Evolution of atmospheric age of particles and its implications for the formation of a severe haze event in eastern China
<p>Atmospheric age reflects how long particles have been suspended in the atmosphere, which is closely associated with the evolution of air pollutants. Severe regional haze events occur frequently in China, influencing air quality, human health, and regional climate. Previous studies have expl...
| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-09-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/23/10563/2023/acp-23-10563-2023.pdf |
| Summary: | <p>Atmospheric age reflects how long particles have been suspended in the atmosphere, which is closely associated with the evolution of air pollutants. Severe regional haze events occur frequently in China, influencing air quality, human health, and regional climate. Previous studies have explored the characteristics of mass concentrations and compositions of fine particulate matter (PM<span class="inline-formula"><sub>2.5</sub></span>) during haze events, but the evolution of atmospheric age remains unclear. In this study, the age-resolved University of California, Davis/California Institute of Technology (UCD/CIT) model was developed and applied to simulate the concentration and age distribution of PM<span class="inline-formula"><sub>2.5</sub></span> during a severe regional haze episode in eastern China. The results indicated that PM<span class="inline-formula"><sub>2.5</sub></span> concentrations in the North China Plain (NCP) gradually accumulated due to stagnant weather conditions during the beginning stage of the haze event. Accordingly, the atmospheric age of elemental carbon (EC), primary organic aerosol (POA), sulfate (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">SO</mi><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="29pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="544235742d8f4a0f97153436b699bab8"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-23-10563-2023-ie00001.svg" width="29pt" height="17pt" src="acp-23-10563-2023-ie00001.png"/></svg:svg></span></span>), and secondary organic aerosol (SOA) gradually increased. The subsequent PM<span class="inline-formula"><sub>2.5</sub></span> concentration growth was driven by the local chemical formation of nitrate (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NO</mi><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="a33a7d42b70ca1fe513ac92c5832eec2"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-23-10563-2023-ie00002.svg" width="25pt" height="16pt" src="acp-23-10563-2023-ie00002.png"/></svg:svg></span></span>) under high relative humidity. The newly formed <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NO</mi><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="a02883d0956e7dc256b9fe9fffa70b09"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-23-10563-2023-ie00003.svg" width="25pt" height="16pt" src="acp-23-10563-2023-ie00003.png"/></svg:svg></span></span> particles led to a decrease in the mean atmospheric age of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NO</mi><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="8a872e45f44a0fc3c08e466e371cfb3a"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-23-10563-2023-ie00004.svg" width="25pt" height="16pt" src="acp-23-10563-2023-ie00004.png"/></svg:svg></span></span> particles. During the regional transport stage, aged particles from the NCP moved to the downwind Yangtze River Delta (YRD) region, leading to a sharp increase in PM<span class="inline-formula"><sub>2.5</sub></span> concentrations and the average age of EC, POA, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">SO</mi><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="29pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="8c898138530c760447165fe6cdc920bb"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-23-10563-2023-ie00005.svg" width="29pt" height="17pt" src="acp-23-10563-2023-ie00005.png"/></svg:svg></span></span>, and SOA in YRD. In contrast, the average age of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M11" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NO</mi><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="eb51cd45ba2a21283d090226a04e61ba"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-23-10563-2023-ie00006.svg" width="25pt" height="16pt" src="acp-23-10563-2023-ie00006.png"/></svg:svg></span></span> and ammonium remained unchanged or even slightly decreased due to continuous local formation in the YRD region. Different evolution of the atmospheric age among these components provides a unique perspective on the formation of PM<span class="inline-formula"><sub>2.5</sub></span> components during the regional haze event. The information can also be used for designing effective control strategies for different components of PM<span class="inline-formula"><sub>2.5</sub></span>.</p> |
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| ISSN: | 1680-7316 1680-7324 |