Duration- and area-dependent influences of plastic film mulch on soil microplastics abundance

Currently, how the duration and coverage area of plastic film mulch influence microplastics (MPs) abundance in diverse agricultural soils is still scarce. Here, we conduct a field campaign and remote sensing to investigate the duration- and area-dependent of plastic film mulch on MPs abundance for farmland in the agro-pastoral ecotone of northern China. The results reveal that the MPs abundances in soil samples ranged from 41.7 to 787.5 items/kg (average: 365.3 ± 181.8 items/kg). MPs abundance positively correlates with mulching duration. Longer mulching durations result in noticeable changes in the fiber-type MPs. The influence of mulch area on MPs abundance was scale-dependent, with the highest correlation observed at 4.5 km. HYSPLIT simulations further indicated potential wind-driven transport pathways. These results demonstrate that we can use the radius of 4.5 km and mulching duration as the possible estimates for the soil-air interface MPs emission simulations. Our findings further emphasize the duration- and area-dependent impacts of plastic film mulch on soil MPs abundance, suggest that further research on the influencing factors is needed.