Combined pollution of soil by heavy metals, microplastics, and pesticides: Mechanisms and anthropogenic drivers

Soil is the foundation of terrestrial ecosystems and a critical resource for agricultural activities. This study investigated internal mechanism and interaction of heavy metals, pesticides (atrazine, pyrimazole and chlorpyrifos) and microplastics in soil. Specifically, certain sampling points exhibited elevated levels of individual heavy metals (Cd, Cr, Zn), exceeding the screening values, while both microplastics and pesticides demonstrated high variability, increasing the potential ecological risks. The interaction between microplastics, heavy metals, and pesticides is complex, involving electrostatic adsorption, surface complexation, biofilm mediation, and physical absorption. From a broader perspective, both heavy metals and microplastics were found to exacerbate the ecological risks posed by pesticides. Further, structural equation model and geographical weighted regression were used to reveal the driving mechanism behind complex pollution, with economic development emerging as a significant factor influencing pollution levels. These findings enhance our understanding of the combined pollution of heavy metals, microplastics, and pesticides.