Measurement report: Effects of anthropogenic emissions and environmental factors on the formation of biogenic secondary organic aerosol (BSOA) in a coastal city of southeastern China
<p>To better understand the formation of biogenic secondary organic aerosol (BSOA), aerosol samples with a 4 h time resolution were collected during summer and winter in the southeast of China, along with online measurements of trace gases, aerosol chemical compositions, and meteorological par...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-06-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/22/7827/2022/acp-22-7827-2022.pdf |
| Summary: | <p>To better understand the formation of biogenic secondary organic aerosol
(BSOA), aerosol samples with a 4 h time resolution were collected during
summer and winter in the southeast of China, along with online
measurements of trace gases, aerosol chemical compositions, and
meteorological parameters. The samples were analyzed by gas
chromatography–mass spectrometry for PM<span class="inline-formula"><sub>2.5</sub></span>-bound secondary organic aerosol (SOA) tracers, including
isoprene (SOA<span class="inline-formula"><sub>I</sub></span>), <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="italic">α</mi><mo>/</mo><mi mathvariant="italic">β</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="23pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="3dc8de5029bb49ec963cf9c880fd1113"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-7827-2022-ie00001.svg" width="23pt" height="14pt" src="acp-22-7827-2022-ie00001.png"/></svg:svg></span></span>-pinene (SOA<span class="inline-formula"><sub>M</sub></span>), <span class="inline-formula"><i>β</i></span>-caryophyllene (SOA<span class="inline-formula"><sub>C</sub></span>), and toluene (ASOA). The average concentrations
of total SOA tracers in winter and summer were 38.8 and 111.9 ng m<span class="inline-formula"><sup>−3</sup></span>,
respectively, with the predominance of SOA<span class="inline-formula"><sub>M</sub></span> (70.1 % and 45.8 %),
followed by SOA<span class="inline-formula"><sub>I</sub></span> (14.0 % and 45.6 %), ASOA (11.0 % and 6.2 %)
and SOA<span class="inline-formula"><sub>C</sub></span> (4.9 % and 2.3 %). Compared to those in winter, the
majority of BSOA tracers in summer showed significant positive correlations
with O<span class="inline-formula"><sub><i>x</i></sub></span> (O<span class="inline-formula"><sub>3</sub>+</span>NO<span class="inline-formula"><sub>2</sub></span>) (<span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.443–0.808), HONO (<span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.299–0.601), ultraviolet (UV) (<span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.382–0.588) and temperature (<span class="inline-formula"><i>T</i></span>) (<span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.529–0.852), indicating the influence of photochemical oxidation under
relatively clean conditions. However, in winter, BSOA tracers were
significantly correlated with PM<span class="inline-formula"><sub>2.5</sub></span> (<span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.407–0.867),
NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M26" 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="d96e0e0e6a6172a7d34ac185b1d0a8a7"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-7827-2022-ie00002.svg" width="9pt" height="16pt" src="acp-22-7827-2022-ie00002.png"/></svg:svg></span></span> (<span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.416–0.884), SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M29" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><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="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="29af680a2c2c3e13b3242191be5b1002"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-7827-2022-ie00003.svg" width="13pt" height="17pt" src="acp-22-7827-2022-ie00003.png"/></svg:svg></span></span> (<span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.419–0.813), and NH<span class="inline-formula"><sub>3</sub></span> (<span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.440–0.757), attributed to the
contributions of anthropogenic emissions. Major BSOA tracers in both seasons
were linearly correlated with aerosol acidity (pH) (<span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.421–0.752),
liquid water content (LWC) (<span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.403–0.876) and SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M39" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><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="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="43551dd6939ff027a946c13e8be02135"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-7827-2022-ie00004.svg" width="13pt" height="17pt" src="acp-22-7827-2022-ie00004.png"/></svg:svg></span></span> (<span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.419–0.813). The results indicated that acid-catalyzed reactive uptake
onto sulfate aerosol particles enhanced the formation of BSOA. In summer,
the clean air mass originated from the ocean, and chlorine depletion was
observed. We also found that concentrations of the total SOA tracers were
correlated with HCl (<span class="inline-formula"><i>R</i><sup>2</sup>=0</span>.545) and chlorine ions (<span class="inline-formula"><i>r</i></span> <span class="inline-formula">=</span> 0.280–0.639) in PM<span class="inline-formula"><sub>2.5</sub></span>, reflecting the contribution of Cl-initiated volatile organic compound (VOC) oxidations to the formation of SOA. In winter, the northeast dominant wind
direction brought continental polluted air mass to the monitoring site,
affecting the transformation of BSOA tracers. This implied that
anthropogenic emissions, atmospheric oxidation capacity and halogen
chemistry have significant effects on the formation of BSOA in the southeast
coastal area.</p> |
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| ISSN: | 1680-7316 1680-7324 |