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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-12-2025-2012</article-id>
<title-group>
<article-title>Five-year record of atmospheric precipitation chemistry in urban Beijing, China</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Yang</surname>
<given-names>F.</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>Tan</surname>
<given-names>J.</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>Shi</surname>
<given-names>Z. B.</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>Cai</surname>
<given-names>Y.</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>He</surname>
<given-names>K.</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>Ma</surname>
<given-names>Y.</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>Duan</surname>
<given-names>F.</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>Okuda</surname>
<given-names>T.</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>Tanaka</surname>
<given-names>S.</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>Chen</surname>
<given-names>G.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Key Laboratory of Computational Geodynamics, College of Earth Science, Graduate University of Chinese Academy of Sciences, Beijing 100049, China</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>School of Geography, Earth and Environmental Science, University of Birmingham, Edgbaston Birmingham B15 2TT, UK</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>School of Environment, Tsinghua University, Beijing100084, China</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Chongqing Environmental Protection Bureau, Chongqing 401147, China</addr-line>
</aff>
<pub-date pub-type="epub">
<day>21</day>
<month>02</month>
<year>2012</year>
</pub-date>
<volume>12</volume>
<issue>4</issue>
<fpage>2025</fpage>
<lpage>2035</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/12/2025/2012/acp-12-2025-2012.html">This article is available from http://www.atmos-chem-phys.net/12/2025/2012/acp-12-2025-2012.html</self-uri>
<self-uri xlink:href="http://www.atmos-chem-phys.net/12/2025/2012/acp-12-2025-2012.pdf">The full text article is available as a PDF file from http://www.atmos-chem-phys.net/12/2025/2012/acp-12-2025-2012.pdf</self-uri>
<abstract>
<p>To investigate the chemical characteristics of precipitation in the polluted
urban atmosphere in Beijing and possible mechanisms influencing their
variations, a total of 131 event-based precipitation samples were collected
from March 2001 to August 2005. The concentrations of major ions in the
samples were analyzed by using ion chromatography. Intermediate pH (6.1–7.3)
was recorded in approximately two-thirds of the precipitation samples and
acidic pH (4.2–5.6) in only 16% of the samples. However, the
precipitation acidity was on the growth track and the process was likely
being accelerated. SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2&amp;minus;&lt;/sup&gt;, NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;minus;&lt;/sup&gt;, NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;, and
Ca&lt;sup&gt;2+&lt;/sup&gt; were the most abundant ions in the precipitations, with their
single volume-weighted mean (VWM) concentration all above 100 μeq l&lt;sup&gt;−1&lt;/sup&gt;. The two major anions and two major cations accounted for more than
80% of total anionic and cationic mass, respectively. The VWM
SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2&amp;minus;&lt;/sup&gt; concentration decreased by 13% compared to that during
1995–1998, much less than the 58% reduction in the annual average
SO&lt;sub&gt;2&lt;/sub&gt; concentration from 1998 to 2005 in Beijing. What seems more
counterintuitive is that the VWM NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;minus;&lt;/sup&gt; concentration nearly doubled
over the period although the annual average NO&lt;sub&gt;2&lt;/sub&gt; concentration decreased
by 5% from 1998 to 2005. These results imply that the conversion of
gaseous precursors to acid compounds and/or the regional transport were
reinforced over the decade. The average ratio of neutralizing potential to
acidifying potential (i.e. NP/AP) was as high as 1.2 but experienced an
evident decline trend. This was mainly ascribed to reduced input of
NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; and Ca&lt;sup&gt;2+&lt;/sup&gt; and increased input of NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;minus;&lt;/sup&gt;.
Furthermore, the equivalent mass ratio of NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;minus;&lt;/sup&gt; to non-sea-salt
SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2&amp;minus;&lt;/sup&gt; presented an increasing trend over the study period,
suggesting that the contribution of NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;minus;&lt;/sup&gt; to the precipitation
acidity increased in recent years. However, the mean ratio was only
0.37 ± 0.11 in the study period, which is significantly lower than those reported
in some metropolitan areas in developed countries. This shows that the
precipitation acidity in Beijing was still dominantly from SO&lt;sub&gt;2&lt;/sub&gt; while the  SO&lt;sub&gt;2&lt;/sub&gt; contribution was progressively substituted by NO&lt;sub&gt;x&lt;/sub&gt;.</p>
</abstract>
<counts><page-count count="11"/></counts>
</article-meta>
</front>
<body/>
<back>
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