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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>Barbara A. Bekins</dc:contributor>
  <dc:contributor>Geoffrey N. Delin</dc:contributor>
  <dc:contributor>Isabelle M. Cozzarelli</dc:contributor>
  <dc:contributor>D.W. Blowes</dc:contributor>
  <dc:contributor>J. D. Kirshtein</dc:contributor>
  <dc:creator>R.T. Amos</dc:creator>
  <dc:date>2011</dc:date>
  <dc:description>&lt;div id="aep-abstract-id16" class="abstract author"&gt;&lt;div id="aep-abstract-sec-id17"&gt;&lt;p id="sp0075"&gt;High resolution direct-push profiling over short vertical distances was used to investigate CH&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;attenuation in a&amp;nbsp;petroleum&amp;nbsp;contaminated&amp;nbsp;aquifer&amp;nbsp;near Bemidji, Minnesota. The&amp;nbsp;contaminant&amp;nbsp;plume was delineated using dissolved gases, redox sensitive components, major ions,&amp;nbsp;carbon isotope ratios&amp;nbsp;in CH&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and CO&lt;sub&gt;2&lt;/sub&gt;, and the presence of methanotrophic bacteria. Sharp redox gradients were observed near the water table. Shifts in δ&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;CH4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;from an average of −&amp;nbsp;57.6‰ (±&amp;nbsp;1.7‰) in the methanogenic zone to −&amp;nbsp;39.6‰ (±&amp;nbsp;8.7‰) at 105&amp;nbsp;m downgradient, strongly suggest CH&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;attenuation through microbially mediated degradation. In the downgradient zone the aerobic/anaerobic transition is up to 0.5&amp;nbsp;m below the water table suggesting that transport of O&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;across the water table is leading to aerobic degradation of CH&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;at this interface. Dissolved N&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;concentrations that exceeded those expected for water in equilibrium with the atmosphere indicated bubble&amp;nbsp;entrapment&amp;nbsp;followed by preferential stripping of O&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;through aerobic degradation of CH&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;or other&amp;nbsp;hydrocarbons.&amp;nbsp;Multivariate and cluster analysis&amp;nbsp;were used to distinguish between areas of significant bubble entrapment and areas where other processes such as the&amp;nbsp;infiltration&amp;nbsp;of O&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;rich&amp;nbsp;recharge&amp;nbsp;water were important O&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;transport mechanisms.&lt;/p&gt;&lt;/div&gt;&lt;/div&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1016/j.jconhyd.2011.04.003</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Elsevier</dc:publisher>
  <dc:title>Methane oxidation in a crude oil contaminated aquifer: Delineation of aerobic reactions at the plume fringes</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>