 1O2, and functional microorganisms, achieving greater GenX and PFOA removal than the saturation system. Pseudomonas (priority for GenX) and Methanobacterium synergistically control GenX transformation, whereas Pseudomonas (second priority for PFOA) and Acinetobacter control PFOA transformation. The soil lenses force more GenX transport and evolution in the horizontal direction. GTF amplifies plume evolution, disproportionately impacting PFOA over GenX. High-amplitude GTF elevated downstream contaminant flux (254.7%) and concentration (114%) of PFOA. This study provides quantitative insights into hydrological-ROS-mineral-microbe synergies essential for optimizing in situ, chain-length-dependent PFAS management within complex soil lenses and dynamic GTF interaction systems.