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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>Christopher T. Green</dc:contributor>
  <dc:contributor>Kenneth Belitz</dc:contributor>
  <dc:contributor>Michael J. Singleton</dc:contributor>
  <dc:contributor>Bradley K. Esser</dc:contributor>
  <dc:creator>Matthew K. Landon</dc:creator>
  <dc:date>2011</dc:date>
  <dc:description>&lt;p&gt;&lt;span class="ScopusTermHighlight"&gt;In&lt;/span&gt;&lt;span&gt;&amp;nbsp;a 2,700-km&amp;nbsp;&lt;/span&gt;&lt;sup&gt;2&lt;/sup&gt;&lt;span&gt;&amp;nbsp;area&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;the eastern San Joaquin Valley, California (USA), data from multiple sources were used to determine interrelations among hydrogeologic factors, reduction-oxidation (redox)&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;conditions&lt;/span&gt;&lt;span&gt;, and temporal and spatial distributions of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;nitrate&lt;/span&gt;&lt;span&gt;&amp;nbsp;(NO&amp;nbsp;&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt;), a widely detected&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;groundwater&lt;/span&gt;&lt;span&gt;&amp;nbsp;contaminant.&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;Groundwater&lt;/span&gt;&lt;span&gt;&amp;nbsp;is predominantly modern, or mixtures of modern water, with detectable NO&amp;nbsp;&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt;&amp;nbsp;and oxic redox&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;conditions&lt;/span&gt;&lt;span&gt;, but some zones have anoxic or mixed redox&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;conditions&lt;/span&gt;&lt;span&gt;. Anoxic&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;conditions&lt;/span&gt;&lt;span&gt;&amp;nbsp;were associated with long residence times that occurred near the valley trough and&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;areas of historical&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;groundwater&lt;/span&gt;&lt;span&gt;&amp;nbsp;discharge with shallow depth to water. Anoxic&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;conditions&lt;/span&gt;&lt;span&gt;&amp;nbsp;also were associated with interactions of shallow, modern&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;groundwater&lt;/span&gt;&lt;span&gt;&amp;nbsp;with soils. NO&amp;nbsp;&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt;&amp;nbsp;concentrations were significantly lower&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;anoxic than oxic or mixed redox&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;groundwater&lt;/span&gt;&lt;span&gt;, primarily because residence times of anoxic waters exceed the duration of increased pumping and fertilizer use associated with modern agriculture. Effects of redox reactions on NO&amp;nbsp;&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt;&amp;nbsp;concentrations were relatively minor. Dissolved N&amp;nbsp;&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;gas data indicated that denitrification has eliminated gt;5 mg/L NO&amp;nbsp;&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt;-N&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;about 10% of 39 wells. Increasing NO&amp;nbsp;&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt;&amp;nbsp;concentrations over time were slightly less prevalent&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;anoxic than oxic or mixed redox&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;groundwater&lt;/span&gt;&lt;span&gt;. Spatial and temporal&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;trends&lt;/span&gt;&lt;span&gt;&amp;nbsp;of NO&amp;nbsp;&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt;&amp;nbsp;are primarily controlled by water and NO&amp;nbsp;&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt;&amp;nbsp;fluxes of modern land use.&amp;nbsp;&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1007/s10040-011-0750-1</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>American Geophysical Union</dc:publisher>
  <dc:title>Relations of hydrogeologic factors, groundwater reduction-oxidation conditions, and temporal and spatial distributions of nitrate, Central-Eastside San Joaquin Valley, California, USA</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>