Spatiotemporal and vertical distribution characteristics and ecological risks of microplastics in typical shallow...

This study investigates microplastics(MPs) in the water layer, viscous sublayer and sediment layer of Baiyangdian(BYD), while also exploring their spatio-temporal and vertical distribution characteristics, as well as associated ecological risks. The results indicate that microplastic abundance in the living area of BYD was the highest during both wet and dry periods. with differing sources being the primary factors influencing the distribution of MPs. During the wet period, the vertical distribution of MPs was highest in the water layer (1900 ± 824 n·m^-3), followed by the viscous sublayer (1625 ± 362 n·kg^-1) and sediment layer (1375 ± 249 n·kg^-1). Conversely, during the depleted period, the abundance distribution exhibited an opposite pattern, with significant changes in vertical distribution influenced by seasonal. Factors such as vertical flow velocities in the water column, shape, specific surface area, polymer type, and biological interactions significantly influence the vertical abundance of MPs, highlighting the critical role of the viscous sublayer at the sediment-water interface in this distribution. The ecological risk assessment model for MPs shows that BYD's risk index is low and unlikely to harm human health.This study elucidates the current distribution of MPs within the BYD ecosystem and provides a foundation for assessing potential pollution risks in the area.