Distribution characteristics of microplastics in soil of Loess Plateau in northwest China and their relationship with land use type.

The widespread distribution of microplastics (MPs) in soil has aroused great concern. The land use type can affect the distribution characteristics of MPs, whereas the abundance of MPs in the Loess Plateau region and the influence of different land use types on it are unclear. This study checked into the distribution of MPs in the Loess Plateau region, studied the abundance of MPs in woodland, construction land, grassland and cultivated land, and analyzed the distribution characteristics of their shape, size, and color. The abundance of MPs in the Loess Plateau region reached 2982.34 items/kg, dominated by black, small size and fragment MPs. The order of average abundance of MPs was: cultivated land (3535 items/kg) > construction land (2809 items/kg) > woodland (2781 items/kg) > grassland (2658 items/kg). Fragment MPs were predominant in woodland, construction land and cultivated land, but film and fiber MPs were predominant in grassland. MPs in cultivated land and construction land mainly sourced from human activities, MPs in woodland and grassland were more likely to come from atmospheric deposition. Human activities and sunlight exposure can cause MPs to break down, while trees in woodland block rays of light, slowing MPs breakage to some extent. And the polymer type of MPs was mostly PE and the main ones were black. This study may provide important data for follow-up research on MPs in terrestrial ecosystems.