Dimethyl sulfide chemistry over the industrial era: comparison of key oxidation mechanisms and long-term observations

<p>Dimethyl sulfide (DMS) is primarily emitted by marine phytoplankton and oxidized in the atmosphere to form methanesulfonic acid (MSA) and sulfate aerosols. Ice cores in regions affected by anthropogenic pollution show an industrial-era decline in MSA, which has previously been interpreted a...

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Main Authors: U. A. Jongebloed, J. I. Chalif, L. Tashmim, W. C. Porter, K. H. Bates, Q. Chen, E. C. Osterberg, B. G. Koffman, J. Cole-Dai, D. A. Winski, D. G. Ferris, K. J. Kreutz, C. P. Wake, B. Alexander
Format: Article
Language:English
Published: Copernicus Publications 2025-04-01
Series:Atmospheric Chemistry and Physics
Online Access:https://acp.copernicus.org/articles/25/4083/2025/acp-25-4083-2025.pdf
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author U. A. Jongebloed
J. I. Chalif
L. Tashmim
W. C. Porter
K. H. Bates
Q. Chen
E. C. Osterberg
B. G. Koffman
J. Cole-Dai
D. A. Winski
D. G. Ferris
K. J. Kreutz
C. P. Wake
B. Alexander
author_facet U. A. Jongebloed
J. I. Chalif
L. Tashmim
W. C. Porter
K. H. Bates
Q. Chen
E. C. Osterberg
B. G. Koffman
J. Cole-Dai
D. A. Winski
D. G. Ferris
K. J. Kreutz
C. P. Wake
B. Alexander
author_sort U. A. Jongebloed
collection DOAJ
description <p>Dimethyl sulfide (DMS) is primarily emitted by marine phytoplankton and oxidized in the atmosphere to form methanesulfonic acid (MSA) and sulfate aerosols. Ice cores in regions affected by anthropogenic pollution show an industrial-era decline in MSA, which has previously been interpreted as indicating a decline in phytoplankton abundance. However, a simultaneous increase in DMS-derived sulfate (bioSO<span class="inline-formula"><sub>4</sub></span>) in a Greenland ice core suggests that pollution-driven oxidant changes caused the decline in MSA by influencing the relative production of MSA versus bioSO<span class="inline-formula"><sub>4</sub></span>. Here we use GEOS-Chem, a global chemical transport model, and a zero-dimensional box model over three time periods (preindustrial era, peak North Atlantic NO<span class="inline-formula"><sub><i>x</i></sub></span> pollution, and 21st century) to investigate the chemical drivers of industrial-era changes in MSA and bioSO<span class="inline-formula"><sub>4</sub></span>, and we examine whether four DMS oxidation mechanisms reproduce trends and seasonality in observations. We find that box model and GEOS-Chem simulations can only partially reproduce ice core trends in MSA and bioSO<span class="inline-formula"><sub>4</sub></span> and that wide variation in model results reflects sensitivity to DMS oxidation mechanism and oxidant concentrations. Our simulations support the hypothesized increase in DMS oxidation by the nitrate radical over the industrial era, which increases bioSO<span class="inline-formula"><sub>4</sub></span> production, but competing factors such as oxidation by BrO result in increased MSA production in some simulations, which is inconsistent with observations. To improve understanding of DMS oxidation, future work should investigate aqueous-phase chemistry, which produces 82 %–99 % of MSA and bioSO<span class="inline-formula"><sub>4</sub></span> in our simulations, and constrain atmospheric oxidant concentrations, including the nitrate radical, hydroxyl radical, and reactive halogens.</p>
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spelling doaj-art-4e7d780f0e284c6bb044d0e559f18bbb2025-08-20T02:16:55ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242025-04-01254083410610.5194/acp-25-4083-2025Dimethyl sulfide chemistry over the industrial era: comparison of key oxidation mechanisms and long-term observationsU. A. Jongebloed0J. I. Chalif1L. Tashmim2W. C. Porter3K. H. Bates4Q. Chen5E. C. Osterberg6B. G. Koffman7J. Cole-Dai8D. A. Winski9D. G. Ferris10K. J. Kreutz11C. P. Wake12B. Alexander13Department of Atmospheric and Climate Science, University of Washington, Seattle, WA 98195, USADepartment of Earth Sciences, Dartmouth College, Hanover, NH 03755, USADepartment of Environmental Sciences, University of California, Riverside, CA 92521, USADepartment of Environmental Sciences, University of