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Comparative analysis of microplastic organization and pollution risk before and after thawing in an urban river in Beijing, China

The Science of The Total Environment 2022 22 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count. Score: 40 ? 0–100 AI score estimating relevance to the microplastics field. Papers below 30 are filtered from public browse.
Baohao Zhang, Dongyu Xu, Wan Xiao-hong, Yazun Wu, Xiaoru Liu, Bo Gao

Summary

Researchers found that microplastic abundance in the Shahe River in Beijing doubled in surface water and nearly tripled in sediments after spring thaw, with polymer diversity also increasing post-thaw, indicating that seasonal freeze-thaw cycles are an important driver of urban river microplastic dynamics.

Study Type Environmental

Urban rivers are potential sinks for microplastic (MP) contamination in the environment. However, the footprint of MPs in urban rivers is not well understood because it is influenced by natural and anthropogenic factors. This study focused on the occurrence, pollution risk, and potential sources of MPs in surface water and sediments before and after thawing in Shahe River, Beijing. The size distribution, morphological characteristics and polymer types of MPs were analyzed using a micro-Raman spectroscopy. The results showed that the average abundance of MP obviously increased after river thawing, from 1772 ± 1668 items·m to 3877 ± 2517 items·m in surface water and 4776 ± 4817 items·kg to 14,004 ± 5371 items·kg in sediments. The MP polymer types were more diverse after thawing. The main MP type in surface water changed from polyethylene terephthalate (PET) to polypropylene (PP). Moreover, PP was the most common type in sediments. Small-sized MPs (SMPs, 10-300 μm) were dominant in Shahe River, with the proportion increasing from 48.5% to 83.3% in surface water and from 84.3% to 94.4% in sediments after thawing. Although the MP pollution risk increased after thawing, it was still low in the Shahe River. Unfortunately, changes in polymer types caused by thawing and the emergence of toxic polymers increased the ecological risk in the urban river. These results revealed the information of MP contamination before and after thawing, and highlighted the barrier influence of river icing on the migration of MPs. Overall, the results presented a new perspective on the environmental behavior of microplastics in urban rivers, suggesting that the occurrence and dominance of SMPs and the emergence of toxic polymers in urban environmental media require close attention in the future.

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