Spatial Risks of Microplastics in Soils and the Cascading Effects Thereof

Microplastic (MP) pollution has become a significant global concern in soil systems. The spatial risk of MPs in soils, the cascading effects of climate, human activities, and air quality, and the ecosystem gradients from natural habitats, agricultural lands, and urban soils remain largely unknown. We compile a comprehensive data set of more than 3000 site-year field observations across agricultural, natural, and urban soil ecosystems in China. By using interpretable machine learning models and statistical approaches, our findings reveal that approximately 4.32% of soil ecosystems in China face potential ecological risks from MPs, with agricultural soils being the most vulnerable (e.g., 14.7% of agricultural soils are at risk). Climate factors (e.g., temperature and precipitation), human activities (e.g., agricultural plastic film use), and air quality (e.g., concentrations of atmospheric particulate matter) have been identified as the primary drivers of MP risk. The cascading effects of climate factors and air quality (p < 0.001) significantly impact the ecological risk of MPs in agricultural and urban soils. This work highlights the urgent need for the coordinated management of human activities, climate, and air quality to mitigate the ecological risks posed by MPs in soils, especially in agricultural lands.