Title: Using Carbon Isotope Fractionation to Constrain the Extent of Methane Dissolution Into the Water Column Surrounding a Natural Hydrocarbon Gas Seep in the Northern Gulf of Mexico

Journal Article · · Geochemistry, Geophysics, Geosystems
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4];  [5]; ORCiD logo [6]
  1. Univ. of Rochester, NY (United States); DOE/OSTI
  2. Univ. of Missouri, Columbia, MO (United States)
  3. Texas A & M Univ., College Station, TX (United States)
  4. Univ. of Bremen (Germany)
  5. Univ. of Texas Rio Grande Valley, Port Isabel. TX (United States); Woods Hole Oceanographic Institution, Woods Hole, MA (United States)
  6. Univ. of Rochester, NY (United States)
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A gas bubble seep located in the northern Gulf of Mexico was investigated over several days to determine whether changes in the stable carbon isotopic ratio of methane can be used as a tracer for methane dissolution through the water column. Gas bubble and water samples were collected at the seafloor and throughout the water column for isotopic ratio analysis of methane. Our results show that changes in methane isotopic ratios are consistent with laboratory experiments that measured the isotopic fractionation from methane dissolution. A Rayleigh isotope model was applied to the isotope data to determine the fraction of methane dissolved at each depth. On average, the fraction of methane dissolved surpasses 90% past an altitude of 400 m above the seafloor. Methane dissolution was also investigated using a modified version of the Texas A&M Oil spill (Outfall) Calculator (TAMOC) where changes in methane isotopic ratios could be calculated. The TAMOC model results show that dissolution depends on depth and bubble size, explaining the spread in measured isotopic ratios during our investigations. Both the Rayleigh and TAMOC models show that methane bubbles quickly dissolve following emission from the seafloor. Together, these results show that it is possible to use measurements of natural methane isotopes to constrain the extent of methane dissolution following seafloor emission.

Research Organization:
Univ. of Rochester, NY (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S); USDOE Office of Fossil Energy (FE)
Grant/Contract Number:
FE0028980
OSTI ID:
1614330
Journal Information:
Geochemistry, Geophysics, Geosystems, Journal Name: Geochemistry, Geophysics, Geosystems Journal Issue: 11 Vol. 19; ISSN 1525-2027
Publisher:
American Geophysical UnionCopyright Statement
Country of Publication:
United States
Language:
English

References (41)

