Mathematical conversion of δ13C-CH4 for methane dissolved in water using raw data collected in the northern Gulf of Mexico, April 12-20, 2015

Gulf of Mexico Integrated Spill Response Consortium (GISR)

DOI:
10.7266/n7-g26b-a359
 
UDI:
R1.x137.000:0028
Last Update:
Sep 26 2018 16:24 UTC
 
Dataset Author(s):
Mihai Leonte, John Kessler
Point of Contact:
Kessler, John
University of Rochester / Department of Earth and Environmental Sciences
210 Hutchison Hall
Rochester, New York  14627
USA
john.kessler@rochester.edu
Funding Source:
RFP-I
Data Collection Period:
2015-04-12 to 2015-04-20

Identified Submitted In-Review Available
3 3 3 3

Suggested Citation:

Mihai Leonte, John Kessler (2018) Mathematical conversion of δ13C-CH4 for methane dissolved in water using raw data collected in the northern Gulf of Mexico, April 12-20, 2015. Distributed by: Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC), Harte Research Institute, Texas A&M University-Corpus Christi. doi:10.7266/n7-g26b-a359

Abstract:

Seawater samples were collected in the Gulf of Mexico at MC118, located at 28° 51.129’N, 88° 29.51’W, from 12 - 20 April, 2015 aboard the E/V Nautilus. The seawater samples were collected directly from waters impacted by seafloor methane seeps. This was carried out using the SUPR sampler [Breier et al., 2014] mounted to the ROV Hercules. The SUPR sampler is an in-situ seawater pumping system and was developed to sample dynamic, high gradient, ocean geochemical features at areas such as seep sites. The inlet of the SUPR sampler was attached with tubing to the ROV arm and is pumped seawater directly into sampling bottles mounted to the ROV chassis. The samples were taken from waters visibly impacted by methane bubbles, so an adapter was placed on the inlet of the sampling tube to collect seawater but not bubbles. Once the ROV was recovered, water collected by the SUPR sampler was transferred to 500 mL glass vials which were immediately capped using a butyl rubber topper and aluminum crimp cap (Wheaton). A helium headspace was then introduced into each vial by removing 10 mL of water while simultaneously injecting 10 mL of helium. Samples for the analysis of δ13C-CH4 were preserved using a supersaturated solution of mercuric chloride (HgCl2) for later analysis in a land-based laboratory. Over the course of 12-24 hours the headspace equilibrates with the water sample and the resulting concentration of methane in the headspace is proportional to the solubility of methane and the dissolved methane concentration in the original water sample. As outlined in [Leonte et al., 2017], an aliquot of this headspace gas is removed from each vial for the purpose of isotopic ratio analysis. The raw data from the analysis of this headspace gas was originally presented in https://doi.org/10.7266/N7610XXW. However, since different methane isotopes have been shown to have slightly different solubilities, the isotopic ratio of the headspace gas is slightly different than the isotopic ratio of methane originally dissolved in the water sample. Here, we convert the isotopic ratios measured in the vial headspace (labeled below as δh) to the δ13C-CH4 originally dissolved in water (δi) before a headspace was inserted by considering the isotopic fractionation associated with gas dissolution (αd) and an isotopic mass balance between methane in the headspace and dissolved in water. The standard deviation was also corrected by considering the uncertainty in measurements of the fractionation factor, dissolved methane concentration, and the isotopic ratio of methane in the headspace gas. Additional details can be found in [Leonte et al., 2018]. This dataset supports the publication: Socolofsky, S. A.; Lavery, A.; Kessler, J.; Wang, B.; Breier, J. A.; Leonte, M.; Chan, E.; Raineault, N. (2016). Fate and transport of gas bubbles from Sleeping Dragon seep in the northern Gulf of Mexico, in New Frontiers in Ocean Exploration: the E/V Nautilus and NOAA Ship Okeanos Explorer 2015 Field Season, Oceanography 29(1), supplement, 88 pp., Bell, K. L. C., Brennan, M. L., Flanders, J., Raineault, N. A., and Wagner, K., eds.. Oceanography, 29, 01, 26-27. doi:10.5670/oceanog.2016.supplement.01

Purpose:

Seawater samples were collected to analyze for dissolved δ13C-CH4. These measurements have a variety of uses, but the intention of the authors here were to use these analyses for determining the extent of bubble dissolution in the water column following seafloor release as well as microbial methane oxidation. The raw data collected from the mass spectrometry analyses were presented previously and can be found in https://doi.org/10.7266/N7610XXW. The raw data reports δ13C-CH4 values measured in the headspace of a water sample vial. In this dataset, those raw data are converted into the values of δ13C-CH4 that were originally dissolved in seawater, prior to headspace equilibration.

