Carbon Isotopes of Biomarkers Derived from Methane-Oxidizing Microbes at Hydrate Ridge, Cascadia Convergent Margin

  1. Charles K. Paull and
  2. William P. Dillon
  1. Marcus Elvert1,
  2. Jens Greinert1,
  3. Erwin Suess1 and
  4. Michael J. Whiticar2

Published Online: 18 MAR 2013

DOI: 10.1029/GM124p0115

Natural Gas Hydrates: Occurrence, Distribution, and Detection

Natural Gas Hydrates: Occurrence, Distribution, and Detection

How to Cite

Elvert, M., Greinert, J., Suess, E. and Whiticar, M. J. (2001) Carbon Isotopes of Biomarkers Derived from Methane-Oxidizing Microbes at Hydrate Ridge, Cascadia Convergent Margin, in Natural Gas Hydrates: Occurrence, Distribution, and Detection (eds C. K. Paull and W. P. Dillon), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM124p0115

Author Information

  1. 1

    Department of Marine Environmental Geology, GEOMAR Research Center for Marine Geosciences, Kiel, Germany

  2. 2

    Biogeochemistry Facility, School of Earth and Ocean Sciences, Victoria, Canada

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 2001

ISBN Information

Print ISBN: 9780875909820

Online ISBN: 9781118668412

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Keywords:

  • Natural gas hydrates

Summary

The microbial community inhabiting anaerobic sediments of Hydrate Ridge, an area characterized by extensive methane-venting and gas hydrate occurrence on the Cascadia accretionary prism, is dominated by a complex consortium of archaea and bacteria which performs anaerobic methane oxidation (AMO). The process is indicated by the dominance of archaeal-derived biomarkers such as crocetane, pentamethylicosane, and archaeol in anaerobic sediments and authigenic carbonates. The biomarkers are highly depleted in 1 3C relative to their methane carbon source, which results in carbon isotopic compositions as low as -128%o PDB. The essentially limitless reservoir of methane available to the archaea in this gas hydrate environment allows the kinetic carbon isotope effect (ϵCH4-biomarker) associated with AMO to be fully developed (ϵmax = 72%o). No substrate depletion effects were detected. Varying isotope effects and concentrations of the biomarkers on and off Hydrate Ridge indicate that the abundance of these compounds is essentially dependent on the supply of methane from this special environmental setting.