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  <dataset>
    <title>Aerosol and chemical measurements from ice cores, Summit, Greenland, 1446-1763</title>
    <creator id="4878308588453970">
      <individualName>
        <givenName>Joseph R.</givenName>
        <surName>McConnell</surName>
      </individualName>
      <organizationName>Desert Research Institute</organizationName>
      <positionName>Research Professor</positionName>
      <address>
        <deliveryPoint>2215 Raggio Parkway</deliveryPoint>
        <city>Reno</city>
        <administrativeArea>NV</administrativeArea>
        <postalCode>89512</postalCode>
        <country>USA</country>
      </address>
      <phone phonetype="voice">(775) 673 - 7348</phone>
      <electronicMailAddress>joe.mcconnell@dri.edu</electronicMailAddress>
      <userId directory="https://orcid.org">https://orcid.org/0000-0001-9051-5240</userId>
    </creator>
    <pubDate>2018</pubDate>
    <abstract>
      <section>
        <para>The main research goal of this project was to provide the first reliable record of pre-industrial carbon monoxide concentration ([CO]) and stable isotopes (δ<superscript>13</superscript>CO and δ<superscript>18</superscript>CO) in the Arctic atmosphere which is representative of a large part of the Northern Hemisphere (NH). Two large diameter ice cores were collected near Summit, Greenland. The deeper core drilled near the old EUROCORE site provides ice from 80 to 170 m depth (air age from ~1960 to ~1640 AD). A second, shallower core drilled near Summit Station provides ice from 80 to 98 m depth (air age from ~1890 to ~1960).  Continuous analyses of trace chemistry were used to establish the ice core chronology and improve understanding of mechanisms of in situ CO production in ice.</para>
      </section>
    </abstract>
    <keywordSet>
      <keyword>EARTH SCIENCE &gt; CRYOSPHERE &gt; SNOW/ICE &gt; SNOW/ICE CHEMISTRY</keyword>
      <keyword>EARTH SCIENCE &gt; ATMOSPHERE &gt; AEROSOLS</keyword>
      <keywordThesaurus>GCMD</keywordThesaurus>
    </keywordSet>
    <intellectualRights>
      <para>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.</para>
    </intellectualRights>
    <coverage>
      <geographicCoverage>
        <geographicDescription>Near Summit Station, Greenland</geographicDescription>
        <boundingCoordinates>
          <westBoundingCoordinate>-38.3</westBoundingCoordinate>
          <eastBoundingCoordinate>-38.3</eastBoundingCoordinate>
          <northBoundingCoordinate>72.6</northBoundingCoordinate>
          <southBoundingCoordinate>72.6</southBoundingCoordinate>
        </boundingCoordinates>
      </geographicCoverage>
      <temporalCoverage>
        <rangeOfDates>
          <beginDate>
            <calendarDate>1446</calendarDate>
          </beginDate>
          <endDate>
            <calendarDate>1763</calendarDate>
          </endDate>
        </rangeOfDates>
      </temporalCoverage>
    </coverage>
    <contact id="3245374339123128">
      <individualName>
        <givenName>Joseph</givenName>
        <surName>McConnell</surName>
      </individualName>
      <organizationName>Desert Research Institute</organizationName>
      <positionName>Research Professor</positionName>
      <address>
        <deliveryPoint>2215 Raggio Parkway</deliveryPoint>
        <city>Reno</city>
        <administrativeArea>NV</administrativeArea>
        <postalCode>89519</postalCode>
        <country>USA</country>
      </address>
      <phone phonetype="voice">(775) 673 - 7348</phone>
      <electronicMailAddress>joe.mcconnell@dri.edu</electronicMailAddress>
      <userId directory="https://orcid.org">https://orcid.org/0000-0001-9051-5240</userId>
    </contact>
    <methods>
      <methodStep>
        <description>
          <para>The cores were analyzed for a range of aerosols and water isotopes using the continuous ice core analytical system at the Desert Research Institute. Different configurations are used to address specific scientific objectives  (see McConnell et al., Proceedings of the National Academy of Sciences, 2017 for a schematic of a recently used configuration). Here instruments for continuous measurements of methane and carbon monoxide were added by French collaborators (Rhodes et al., Science, 2015; Fain et al., Clim Past, 2014) and protocols were adjusted accordingly. The core chronologies were established using multi-parameter annual layer counting (e.g., Sigl et al., Clim Past, 2016; McConnell et al., PNAS, 2018) constrained by volcanic synchronization to well-documented eruptions recorded in other precisely dated Greenland ice cores (Sig et al., Nature, 2015).  Dating uncertainty is estimated to be &lt;1 year.</para>
        </description>
      </methodStep>
      <sampling>
        <studyExtent>
          <description>
            <para>No study extent description provided.</para>
          </description>
        </studyExtent>
        <samplingDescription>