Theme Keywords:

MC118, Methane, Gas Bubbles, Isotopes, Woolsey Mound

File Format:

csv, pdf

Filename:

IsotopeConversion.zip (109.84 KB)

Dataset Downloads:

4

Mathematical conversion of δ13C-CH4 for methane dissolved in water using raw data collected in the northern Gulf of Mexico, April 12-20, 2015



Identification Information
Distribution Information
Metadata Maintenance Information

Metadata: 
  File identifier: 
      R1.x137.000-0028-metadata.xml
  Language: 
      eng; USA
  Character set: 
    Character set code: 
      utf8
  Hierarchy level: 
    Scope code: 
      dataset
  Metadata author: 
    Responsible party: 
      Individual name: 
          John Kessler
      Organisation name: 
          University of Rochester / Department of Earth and Environmental Sciences
      Position name: 
          Associate Professor
      Contact info: 
        Contact: 
          Phone: 
            Telephone: 
              Voice: 
                  5852734572
              Facsimile: 
          Address: 
            Address: 
              Delivery point: 
                  210 Hutchison Hall
              City: 
                  Rochester
              Administrative area: 
                  New York
              Postal code: 
                  14627
              Country: 
                  USA
              Electronic mail address: 
                  john.kessler@rochester.edu
      Role: 
        Role code: 
          pointOfContact
  Date stamp: 
      2018-10-12T20:19:29+00:00
  Metadata standard name: 
      ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data
  Metadata standard version: 
      ISO 19115-2:2009(E)
  Dataset URI: 
      https://data.gulfresearchinitiative.org/metadata/R1.x137.000:0028
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Identification info: Data identification: Citation: Citation: Title: Mathematical conversion of δ13C-CH4 for methane dissolved in water using raw data collected in the northern Gulf of Mexico, April 12-20, 2015 Alternate title: δ13C-CH4 for dissolved methane Date: Date: Date: 2018-09-25 Date type: Date type code: revision Abstract: Seawater samples were collected in the Gulf of Mexico at MC118, located at 28° 51.129’N, 88° 29.51’W, from 12 - 20 April, 2015 aboard the E/V Nautilus. The seawater samples were collected directly from waters impacted by seafloor methane seeps. This was carried out using the SUPR sampler [Breier et al., 2014] mounted to the ROV Hercules. The SUPR sampler is an in-situ seawater pumping system and was developed to sample dynamic, high gradient, ocean geochemical features at areas such as seep sites. The inlet of the SUPR sampler was attached with tubing to the ROV arm and is pumped seawater directly into sampling bottles mounted to the ROV chassis. The samples were taken from waters visibly impacted by methane bubbles, so an adapter was placed on the inlet of the sampling tube to collect seawater but not bubbles. Once the ROV was recovered, water collected by the SUPR sampler was transferred to 500 mL glass vials which were immediately capped using a butyl rubber topper and aluminum crimp cap (Wheaton). A helium headspace was then introduced into each vial by removing 10 mL of water while simultaneously injecting 10 mL of helium. Samples for the analysis of δ13C-CH4 were preserved using a supersaturated solution of mercuric chloride (HgCl2) for later analysis in a land-based laboratory. Over the course of 12-24 hours the headspace equilibrates with the water sample and the resulting concentration of methane in the headspace is proportional to the solubility of methane and the dissolved methane concentration in the original water sample. As outlined in [Leonte et al., 2017], an aliquot of this headspace gas is removed from each vial for the purpose of isotopic ratio analysis. The raw data from the analysis of this headspace gas was originally presented in https://doi.org/10.7266/N7610XXW. However, since different methane isotopes have been shown to have slightly different solubilities, the isotopic ratio of the headspace gas is slightly different than the isotopic ratio of methane originally dissolved in the water sample. Here, we convert the isotopic ratios measured in the vial headspace (labeled below as δh) to the δ13C-CH4 originally dissolved in water (δi) before a headspace was inserted by considering the isotopic fractionation associated with gas dissolution (αd) and an isotopic mass balance between methane in the headspace and dissolved in water. The standard deviation was also corrected by considering the uncertainty in measurements of the fractionation factor, dissolved methane concentration, and the isotopic ratio of methane in the headspace gas. Additional details can be found in [Leonte et al., 2018]. This dataset supports the publication: Socolofsky, S. A.; Lavery, A.; Kessler, J.; Wang, B.; Breier, J. A.; Leonte, M.; Chan, E.; Raineault, N. (2016). Fate and transport of gas bubbles from Sleeping Dragon seep in the northern Gulf of Mexico, in New Frontiers in Ocean Exploration: the E/V Nautilus and NOAA Ship Okeanos Explorer 2015 Field Season, Oceanography 29(1), supplement, 88 pp., Bell, K. L. C., Brennan, M. L., Flanders, J., Raineault, N. A., and Wagner, K., eds.. Oceanography, 29, 01, 26-27. doi:10.5670/oceanog.2016.supplement.01 Purpose: Seawater samples were collected to analyze for dissolved δ13C-CH4. These measurements have a variety of uses, but the intention of the authors here were to use these analyses for determining the extent of bubble dissolution in the water column following seafloor release as well as microbial methane oxidation. The raw data collected from the mass spectrometry analyses were presented previously and can be found in https://doi.org/10.7266/N7610XXW. The raw data reports δ13C-CH4 values measured in the headspace of a water sample vial. In this dataset, those raw data are converted into the values of δ13C-CH4 that were originally dissolved in seawater, prior to headspace equilibration. Status: Progress code: completed Point of contact: Responsible party: Individual name: John Kessler Organisation name: University of Rochester / Department of Earth and Environmental Sciences Position name: Associate Professor Contact info: Contact: Phone: Telephone: Voice: 5852734572 Facsimile: Address: Address: Delivery point: 210 Hutchison Hall City: Rochester Administrative area: New York Postal code: 14627 Country: USA Electronic mail address: john.kessler@rochester.edu Role: Role code: pointOfContact Descriptive keywords: Keywords: Keyword: MC118 Keyword: Methane Keyword: Gas Bubbles Keyword: Isotopes Keyword: Woolsey Mound Type: Keyword type code: theme Descriptive keywords: Keywords: Keyword: northern Gulf of Mexico Type: Keyword type code: place Language: eng; USA Topic category: Topic category code: oceans Extent: Extent: Geographic element: Geographic bounding box: West bound longitude: -88.49183 East bound longitude: -88.49183 South bound latitude: 28.85215 North bound latitude: 28.85215 Geographic element: BoundingPolygon: Polygon: gml:MultiPoint: gml:pointMember: Point: gml:pos: 28.85215 -88.49183 Temporal element: Temporal extent: Extent: Time period: Description: ground condition Begin date: 2015-04-12 End date: 2015-04-20 Supplemental Information: Dive number, Sample ID, d13C-CH4 (per mille, ‰), Standard Deviation of d13C-CH4 (per mille, ‰), Converted d13C-CH4 (per mille, ‰), Converted Standard Deviation of d13C-CH4 (per mille, ‰). The dive information (latitude, longitude, and date) can be found under GRIIDC UDI R1.x137.000:0025 (doi: 10.7266/N7610XXW).|||||Breier, J., Sheik, C., Gomez-Ibanez, D., Sayre-McCord, R., Sanger, R., Rauch, C., Coleman, M., Bennett, S., Cron, B., Li, M., 2014. A large volume particulate and water multi-sampler with in situ preservation for microbial and biogeochemical studies. Deep Sea Research Part I: Oceanographic Research Papers 94, 195-206. doi:10.1016/j.dsr.2014.08.008
          
