マイクロプラスチックが雲形成に影響、気象や気候に影響か(Microplastics impact cloud formation, likely affecting weather and climate)

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2024-11-07 ペンシルベニア州立大学(PennState)

ペンシルベニア州立大学の研究により、マイクロプラスチックが大気中で氷核形成粒子として機能し、雲の形成に影響を与えることが明らかになりました。これにより、降水パターンや気候モデル、さらには航空安全性にも影響を及ぼす可能性があります。研究チームは、4種類のマイクロプラスチック(LDPE、PP、PVC、PET)を用いて実験を行い、これらが水滴の凍結温度を5~10度上昇させることを確認しました。この発見は、マイクロプラスチックが気候システムに与える影響を理解する上で重要な一歩となります。

<関連情報>

原始的なマイクロプラスチックと老化したマイクロプラスチックは、浸漬凍結によって氷を核生成することができる Pristine and Aged Microplastics Can Nucleate Ice through Immersion Freezing

Heidi L. Busse,Devaka Dharmapriya Ariyasena,Jessica Orris,Miriam Arak Freedman
ACS ES&T Air  Published November 7, 2024
DOI:https://doi.org/10.1021/acsestair.4c00146

Abstract

マイクロプラスチックが雲形成に影響、気象や気候に影響か(Microplastics impact cloud formation, likely affecting weather and climate)

Microplastics (MP) are ubiquitous in the environment; their atmospheric relevance is being increasingly recognized. Because of their atmospheric concentrations, there is the question of whether MP can act as ice nucleating particles in the atmosphere. This study investigates the immersion freezing activity of lab-prepared MP of four different compositions─low density polyethylene (LDPE), polypropylene (PP), poly(vinyl chloride) (PVC), and poly(ethylene terephthalate) (PET)─using droplet freezing assays. The MP are also exposed to ultraviolet light, ozone, sulfuric acid, and ammonium sulfate to mimic environmental aging of the plastics to elucidate the role that these processes play in the ice nucleating activity of MP. Results show that all studied MP act as immersion nuclei, and aging processes can modify this ice nucleating activity, leading, primarily, to decreases in ice nucleating activity for LDPE, PP, and PET. The ice nucleating activity of PVC generally increased following aging, which we attribute to a cleaning of chemical defects present on the surface of the stock material. Chemical changes were monitored with infrared spectroscopy (ATR-FTIR), and the growth of a peak at 1650–1800 cm–1 was associated with a decrease in ice nucleating activity while loss of an existing peak in that region was associated with an increase in ice nucleating activity. The studied MP have ice nucleating activities sufficient to be a non-negligible source of ice nucleating particles in the atmosphere if present in sufficiently high concentrations.

1702地球物理及び地球化学
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