Accelerating natural purification of contaminated soils through endogenous iron cycle and hydroxyl radical production regulation

Soil contamination with organic chemicals is a critical global environmental challenge. Recently, monitored natural purification, though eco-friendly, suffers from slow remediation rates. Here, we report an innovative approach through regulating endogenous iron cycle and hydroxyl radical (•OH) productions to accelerate natural soil purification while maintaining soil functionality. By periodically adding mild concentrations of H₂O₂ to activate soil iron minerals, we triggered an endogenous Fenton-like reaction, resulting in a significant 10.4-fold increase in •OH generation. Simultaneously, oxidized iron was regenerated through microbial reduction, completing the biogeochemical redox cycles of iron. Over five cycles of these redox processes, pollutant removal rate was enhanced by 6.3-fold, achieving >95% phenol degradation. Compared to chemical remediation, this approach reduced organic matter loss by 91% and preserved 96% microbial activity. Furthermore, treated soils maintained fertility, supporting vigorous lettuce and cabbage growth. To further advance this system, we developed an on-site H₂O₂ production system powered solely by sunlight, water, and air, eliminating the need for additional energy or chemical inputs. This integrated system demonstrates the potential for accelerated and sustainable soil remediation. Our findings highlight the promise of accelerated natural purification as a transformative approach to address soil contamination while safeguarding environmental health and agricultural productivity.