[Occurrence Characteristics and Ecological Risk Assessment of Microplastic Pollution in the Yellow River Basin]

The Yellow River, as the "mother river" of China, urgently needs research and analysis on the MPs pollution status and ecological risks in the Yellow River Basin. The aim of the study was to explore the spatial distribution and composition characteristics of MPs in the Yellow River Basin, establish a comprehensive investigation and evaluation system for MPs at the watershed scale, and based on a two-dimensional risk assessment matrix, evaluate the absolute ecological risk of MPs at each sampling point within the watershed. The results showed that the abundance range of MPs in the study area was （0.49-350 280.00）×10³ items·m^-3, with an average abundance of （31 050.00±7 740.00）×10³ items·m^-3. In terms of spatial distribution, the abundance of tributaries in the middle reaches of the Yellow River was higher than that of the main stream, and the Yellow River estuary was the area with the highest detected abundance. The size of MPs in the watershed was concentrated between 0-1 000 μm, with fibers and fragments as the main shapes and colored and transparent as the main colors. The risk index range of the two-dimensional risk assessment matrix was 3-20 levels, with 77.78% of the area classified as high-risk. The Liujiaxia Reservoir is a water source area that requires special attention.