Abstract: As a transition zone between land and ocean, estuarine intertidal zone has become a hotspot in studies on microplastics. We investigated the composition and distribution characteristics of microplastics in the sediments in a typical estuarine intertidal zone of China, the intertidal zones of the Yangtze Estuary. In April 2019, sediments in eight fixed sampling sites in the vegetated areas of the intertidal zones around the Chongming Island, Changxing Island, and Hengsha Island were sampled and analyzed. The results showed that average abundance of microplastics in the sediment was 0.015±0.002 n·g^-1. The average size of microplastics ranged from 204.4 to 546.4 μm. According to the shape, fibers and fragments were the dominant components, accounting for 59.8% and 29.9% of the total, respectively. As for the color, the transparent, blue, and white were the main colors. The most popular material types of microplastics were polypropylene (PP), ethylene-propylene copolymer (EPM), polyethylene (PE), and polyethylene terephthalate (PET). There were significant differences in the abundance and size of microplastics among different sites, but without vertical variation in the sediments. In some sites, the abundance and size of microplastics were significantly correlated with the median particle size, TOC content, water content, and bulk density of the sediments. We concluded that the composition and distribution characteristics of microplastics in the intertidal zone sediments of the YangtzeEstuary differed significantly between the mud flat and the vegetated area, which were affected by the land ocean interactions, human activities, intertidal vegetation, physical and chemical characteristics of the sediments.

Key words: microplastics, sediment, distribution characteristics, intertidal zone, Yangtze Estuary.