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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>Erik D. Pollock</dc:contributor>
  <dc:contributor>Matthew D. Covington</dc:contributor>
  <dc:contributor>Phillip D. Hays</dc:contributor>
  <dc:contributor>Kristofor R. Brye</dc:contributor>
  <dc:creator>Katherine J. Knierim</dc:creator>
  <dc:date>2017</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;The nature of carbon (C) cycling in the unsaturated zone where groundwater is in contact with abundant gas-filled voids is poorly understood. The objective of this study was to trace inorganic-C cycling in a karst landscape using stable-C isotopes, with emphasis on a shallow groundwater flow path through the soil, to an underlying cave, and to the spring outlet of a cave stream in the Ozark Plateaus of northwestern Arkansas. Carbon dioxide (CO&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;) concentration and isotopic composition (δ&lt;/span&gt;&lt;sup&gt;13&lt;/sup&gt;&lt;span&gt;C-CO&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;) in gas and dissolved inorganic carbon (DIC) concentration and isotopic composition (δ&lt;/span&gt;&lt;sup&gt;13&lt;/sup&gt;&lt;span&gt;C-DIC) in water were measured in samples collected from two suction-cup soil samplers above the cave, three sites in the cave, and at the spring outlet of the cave stream. Soil-gas CO&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt; concentration (median 2,578&amp;nbsp;ppm) and δ&lt;/span&gt;&lt;sup&gt;13&lt;/sup&gt;&lt;span&gt;C-CO&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt; (median −&amp;nbsp;21.5‰) were seasonally variable, reflecting the effects of surface temperature changes on soil-CO&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt; production via respiration and organic-matter decomposition. Cave-air CO&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt; (median 1,026&amp;nbsp;ppm) was sourced from the soil zone and the surface atmosphere, with seasonally changing proportions of each source controlled by surface temperature-driven air density gradients. Soil-DIC concentration (median 1.7&amp;nbsp;mg&amp;nbsp;L&lt;/span&gt;&lt;sup&gt;−&amp;nbsp;1&lt;/sup&gt;&lt;span&gt;) was lower and soil-δ&lt;/span&gt;&lt;sup&gt;13&lt;/sup&gt;&lt;span&gt;C-DIC (median −&amp;nbsp;19.5‰) was lighter compared to the cave (median 23.3&amp;nbsp;mg&amp;nbsp;L&lt;/span&gt;&lt;sup&gt;−&amp;nbsp;1&lt;/sup&gt;&lt;span&gt; and −&amp;nbsp;14.3‰, respectively) because carbonate-bedrock dissolution provided an inorganic source of C to the cave. Carbon species in the soil had a unique, light stable-C isotopic signature compared to the cave. Discrimination of soil-C sources to karst groundwater was achieved, which is critical for developing hydrologic budgets using environmental tracers such as C.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1016/j.geodrs.2017.05.004</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Elsevier</dc:publisher>
  <dc:title>Carbon cycling in the mantled karst of the Ozark Plateaus, central United States</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>