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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-6-5049-2006</article-id>
<title-group>
<article-title>Changes in background aerosol composition in Finland during polluted and clean periods studied by TEM/EDX individual particle analysis</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Niemi</surname>
<given-names>J. V.</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>Saarikoski</surname>
<given-names>S.</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>Tervahattu</surname>
<given-names>H.</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>Mäkelä</surname>
<given-names>T.</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>Hillamo</surname>
<given-names>R.</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>Vehkamäki</surname>
<given-names>H.</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Sogacheva</surname>
<given-names>L.</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Kulmala</surname>
<given-names>M.</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Department of Biological and Environmental Sciences, University of Helsinki, P.O. Box 27, FI-00014 Helsinki, Finland</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Nordic Envicon Ltd., Koetilantie 3, FI-00790 Helsinki, Finland</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Department of Physical Sciences, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland</addr-line>
</aff>
<pub-date pub-type="epub">
<day>03</day>
<month>11</month>
<year>2006</year>
</pub-date>
<volume>6</volume>
<issue>12</issue>
<fpage>5049</fpage>
<lpage>5066</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/6/5049/2006/acp-6-5049-2006.html">This article is available from http://www.atmos-chem-phys.net/6/5049/2006/acp-6-5049-2006.html</self-uri>
<self-uri xlink:href="http://www.atmos-chem-phys.net/6/5049/2006/acp-6-5049-2006.pdf">The full text article is available as a PDF file from http://www.atmos-chem-phys.net/6/5049/2006/acp-6-5049-2006.pdf</self-uri>
<abstract>
<p>Aerosol samples were collected at a rural background site in southern
Finland in May 2004 during pollution episode (PM&lt;sub&gt;1&lt;/sub&gt;~16 &amp;micro;g m&lt;sup&gt;&amp;minus;3&lt;/sup&gt;,
backward air mass trajectories from south-east), intermediate
period (PM&lt;sub&gt;1&lt;/sub&gt;~5 &amp;micro;g m&lt;sup&gt;&amp;minus;3&lt;/sup&gt;, backtrajectories from
north-east) and clean period (PM&lt;sub&gt;1&lt;/sub&gt;~2 &amp;micro;g m&lt;sup&gt;&amp;minus;3&lt;/sup&gt;,
backtrajectories from north-west/north). The elemental composition,
morphology and mixing state of individual aerosol particles in three size
fractions were studied using transmission electron microscopy (TEM) coupled
with energy dispersive X-ray (EDX) microanalyses. The TEM/EDX results were
complemented with the size-segregated bulk chemical measurements of selected
ions and organic and elemental carbon. Many of the particles in PM&lt;sub&gt;0.2&amp;ndash;1&lt;/sub&gt;
and PM&lt;sub&gt;1&amp;ndash;3.3&lt;/sub&gt; size fractions were strongly internally mixed with S, C
and/or N. The major particle types in PM&lt;sub&gt;0.2&amp;ndash;1&lt;/sub&gt; samples were 1) soot and
2) (ammonium)sulphates and their mixtures with variable amounts of C, K,
soot and/or other inclusions. Number proportions of those two particle groups
in PM&lt;sub&gt;0.2&amp;ndash;1&lt;/sub&gt; samples were 0&amp;ndash;12% and 83&amp;ndash;97%, respectively. During
the pollution episode, the proportion of Ca-rich particles was very high
(26&amp;ndash;48%) in the PM&lt;sub&gt;1&amp;ndash;3.3&lt;/sub&gt; and PM&lt;sub&gt;3.3&amp;ndash;11&lt;/sub&gt; samples, while the
PM&lt;sub&gt;0.2&amp;ndash;1&lt;/sub&gt; and PM&lt;sub&gt;1&amp;ndash;3.3&lt;/sub&gt; samples contained elevated proportions of
silicates (22&amp;ndash;33%), metal oxides/hydroxides (1&amp;ndash;9%) and tar balls
(1&amp;ndash;4%). These aerosols originated mainly from polluted areas of Eastern
Europe, and some open biomass burning smoke was also brought by long-range
transport. During the clean period, when air masses arrived from the Arctic
Ocean, PM&lt;sub&gt;1&amp;ndash;3.3&lt;/sub&gt; samples contained mainly sea salt particles (67&amp;ndash;89%)
with a variable rate of Cl substitution (mainly by NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;minus;&lt;/sup&gt;). During
the intermediate period, the PM&lt;sub&gt;1&amp;ndash;3.3&lt;/sub&gt; sample contained porous
(sponge-like) Na-rich particles (35%) with abundant S, K and O. They
might originate from the burning of wood pulp wastes of paper industry. The
proportion of biological particles and C-rich fragments (probably also
biological origin) were highest in the PM&lt;sub&gt;3.3&amp;ndash;11&lt;/sub&gt; samples (0&amp;ndash;81% and
0&amp;ndash;22%, respectively). The origin of different particle types and the
effect of aging processes on particle composition and their hygroscopic and
optical properties are discussed.</p>
</abstract>
<counts><page-count count="18"/></counts>
</article-meta>
</front>
<body/>
<back>
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