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Published October 4, 2022 | Supplemental Material + Published
Journal Article Open

High Gas-Phase Methanesulfonic Acid Production in the OH-Initiated Oxidation of Dimethyl Sulfide at Low Temperatures

Abstract

Dimethyl sulfide (DMS) influences climate via cloud condensation nuclei (CCN) formation resulting from its oxidation products (mainly methanesulfonic acid, MSA, and sulfuric acid, H₂SO₄). Despite their importance, accurate prediction of MSA and H2SO4 from DMS oxidation remains challenging. With comprehensive experiments carried out in the Cosmics Leaving Outdoor Droplets (CLOUD) chamber at CERN, we show that decreasing the temperature from +25 to −10 °C enhances the gas-phase MSA production by an order of magnitude from OH-initiated DMS oxidation, while H₂SO₄ production is modestly affected. This leads to a gas-phase H₂SO₄-to-MSA ratio (H₂SO₄/MSA) smaller than one at low temperatures, consistent with field observations in polar regions. With an updated DMS oxidation mechanism, we find that methanesulfinic acid, CH₃S(O)OH, MSIA, forms large amounts of MSA. Overall, our results reveal that MSA yields are a factor of 2–10 higher than those predicted by the widely used Master Chemical Mechanism (MCMv3.3.1), and the NOₓ effect is less significant than that of temperature. Our updated mechanism explains the high MSA production rates observed in field observations, especially at low temperatures, thus, substantiating the greater importance of MSA in the natural sulfur cycle and natural CCN formation. Our mechanism will improve the interpretation of present-day and historical gas-phase H₂SO₄/MSA measurements.

Additional Information

© 2022 The Authors. Published by American Chemical Society. Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/). This research has received funding from the Academy of Finland ACCC Flagship (no. 337549), the Academy of Finland Academy professorship (no. 302958), the Academy of Finland (nos. 307331, 337550, 296628, 328290), the European Research Council (ERC) (Projects 742206, 714621, 101002728, and 850614); the EU H2020 programme Marie Skłodowska Curie ITN "CLOUD-TRAIN" (764991), the Swiss National Science Foundation (no. 200021_169090, 200020_172602, 20FI20_172622), the US National Science Foundation (no. AGS1531284, AGS1801574, AGS1801897, AGS1801280, AGS2215522); the European Union's Horizon 2020 Research and Innovation Programme (Marie Skłodowska Curie no. 895875 "NPF-PANDA"), the Portuguese Foundation for Science and Technology (no. CERN/FIS-COM/0028/2019), the Swedish Research Council Formas Project (no. 2018-01745-COBACCA), the Swedish Research Council VR Project (no. 2019-05006), the Crafoord Foundation Project (no. 20210969), EU H2020 project FORCeS (no. 821205), German Federal Ministry of Education and Research, CLOUD-16 (01LK1601A), and the doctoral scholarship (2021/1) of the University of Innsbruck. The authors thank the European Organization for Nuclear Research (CERN) for supporting CLOUD with important technical and financial resources and for providing a particle beam from the CERN Proton Synchrotron. Author Contributions. J.S., X.-C.H., and M.Sip. planned the experiments. J.S., W.S., X.-C.H., G.M., M.W., R.M., B.R., R.B., L.C., F.A., D.M.B., B.B., Z.B., D.C., B.C., L.D., J.D., H.F., M.G., R.G., M.H., V.H., W.K., J.E.K., A.K., H.L., C.P.L., B.L., N.G.A.M., H.E.M., D.M., R.L.M., B.M., T.M., T.P., J.P., M.P., A.A.P., S.S., M.Si., M.Su., Y.J.T., A.T., N.S.U., D.W., Y.Wang., S.K.W., A.W., Y.Wu., M.Z.-W., U.B., J.C., R.C.F., R.V., O.M., K.M., K.L., M.R., J.K., I.E.-H., F.B., and M.Sip. prepared the CLOUD facility or measuring instruments. J.S., W.S., X.-C.H., G.M., M.W., R.M., B.R., R.B., L.C., A.A., F.A., D.M.B., B.B., D.C., J.D., H.F., M.G., M.H., V.H., D.K., W.K., J.E.K., H.L., C.P.L., B.L., N.G.A.M., D.M., R.L.M., B.M., T.M., J.P., M.Sim., M.Su., Y.J.T., A.T., D.W., S.K.W., Y.Wu., M.Z.-W., J.C., R.C.F., R.V., and J.K. collected the data. J.S., W.S., X.-C.H., P.Z., G.M., M.W., R.M., B.R., L.C., S.I., J.K., M.Sim., M.Su., and S.K.W. analyzed the data. J.S., W.S., X.-C.H., P.Z., S.I., P.R., M.Sim., D.S., R.W.D.J., U.B., J.C., R.C.F., A.H., K.M., K.L., M.R., J.K., I.E.-H., F.B., M.Sip., N.M.D., and D.R.W. contributed to the scientific discussion. J.S. and N.M.D. wrote the manuscript with contributions from W.S., X.-C.H., M.R., J.K., I.E.-H., F.B., and D.R.W. J.S., W.S., X.-C.H., P.Z., R.B., Z.B., J.D., H.F., N.G.A.M., R.G., P.R., R.W.D.J., S.S., D.S., D.W., M.Z.-W., U.B., M.R., J.K., I.E.-H., F.B., M.S., N.M.D., and D.R.W. commented on and edited the manuscript. The authors declare no competing financial interest.

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Additional details

Created:
August 22, 2023
Modified:
October 24, 2023