2024-12-20 パシフィック・ノースウェスト国立研究所
＜関連情報＞
- https://www.pnnl.gov/publications/organonitrates-atmospheric-particles-vary-altitude
- https://pubs.acs.org/doi/10.1021/acs.est.4c02090
テザー気球システムと高分解能質量分析により、地上と比較して上空で有機硝酸塩が増加していることが明らかになった Tethered balloon system and High-Resolution Mass Spectrometry Reveal Increased Organonitrates Aloft Compared to the Ground Level
Gregory W. Vandergrift,Darielle N. Dexheimer,Damao Zhang,Zezhen Cheng,Nurun Nahar Lata,Mickey M. Rogers,Manish Shrivastava,Jie Zhang,Brian J. Gaudet,Fan Mei,and Swarup China
Environmental Science & Technology Published: May 6, 2024
DOI:https://doi.org/10.1021/acs.est.4c02090
Abstract
Atmospheric particles play critical roles in climate. However, significant knowledge gaps remain regarding the vertically resolved organic molecular-level composition of atmospheric particles due to aloft sampling challenges. To address this, we use a tethered balloon system at the Southern Great Plains Observatory and high-resolution mass spectrometry to, respectively, collect and characterize organic molecular formulas (MF) in the ground level and aloft (up to 750 m) samples. We show that organic MF uniquely detected aloft were dominated by organonitrates (139 MF; 54% of all uniquely detected aloft MF). Organonitrates that were uniquely detected aloft featured elevated O/C ratios (0.73 ± 0.23) compared to aloft organonitrates that were commonly observed at the ground level (0.63 ± 0.22). Unique aloft organic molecular composition was positively associated with increased cloud coverage, increased aloft relative humidity (∼40% increase compared to ground level), and decreased vertical wind variance. Furthermore, 29% of extremely low volatility organic compounds in the aloft sample were truly unique to the aloft sample compared to the ground level, emphasizing potential oligomer formation at higher altitudes. Overall, this study highlights the importance of considering vertically resolved organic molecular composition (particularly for organonitrates) and hypothesizes that aqueous phase transformations and vertical wind variance may be key variables affecting the molecular composition of aloft organic aerosol.
