Atmospheric fate of organosulfates through gas-phase and aqueous-phase reactions with hydroxyl radicals: implications for inorganic sulfate formation
<p>Organosulfates are important tracers for aerosol particles, yet their influence on aerosol chemical composition remains poorly understood. This study uses quantum chemical calculations based on density functional theory to explore the reactions of some prevalent organosulfates, specifically...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-08-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/8575/2025/acp-25-8575-2025.pdf |
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| Summary: | <p>Organosulfates are important tracers for aerosol particles, yet their influence on aerosol chemical composition remains poorly understood. This study uses quantum chemical calculations based on density functional theory to explore the reactions of some prevalent organosulfates, specifically methyl sulfate and glycolic acid sulfate, with hydroxyl radicals (HO<span class="inline-formula"><span class="Radical">⚫</span></span>) in the gas phase and aqueous phase. Results indicate that all reactions initiate with hydrogen abstraction by HO<span class="inline-formula"><span class="Radical">⚫</span></span> from CH<span class="inline-formula"><sub>3</sub></span>- in methyl sulfate and from -CH<span class="inline-formula"><sub>2</sub></span>- and -COOH in glycolic acid sulfate, followed by the further reaction of the resulting radicals through self-decomposition, interaction with O<span class="inline-formula"><sub>2</sub></span> and, possibly, O<span class="inline-formula"><sub>3</sub></span>. We found that the hydrogen abstraction from the -COOH group in glycolic acid sulfate could lead to decarboxylation and eventually form similar products as methyl sulfate. The primary reaction products are inorganic sulfate, carbonyl compounds, and formic sulfuric anhydride. Rate constants of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">1.14</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">13</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="61pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="e573a49fdbb0264d0005a2439f4a9648"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-25-8575-2025-ie00001.svg" width="61pt" height="14pt" src="acp-25-8575-2025-ie00001.png"/></svg:svg></span></span> and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">6.17</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">12</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="61pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="ce6c5e33ae3ba14f90fde1e2817ed208"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-25-8575-2025-ie00002.svg" width="61pt" height="14pt" src="acp-25-8575-2025-ie00002.png"/></svg:svg></span></span> cm<span class="inline-formula"><sup>3</sup></span> molec.<span class="inline-formula"><sup>−1</sup></span> s<span class="inline-formula"><sup>−1</sup></span> at 298.15 K were determined for the gas-phase reactions of methyl sulfate and glycolic acid sulfate, respectively. The former value is consistent with a previous experimental report. Additionally, besides O<span class="inline-formula"><sub>2</sub></span> as the primary oxidant in the fragmentation of organosulfates, this study unveils that O<span class="inline-formula"><sub>3</sub></span> may be a complementary oxidant in this process, especially in environments enriched with ozone. Overall, this study elucidates mechanisms for HO<span class="inline-formula"><span class="Radical">⚫</span></span>-initiated transformation of organosulfates and highlights the potential role of chemical substitution, thereby enhancing our understanding of their atmospheric chemistry and implications for inorganic sulfate formation, which are vital for evaluating their impact on aerosol properties and climate processes.</p> |
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| ISSN: | 1680-7316 1680-7324 |