Pollution Characteristics and Ecological Risk Assessment of Microplastics in the Yangtze River Basin

The Yangtze River，the largest river in China，has not been comprehensively studied for its basin’s microplastic pollution status. Therefore，a comprehensive investigation and assessment system of microplastics was developed at the river basin scale to characterize the spatial distribution and composition of microplastics in the Yangtze River Basin in order to analyze their influencing factors and assess their ecological risks. The results showed that the microplastic abundance in the study area ranged from 21 to 44 080 n·m−3，with an average abundance of 4 483 n·m−3. The spatial distribution of microplastic abundance was higher in the tributaries than in the main streams（except the Ganjiang Basin），with the Chengdu of the Minjiang Basin being the tributary area with the highest abundance of microplastics detected. The size of microplastics in the river basin was concentrated in the 0-1 mm range；the shapes were mainly fiber and fragment；and the colors were mainly colored and transparent. Further，introducing the diversity index of microplastics，it was found that both the Simpson index and the Shannon-Wiener index could quantify the diversity of microplastic characteristic composition in the river basin，but there were certain differences in the changing trends between the two. Regression analysis showed that anthropogenic activities were significantly and positively correlated with microplastic abundance（P © 2024 Science Press. All rights reserved.