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Microplastics in the Koshi River, a remote alpine river crossing the Himalayas from China to Nepal

Environmental Pollution 2021 108 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count. Score: 60 ? 0–100 AI score estimating relevance to the microplastics field. Papers below 30 are filtered from public browse.

Yulan Zhang, Yulan Zhang, Yulan Zhang, Yulan Zhang, Yulan Zhang, Ling Yang, Ling Yang, Ling Yang, Ling Yang, Ling Yang, Ling Yang, Fan Zhang, Shichang Kang, Ling Yang, Shichang Kang, Yulan Zhang, Yulan Zhang, Yulan Zhang, Yulan Zhang, Yulan Zhang, Fan Zhang, Shichang Kang, Yulan Zhang, Yulan Zhang, Yulan Zhang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Wei Luo, Wei Luo, Shichang Kang, Yulan Zhang, Yulan Zhang, Shichang Kang, Shichang Kang, Yulan Zhang, Yulan Zhang, Yulan Zhang, Yulan Zhang, Yulan Zhang, Shichang Kang, Yulan Zhang, Yulan Zhang, Yulan Zhang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Yulan Zhang, Shichang Kang, Yulan Zhang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Yulan Zhang, Yulan Zhang, Yulan Zhang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Ling Yang, Fan Zhang, Zhao Pin, Zhao Pin, Zhao Pin, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Shichang Kang, Ling Yang, Ling Yang, Ling Yang, Yulan Zhang, Yulan Zhang, Yulan Zhang, Shichang Kang, Shichang Kang, John P. Giesy Shichang Kang, John P. Giesy Shichang Kang, John P. Giesy Yulan Zhang, John P. Giesy John P. Giesy John P. Giesy John P. Giesy John P. Giesy Ling Yang, John P. Giesy John P. Giesy John P. Giesy Fan Zhang, John P. Giesy Yulan Zhang, John P. Giesy John P. Giesy John P. Giesy

Summary

Researchers investigated microplastic pollution in the Koshi River, a remote alpine river that flows from China through the Himalayas to Nepal. They found an average of 202 microplastic particles per cubic meter in water and 58 per kilogram in sediment, with fibers and fragments being the most common types. The study demonstrates that even rivers in remote, high-altitude regions are not free from microplastic contamination, likely due to atmospheric deposition and upstream human activities.

Polymers

PA PE PET PP PS

Study Type Environmental

Studies of microplastics (MPs) in remote, trans-boundary and alpine rivers are currently lacking. To understand the sinks and transport mechanisms of MPs, this study investigated the distributions and sources of MPs in the surface waters and sediments of five tributaries of the Koshi River (KR), a typical alpine river in the Himalayas between China and Nepal. Mean abundances of MPs in water and sediment were 202 ± 100 items/m and 58 ± 27 items/kg, dry weight, respectively. The upstream tributary, Pum Qu in China, had the smallest abundance of MPs, while the middle tributary, Sun Koshi in Nepal, had the greatest abundance. Compared to international values in rivers, contamination of the KR with MPs was low to moderate. Fibers represented 98% of all MP particles observed, which consisted of polyethylene, polyethyleneterephthalate, polyamide, polypropylene, and polystyrene. Blue and black MPs were prevalent, and small MPs (<1 mm) accounted for approximately 60% of all MPs. Atmospheric transmission and deposition were considered to be the principal sources of MPs in the upstream tributary. The results imply that point sources associated with mostly untreated sewage effluents and solid wastes from households, major settlements, towns, and cities were most important sources of MPs in the KR. Non-point sources from agricultural runoff and atmospheric transport and deposition in the middle stream tributaries also contribute a part of microplastics, while the least amount was from fishing in the downstream tributary. Urbanization, agriculture, traffic, and tourism contributed to pollution in the KR by MPs. Equations to predict abundances of MPs based on river altitudes revealed that different trends were affected by both natural and human factors within the KR basin. This study presents new insights into the magnitude of MP pollution of a remote alpine river and provides valuable data for developing MP monitoring and mitigation strategies in similar environments worldwide.

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