Transforming Cadmium in Paddy Soils into a Catalytic Driver for Chlorantraniliprole Degradation: Implications for an Integrated Strategy for Tackling Heavy Metal–Organic Cocontamination

Developing remediation strategies for heavy metal–organic cocontamination in paddy soils is imperative to ensure food safety. Current soil remediation strategies typically address these pollutant classes separately, often creating trade-offs in which mitigating one class of contaminants exacerbates the mobility or persistence of the other. Here, we demonstrate an integrated strategy that transforms heavy metal contaminants into a functional driver for organic contaminant degradation. Using cadmium (Cd)–chlorantraniliprole (CAP) cocontaminated paddy soil as a model system, we show that amendment with 0.5 wt % porous calcium-doped iron oxide (P-Ca@Fe2O3) achieves efficient Cd sequestration via Ca–Cd isomorphous substitution. This structural incorporation restructures the mineral electronic environment, generating abundant oxygen vacancies that activate ambient oxygen and water to produce reactive oxygen species, which drive the catalytic degradation of CAP applied during rice cultivation. Accordingly, Cd and CAP concentrations in rice grain are reduced by 77% and 61%, respectively, at the end of the 140-day rice cultivation experiment. By repurposing a soil pollutant into a functional component of the remediation process, our strategy provides a scalable, closed-loop catalytic process that restores contaminated croplands with minimal external inputs while safeguarding food safety.