Microplastics Present in Sediments of Yushan River: A Case Study for Urban Tributary of the Yangtze River

Microplastics (MPs) have become a worldwide concern due to their potential impacts on ecological systems. This study investigated the MPs in sediments of Yushan River, an urban river tributary of the Yangtze River, China. MPs were observed to be present in the sediments with 3.5–53 mg·kg−1 or 30–70 items·kg−1. The average abundance of 44 items kg−1 found in this study was relatively lower compared to other study reports in China. Fourier Infrared Spectrometer analysis shows polyethylene was the major polymer found from the samples, followed by polypropylene and polyester. According to their shapes, MPs had number fractions of 31.8% for fiber, 64.8% for film and 3.4% for fragment, which is coupled with transparent type as the majority (58.0% of the total number) followed by green (14.8%), blue (10.2%) and white (9.1%). As the dominant, transparent film MPs were derived mainly from polyethylene bags and polypropylene woven sacks. Moreover, due to aging processes, the surfaces of MPs were rough and uneven, enhancing their interactions with environmental substances like clay, silicon and iron. Principal Component Analysis indicates that the source of MPs in sediment was the same as that of specific contaminants in water.