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<p class="MsoNormal">Diwei Wang, Zhenxing Shen, Gezi Bai, Leiming Zhang, Shasha Huang, Jian Sun, Hongmei Xu, and Junji Cao. Insight into the molecular photooxidation evolution mechanism of brown carbon released from residential solid fuel combustion.
<i>Journal of Geophysical Research: Atmospheres</i>, 130, e2024JD041827. <a href="https://doi.org/10.1029/2024JD041827">
https://doi.org/10.1029/2024JD041827</a>, 2024. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><b>Abstract</b>. Solid fuels were one of the important emission sources of brown carbon (BrC). This study investigates molecular composition of BrC derived from combustion of five types of residential solid fuels (i.e., firewood, corn cob,
bituminous coal, anthracite, and biomass briquette) and their photooxidation evolution mechanisms using an oxidation flow reactor. Results show that nitrogen-containing and sulfur-containing organic compounds are the main components of molecular composition
of methanol-soluble organic compounds (MSOC) emitted from these fuels, with their intensity being 33%–43% and 23%–56%, respectively, depending on fuel type. The photooxidation processes mediated by NO<sub>3</sub><span style="font-family:"Cambria Math",serif">⋅</span>
and <span style="font-family:"Cambria Math",serif">⋅</span> OH significantly altered the molecular composition and distribution of aged MSOC. The formation of typical nitrogen-containing BrC chromophores (e.g., nitro-aromatic compounds) also proves the role
of NO<sub>3</sub> <span style="font-family:"Cambria Math",serif">⋅</span> in the photooxidation reaction. However, the photo-enhancement effect of NO<sub>3</sub> <span style="font-family:"Cambria Math",serif">⋅</span> mediated photooxidation reaction could
not offset the destruction of the molecular conjugation degree and aromaticity of BrC by
<span style="font-family:"Cambria Math",serif">⋅</span> OH oxidation, resulting in a significant reduction in the light absorption capacity of BrC. The mass absorption coefficient at 365 nm of BrC aged for 12 days derived from the remaining fuels decreased
by 47.0%–55.8% compared to that of fresh BrC, except for firewood, which only decreased by 5.3%. These findings on the molecular evolution and oxidation mechanism of BrC generated from solid fuels are useful in reducing uncertainties in climate change studies
involving BrC aerosol.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a href="https://sites.google.com/site/pamwiki/publications-using-the-pam-oxidation-flow-reactor?authuser=0">PAM Wiki - Publications Using the PAM Oxidation Flow Reactor</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="mso-ligatures:none">Andrew Lambe<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ligatures:none">Principal Scientist<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ligatures:none">Aerodyne Research, Inc. <o:p>
</o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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