Abundance, characteristics, and distribution of microplastics in the Xiangjiang river, China

Abstract

The source and distribution characteristics of microplastics in the freshwater environment remain to be investigated, and there are many limitations in the microplastics baseline database of freshwater area. This study investigates the characteristics of microplastic pollution in the sediments of the Xiangjiang River, China. Samples obtained were identified using stereoscopic microscopy and Fourier-transform infrared spectroscopy after oxidative digestion and density separation. The microplastic abundance in the sediment of the river ranged from 144 to 510 items/kg (dw) with an average abundance at 288 ± 60 items/kg. Furthermore, nine polymer compositions of the microplastics were detected. Upstream inflow, domestic effluent, industrial, agriculture, and air settlement are considered as sources of microplastics in Xiangjiang River. The microplastic abundance of the lower reach of the Xiangjiang River is significantly higher than those of the upper and middle reaches, particularly in Changsha and Dongting Lake areas. Different types of microplastics show a different distribution characteristic. Hydrodynamic condition is an important factor affecting the distribution of microplastics. The results of this study not only fill the gap in current baseline data on microplastic pollution, however, the data obtained serve as a reference for following studies in other freshwater areas.