Seasonal Variation Of Microplastics In Surface Water and Sediment Of The Xiangjiang River : An Inland Urban Drinking Water Source

While the Xiangjiang (XJ) River acts as an inland drinking water source, it may experience microplastics emissions originating from Changsha (CS) City. The aim of this study was to characterize the occurrence and distribution of microplastics in the XJ River during both the flooding and dry periods. Samples of surface river water and sediment of the XJ River in CS City were collected in August and December, 2020 and analyzed for composition of microplastics. The results showed ubiquitous presence of microplastics in surface water and sediment of the XJ River at abundances of 0.72–18.6 (7.32 ± 2.36) items L−1 and 26.3–302 (150 ± 75.6) items kg−1 dry weight (dw), respectively, during the flooding period, lower than those of 2.88–17.7 (11.0 ± 3.08) items L−1 and 27.0–651 (249 ± 182) items kg−1 dw during the dry period. Higher microplastic abundance was found mainly in urban centers as well as downstream of wastewater treatment plants, implying anthropogenic activities to be a source of microplastics. The high variances in the shapes, color, and types of microplastics in surface waters and sediments implied the action of specific enrichment processes and long-term sources of microplastics pollution. Most (60%) of microplastics particles in both the river water and sediment were in the size range of 50–100 μm. Fourier transform infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) indicated that microplastics were subjected to weathering in the environment, contributing to the production of oxygen-containing functional groups and surface cleavage features. Energy Dispersive Spectroscopy (EDS) showed that microplastics bonded to multiple heavy metals, emphasizing the complex nature of microplastics pollution. The results indicate concerning levels of microplastics in the XJ River, despite its status as a high-quality water source