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<front>
<journal-meta>
<journal-id journal-id-type="publisher">ACP</journal-id>
<journal-title-group>
<journal-title>Atmospheric Chemistry and Physics</journal-title>
<abbrev-journal-title abbrev-type="publisher">ACP</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1680-7324</issn>
<publisher><publisher-name>Copernicus GmbH</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/acp-10-5965-2010</article-id>
<title-group>
<article-title>Water-Soluble Organic Aerosol material and the light-absorption characteristics of aqueous extracts measured over the Southeastern United States</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Hecobian</surname>
<given-names>A.</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>Zhang</surname>
<given-names>X.</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>Zheng</surname>
<given-names>M.</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>Frank</surname>
<given-names>N.</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>Edgerton</surname>
<given-names>E. S.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Weber</surname>
<given-names>R. J.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Georgia Institute of Technology, School of Earth and Atmospheric Sciences, Atlanta, Georgia, USA</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Office of Air Quality Planning &amp; Standards, US Environmental Protection Agency, 109 TW Alexander Drive, Research Triangle Park, NC, USA</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Atmospheric Research and Analysis, Inc, Durham, North Carolina, USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>02</day>
<month>07</month>
<year>2010</year>
</pub-date>
<volume>10</volume>
<issue>13</issue>
<fpage>5965</fpage>
<lpage>5977</lpage>
<permissions>
<license xlink:type="simple">
<license-p>This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.</license-p>
</license>
</permissions>
<self-uri xlink:href="http://www.atmos-chem-phys.net/10/5965/2010/acp-10-5965-2010.html">This article is available from http://www.atmos-chem-phys.net/10/5965/2010/acp-10-5965-2010.html</self-uri>
<self-uri xlink:href="http://www.atmos-chem-phys.net/10/5965/2010/acp-10-5965-2010.pdf">The full text article is available as a PDF file from http://www.atmos-chem-phys.net/10/5965/2010/acp-10-5965-2010.pdf</self-uri>
<abstract>
<p>Light absorption of fine particle (PM&lt;sub&gt;2.5&lt;/sub&gt;) aqueous extracts between
wavelengths of 200 and 800 nm were investigated from two data sets: 24-h
Federal Reference Method (FRM) filter extracts from 15 Southeastern US
monitoring sites over the year of 2007 (900 filters), and online
measurements from a Particle-Into-Liquid Sampler deployed from July to
mid-August 2009 in Atlanta, Georgia. Three main sources of soluble
chromophores were identified: biomass burning, mobile source emissions, and
compounds linked to secondary organic aerosol (SOA) formation. Absorption
spectra of aerosol solutions from filter extracts were similar for different
sources. Angstrom exponents were ~7&amp;plusmn;1 for biomass burning and
non-biomass burning-impacted 24-h filter samples (delineated by a
levoglucosan concentration of 50 ng m&lt;sup&gt;−3&lt;/sup&gt;) at both rural and urban sites.
The absorption coefficient from measurements averaged between wavelength 360
and 370 nm (Abs&lt;sub&gt;365&lt;/sub&gt;, in units m&lt;sup&gt;−1&lt;/sup&gt;) was used as a measure of overall
brown carbon light absorption. Biomass-burning-impacted samples were highest
during winter months and Abs&lt;sub&gt;365&lt;/sub&gt; was correlated with levoglucosan at all
sites. During periods of little biomass burning in summer, light absorbing
compounds were still ubiquitous and correlated with fine particle
Water-Soluble Organic Carbon (WSOC), but comprised a much smaller fraction
of the WSOC, where Abs&lt;sub&gt;365&lt;/sub&gt;/WSOC (i.e., mass absorption efficiency) was
typically ~3 times higher in biomass burning-impacted samples. Factor
analysis attributed 50% of the yearly average Abs&lt;sub&gt;365&lt;/sub&gt; to biomass burning
sources. Brown carbon from primary urban emissions (mobile sources) was also
observed and accounted for ~10% of the regional yearly average
Abs&lt;sub&gt;365&lt;/sub&gt;. Summertime diurnal profiles of Abs&lt;sub&gt;365&lt;/sub&gt; and WSOC showed that
morning to midday increases in WSOC from photochemical production were
associated with a decrease in Abs&lt;sub&gt;365&lt;/sub&gt;/WSOC. After noon, this ratio
substantially increased, indicating that either some fraction of the
non-light absorbing fresh SOA was rapidly (within hours) converted to
chromophores heterogeneously, or that SOA from gas-particle partitioning
later in the day was more light-absorbing. Factor analysis on the 24-h
integrated filter data associated ~20 to 30% of Abs&lt;sub&gt;365&lt;/sub&gt; over 2007
with a secondary source that was highest in summer and also the main source
for oxalate, suggesting that aqueous phase reactions may account for the
light-absorbing fraction of WSOC observed throughout the Southeastern US
in summer.</p>
</abstract>
<counts><page-count count="13"/></counts>
</article-meta>
</front>
<body/>
<back>
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