• • ORP and DO increase significantly along the plume direction, while Fe2+, NH4+, TOC, and HCO3− decrease, indicating a shift from reducing to oxidizing conditions.
• • The redox zones are sequentially identified as sulfate reduction, iron reduction, manganese reduction, nitrate reduction, and oxidation zones, based on redox-sensitive indicators and microbial community structure.
• • COD is almost completely attenuated within the redox zones, effectively reducing the environmental impact on downstream groundwater.
• • The study provides a scientific basis for groundwater pollution prevention and control, with implications for graded management of contaminated sites.