Mathematical conversion of δ13C-CH4 for methane dissolved in water using raw data collected in the northern Gulf of Mexico, April 12-20, 2015 dataset January 2018
Concentrations of gas dissolved in seawater and in gas bubbles collected in the northern Gulf of Mexico, April 12-20, 2015 dataset January 2018
Simulation of the fates of natural gas seep bubbles with isotope ratio calculation at MC 118, Gulf of Mexico, April 17-18, 2015 dataset January 2018
Acoustic estimates of methane gas flux from the seabed in a 6000 km 2 region in the Northern Gulf of Mexico journal May 2014
Dynamic morphology of gas hydrate on a methane bubble in water: Observations and new insights for hydrate film models: Dynamic hydrate morphology on a bubble journal October 2014
Observations of bubbles in natural seep flares at MC 118 and GC 600 using in situ quantitative imaging journal April 2016
Pressurized laboratory experiments show no stable carbon isotope fractionation of methane during gas hydrate dissolution and dissociation: No isotope fractionation during hydrate dissolution journal December 2011
Evaluation of a seawater equilibrator for shipboard analysis of dissolved oceanic trace gases journal August 1999
A new gas-tight isobaric sampler for hydrothermal fluids journal January 2002
Quantification of CH4 loss and transport in dissolved plumes of the Santa Barbara Channel, California journal January 2012
Spatial distribution of seafloor bio-geological and geochemical processes as proxies of fluid flux regime and evolution of a carbonate/hydrates mound, northern Gulf of Mexico journal April 2013
A large volume particulate and water multi-sampler with in situ preservation for microbial and biogeochemical studies journal December 2014
A deep-sea, high-speed, stereoscopic imaging system for in situ measurement of natural seep bubble and droplet characteristics journal October 2015
Dissolved methane and carbon dioxide fluxes in Subarctic and Arctic regions: Assessing measurement techniques and spatial gradients journal February 2016
Rapid rates of aerobic methane oxidation at the feather edge of gas hydrate stability in the waters of Hudson Canyon, US Atlantic Margin journal May 2017
Controls on methane bubble dissolution inside and outside the hydrate stability field from open ocean field experiments and numerical modeling journal April 2009
Mesoscale biogeophysical characterization of Woolsey Mound (northern Gulf of Mexico), a new attribute of natural marine hydrocarbon seeps architecture journal October 2016
Simulating Gas–Liquid−Water Partitioning and Fluid Properties of Petroleum under Pressure: Implications for Deep-Sea Blowouts journal April 2016
Assessment of the Spatial and Temporal Variability of Bulk Hydrocarbon Respiration Following the Deepwater Horizon Oil Spill journal September 2012
Effects of Solutes on the Strength of Hydrophobic Interaction and Its Temperature Dependence journal January 1974
Solubility of butane in water and salt solutions at low temperatures journal April 1976
Equilibrium solubilities of methane, carbon monoxide, and hydrogen in water and sea water journal October 1979
Fate of rising methane bubbles in stratified waters: How much methane reaches the atmosphere? journal January 2006
Methane flux to the atmosphere from the Deepwater Horizon oil disaster: METHANE FLUX FROM THE DEEPWATER HORIZON journal January 2011
Methane fluxes to the atmosphere from deepwater hydrocarbon seeps in the northern Gulf of Mexico: AIR-SEA FLUX OF CH journal January 2012
Kinetic isotopic fractionation during air-water gas transfer of O 2 , N 2 , CH 4 , and H 2 journal January 1992
Carbon isotope fractionation during microbial methane oxidation journal September 1981
The rise and fall of methanotrophy following a deepwater oil-well blowout journal May 2014
Considerable methane fluxes to the atmosphere from hydrocarbon seeps in the Gulf of Mexico journal July 2009
Solubility isotope effects in aqueous solutions of methane journal June 2002
Petroleum dynamics in the sea and influence of subsea dispersant injection during Deepwater Horizon journal August 2017
Der thermodynamische Kohlenstoffisotopieeffekt im System CH 4 –H 2 O journal January 1976
Stable isotopes in precipitation journal November 1964
A Persistent Oxygen Anomaly Reveals the Fate of Spilled Methane in the Deep Gulf of Mexico journal January 2011
Solubility of Propane and n-Butane in Salt Solution [プロパンおよびn-ブタンの水および食塩溶液への溶解度] journal January 1958
Stable isotopes in precipitation text January 2021
Stable isotopes in precipitation journal January 1964
Different methanotrophic potentials in stratified polar fjord waters (Storfjorden, Spitsbergen) identified by using a combination of methane oxidation techniques journal January 2013
Mathematical conversion of δ13C-CH4 for methane dissolved in water using raw data collected in the northern Gulf of Mexico, April 12-20, 2015 dataset January 2018
Concentrations of gas dissolved in seawater and in gas bubbles collected in the northern Gulf of Mexico, April 12-20, 2015 dataset January 2018
Simulation of the fates of natural gas seep bubbles with isotope ratio calculation at MC 118, Gulf of Mexico, April 17-18, 2015 dataset January 2018

Cited By (3)

Major CO 2 blowouts from offshore wells are strongly attenuated in water deeper than 50 m journal November 2019
Methane Sources in the Waters of Lake Michigan and Lake Superior as Revealed by Natural Radiocarbon Measurements journal May 2019
Global ocean methane emissions dominated by shallow coastal waters journal October 2019

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58 GEOSCIENCES
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