Levels of microplastics (MPs) in China are completely unknown. This study characterizes suspended MPs
quantitatively and qualitatively for the Yangtze Estuary and East China Sea. MPs were extracted via a floatation
method. MPs were counted and categorized according to shape and size under a stereomicroscope.
The MP densities were 4137.3 ± 2461.5 and 0.167 ± 0.138 n/m3, respectively, in the estuarine and the sea
samples. Plastic abundances varied significantly in the estuary. Higher densities in three sea trawls confirmed
that rivers were the important sources of MP to the marine environment. Plastic particles (>5 mm)
were observed with a maximum size of 12.46 mm, but MPs (0.5–5 mm) constituted more than 90% by
number of items. The most frequent geometries were fibres, followed by granules and films. Plastic
spherules occurred sparsely. Transparent and coloured plastics comprised the majority of the particles.
This study provides clues in understanding the fate and potential sources of MPs.