Understanding summertime peroxyacetyl nitrate (PAN) formation and its relation to aerosol pollution: insights from high-resolution measurements and modeling
<p>Peroxyacetyl nitrate (PAN), a key indicator of photochemical pollution, is generated similarly to ozone (O<span class="inline-formula"><sub>3</sub></span>), through reactions involving specific volatile organic compounds (VOCs) and nitrogen oxides. Notably,...
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Copernicus Publications
2025-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/905/2025/acp-25-905-2025.pdf |
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| author | B. Hu B. Hu B. Hu N. Chen N. Chen R. Li M. Huang M. Huang M. Huang J. Chen J. Chen Y. Hong Y. Hong L. Xu L. Xu X. Fan X. Fan M. Li M. Li L. Tong Q. Zheng Y. Yang |
| author_facet | B. Hu B. Hu B. Hu N. Chen N. Chen R. Li M. Huang M. Huang M. Huang J. Chen J. Chen Y. Hong Y. Hong L. Xu L. Xu X. Fan X. Fan M. Li M. Li L. Tong Q. Zheng Y. Yang |
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| description | <p>Peroxyacetyl nitrate (PAN), a key indicator of photochemical pollution, is generated similarly to ozone (O<span class="inline-formula"><sub>3</sub></span>), through reactions involving specific volatile organic compounds (VOCs) and nitrogen oxides. Notably, PAN has been observed at unexpectedly high concentrations (maximum: 3.04 ppb) during the summertime. The average daily values of PAN show a strong correlation with black carbon (BC) (<span class="inline-formula"><i>R</i></span> <span class="inline-formula">=</span> 0.77) and O<span class="inline-formula"><sub>3</sub></span> (<span class="inline-formula"><i>R</i></span> <span class="inline-formula">=</span> 0.77), suggesting a close connection between summertime haze and photochemical pollution. We addressed the puzzle of summertime PAN formation and its association with aerosol pollution under high-O<span class="inline-formula"><sub>3</sub></span> conditions in Xiamen, a coastal city in southeastern China, by analyzing continuous high-temporal-resolution data utilizing box modeling in conjunction with the Master Chemical Mechanism (MCM) model. The MCM model, with an index of agreement (IOA) value of 0.75, effectively investigates PAN formation, performing better during the clean period (<span class="inline-formula"><i>R</i><sup>2</sup></span>: 0.68; slope <span class="inline-formula"><i>K</i></span>: 0.91) than the haze one (<span class="inline-formula"><i>R</i><sup>2</sup></span>: 0.47; slope <span class="inline-formula"><i>K</i></span>: 0.75). Using eXtreme Gradient Boosting (XGBoost), we identified NH<span class="inline-formula"><sub>3</sub></span>, NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="a192f22c747584054322d55d69a940ca"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-25-905-2025-ie00001.svg" width="9pt" height="16pt" src="acp-25-905-2025-ie00001.png"/></svg:svg></span></span>, and PM<span class="inline-formula"><sub>2.5</sub></span> as the primary factors for simulation bias. Moreover, the net production rate of PAN becomes negative with PAN constrained, suggesting an unknown compensatory mechanism. Both relative incremental reactivity (RIR) and empirical kinetic modeling approach (EKMA) analyses indicate that PAN formation is VOC-controlled. Controlling emissions of VOCs, particularly alkenes, C<span class="inline-formula"><sub>5</sub></span>H<span class="inline-formula"><sub>8</sub></span>, and aromatics, would mitigate PAN pollution. PAN promotes OH and HO<span class="inline-formula"><sub>2</sub></span> while inhibiting the formation of O<span class="inline-formula"><sub>3</sub></span>, RO<span class="inline-formula"><sub>2</sub></span>, NO, and NO<span class="inline-formula"><sub>2</sub></span>. This study deepens our comprehension of PAN photochemistry while also offering scientific insights for guiding future PAN pollution control strategies.</p> |
| format | Article |
| id | doaj-art-7e69bd28d3cf4eff82f6d7aeafc5fc2c |
| institution | Kabale University |
| issn | 1680-7316 1680-7324 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Copernicus Publications |
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| spelling | doaj-art-7e69bd28d3cf4eff82f6d7aeafc5fc2c2025-01-23T08:13:48ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242025-01-012590592110.5194/acp-25-905-2025Understanding summertime peroxyacetyl nitrate (PAN) formation and its relation to aerosol pollution: insights from high-resolution measurements and modelingB. Hu0B. Hu1B. Hu2N. Chen3N. Chen4R. Li5M. Huang6M. Huang7M. Huang8J. Chen9J. Chen10Y. Hong11Y. Hong12L. Xu13L. Xu14X. Fan15X. Fan16M. Li17M. Li18L. Tong19Q. Zheng20Y. Yang21College of Chemistry, Chemical Engineering and Environment, Minnan Normal University, Zhangzhou 363000, ChinaFujian Provincial Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000, ChinaFujian Province University Key Laboratory of Pollution Monitoring and Control, Minnan Normal University, Zhangzhou 363000, ChinaCollege of Chemistry, Chemical Engineering and Environment, Minnan Normal University, Zhangzhou 363000, ChinaPingtan Environmental Monitoring Center of Fujian, Fuzhou, Pingtan 350400, ChinaKey Laboratory of Geographic Information Science of the Ministry of Education, School of Geographic Science, East China Normal University, Shanghai 200241, ChinaCollege of Chemistry, Chemical Engineering and Environment, Minnan Normal University, Zhangzhou 363000, ChinaFujian Provincial Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000, ChinaFujian Province University Key Laboratory of Pollution Monitoring and Control, Minnan Normal University, Zhangzhou 