          <para>The two ice cores were drilled with Ice Drilling Design and Operations' (IDDO)'s large diameter (24.1 cm) Blue Ice Drill (BID) drill without the use of drilling fluids. Only ice cores from below 80 m depth (pore close off) were kept and shipped to the National Science Foundation Ice Core Facility (NSF-ICF) (formerly NICL) in Denver. There a slab was sliced off and two ~3.5 by ~3.5 cm longitudinal samples cut from the slab. These were transported frozen to the Desert Research Institute where they were analyzed. Caution is advised when using these records since because of the large diameter of the BID drill, angled breaks can span relatively large depth ranges. The angled core breaks were not aligned prior to cutting the slab so some sections (generally &lt;10 cm) of the ice record may be represented twice and some sections may be missing.</para>
        </samplingDescription>
      </sampling>
    </methods>
    <project>
      <title>Collaborative Research: Reconstruction of Carbon Monoxide in the Pre-Industrial Arctic Atmosphere from Ice Cores at Summit, Greenland</title>
      <personnel id="7052979573505370">
        <individualName>
          <givenName>Joseph</givenName>
          <surName>McConnell</surName>
        </individualName>
        <role>principalInvestigator</role>
      </personnel>
      <abstract>
        <para>The main goal of the proposed work is to provide the first reliable record of pre-industrial carbon monoxide (CO) concentration and stable isotope composition in the Arctic atmosphere, which would also be representative of a large part of the Northern Hemisphere. Carbon monoxide concentrations are a crucial component of any complete modern or past atmospheric data set because CO plays a key role in global atmospheric chemistry by being the largest single sink of hydroxyl radicals in the lower atmosphere. Carbon monoxide concentration in combination with stable isotopes is also a powerful tracer for large-scale biomass burning variations. Pre-industrial carbon monoxide concentration in the northern hemisphere (where anthropogenic impacts have been by far the strongest) is poorly characterized, with prior measurements made using an older technique in the 1990s on only a few samples from one ice core. No published carbon monoxide isotope measurements from northern hemisphere ice cores are currently available.</para>
        <para>The investigators propose to collect a new large diameter ice core near Summit, Greenland using the Blue Ice Drill (BID), providing ice from 80 to 170 meters depth (air age from about 1960 to about 1600 AD). Continuous measurements of carbon monoxide concentration would provide a high-resolution record over the entire ice core and identify ice layers where carbon monoxide is well preserved. High-precision discrete analyses of carbon monoxide concentration and isotopic composition would then target ice from these layers. Continuous analyses of trace chemistry and discrete analyses of trace organics would also be conducted to establish the ice core chronology and improve understanding of mechanisms of in situ carbon monoxide production in ice. Atmospheric histories for carbon monoxide concentration and isotopic composition would be derived using a combination of firn-ice gas transport and inverse models, and the implications for pre-industrial carbon monoxide budget would be investigated with the use of a climate-chemistry model. The proposed approach maximizes the chance of obtaining a reliable history of carbon monoxide concentration and isotopic composition through careful site selection and the application of novel ice drilling and analytical techniques. Results from the study will be made available to the scientific community and the general public through the NSIDC and NOAA Paleoclimatology data centers. The work will contribute to the training of two graduate and 2 undergraduate students, support an early career investigator, and establish several new collaborations among the investigators. The investigators have a strong history of and commitment to scientific outreach in the forms of media interviews, participation in educational films, as well as speaking to schools and the public about their research, and will continue these activities as part of the proposed work.</para>
      </abstract>
      <funding>1406219</funding>
    </project>
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small sections of the record may be missing or repeated. 	Measurements were made using the DRI continuous ice core analytical system.	Configurations vary - see McConnell et al. PNAS, 2017 and Rhodes et al., Science, 2015 for approximate configurations used for this measurement campaign.	Missing data shown as -0.999	No correction made for potential ICP-MS under-recovery (McConnell et al., PNAS, 2018).</entityDescription>
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      <attributeList>
        <attribute>
          <attributeName>depth_m</attributeName>
          <attributeLabel>depth measured from the middle of the core</attributeLabel>
          <attributeDefinition>depth measured from the middle of the core</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>meter</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>depth_mweq</attributeName>
          <attributeLabel>depth measured from the middle of the core</attributeLabel>
          <attributeDefinition>depth from the middle of the core in meters of water equivalent</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>meter</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>year</attributeName>
