Differences in the key volatile organic compound species between their emitted and ambient concentrations in ozone formation
<p>The emissions and secondary transformations of volatile organic compounds (VOCs) play a significant role in ozone (<span class="inline-formula">O<sub>3</sub></span>) formation. Previous studies have often relied on ambient VOC concentrations to identify key...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-04-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/3807/2025/acp-25-3807-2025.pdf |
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| Summary: | <p>The emissions and secondary transformations of volatile organic compounds (VOCs) play a significant role in ozone (<span class="inline-formula">O<sub>3</sub></span>) formation. Previous studies have often relied on ambient VOC concentrations to identify key species. However, ambient concentrations represent the residual concentrations after the emitted VOCs have been consumed, which can introduce substantial uncertainties. To address this issue, this study proposes a novel method to identify the key VOC species in both anthropogenic and biogenic emissions. The emitted VOC concentrations are calculated during both nighttime and daytime in summer using the nitrate radical, <span class="inline-formula">O<sub>3</sub></span>, and hydroxyl radical reaction rates and ambient concentrations of 99 VOCs measured at Deyang, Chengdu, and Meishan, China. The emitted concentrations of alkenes and aromatics are higher than the ambient concentrations. The largest differences between emitted and ambient concentrations are 1.04 ppbv for <i>cis</i>-2-butene at Deyang, 0.81 ppbv for isoprene at Chengdu, and 1.79 ppbv for isoprene at Meishan. In contrast, due to secondary production, the emitted concentrations of oxygenated VOCs are lower than the ambient concentrations. The largest differences are <span class="inline-formula">−0.54</span> ppbv for acetone at Deyang, <span class="inline-formula">−0.58</span> ppbv for acetaldehyde at Chengdu, and <span class="inline-formula">−0.5</span> ppbv for acetone at Meishan. Based on the emitted concentrations, isoprene is one of the top three species contributing to <span class="inline-formula">O<sub>3</sub></span> formation at all three sites, which may be overlooked in observed concentrations. Comprehensive calculation of the emitted VOC concentrations enables the key VOC species in <span class="inline-formula">O<sub>3</sub></span> formation to be accurately identified.</p> |
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| ISSN: | 1680-7316 1680-7324 |