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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>John Karl Bohlke</dc:contributor>
  <dc:contributor>Krystle Pelham</dc:contributor>
  <dc:contributor>David M. Langlais</dc:contributor>
  <dc:contributor>Gregory J. Walsh</dc:contributor>
  <dc:creator>James R. Degnan</dc:creator>
  <dc:date>2016</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;Explosives used in construction have been implicated as sources of NO&lt;/span&gt;&lt;sub&gt;&lt;span&gt;3&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;ndash;&lt;/span&gt;&lt;span&gt;&amp;nbsp;contamination in groundwater, but direct forensic evidence is limited. Identification of blasting-related NO&lt;/span&gt;&lt;sub&gt;&lt;span&gt;3&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;ndash;&lt;/span&gt;&lt;span&gt;&amp;nbsp;can be complicated by other NO&lt;/span&gt;&lt;sub&gt;&lt;span&gt;3&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;ndash;&lt;/span&gt;&lt;span&gt;&amp;nbsp;sources, including agriculture and wastewater disposal, and by hydrogeologic factors affecting NO&lt;/span&gt;&lt;sub&gt;&lt;span&gt;3&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;ndash;&lt;/span&gt;&lt;span&gt;&amp;nbsp;transport and stability. Here we describe a study that used hydrogeology, chemistry, stable isotopes, and mass balance calculations to evaluate groundwater NO&lt;/span&gt;&lt;sub&gt;&lt;span&gt;3&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;ndash;&lt;/span&gt;&lt;span&gt;&amp;nbsp;sources and transport in areas surrounding a highway construction site with documented blasting in New Hampshire. Results indicate various groundwater responses to contamination: (1) rapid breakthrough and flushing of synthetic NO&lt;/span&gt;&lt;sub&gt;&lt;span&gt;3&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;ndash;&lt;/span&gt;&lt;span&gt;&amp;nbsp;(low &amp;delta;&lt;/span&gt;&lt;span&gt;15&lt;/span&gt;&lt;span&gt;N, high &amp;delta;&lt;/span&gt;&lt;span&gt;18&lt;/span&gt;&lt;span&gt;O) from dissolution of unexploded NH&lt;/span&gt;&lt;sub&gt;&lt;span&gt;4&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;NO&lt;/span&gt;&lt;sub&gt;&lt;span&gt;3&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;blasting agents in oxic groundwater; (2) delayed and reduced breakthrough of synthetic NO&lt;/span&gt;&lt;sub&gt;&lt;span&gt;3&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;ndash;&lt;/span&gt;&lt;span&gt;&amp;nbsp;subjected to partial denitrification (high &amp;delta;&lt;/span&gt;&lt;sup&gt;&lt;span&gt;15&lt;/span&gt;&lt;/sup&gt;&lt;span&gt;N, high &amp;delta;&lt;/span&gt;&lt;sup&gt;&lt;span&gt;18&lt;/span&gt;&lt;/sup&gt;&lt;span&gt;O); (3) relatively persistent concentrations of blasting-related biogenic NO&lt;/span&gt;&lt;sub&gt;&lt;span&gt;3&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;ndash;&lt;/span&gt;&lt;span&gt;&amp;nbsp;derived from nitrification of NH&lt;/span&gt;&lt;sub&gt;&lt;span&gt;4&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;+&lt;/span&gt;&lt;span&gt;&amp;nbsp;(low &amp;delta;&lt;/span&gt;&lt;sup&gt;&lt;span&gt;15&lt;/span&gt;&lt;/sup&gt;&lt;span&gt;N, low &amp;delta;&lt;/span&gt;&lt;sup&gt;&lt;span&gt;18&lt;/span&gt;&lt;/sup&gt;&lt;span&gt;O); and (4) stable but spatially variable biogenic NO&lt;/span&gt;&lt;sub&gt;&lt;span&gt;3&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;ndash;&lt;/span&gt;&lt;span&gt;&amp;nbsp;concentrations, consistent with recharge from septic systems (high &amp;delta;&lt;/span&gt;&lt;sup&gt;&lt;span&gt;15&lt;/span&gt;&lt;/sup&gt;&lt;span&gt;N, low &amp;delta;&lt;/span&gt;&lt;sup&gt;&lt;span&gt;18&lt;/span&gt;&lt;/sup&gt;&lt;span&gt;O), variably affected by denitrification. Source characteristics of denitrified samples were reconstructed from dissolved-gas data (Ar, N&lt;/span&gt;&lt;sub&gt;&lt;span&gt;2&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;) and isotopic fractionation trends associated with denitrification (&amp;Delta;&amp;delta;&lt;/span&gt;&lt;sup&gt;&lt;span&gt;15&lt;/span&gt;&lt;/sup&gt;&lt;span&gt;N/&amp;Delta;&amp;delta;&lt;/span&gt;&lt;sup&gt;&lt;span&gt;18&lt;/span&gt;&lt;/sup&gt;&lt;span&gt;O &amp;asymp; 1.31). Methods and data from this study are expected to be applicable in studies of other aquifers affected by explosives used in construction.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1021/acs.est.5b03671</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>American Chemical Society</dc:publisher>
  <dc:title>Identification of groundwater nitrate contamination from explosives used in road construction: Isotopic, chemical, and hydrologic evidence</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>