Goethite Promotes the Degradation of Polyethylene Microplastics ( PE ‐ MPs ) in Soil

ABSTRACT Understanding microplastics (MPs) degradation in soil is crucial for assessing its environmental impacts and pollution remediation. However, the ageing or degradation mechanisms of MPs mediated by soil iron oxides remain poorly understood. This study investigated the degradation of polyethylene microplastics (PE‐MPs) in agricultural soil amended with goethite (α‐FeOOH) gradiently through quantitative incubation experiments. Attenuated total reflection‐Fourier transform infrared spectroscopy (ATR‐FTIR) revealed the formation of C–O and C═O bonds on the PE‐MPs surface. The addition of ≤ 1.0% goethite significantly increased both the C–O peak area and the carbonyl index (CI), and the scanning electron microscopy coupled with energy‐dispersive x‐ray spectroscopy (SEM‐EDX) confirmed a significantly enhanced distribution of oxygen on the PE‐MPs surface. These results collectively demonstrate that a moderate dosage of goethite can significantly promote the degradation of PE‐MPs in soil. Furthermore, partial least squares path modeling (PLS‐PM) indicated that changes in goethite addition influence PE‐MPs degradation indirectly by altering the transformation dynamics of iron oxides within the soil rather than affecting directly. This study provides insights into the effects of goethite on MPs degradation in soil, implying the possibility and potential of soil MPs pollution remediation by iron oxides.