Microplastics profile in a typical urban river in Beijing

Area of Science:

• Environmental Science
• Water Quality Research
• Pollution Studies

Background:

• Municipal wastewater treatment plants (WWTPs) are significant sources of microplastic pollution discharged into rivers.
• The environmental fate and distribution of microplastics in urban river systems remain poorly understood.

Purpose of the Study:

• To investigate the microplastic pollution profile in the Qing River, Beijing, focusing on effluents from WWTPs and the river itself.
• To determine the primary sources and fate of microplastics within the urban river ecosystem.

Main Methods:

• Micro-Fourier-transform infrared spectroscopy was used to identify and confirm 18 different polymer types.
• Microplastics were categorized by shape (fragment, fiber, film, pellet).
• Microplastic abundance was compared between July and November sampling periods and between effluent outfalls and river locations.

Main Results:

• Fragments were the most abundant microplastic shape, followed by fibers, films, and pellets.
• Microplastic abundance in the main river body was slightly higher in November than in July, while effluent outfall levels remained consistent.
• Up to 80% of microplastics in the Qing River were retained upstream of dams, indicated by a reduced polymer-diversity index downstream.

Conclusions:

• WWTPs are the primary source of microplastic pollution in the Qing River.
• Riverine dams play a crucial role in retaining microplastics, significantly influencing their downstream transport and distribution.