Wind erosion induced low-density microplastics migration at landscape scale in a semi-arid region of northern China

Microplastics (MPs) have been extensively investigated in terrestrial environments, while the occurrence and move-ment of MPs at the landscape scale in semi-arid regions with serious wind erosion are less well studied. Here, we sam-pled film mulching farmland and downwind nearby grassland surface soils in a semi-arid region of northern China to explore the distribution of MPs at different downwind distances and the potential environmental risk to the local land-scapes. The results revealed that the MP abundances presented a decreasing trend with increasing downwind distance (Mann-Kendall test, P < 0.01). The MP size distributions at different distances showed similar sigmoid trends described by logistic models. MP fiber size (500-2000 mu m) abundance in the farmland was higher than that of the grassland. By contrast, MP non -fiber size (<1000 mu m) abundance of farmlands was less than that of the grassland. The abundances of fibers larger than 500 mu m and non -fibers larger than 1000 mu m in size decreased exponentially with increasing down-wind distance. The size of transported MPs at the landscape scale was larger than that of long-distance dispersal. The migration of MPs from farmlands can pose a potential threat to the downwind landscape, leading the downwind grass-land to be a potential MP emission source. This study presents the first insights into the MPs distribution among differ-ent downwind distances at the landscape scale. Future research is required to deploy aeolian sediment sampling devices and establish the connection between the field data and the MP emission models.