Distribution characteristics of microplastics in urban rivers in Chengdu city: The influence of land-use type and population and related suggestions

In this study, microplastics (MPs) in urban rivers in the Chengdu eco-zone were systematically studied. Microscopic observations and Fourier-transform infrared spectroscopy were used to determine the microplastic (MP) types. The MPs abundance ranged from 20.92 items/L to 762.95 items/L in water and from 20.92 items/100 g dry weight to 58.57 items/100 g dry weight in sediment. In both the water sample and sediment samples, the dominant MPs morphologies were fibres, lumps, and fragments, and the size of MPs was predominantly distributed in the 50-500 μm rage. The primary polymers were polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET). Locations with large populations and large areas of woodland and construction land tended to exhibit higher concentrations of MPs. Additionally, compared to water samples, sediment exhibited a more reliable correlation fitting data, thus indicating that sediment was more stable in reflecting the presence of MPs in rivers. This study supplemented the gap in MPs pollution in urban rivers in Chengdu city and discussed the impact of land use and population on the distribution of MPs. Suggestions were provided to alleviate MPs pollution in urban rivers from the perspective of urban planning.