          <attributeLabel>year in decimal format, measured from the middle of the core</attributeLabel>
          <attributeDefinition>year in decimal format, measured from the middle of the core</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>nominalYear</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>BCconc_ppb</attributeName>
          <attributeLabel>black carbon concentration in parts per billion (nanograms per gram (ng/g))</attributeLabel>
          <attributeDefinition>black carbon concentration in nanograms per gram (ng/g)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>h2o2_uM</attributeName>
          <attributeLabel>Hydrogen peroxide concentration in microMoles</attributeLabel>
          <attributeDefinition>Hydrogen peroxide concentration in microMoles</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>nh4_uM</attributeName>
          <attributeLabel>Ammonium concentration in microMoles</attributeLabel>
          <attributeDefinition>Ammonium concentration in microMoles</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>hno3_uM</attributeName>
          <attributeLabel>Nitrate concentrations in microMoles</attributeLabel>
          <attributeDefinition>Nitrate concentrations in microMoles</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>insoluble_particle_counts_ug_g</attributeName>
          <attributeLabel>Insoluble particle concentration in micrograms per gram (ug/g)</attributeLabel>
          <attributeDefinition>Insoluble particle concentration (0.8 to 10 um) in micrograms per gram (ug/g) measured used a laser-based Abakus instrument</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>dO18_permil</attributeName>
          <attributeLabel>delta Oxygen-18 isotope (d18O) in parts per thousand (permil)</attributeLabel>
          <attributeDefinition>delta Oxygen-18 isotope (d18O) in parts per thousand (permil)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>dD_permil</attributeName>
          <attributeLabel>delta Deuterium (Hydrogen 2 isotope) in parts per thousand (permil)</attributeLabel>
          <attributeDefinition>delta Deuterium (Hydrogen 2 isotope) in parts per thousand (permil)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>Na_ng_g</attributeName>
          <attributeLabel>Sodium concentration in nanogams per gram (ng/g)</attributeLabel>
          <attributeDefinition>Sodium concentration in nanogams per gram (ng/g)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
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              <numericDomain>
                <numberType>real</numberType>
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          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>S_ng_g</attributeName>
          <attributeLabel>Sulfur concentration in nanogams per gram (ng/g)</attributeLabel>
          <attributeDefinition>Sulfur concentration in nanogams per gram (ng/g)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
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          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>Cl_ng_g</attributeName>
          <attributeLabel>Chlorine concentration in nanogams per gram (ng/g)</attributeLabel>
          <attributeDefinition>Chlorine concentration in nanogams per gram (ng/g)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
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          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>Ca_ng_g</attributeName>
          <attributeLabel>Calcium concentration in nanogams per gram (ng/g)</attributeLabel>
          <attributeDefinition>Calcium concentration in nanogams per gram (ng/g)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
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              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>Br_ng_g</attributeName>
          <attributeLabel>Bromine concentration in nanogams per gram (ng/g)</attributeLabel>
          <attributeDefinition>Bromine concentration in nanogams per gram (ng/g)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>Sr_ng_g</attributeName>
          <attributeLabel>Strontium concentration in ng/g</attributeLabel>
          <attributeDefinition>Strontium concentration in ng/g</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
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          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
      </attributeList>
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small sections of the record may be missing or repeated. 	Measurements were made using the DRI continuous ice core analytical system.	Configurations vary - see McConnell et al. PNAS, 2017 and Rhodes et al., Science, 2015 for approximate configurations used for this measurement campaign.	Missing data shown as -0.999	No correction made for potential ICP-MS under-recovery (McConnell et al., PNAS, 2018).</entityDescription>
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          <attributeLabel>depth measured from the middle of the core</attributeLabel>
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          <measurementScale>
            <ratio>
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          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>year</attributeName>
