Campbell, James R.Battaglia Jr., MichaelDingilian, KayaneCesler-Maloney, MeetaClair, Jason St.Hanisco, Thomas F.Robinson, EllisDeCarlo, PeterSimpson, WilliamNenes, AthanasiosWeber, Rodney J.Mao, Jingqiu2023-07-312023-07-312022-05-11Campbell, James R., Michael Jr. Battaglia, Kayane Dingilian, Meeta Cesler-Maloney, Jason M. St Clair, Thomas F. Hanisco, Ellis Robinson, et al. “Source and Chemistry of Hydroxymethanesulfonate (HMS) in Fairbanks, Alaska.” Environmental Science & Technology 56, no. 12 (June 21, 2022): 7657–67. https://doi.org/10.1021/acs.est.2c00410.https://doi.org/10.1021/acs.est.2c00410http://hdl.handle.net/11603/28929Fairbanks, Alaska, is a subarctic city with fine particle (PM₂.₅) concentrations that exceed air quality regulations in winter due to weak dispersion caused by strong atmospheric inversions, local emissions, and the unique chemistry occurring under the cold and dark conditions. Here, we report on observations from the winters of 2020 and 2021, motivated by our pilot study that showed exceptionally high concentrations of fine particle hydroxymethanesulfonate (HMS) or related sulfur(IV) species (e.g., sulfite and bisulfite). We deployed online particle-into-liquid sampler–ion chromatography (PILS-IC) in conjunction with a suite of instruments to determine HMS precursors (HCHO, SO₂) and aerosol composition in general, with the goal to characterize the sources and sinks of HMS in wintertime Fairbanks. PM₂.₅ HMS comprised a significant fraction of PM₂.₅ sulfur (26–41%) and overall PM₂.₅ mass concentration of 2.8–6.8% during pollution episodes, substantially higher than what has been observed in other regions, likely due to the exceptionally low temperatures. HMS peaked in January, with lower concentrations in December and February, resulting from changes in precursors and meteorological conditions. Strong correlations with inorganic sulfate and organic mass during pollution events suggest that HMS is linked to processes responsible for poor air quality episodes. These findings demonstrate unique aspects of air pollution formation in cold and humid atmospheres.11 pagesen-USThis work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.Public Domain Mark 1.0Text