Now, clouds have no silver lining, but microplastics

Low-altitude and denser clouds contained greater amounts of microplastics.

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Through atmospheric transport, microplastics (MPs) in the air can travel great distances and go through several cloud processes. On the other hand, more must be understood about how MPs and clouds interact.

A new study reports the evidence for abundant and various MPs in cloud water samples. Scientists have examined microplastics in clouds hovering above mountains. They imply that these microscopic particles can contribute to cloud formation, influencing weather patterns.

Scientists are learning more about microplastics in the atmosphere and how they might contribute to cloud formation as the field of study develops. For instance, scientists recently found water-attracting plastic granules in clouds above Japanese mountains.

In this study, scientists set out to look for microplastics in mountain clouds. They used computer models to figure out how they could have gotten there and tested how the particles could have impacted — and been impacted by — the clouds.

Scientists collected 28 samples of liquid from clouds at the top of Mount Tai in eastern China. After analyzing the samples, they found greater microplastics in low-altitude and denser clouds.

The microplastic particles they found were made of common polymers, including polyethylene terephthalate, polypropylene, polyethylene, polystyrene, and polyamide. These particles were smaller than 100 micrometers, although some were as long as 1,500 micrometers.

Moreover, older, rougher particles had more lead, mercury, and oxygen attached to their surfaces, which the researchers suggest could facilitate cloud development.

Yan Wang and colleagues used computer models to determine how the plastic particles traveled to reach Mount Tai to study the origin of the particles in the clouds. These models proposed that the primary source of the fragments was airflow from densely inhabited interior areas rather than over the ocean or other neighboring mountains.

Through laboratory studies, the scientists showed that microplastics exposed to UV radiation and filtered cloud-sourced water had rougher surfaces and smaller diameters than microplastics exposed to pure air or water. Particles affected by the cloud-like circumstances also had higher concentrations of oxygen-containing groups, lead, and mercury.

Scientists noted, “These results suggest that clouds modify microplastics in ways that could enable the particles to affect cloud formation and the fate of airborne metals. The researchers conclude that more work is needed to understand how microplastics affect clouds and the weather fully.”

Journal Reference:

  1. Xinmiao Xu, Tao Li, Jiebo Zhen, Yuqian Jiang, Xiaoling Nie et al. Characterization of Microplastics in Clouds over Eastern China. Environ. Sci. Technol. Lett. DOI: 10.1021/acs.estlett.3c00729
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