Long-term trends and drivers of aerosol pH in eastern China
<p>Aerosol acidity plays a key role in regulating the chemistry and toxicity of atmospheric aerosol particles. The trend of aerosol pH and its drivers is crucial in understanding the multiphase formation pathways of aerosols. Here, we reported the first trend analysis of aerosol pH from 2011 t...
| Main Authors: | , , , , , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-10-01
|
| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/22/13833/2022/acp-22-13833-2022.pdf |
| Summary: | <p>Aerosol acidity plays a key role in regulating the chemistry and toxicity of atmospheric aerosol particles. The trend of aerosol pH and its drivers is crucial in understanding the multiphase formation pathways of aerosols.
Here, we reported the first trend analysis of aerosol pH from 2011 to 2019
in eastern China, calculated with the ISORROPIA model based on observed gas
and aerosol compositions. The implementation of the Air Pollution Prevention and Control Action Plan led to <span class="inline-formula">−35.8</span> %, <span class="inline-formula">−37.6</span> %, <span class="inline-formula">−9.6</span> %, <span class="inline-formula">−81.0</span> % and 1.2 % changes of PM<span class="inline-formula"><sub>2.5</sub></span>, <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">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="a8455a3a3390243c17ea2f3ca419ac4e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-13833-2022-ie00001.svg" width="29pt" height="17pt" src="acp-22-13833-2022-ie00001.png"/></svg:svg></span></span>, <span class="inline-formula">NH<sub><i>x</i></sub></span>, non-volatile cations (NVCs) and <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-22-13833-2022-ie00002.svg" width="25pt" height="16pt" src="acp-22-13833-2022-ie00002.png"/></svg:svg></span></span> in the Yangtze River Delta (YRD) region during this period. Different from the drastic changes of aerosol compositions due to the implementation of the Air Pollution Prevention and Control Action Plan, aerosol pH showed a minor change of <span class="inline-formula">−0.24</span> over the 9 years. Besides the multiphase buffer effect, the opposite effects from the changes of <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-22-13833-2022-ie00003.svg" width="29pt" height="17pt" src="acp-22-13833-2022-ie00003.png"/></svg:svg></span></span> and non-volatile cations played key roles in determining this minor pH trend, contributing to a change of <span class="inline-formula">+0.3</span>8 and <span class="inline-formula">−0.35</span>, respectively. Seasonal variations in aerosol pH were mainly driven by the temperature, while the diurnal variations were driven by both temperature and relative humidity. In the future, <span class="inline-formula">SO<sub>2</sub></span>, <span class="inline-formula">NO<sub><i>x</i></sub></span> and <span class="inline-formula">NH<sub>3</sub></span> emissions are expected to be further reduced by 86.9 %, 74.9 % and 41.7 % in 2050 according to the best health effect pollution control scenario (SSP1-26-BHE). The corresponding aerosol pH in eastern China is estimated to increase by <span class="inline-formula">∼0.19</span>, resulting in 0.04 less
<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M17" 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="822fcc3376206f5298bc14405cca7022"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-13833-2022-ie00004.svg" width="25pt" height="16pt" src="acp-22-13833-2022-ie00004.png"/></svg:svg></span></span> and 0.12 less <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M18" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">NH</mi><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="7b888eb222795ca6a6dd2ceb535b59a0"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-13833-2022-ie00005.svg" width="24pt" height="15pt" src="acp-22-13833-2022-ie00005.png"/></svg:svg></span></span> partitioning ratios, which suggests that <span class="inline-formula">NH<sub>3</sub></span> and <span class="inline-formula">NO<sub><i>x</i></sub></span> emission controls are effective in mitigating haze pollution in eastern China.</p> |
|---|---|
| ISSN: | 1680-7316 1680-7324 |