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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>Carol Kendall</dc:contributor>
  <dc:contributor>Scott D. Wankel</dc:contributor>
  <dc:contributor>Douglas A. Burns</dc:contributor>
  <dc:contributor>E.W. Boyer</dc:contributor>
  <dc:contributor>K. Harlin</dc:contributor>
  <dc:contributor>Daniel J Bain</dc:contributor>
  <dc:contributor>T.J. Butler</dc:contributor>
  <dc:creator>Emily M. Elliott</dc:creator>
  <dc:date>2007</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;Global inputs of NO&lt;/span&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;&lt;span&gt;&amp;nbsp;are dominated by fossil fuel combustion from both stationary and vehicular sources and far exceed natural NO&lt;/span&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;&lt;span&gt;&amp;nbsp;sources. However, elucidating NO&lt;/span&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;&lt;span&gt;&amp;nbsp;sources to any given location remains a difficult challenge, despite the need for this information to develop sound regulatory and mitigation strategies. We present results from a regional-scale study of nitrogen isotopes (δ&lt;/span&gt;&lt;sup&gt;15&lt;/sup&gt;&lt;span&gt;N) in wet nitrate deposition across 33 sites in the midwestern and northeastern U.S. We demonstrate that spatial variations in δ&lt;/span&gt;&lt;sup&gt;15&lt;/sup&gt;&lt;span&gt;N are strongly correlated with NO&lt;/span&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;&lt;span&gt;&amp;nbsp;emissions from surrounding stationary sources and additionally that δ&lt;/span&gt;&lt;sup&gt;15&lt;/sup&gt;&lt;span&gt;N is more strongly correlated with surrounding stationary source NO&lt;/span&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;&lt;span&gt;&amp;nbsp;emissions than pH, SO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;&lt;span&gt;, or NO&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;&lt;span&gt;&amp;nbsp;concentrations. Although emission inventories indicate that vehicle emissions are the dominant NO&lt;/span&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;&lt;span&gt;&amp;nbsp;source in the eastern U.S., our results suggest that wet NO&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;&lt;span&gt;&amp;nbsp;deposition at sites in this study is strongly associated with NO&lt;/span&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;&lt;span&gt;&amp;nbsp;emissions from stationary sources. This suggests that large areas of the landscape potentially receive atmospheric NO&lt;/span&gt;&lt;i&gt;&lt;sub&gt;y&lt;/sub&gt;&lt;/i&gt;&lt;span&gt;&amp;nbsp;deposition inputs in excess of what one would infer from existing monitoring data alone. Moreover, we determined that spatial patterns in δ&lt;/span&gt;&lt;sup&gt;15&lt;/sup&gt;&lt;span&gt;N values are a robust indicator of stationary NO&lt;/span&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;&lt;span&gt;&amp;nbsp;contributions to wet NO&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;&lt;span&gt;&amp;nbsp;deposition and hence a valuable complement to existing tools for assessing relationships between NO&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;&lt;span&gt;&amp;nbsp;deposition, regional emission inventories, and for evaluating progress toward NO&lt;/span&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;&lt;span&gt;&amp;nbsp;reduction goals.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1021/es070898t</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>American Chemical Society</dc:publisher>
  <dc:title>Nitrogen isotopes as indicators of NOx source contributions to atmospheric nitrate deposition across the midwestern and northeastern United States</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>