Occurrence characteristics and ecological impact of agricultural soil microplastics in the Qinghai Tibetan Plateau, China

Plastic mulch is widely recognized as a significant contributor to microplastics (MPs) pollution in agricultural soil. However, its direct impact on remote areas with low population density remains uncertain due to multiple pollution sources. This study aims to investigate MPs pollution and its risks regarding agricultural soil in the Qinghai Tibetan Plateau (QTP) in China. The results revealed that soil samples from the study area exhibited a range of MPs abundance, varying from 16.67 to 950 items/kg, with the highest average abundance observed in Chengguan district (CG) soil samples (611.11 items/kg). Polyethylene terephthalate (PET), polypropylene (PP), and polyethylene (PE) were identified as the predominant components of MPs in farmland soil. Furthermore, significantly higher levels of MPs were found in the facility agriculture soil compared to the control soil. Diversity and risk of MPs in different regions and cultivation conditions were significantly different. According to the employed risk assessment models, agricultural soil demonstrated a relatively high polymer risk (47% of areas classified as level III). In addition to being influenced by exogenous factors, the diversity of MPs also plays an intrinsic role in regulating the risk of MPs pollution. This study contributes to an enhanced comprehension of the issue of MPs pollution in QTP farmland soil, providing valuable empirical evidence and theoretical underpinning for the development of efficacious control strategies.