Protocol

Hydrocarbon and Lipid Microbiology Protocols

Part of the series Springer Protocols Handbooks pp 277-303

Date:

Protocols for Radiotracer Estimation of Methane Oxidation Rates at In Situ Methane Concentrations in Marine Sediments

  • Ryan SibertAffiliated withDepartment of Marine Sciences, University of Georgia
  • , Vladimir A. SamarkinAffiliated withDepartment of Marine Sciences, University of Georgia
  • , Samantha B. JoyeAffiliated withDepartment of Marine Sciences, University of Georgia Email author 

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Abstract

The microbial consumption of methane acts as a biofilter in deep marine environments, significantly limiting the flux of methane from ocean to atmosphere. Measurements of both anaerobic and aerobic oxidation of methane are necessary to constrain net carbon flux from deeply buried sediments to the overlying water column. Precise methods for quantifying methane oxidation (MOx) rates are crucial to these efforts. Most protocols describe conducting incubations at 1 atm pressure, limiting methane concentrations to seawater saturation values (~1.2 mM CH4). Deep sediment porewaters are often supersaturated with methane relative to atmospheric pressure, which introduces potentially significant error into MOx rate measurements. Here, we present a detailed method for determining rates of anaerobic oxidation of methane (AOM) at in situ pressure and methane concentration for sediments and deep waters. By conducting MOx rate assays at in situ pressure and realistic environmental methane concentrations, methane dynamics can be constrained with greater accuracy.

Keywords:

Deep-sea methane oxidation Marine sediment Pressure vessel incubation Radiotracer Rate measurements