First Author: NIU Jinqiong
Corresponding Author: GAO Bo
Journal: npj Clean Water

Abstract

As an emerging pollutant of global concern, microplastics have become an important issue and research focus in ecological and environmental protection worldwide. Studies have shown that microplastics are widely present in urban water bodies, road dust, sediments, and rainfall, indicating that microplastic pollution in urban environments cannot be ignored and poses a potential threat to the health and stability of urban aquatic ecosystems.

This study focuses on urban water bodies in Beijing, including rivers, lakes, rainfall, and suburban sewage. Microplastic particles (10–5000 μm) in these water bodies were analyzed using Raman spectroscopy for both qualitative and quantitative assessments to reveal their abundance (concentration, size, morphology, polymer types) and associated pollution risks. Results show that different types of water bodies in Beijing all contain detectable microplastic pollution. Of particular concern, a high abundance of microplastics was observed in untreated wastewater. Lakes exhibited higher microplastic abundances than rivers, reflecting the accumulation of microplastics in lentic water systems. In addition, rainfall facilitated the migration of microplastics into urban aquatic environments through surface runoff and deposition.

Based on microplastic diversity and conditional fragmentation modeling, the sources of different microplastic polymers were traced. The results indicated that riverine and lacustrine microplastics in Beijing shared a high similarity, primarily originating from sewage, road dust, and sediments. Among polymer types, PP (polypropylene) was mainly associated with soil and dust inputs, whereas PET (polyethylene terephthalate) fibers primarily contributed to sewage-derived microplastics.

This study provides a new perspective for source apportionment and pollution risk analysis of urban microplastics, offering scientific insights for better understanding the environmental fate of microplastics and informing urban pollution prevention strategies.

Keywords: Microplastics; Beijing; Water bodies; Conditional fragmentation model; Source analysis