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Spatiotemporal dynamics of microplastics in urban stormwater runoff: Functional area effects and transport pathways (Shanghai, China)

Journal of Contaminant Hydrology 2026 Score: 40 ? 0–100 AI score estimating relevance to the microplastics field. Papers below 30 are filtered from public browse.
Junhao Li, Bowen Yu, Bowen Yu, Chengjin Cao, Chengjin Cao, Liuxing Wu, Liuxing Wu, Yaping Zhao, Yaping Zhao, Ruiyun Zhu, Yangyang Hu, Minsheng Huang, Lei Wang, Lei Wang, Xinlin Yan

Summary

During a heavy rainfall event in Shanghai, microplastic concentrations in stormwater peaked within just 5 minutes in dining areas (nearly 690 particles per liter), far exceeding residential and parking zones, driven by a pronounced first-flush effect. The results show that food-service land use is an underrecognized microplastic hotspot, with urban stormwater rapidly exporting these particles to waterways.

Polymers

Urban stormwater runoff is a critical pathway for microplastics pollution, yet its detailed transport dynamics remain poorly characterized. This study employed intra-event time-series sampling (at intervals of 0, 5, 15, 30, 60, 120, and 240 min after runoff initiation) during a heavy rainfall event in Shanghai (China) to investigate microplastics concentrations and characteristics across three urban functional areas. Our results revealed that microplastic pollution levels were strongly land-use-dependent: the dining area was a severe hotspot, with a time-weighted average concentration of 689.7 ± 214.1 items/L, which was significantly higher than the residential area (215.6 ± 38.9 items/L) and the parking area (172.8 ± 18.8 items/L), and all concentrations far exceeded local aquatic background values. A pronounced first flush effect was observed, particularly in the dining area, where the peak concentration was reached within just 5 min. The runoff was dominated by small-sized (<1.0 mm) and fibrous microplastics composed of PET and PP. These small fibers were preferentially exported in the early phase of runoff (within the first 30 min), whereas granules and larger-sized microplastics accumulated in the later phase. By elucidating the land-use-dependent transport dynamics and fate of microplastics, this study provides a scientific basis for targeted source control, including prioritizing initial flush interception, and stormwater management in global megacities.

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