Tracer-based investigation of organic aerosols in marine atmospheres from marginal seas of China to the northwest Pacific Ocean
<p>We investigated the geographic distributions of organic tracers in total suspended particles over the marginal seas of China, including the Yellow and Bohai seas (YBS) and the South China Sea (SCS), and the northwest Pacific Ocean (NWPO) in spring, when Asian outflows strongly affect downwi...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-04-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/20/5055/2020/acp-20-5055-2020.pdf |
| Summary: | <p>We investigated the geographic distributions of organic tracers in
total suspended particles over the marginal seas of China, including the Yellow
and Bohai seas (YBS) and the South China Sea (SCS), and the northwest
Pacific Ocean (NWPO) in spring, when Asian outflows strongly affect downwind
marine atmospheres. The comparison of levoglucosan observed in this study
with values from the literature showed that the concentrations of biomass
burning aerosols over the NWPO increased largely in 2014. However more observations,
in addition to our snapshot measurement, are need to confirm whether the
large increase has occurred continuously over the last few decades. The increase
led to a mean observed levoglucosan value (<span class="inline-formula">8.2±14</span> ng m<span class="inline-formula"><sup>−3</sup></span>) over
the NWPO that was close to that over the SCS (<span class="inline-formula">9.6±8.6</span> ng m<span class="inline-formula"><sup>−3</sup></span>) and almost
half of that over the YBS (<span class="inline-formula">21±11</span> ng m<span class="inline-formula"><sup>−3</sup></span>). Small geographic
differences in monoterpene-derived and sesquiterpene-derived secondary
organic tracer concentrations were obtained among the three atmospheres,
although the causes may differ. By contrast, a large difference in
isoprene-derived secondary organic tracer concentrations was observed among
the three atmospheres, with the sum of tracer concentrations over the SCS
(<span class="inline-formula">45±54</span> ng m<span class="inline-formula"><sup>−3</sup></span>) being several times and approximately 1 order of
magnitude greater than that over the YBS (<span class="inline-formula">15±16</span> ng m<span class="inline-formula"><sup>−3</sup></span>) and the
NWPO (<span class="inline-formula">2.3±1.6</span> ng m<span class="inline-formula"><sup>−3</sup></span>), respectively. The geographic distribution
of aromatic-derived secondary organic tracers was similar to that of
isoprene-derived secondary organic tracers, with a slightly narrower
difference: <span class="inline-formula">1.8±1.7</span>, <span class="inline-formula">1.1±1.4</span> and
<span class="inline-formula">0.3±0.5</span> ng m<span class="inline-formula"><sup>−3</sup></span> over the SCS, the YBS and the NWPO, respectively.
We discuss the causes of the distinctive geographic distributions of these
tracers and present the tracer-based estimation of organic carbon.</p> |
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| ISSN: | 1680-7316 1680-7324 |