宇宙線起源ベリリウム同位体により成層圏を経由するマイクロ・ナノプラスチック輸送経路を解明(Cosmogenic Beryllium Isotopes Reveal Stratospheric Transport Pathway of Micro/Nanoplastics)

2026-07-24 中国科学院(CAS)

中国科学院地球環境研究所の研究チームは、宇宙線生成核種であるベリリウム同位体(¹⁰Be、⁷Be)を環境トレーサーとして利用し、成層圏がマイクロ・ナノプラスチック(MNPs)の長距離輸送に果たす役割を初めて定量的に解明した。加速器質量分析、熱分解GC/MS、赤外線イメージング、数値シミュレーションを組み合わせ、チベット高原ラサで観測を実施した結果、MNPsの濃度は0.0059~0.11μg/m³で、PET、PVC、ポリカーボネートが全体の6割超を占めた。¹⁰Be/⁷Be比の変化から、成層圏空気が約1か月で地表付近まで下降し、MNPsを運搬することを確認した。この過程により、成層圏でのMNPsの滞留期間は従来推定の1~2年から1~3か月へ短縮され、乾性沈着量は約3倍、地表オゾン濃度は約34%増加した。また、冬季の偏西風ジェットが成層圏空気の下降を促進し、チベット高原がMNPsの「二次汚染源」となる可能性も示された。本手法は、新興汚染物質の越層輸送や環境動態の解明に有望な技術と期待される。

<関連情報>

成層圏大気中のベリリウム同位体シグネチャーの証拠は、チベット高原南部におけるマイクロ/ナノプラスチックの長距離輸送を示している Evidence of beryllium isotope signatures in stratospheric air reveals long distance transport of micro/nano-plastics in the Southern Tibetan Plateau

Xuke Liu, Haogen Li, Yunchong Fu, Guohui Li, Peng Cheng, Guocheng Dong, Wen Liu
Journal of Hazardous Materials  Available online: 15 July 2026
DOI:https://doi.org/10.1016/j.jhazmat.2026.142992

宇宙線起源ベリリウム同位体により成層圏を経由するマイクロ・ナノプラスチック輸送経路を解明(Cosmogenic Beryllium Isotopes Reveal Stratospheric Transport Pathway of Micro/Nanoplastics)

Highlights

  • The MNPs is 0.0059–0.11 μg/m³ , and the cosmogenic 10Be/7Be is 0.63–1.08 in the southern TP.
  • These periods of high MNP concentration are accompanied by strong stratospheric 7Be and 10Be fingerprint signals.
  • The unique terrain and vertical circulation over the southern Tibetan Plateau can promote the accumulation of MNPs.
  • The magnitude, retention period, and flux of MNP driven by vertical circulation in the upper atmosphere were evaluated.

Abstract

The new threat from atmospheric Micro/nano-plastics (MNPs) emissions now reaches far beyond the conventional scope of plastic-related issues. While MNP horizontal transport within the planetary boundary layer is well understood, limited knowledge of their vertical transport in the free troposphere and stratosphere hinder comprehensive modeling of their global atmospheric circulation. Considering that the production rates of radioactive beryllium isotopes (7Be and 10Be) above the tropopause is over 100 times higher than that in the near surface atmosphere, if relatively high concentrations and ratios of 10Be and 7Be can be observed near the surface, this phenomenon can serve as a unique isotope “fingerprint” for the invasion of deep stratospheric air invasion. Here, we present evidence of MNPs at mass concentrations of 0.0059–0.11 μg/m³ detected in Lhasa, southern Tibetan Plateau. And through synchronous high-precision observations of 7Be and 10Be, we have discovered strong stratospheric air signals during periods of high MNP concentration. Through the atmospheric transport models to delineate the occurrence, magnitude, retention period, flux, and characteristics of MNP pollution driven by upper-atmospheric vertical circulation in this high-elevation region. We found that under special topographic and aerodynamic conditions, atmospheric vertical circulation will promote the accumulation of MNPs for the enrichment and redistribution of MNPs. This work reveals the importance of vertical circulation in the upper atmosphere in the dynamics of MNP circulation based on evidence from beryllium isotopes.

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