[Basin Distribution and Ecological Risk of Microplastics in Surface Water Bodies in China].

Abstract

To gain a comprehensive understanding of the distribution of microplastics in surface waters in China and clarify the related ecological risks, data of surface water bodies, such as rivers, lakes, reservoirs, and estuaries in China from 2014 to 2023 were collected, and the potential ecological risk index method was used to comprehensively evaluate the ecological risk of microplastics in surface water bodies of ten major basins in China. The results showed that the rivers, lakes, reservoirs, and estuaries in different basins of China were all polluted by microplastics. The main materials were polypropylene and polyethylene, mainly colorless transparent fibers and fragments, and the size was mostly <1 mm, but the abundance of microplastics was significantly different. The median abundance of microplastics in the surface water of rivers, lakes, and estuaries in each basin ranged from 628 to 35 804, 1 to 4 738, and 869 to 792 100 items·m^-3, respectively. The median abundance of microplastics in sediments ranged from 61 to 1 531, 19 to 1 236, and 120 to 1 228 items·kg^-1, respectively. From the total potential ecological risk index （PERI_tot） of microplastics in rivers, the Haihe River Basin was at high ecological risk （level Ⅳ）, while the Yellow River Basin and the Yangtze River Basin were at medium ecological risk （level Ⅲ）. The majority of PERI_tot in the rivers of the Haihe River Basin came from polyurethane, with a highest contribution rate of 99.88%, while the main contributors to the PERI_tot of rivers and lakes in the Yellow River and the Yangtze River Basin and the PERI_tot of the surface water in the Yellow River Estuary were polyvinyl chloride and polystyrene, respectively. Microplastic pollution on the surface water bodies of the southeast side of HU Huan-yong Line was crucial, whereas a few research reports were available on microplastics in the surface water bodies on the northwest side, and the pollution status remained unclear. The abundance of microplastics in surface water bodies in different regions was significantly positively correlated with the population density and local gross domestic product （P<0.05）. The study shows the basin distribution characteristics and ecological risks of microplastics in surface water bodies in China, which can provide scientific basis for the prevention and control of microplastic pollution in surface water bodies.