          <attributeLabel>year in decimal format, measured from the middle of the core</attributeLabel>
          <attributeDefinition>year in decimal format, measured from the middle of the core</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
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              </unit>
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              </numericDomain>
            </ratio>
          </measurementScale>
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            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>BCconc_ppb</attributeName>
          <attributeLabel>black carbon concentration in parts per billion (nanograms per gram (ng/g))</attributeLabel>
          <attributeDefinition>black carbon concentration in nanograms per gram (ng/g)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
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            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>h2o2_uM</attributeName>
          <attributeLabel>Hydrogen peroxide concentration in microMoles</attributeLabel>
          <attributeDefinition>Hydrogen peroxide concentration in microMoles</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>nh4_uM</attributeName>
          <attributeLabel>Ammonium concentration in microMoles</attributeLabel>
          <attributeDefinition>Ammonium concentration in microMoles</attributeDefinition>
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              <unit>
                <standardUnit>dimensionless</standardUnit>
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          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
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        <attribute>
          <attributeName>hno3_uM</attributeName>
          <attributeLabel>Nitrate concentrations in microMoles</attributeLabel>
          <attributeDefinition>Nitrate concentrations in microMoles</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
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                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>insoluble_particle_counts_ug_g</attributeName>
          <attributeLabel>Insoluble particle concentration in micrograms per gram (ug/g)</attributeLabel>
          <attributeDefinition>Insoluble particle concentration (0.8 to 10 um) in micrograms per gram (ug/g) measured used a laser-based Abakus instrument</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>dO18_permil</attributeName>
          <attributeLabel>delta Oxygen-18 isotope (d18O) in parts per thousand (permil)</attributeLabel>
          <attributeDefinition>delta Oxygen-18 isotope (d18O) in parts per thousand (permil)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>dD_permil</attributeName>
          <attributeLabel>delta Deuterium (Hydrogen 2 isotope) in parts per thousand (permil)</attributeLabel>
          <attributeDefinition>delta Deuterium (Hydrogen 2 isotope) in parts per thousand (permil)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>Na_ng_g</attributeName>
          <attributeLabel>Sodium concentration in nanogams per gram (ng/g)</attributeLabel>
          <attributeDefinition>Sodium concentration in nanogams per gram (ng/g)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>S_ng_g</attributeName>
          <attributeLabel>Sulfur concentration in nanogams per gram (ng/g)</attributeLabel>
          <attributeDefinition>Sulfur concentration in nanogams per gram (ng/g)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>Cl_ng_g</attributeName>
          <attributeLabel>Chlorine concentration in nanogams per gram (ng/g)</attributeLabel>
          <attributeDefinition>Chlorine concentration in nanogams per gram (ng/g)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>Ca_ng_g</attributeName>
          <attributeLabel>Calcium concentration in nanogams per gram (ng/g)</attributeLabel>
          <attributeDefinition>Calcium concentration in nanogams per gram (ng/g)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>Br_ng_g</attributeName>
          <attributeLabel>Bromine concentration in nanogams per gram (ng/g)</attributeLabel>
          <attributeDefinition>Bromine concentration in nanogams per gram (ng/g)</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>Ice at particular depth was missing or too damaged from drilling and handling to measure. Some missing values are also due to technical problems on one or more instrument during the analyses.</codeExplanation>
          </missingValueCode>
        </attribute>
        <attribute>
          <attributeName>Sr_ng_g</attributeName>
          <attributeLabel>Strontium concentration in ng/g</attributeLabel>
          <attributeDefinition>Strontium concentration in ng/g</attributeDefinition>
          <measurementScale>
            <ratio>
              <unit>
                <standardUnit>dimensionless</standardUnit>
              </unit>
              <numericDomain>
                <numberType>real</numberType>
              </numericDomain>
            </ratio>
          </measurementScale>
          <missingValueCode>
            <code> -999</code>
            <codeExplanation>16</codeExplanation>
          </missingValueCode>
        </attribute>
      </attributeList>
    </dataTable>
  </dataset>
</eml:eml>