Abstract: Microplastics as a type of emerging pollutant has received great concerns worldwide. The source region of the Yangtze River is the “Chinese Water Tower” and is also one of the most important ecological function areas in China; but the pollution level and distribution of microplastics in this area are unclear. In this study we investigated into the microplastics pollution in the surface water of the source region of the Yangtze River. Results unveil that microplastics is detected at different sampling sites, with an abundance range of 247-2 686/m³ and an average abundance of 1 823±949/m³; microplastics with particle size smaller than 0.05 mm were dominant, accounting for about 70%; fragments were observed in all the water samples and were superior in numbers, accounting for about 96.2%; most microplastics were transparent. In addition, the most common types of polymers in microplastics are nylon and polyethylene, both accounting for about 30%. Our results suggest that the source region of the Yangtze River is being polluted by microplastics, and research on microplastics in this region should be deepened.

Key words: source region of the Yangtze River, water body, microplastics, distribution characteristics, ecological security