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Characterization and ecological risks of microplastics in urban road runoff
Yinghong Lin1, Yuhong Wang1, Yuen-Wa Ho2
1Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong.
The Science of the Total Environment
|September 29, 2024
Summary
Urban roads are a major source of microplastics (MPs) in stormwater runoff, with initial road runoff showing significantly higher MP concentrations than rainwater. This highlights the need to manage initial runoff for effective pollution control.
Area of Science:
- Environmental Science
- Water Quality
- Pollution Studies
Background:
- Microplastics (MPs) from urban roads enter water bodies via drainage, yet their characteristics and impacts in road runoff are poorly understood.
- Initial road runoff may contain particularly high concentrations of MPs, posing ecological risks.
Purpose of the Study:
- To analyze the characteristics and dynamics of MPs in urban road runoff.
- To assess the ecological risks associated with MPs in Hong Kong's stormwater.
- To identify factors influencing MP concentrations in rainfall events.
Main Methods:
- Collected stormwater and rainwater samples from seven Hong Kong locations over 11 rainfall events (Feb 2021-Sep 2022).
- Analyzed MP characteristics (polymers, shapes, sizes) and concentrations.
- Assessed ecological risks using the Polymer Risk Index (PRI).
Main Results:
- Median MP abundance in runoff (185 particles/L) was 4.6 times higher than in rainwater (40 particles/L).
- Polyethylene, polypropylene, and polystyrene fragments <300 μm were dominant MP types.
- PRI indicated moderate to high ecological risks (pollution classes II-III) at most road sites.
- MP abundance was significantly influenced by seasonal changes.
Conclusions:
- Urban roads are a significant source of MPs in stormwater runoff.
- Initial road runoff is critical for MP pollution and requires targeted management.
- Understanding MP dynamics in runoff is crucial for effective pollution control strategies.