California, Riverside, CA 92521, USADepartment of Mechanical Engineering, University of Colorado, Boulder, CO 80309, USADepartment of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong SAR 999077, ChinaDepartment of Earth Sciences, Dartmouth College, Hanover, NH 03755, USADepartment of Geology, Colby College, Waterville, ME 04901, USADepartment of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57006, USAClimate Change Institute and School of Earth and Climate Science, University of Maine, Orono, ME 04469, USADepartment of Earth Sciences, Dartmouth College, Hanover, NH 03755, USAClimate Change Institute and School of Earth and Climate Science, University of Maine, Orono, ME 04469, USAThe Center for North Atlantic Studies, University of New England, Portland, ME 04103, USADepartment of Atmospheric and Climate Science, University of Washington, Seattle, WA 98195, USA<p>Dimethyl sulfide (DMS) is primarily emitted by marine phytoplankton and oxidized in the atmosphere to form methanesulfonic acid (MSA) and sulfate aerosols. Ice cores in regions affected by anthropogenic pollution show an industrial-era decline in MSA, which has previously been interpreted as indicating a decline in phytoplankton abundance. However, a simultaneous increase in DMS-derived sulfate (bioSO<span class="inline-formula"><sub>4</sub></span>) in a Greenland ice core suggests that pollution-driven oxidant changes caused the decline in MSA by influencing the relative production of MSA versus bioSO<span class="inline-formula"><sub>4</sub></span>. Here we use GEOS-Chem, a global chemical transport model, and a zero-dimensional box model over three time periods (preindustrial era, peak North Atlantic NO<span class="inline-formula"><sub><i>x</i></sub></span> pollution, and 21st century) to investigate the chemical drivers of industrial-era changes in MSA and bioSO<span class="inline-formula"><sub>4</sub></span>, and we examine whether four DMS oxidation mechanisms reproduce trends and seasonality in observations. We find that box model and GEOS-Chem simulations can only partially reproduce ice core trends in MSA and bioSO<span class="inline-formula"><sub>4</sub></span> and that wide variation in model results reflects sensitivity to DMS oxidation mechanism and oxidant concentrations. Our simulations support the hypothesized increase in DMS oxidation by the nitrate radical over the industrial era, which increases bioSO<span class="inline-formula"><sub>4</sub></span> production, but competing factors such as oxidation by BrO result in increased MSA production in some simulations, which is inconsistent with observations. To improve understanding of DMS oxidation, future work should investigate aqueous-phase chemistry, which produces 82 %–99 % of MSA and bioSO<span class="inline-formula"><sub>4</sub></span> in our simulations, and constrain atmospheric oxidant concentrations, including the nitrate radical, hydroxyl radical, and reactive halogens.</p>https://acp.copernicus.org/articles/25/4083/2025/acp-25-4083-2025.pdf
spellingShingle U. A. Jongebloed
J. I. Chalif
L. Tashmim
W. C. Porter
K. H. Bates
Q. Chen
E. C. Osterberg
B. G. Koffman
J. Cole-Dai
D. A. Winski
D. G. Ferris
K. J. Kreutz
C. P. Wake
B. Alexander
Dimethyl sulfide chemistry over the industrial era: comparison of key oxidation mechanisms and long-term observations
Atmospheric Chemistry and Physics
title Dimethyl sulfide chemistry over the industrial era: comparison of key oxidation mechanisms and long-term observations
title_full Dimethyl sulfide chemistry over the industrial era: comparison of key oxidation mechanisms and long-term observations
title_fullStr Dimethyl sulfide chemistry over the industrial era: comparison of key oxidation mechanisms and long-term observations
title_full_unstemmed Dimethyl sulfide chemistry over the industrial era: comparison of key oxidation mechanisms and long-term observations
title_short Dimethyl sulfide chemistry over the industrial era: comparison of key oxidation mechanisms and long-term observations
title_sort dimethyl sulfide chemistry over the industrial era comparison of key oxidation mechanisms and long term observations
url https://acp.copernicus.org/articles/25/4083/2025/acp-25-4083-2025.pdf
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