Surprisingly robust photochemistry in subarctic particles during winter: evidence from photooxidants

Heinlein, Laura M. D.; He, Junwei; Sunday, Michael Oluwatoyin; Guo, Fangzhou; Campbell, James; Moon, Allison; Kapur, Sukriti; Fang, Ting; Edwards, Kasey; Cesler-Maloney, Meeta; Burns, Alyssa J.; Dibb, Jack; Simpson, William; Shiraiwa, Manabu; Alexander, Becky; Mao, Jingqiu; Flynn III, James H.; Stutz, Jochen; Anastasio, Cort

doi:https://doi.org/10.5194/acp-25-9561-2025

Articles | Volume 25, issue 16

https://doi.org/10.5194/acp-25-9561-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-25-9561-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 25, issue 16

Research article

|

29 Aug 2025

Research article |

| 29 Aug 2025

Surprisingly robust photochemistry in subarctic particles during winter: evidence from photooxidants

Laura M. D. Heinlein, Junwei He, Michael Oluwatoyin Sunday, Fangzhou Guo, James Campbell, Allison Moon, Sukriti Kapur, Ting Fang, Kasey Edwards, Meeta Cesler-Maloney, Alyssa J. Burns, Jack Dibb, William Simpson, Manabu Shiraiwa, Becky Alexander, Jingqiu Mao, James H. Flynn III, Jochen Stutz, and Cort Anastasio

Supplement

https://doi.org/10.5194/acp-25-9561-2025-supplement

Data sets

Enhanced aqueous formation and neutralization of fine atmospheric particles driven by extreme cold, Fairbanks, Alaska, 2022 James Campbell et al. https://doi.org/10.18739/A2G73757K

Hydroxymethanesulfonate and Sulfur (IV) in FairbanksWinter During the Alaskan Layered Pollution and Chemical Analysis (ALPACA) Study, 2022 Kayane Dingilian et al. https://doi.org/10.18739/A2VD6P65Q

Fairbanks sulfate isotope measurements during ALPACA (2022) Allison Moon et al. https://doi.org/10.18739/A2Q52FF68

Gas and meteorological measurements at the CTC site and Birch Hill in Fairbanks, Alaska, during the ALPACA-2022 field study William Simpson et al. https://doi.org/10.18739/A27D2Q87W

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Short summary

High-latitude cities like Fairbanks, Alaska, experience severe wintertime pollution episodes. While conventional wisdom holds that oxidation is slow under these conditions, field measurements find oxidized products in particles. To explore this, we measured oxidants in aqueous extracts of winter particles from Fairbanks. We find high concentrations of oxidants during illumination experiments, indicating that particle photochemistry can be significant even in high latitudes during winter.