Distribution Patterns of Microplastics Pollution in Urban Fresh Waters: A Case Study of Rivers in Chengdu, China

Microplastics are widely found in oceans and rivers. In China, the research on microplastic pollution in inland urban fresh waters of China is insufficient. We studied microplastics in the surface waters of urban rivers in Chengdu, which is the largest city in western China. The concentration of microplastics in the analysis environment ranged from 5.00 to 10.5 items/L, and the average quantity was 8.82 items/L. The majority of the microplastics were transparent and took the form of fragments, particles, and fibers. Polyethylene terephthalate (PET) and polyamide (PA) were the dominant polymer types of the microplastics analyzed. Plastic particles ≤ 500 μm accounted for 69.8% of the total. This large proportion of small transparent microplastics in urban rivers in Chengdu is a potential threat to the growth of aquatic organisms and birds foraging from the river and may pose hazards to human health. Additionally, the correlation of microplastic content with population quantity and economic level was calculated by the Pearson coefficient method (p < 0.05), and the results showed that both have an important effect on the number of microplastics in rivers. This research provides a reference for understanding the level of microplastics in urban rivers in Chengdu and pollution control.