Distribution characteristics of microplastics in soil profiles and aggregates of farmland with different mulching...

Plastic film has emerged as a nonnegligible source of microplastics (MPs) in farmland soil. However, knowledge of regarding the distribution characteristics of MPs in soil profiles and aggregates remains limited. This study focuses on the typical plastic film mulching area of Shihezi, in Xinjiang Uygur Autonomous Region, analyzing the spatial distribution of MPs in soils and soil aggregates over various durations of mulching. The results indicated that the abundance of MPs in the soil of 3-23 years of continuous mulching fields ranged from 20.90 ± 9.66-54.17 ± 21.19 items g^-1, with its abundance increased linearly with the increase of film mulching years. MPs showed obvious vertical differentiation characteristics in the soil profiles. Among them, the abundance of MPs in the surface 0-10 cm soil layer was the highest, decreasing with the increase of depth. The abundance of MPs in aggregates was positively correlated with their size. Utilizing these data, a random forest model was developed to predict MPs abundance in soil profiles and aggregates across different mulching durations. This study contributes valuable data to enhance the understanding of MPs distribution in soil layers and aggregates under long-term mulching conditions.