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<front>
<journal-meta>
<journal-id journal-id-type="publisher">EGUsphere</journal-id>
<journal-title-group>
<journal-title>EGUsphere</journal-title>
<abbrev-journal-title abbrev-type="publisher">EGUsphere</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">EGUsphere</abbrev-journal-title>
</journal-title-group>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/egusphere-2026-6251</article-id>
<title-group>
<article-title>Fuel moisture and fuel state regulate CO&lt;sub&gt;2&lt;/sub&gt;&amp;ndash;CO&amp;ndash;CH&lt;sub&gt;4&lt;/sub&gt; partitioning: from laboratory emission factors to a regional inventory</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Xie</surname>
<given-names>Heng</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Hu</surname>
<given-names>Yuqi</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Xian</surname>
<given-names>Yaohan</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Wan</surname>
<given-names>Chuan</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Li</surname>
<given-names>Yuan</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Qi</surname>
<given-names>Guowei</given-names>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Yang</surname>
<given-names>Fumo</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Wang</surname>
<given-names>Nan</given-names>
<ext-link>https://orcid.org/0000-0002-1775-7371</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>College of Carbon Neutrality Future Technology, Sichuan University, Chengdu, 610207, PR China</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Sichuan Fire Research Institute of Ministry of Emergency Management, Chengdu, 610036, PR China</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Sichuan Academy of Environmental Sciences, Chengdu, 610041, PR China</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>School of Environment, Tsinghua University, Beijing, 100084, PR China</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Sichuan Leshan Ecological Environment Monitoring Center Station, Leshan, 614099, PR China</addr-line>
</aff>
<pub-date pub-type="epub">
<day>22</day>
<month>10</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>27</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Heng Xie et al.</copyright-statement>
<copyright-year>2026</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-6251/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-6251/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-6251/egusphere-2026-6251.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-6251/egusphere-2026-6251.pdf</self-uri>
<abstract>
<p>Bottom-up wildfire inventories commonly assign fixed emission factors (EFs) to vegetation classes, introducing uncertainty because EFs vary with fuel conditions. Here, we conducted laboratory burns of live-origin and litter-derived dead &lt;em&gt;Pinus massoniana&lt;/em&gt; needles across a broad range of dry-basis moisture contents (MC) to quantify stable-spread-stage EFs for CO&lt;sub&gt;2&lt;/sub&gt;, CO, and CH&lt;sub&gt;4&lt;/sub&gt; and develop fuel-condition-resolved parameterizations. Burning was smoldering-dominated, with sustained flaming observed only for litter-derived dead needles at 0.89 % MC. Increasing MC decreased EF(CO&lt;sub&gt;2&lt;/sub&gt;) and increased EF(CO) for live-origin needles, whereas the opposite responses occurred for smoldering-dominated litter-derived dead needles. The moisture-response regressions for EF(CO&lt;sub&gt;2&lt;/sub&gt;) and EF(CO) explained 60.3&amp;ndash;81.5 % of the variability in mean EFs, while EF(CH&lt;sub&gt;4&lt;/sub&gt;) showed no detectable moisture dependence and was represented by fuel-state-specific means of 15.7 &amp;plusmn; 4.3 and 8.0 &amp;plusmn; 2.1 g kg&lt;sup&gt;-1&lt;/sup&gt; for live and dead fuels, respectively. Applying these parameterizations in a bottom-up wildfire emission framework showed that similar total gaseous carbon emissions can mask substantial shifts in species-level carbon partitioning. Over 2012&amp;ndash;2021, cumulative gaseous carbon emissions differed by only 4.3 % from a fixed-EF baseline, whereas CO&lt;sub&gt;2&lt;/sub&gt;-C fell by 14.0 % and CO-C and CH&lt;sub&gt;4&lt;/sub&gt;-C rose by 154.6 % and 344.1 %, respectively. These shifts translated into an approximately 65.63 % greater 20-year global warming potential-based near-term climate impact. These findings highlight the importance of fuel-condition-resolved EFs for better representing wildfire emission composition and its atmospheric and climate implications.</p>
</abstract>
<counts><page-count count="27"/></counts>
<funding-group>
<award-group id="gs1">
<funding-source>National Key Research and Development Program of China</funding-source>
<award-id>2023YFC3709304</award-id>
</award-group>
<award-group id="gs2">
<funding-source>National Natural Science Foundation of China</funding-source>
<award-id>42575120</award-id>
</award-group>
</funding-group>
</article-meta>
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