Assessment of microplastic ecological risk and environmental carrying capacity of agricultural soils based on integrated characterization: A case study

Microplastic pollution in agricultural soils poses a significant threat to soil quality and environmental sustainability. This study investigated the composition, abundance, distribution, ecological risk, and environmental carrying capacity of microplastic pollution in the Tarim River Basin (TRB), China. The risk quotient combined with soil environmental carrying capacity (SECC) approaches was proposed to evaluate ecological risks and soil sustainability. Microplastic abundances ranged from 0 to 4000 items/kg (average = 570 items/kg), with polyethylene (PE) polytetrafluoroethylene (PTFE) and polypropylene (PP) as dominant polymers. In addition, various factors affecting the occurrence of microplastics were analyzed. Agricultural mulching and drip irrigation were associated with higher microplastic levels. The risk assessment showed that among the different shapes, size ranges and categories of microplastics, fragmented (film), large-sized microplastics and PE had the highest risk, respectively. While current levels are within SECC limits, early warning model predicts PE and PP may reach threshold limits in recent years. This study provides crucial insights for managing microplastic pollution in agricultural regions, emphasizing the need for targeted mitigation strategies to maintain soil ecology sustainability.