Production of oxygenated volatile organic compounds from the ozonolysis of coastal seawater
<p>Dry deposition of ozone (O<span class="inline-formula"><sub>3</sub></span>) to the ocean surface and the ozonolysis of organics in the sea surface microlayer (SSML) are potential sources of volatile organic compounds (VOCs) to the marine atmosphere. We use...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2024-03-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/24/3729/2024/acp-24-3729-2024.pdf |
| Summary: | <p>Dry deposition of ozone (O<span class="inline-formula"><sub>3</sub></span>) to the ocean surface and the ozonolysis of organics in the sea surface microlayer (SSML) are potential sources of volatile organic compounds (VOCs) to the marine atmosphere. We use a gas chromatography system coupled to a Vocus proton-transfer-reaction time-of-flight mass spectrometer to determine the chemical composition and product yield of select VOCs formed from ozonolysis of coastal seawater collected from Scripps Pier in La Jolla, California. Laboratory-derived results are interpreted in the context of direct VOC vertical flux measurements made at Scripps Pier. The dominant products of laboratory ozonolysis experiments and the largest non-sulfur emission fluxes measured in the field correspond to Vocus C<span class="inline-formula"><sub><i>x</i></sub></span>H<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi>y</mi><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="41e953fd4febe470d043b196a09b23d0"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-3729-2024-ie00001.svg" width="8pt" height="16pt" src="acp-24-3729-2024-ie00001.png"/></svg:svg></span></span> and C<span class="inline-formula"><sub><i>x</i></sub></span>H<span class="inline-formula"><sub><i>y</i></sub></span>O<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi>z</mi><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="9578549e498a27342443c24d95ed66a8"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-3729-2024-ie00002.svg" width="8pt" height="14pt" src="acp-24-3729-2024-ie00002.png"/></svg:svg></span></span> ions. Gas chromatography (GC) analysis suggests that C<span class="inline-formula"><sub>5</sub></span>–C<span class="inline-formula"><sub>11</sub></span> oxygenated VOCs, primarily aldehydes, are the largest contributors to these ion signals. In the laboratory, using a flow reactor experiment, we determine a VOC yield of 0.43–0.62. In the field at Scripps Pier, we determine a maximum VOC yield of 0.04–0.06. Scaling the field and lab VOC yields for an average O<span class="inline-formula"><sub>3</sub></span> deposition flux and an average VOC structure results in an emission source of 10.7 to 167 Tg C yr<span class="inline-formula"><sup>−1</sup></span>, competitive with the DMS source of approximately 20.3 Tg C yr<span class="inline-formula"><sup>−1</sup></span>. This study reveals that O<span class="inline-formula"><sub>3</sub></span> reactivity to dissolved organic carbon can be a significant carbon source to the marine atmosphere and warrants further investigation into the speciated VOC composition from different seawater samples and the reactivities and secondary organic aerosol (SOA) yields of these molecules in marine-relevant, low NO<span class="inline-formula"><sub><i>x</i></sub></span> conditions.</p> |
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| ISSN: | 1680-7316 1680-7324 |