Leonte, M., Kessler, J.D., Kellermann, M.Y., Arrington, E.C., Valentine, D.L., Sylva, S.P., 2017. Rapid rates of aerobic methane oxidation at the feather edge of gas hydrate stability in the waters of Hudson Canyon, US Atlantic Margin. Geochimica et Cosmochimica Acta 204, 375-387. doi:10.1016/j.gca.2017.01.009
          
Leonte, M., Wang, B., Socolofsky, S.A., Breier, J.A., and Kessler, J.D., 2018. Using carbon isotope fractionation to constrain the extent of methane dissolution into the water column surrounding a natural hydrocarbon gas plume in the Northern Gulf of Mexico. In Review at Geochemistry, Geophysics, Geosystems.
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Distribution info: Distribution: Distributor: Distributor: Distributor contact: Responsible party: Organisation name: Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC) Contact info: Contact: Phone: Telephone: Voice: 3618253604 Address: Address: Delivery point: 6300 Ocean Drive City: Corpus Christi Administrative area: TX Postal code: 78412 Country: USA Electronic mail address: griidc@gomri.org Online Resource: Online Resource: Linkage: URL: https://data.gulfresearchinitiative.org Role: Role code: distributor Distributor format: Format: Name: csv, pdf Version: inapplicable File decompression technique: zip Distributor transfer options: Digital transfer options: Transfer size: 0.1098 Online: Online Resource: Linkage: URL: https://data.gulfresearchinitiative.org/data/R1.x137.000:0028 Protocol: https Name: Data Landing Page Description: GRIIDC dataset landing page Function: Online function code: information
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Metadata maintenance: Maintenance information: Maintenance and update frequency: unknown Maintenance note: This ISO metadata record was automatically generated from information provided to GRIIDC for dataset: R1.x137.000:0028 on 2019-11-19T17:24:16-06:00
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