<?xml version='1.0' encoding='utf-8'?>
<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>R. L. Smith</dc:contributor>
  <dc:creator>D.N. Miller</dc:creator>
  <dc:date>2009</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;Groundwater&amp;nbsp;nitrification&amp;nbsp;is a poorly characterized process affecting the speciation and transport of nitrogen. Cores from two sites in a plume of contamination were examined using culture-based and molecular techniques targeting nitrification processes. The first site, located beneath a sewage&amp;nbsp;effluent&amp;nbsp;infiltration bed, received treated effluent containing O&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;(&amp;gt;&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span&gt;300&amp;nbsp;µM) and NH&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;&lt;span&gt;&amp;nbsp;(51–800&amp;nbsp;µM). The second site was 2.5&amp;nbsp;km down-gradient near the leading edge of the&amp;nbsp;ammonium&amp;nbsp;zone within the contaminant plume and featured vertical gradients of O&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;, NH&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;&lt;span&gt;, and NO&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt;&lt;span&gt;&amp;nbsp;(0–300, 0–500, and 100–200&amp;nbsp;µM with depth, respectively). Ammonia- and nitrite-oxidizers enumerated by the culture-based MPN method were low in abundance at both sites (1.8 to 350&amp;nbsp;g&lt;/span&gt;&lt;sup&gt;−&amp;nbsp;1&lt;/sup&gt;&lt;span&gt;&amp;nbsp;and 33 to 35,000&amp;nbsp;g&lt;/span&gt;&lt;sup&gt;−&amp;nbsp;1&lt;/sup&gt;&lt;span&gt;, respectively). Potential nitrifying activity measured in core material in the laboratory was also very low, requiring several weeks for products to accumulate.&amp;nbsp;Molecular analysis&amp;nbsp;of&amp;nbsp;aquifer&amp;nbsp;DNA&amp;nbsp;(nested PCR followed by&amp;nbsp;cloning&amp;nbsp;and 16S rDNA sequencing) detected primarily sequences associated with the&amp;nbsp;&lt;/span&gt;&lt;i&gt;Nitrosospira&lt;/i&gt;&lt;span&gt;&amp;nbsp;genus throughout the cores at the down-gradient site and a smaller proportion from the&amp;nbsp;&lt;/span&gt;&lt;span&gt;&lt;i&gt;Nitrosomonas&lt;/i&gt;&lt;/span&gt;&lt;span&gt;&amp;nbsp;genus in the deeper anoxic, NH&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;&lt;span&gt;&amp;nbsp;zone at the down-gradient site. Only a single&amp;nbsp;&lt;/span&gt;&lt;i&gt;Nitrosospira&lt;/i&gt;&lt;span&gt;&amp;nbsp;sequence was detected beneath the infiltration bed. Furthermore, the majority of&amp;nbsp;&lt;/span&gt;&lt;i&gt;Nitrosospira&lt;/i&gt;&lt;span&gt;-associated sequences represent an unrecognized cluster. We conclude that an uncharacterized group associated with&amp;nbsp;&lt;/span&gt;&lt;i&gt;Nitrosospira&lt;/i&gt;&lt;span&gt;&amp;nbsp;dominate at the geochemically stable, down-gradient site, but found little evidence for Betaproteobacteria nitrifiers beneath the infiltration beds where geochemical conditions were more variable.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1016/j.jconhyd.2008.10.011</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Elsevier</dc:publisher>
  <dc:title>Microbial characterization of nitrification in a shallow, nitrogen-contaminated aquifer, Cape Cod, Massachusetts and detection of a novel cluster associated with nitrifying Betaproteobacteria</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>