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Article Dans Une Revue Atmospheric Chemistry and Physics Année : 2020

Glyoxal's impact on dry ammonium salts: fast and reversible surface aerosol browning

David de Haan
  • Fonction : Auteur
Lelia Hawkins
  • Fonction : Auteur
Kevin Jansen
  • Fonction : Auteur
Hannah Welsh
  • Fonction : Auteur
Raunak Pednekar
  • Fonction : Auteur
Alexia de Loera
  • Fonction : Auteur
Natalie Jimenez
  • Fonction : Auteur
Margaret Tolbert
  • Fonction : Auteur
Mathieu Cazaunau
Aline Gratien
Antonin Bergé
  • Fonction : Auteur
Edouard Pangui
  • Fonction : Auteur
Jean-François Doussin

Résumé

Abstract. Alpha-dicarbonyl compounds are believed to form brown carbon in the atmosphere via reactions with ammonium sulfate (AS) in cloud droplets and aqueous aerosol particles. In this work, brown carbon formation in AS and other aerosol particles was quantified as a function of relative humidity (RH) during exposure to gas-phase glyoxal (GX) in chamber experiments. Under dry conditions (RH < 5 %), solid AS, AS–glycine, and methylammonium sulfate (MeAS) aerosol particles brown within minutes upon exposure to GX, while sodium sulfate particles do not. When GX concentrations decline, browning goes away, demonstrating that this dry browning process is reversible. Declines in aerosol albedo are found to be a function of [GX]2 and are consistent between AS and AS–glycine aerosol. Dry methylammonium sulfate aerosol browns 4 times more than dry AS aerosol, but deliquesced AS aerosol browns much less than dry AS aerosol. Optical measurements at 405, 450, and 530 nm provide an estimated Ångstrom absorbance coefficient of -16±4. This coefficient and the empirical relationship between GX and albedo are used to estimate an upper limit to global radiative forcing by brown carbon formed by 70 ppt GX reacting with AS (+7.6×10-5 W m−2). This quantity is < 1 % of the total radiative forcing by secondary brown carbon but occurs almost entirely in the ultraviolet range.
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hal-03330713 , version 1 (02-09-2021)

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David de Haan, Lelia Hawkins, Kevin Jansen, Hannah Welsh, Raunak Pednekar, et al.. Glyoxal's impact on dry ammonium salts: fast and reversible surface aerosol browning. Atmospheric Chemistry and Physics, 2020, 20 (16), pp.9581-9590. ⟨10.5194/acp-20-9581-2020⟩. ⟨hal-03330713⟩
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