Preprints
https://doi.org/10.5194/acp-2020-1324
https://doi.org/10.5194/acp-2020-1324

  08 Feb 2021

08 Feb 2021

Review status: this preprint is currently under review for the journal ACP.

Secondary aerosol formation from dimethyl sulfide – improved mechanistic understanding based on smog chamber experiments and modelling

Robin Wollesen de Jonge1, Jonas Elm2, Bernadette Rosati2,4, Sigurd Christiansen2, Noora Hyttinen3, Dana Lüdemann1, Merete Bilde2, and Pontus Roldin1 Robin Wollesen de Jonge et al.
  • 1Division of Nuclear Physics, Lund University, P.O. Box 118, Lund, Sweden
  • 2Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus, Denmark
  • 3Nano and Molecular Systems Research Unit, University of Oulu, P.O. Box 3000, FI-90014 Oulu, Finland
  • 4Faculty of Physics, University of Vienna, Boltzmanngasse 5, AT-1090 Vienna, Austria

Abstract. Dimethyl sulfide (DMS) is the dominant biogenic sulphur compound in the ambient atmosphere. Low volatile acids from DMS oxidation promote the formation and growth of sulphur aerosols, and ultimately alter cloud properties and Earth's climate. We studied the OH-initiated oxidation of DMS in the Aarhus University research on aerosols (AURA) smog chamber and the marine boundary layer (MBL) with the aerosol dynamics, gas- and particle-phase chemistry kinetic multilayer model ADCHAM. Our work involved the development of a revised and comprehensive multiphase DMS oxidation mechanism, both capable of reproducing smog chamber and atmospheric relevant conditions. The secondary aerosol mass yield in the AURA chamber was found to have a strong dependence on the reaction of methyl sulfinic acid (MSIA) and OH at low relative humidity (RH), while the autoxidation of the intermediate radical CH3SCH2OO forming hydroperoxymethyl thioformate (HPMTF) proved important at high RH. The observations and modelling strongly support that a liquid water film existed on the Teflon surface of the chamber bag, which enhanced the wall loss of water soluble intermediates and oxidants DMSO, MSIA, HPMTF, SO2, MSA, SA and H2O2. The effect caused a decrease in the secondary aerosol mass yield obtained at both dry (0–12 % RH) and humid (50–80 % RH) conditions. Model runs reproducing the ambient marine atmosphere indicate that OH comprise a strong sink of DMS in the MBL, although less important than halogen species Cl and BrO. Cloudy conditions promote the production of SO42− particular mass (PM) from SO2 accumulated in the gas-phase, while cloud-free periods facilitate MSA formation in the deliquesced particles. The exclusion of aqueous-phase chemistry lowers the DMS sink as no halogens are activated in the sea spray particles, and underestimates the secondary aerosol mass yield by neglecting SO42− and MSA PM production in the particle phase. Overall, this study demonstrated that the current DMS oxidation mechanisms reported in literature are inadequate in reproducing the results obtained in the AURA chamber, whereas the revised chemistry captured the formation, growth and chemical composition of the formed aerosol particles well. Furthermore, we emphasise the importance of OH-initiated oxidation of DMS in the ambient marine atmosphere during conditions with low sea spray emissions.

Robin Wollesen de Jonge et al.

Status: open (until 05 Apr 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Robin Wollesen de Jonge et al.

Robin Wollesen de Jonge et al.

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Short summary
This study presents a detailed analysis of the OH-initiated oxidation of dimethyl sulfide (DMS) based on experiments performed in the Aarhus University research on aerosols (AURA) smog chamber and the gas- and particle-phase chemistry kinetic multilayer model (ADCHAM). We capture the formation, growth and chemical composition of aerosols in the chamber setup by an improved multiphase oxidation mechanism, and utilize our results to reproduce the important role of DMS in the marine boundary layer.
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