Aging microplastics and coupling of “microplastic-electric fields” can affect soil water-stable aggregates’ stability

As plastic waste continues to accumulate in natural environments, the impact of aged microplastics (MPs) on soil ecosystems is increasingly becoming a matter of global concern. However, the effects of aged MPs on the stability of water-stable soil aggregates have not been clearly elucidated. Therefore, we investigated the influence of two types of aged MPs, namely, polystyrene and polypropylene, on soil aggregate stability. We found that MPs have a notable effect on the fundamental structural units of soil aggregates, including organic matter and microorganisms. Consequently, reducing the structural stability of soil aggregates by disrupting the bonding mechanisms of soil particles affects the erosion resistance of coarse aggregates. Furthermore, we investigated the coupled effects of "soil electric field-MPs" on aggregate stability. The results showed that the critical potential for aggregate explosive fragmentation corresponds to an electric field intensity at an electrolyte concentration of 10 mol·L. In this study, we have clarified the primary factors through which MPs affect the stability of water-stable soil aggregates, providing new insights for a more accurate assessment of the impact of MPs on soil aggregates.