363000, ChinaCenter for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, ChinaFujian Key Laboratory of Atmospheric Ozone Pollution Prevention, Chinese Academy of Sciences, Xiamen 361021, ChinaCenter for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, ChinaFujian Key Laboratory of Atmospheric Ozone Pollution Prevention, Chinese Academy of Sciences, Xiamen 361021, ChinaCenter for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, ChinaFujian Key Laboratory of Atmospheric Ozone Pollution Prevention, Chinese Academy of Sciences, Xiamen 361021, ChinaCenter for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, ChinaFujian Key Laboratory of Atmospheric Ozone Pollution Prevention, Chinese Academy of Sciences, Xiamen 361021, ChinaCenter for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, ChinaFujian Key Laboratory of Atmospheric Ozone Pollution Prevention, Chinese Academy of Sciences, Xiamen 361021, ChinaCenter for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, ChinaXiamen Key Laboratory of Straits Meteorology, Xiamen Meteorological Bureau, Xiamen 361012, ChinaPingtan Environmental Monitoring Center of Fujian, Fuzhou, Pingtan 350400, China<p>Peroxyacetyl nitrate (PAN), a key indicator of photochemical pollution, is generated similarly to ozone (O<span class="inline-formula"><sub>3</sub></span>), through reactions involving specific volatile organic compounds (VOCs) and nitrogen oxides. Notably, PAN has been observed at unexpectedly high concentrations (maximum: 3.04 ppb) during the summertime. The average daily values of PAN show a strong correlation with black carbon (BC) (<span class="inline-formula"><i>R</i></span> <span class="inline-formula">=</span> 0.77) and O<span class="inline-formula"><sub>3</sub></span> (<span class="inline-formula"><i>R</i></span> <span class="inline-formula">=</span> 0.77), suggesting a close connection between summertime haze and photochemical pollution. We addressed the puzzle of summertime PAN formation and its association with aerosol pollution under high-O<span class="inline-formula"><sub>3</sub></span> conditions in Xiamen, a coastal city in southeastern China, by analyzing continuous high-temporal-resolution data utilizing box modeling in conjunction with the Master Chemical Mechanism (MCM) model. The MCM model, with an index of agreement (IOA) value of 0.75, effectively investigates PAN formation, performing better during the clean period (<span class="inline-formula"><i>R</i><sup>2</sup></span>: 0.68; slope <span class="inline-formula"><i>K</i></span>: 0.91) than the haze one (<span class="inline-formula"><i>R</i><sup>2</sup></span>: 0.47; slope <span class="inline-formula"><i>K</i></span>: 0.75). Using eXtreme Gradient Boosting (XGBoost), we identified NH<span class="inline-formula"><sub>3</sub></span>, NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="a192f22c747584054322d55d69a940ca"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-25-905-2025-ie00001.svg" width="9pt" height="16pt" src="acp-25-905-2025-ie00001.png"/></svg:svg></span></span>, and PM<span class="inline-formula"><sub>2.5</sub></span> as the primary factors for simulation bias. Moreover, the net production rate of PAN becomes negative with PAN constrained, suggesting an unknown compensatory mechanism. Both relative incremental reactivity (RIR) and empirical kinetic modeling approach (EKMA) analyses indicate that PAN formation is VOC-controlled. Controlling emissions of VOCs, particularly alkenes, C<span class="inline-formula"><sub>5</sub></span>H<span class="inline-formula"><sub>8</sub></span>, and aromatics, would mitigate PAN pollution. PAN promotes OH and HO<span class="inline-formula"><sub>2</sub></span> while inhibiting the formation of O<span class="inline-formula"><sub>3</sub></span>, RO<span class="inline-formula"><sub>2</sub></span>, NO, and NO<span class="inline-formula"><sub>2</sub></span>. This study deepens our comprehension of PAN photochemistry while also offering scientific insights for guiding future PAN pollution control strategies.</p>https://acp.copernicus.org/articles/25/905/2025/acp-25-905-2025.pdf |
| spellingShingle | B. Hu B. Hu B. Hu N. Chen N. Chen R. Li M. Huang M. Huang M. Huang J. Chen J. Chen Y. Hong Y. Hong L. Xu L. Xu X. Fan X. Fan M. Li M. Li L. Tong Q. Zheng Y. Yang Understanding summertime peroxyacetyl nitrate (PAN) formation and its relation to aerosol pollution: insights from high-resolution measurements and modeling Atmospheric Chemistry and Physics |
| title | Understanding summertime peroxyacetyl nitrate (PAN) formation and its relation to aerosol pollution: insights from high-resolution measurements and modeling |
| title_full | Understanding summertime peroxyacetyl nitrate (PAN) formation and its relation to aerosol pollution: insights from high-resolution measurements and modeling |
| title_fullStr | Understanding summertime peroxyacetyl nitrate (PAN) formation and its relation to aerosol pollution: insights from high-resolution measurements and modeling |
| title_full_unstemmed | Understanding summertime peroxyacetyl nitrate (PAN) formation and its relation to aerosol pollution: insights from high-resolution measurements and modeling |
| title_short | Understanding summertime peroxyacetyl nitrate (PAN) formation and its relation to aerosol pollution: insights from high-resolution measurements and modeling |
| title_sort | understanding summertime peroxyacetyl nitrate pan formation and its relation to aerosol pollution insights from high resolution measurements and modeling |
| url | https://acp.copernicus.org/articles/25/905/2025/acp-25-905-2025.pdf |
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