Colloquium Series

Date: 

Monday, November 23, 2015, 4:00pm to 5:00pm

Location: 

Geology Museum (GM 102)
"Clumped Isotopologue (13CH3D) Fingerprinting of Methane Sources in the Environment"

by Shuhei Ono (MIT)

Abstract:

Methane is a significant greenhouse gas and energy resource, which generates about a third of electricity in the US today.  It is derived from diverse sources, yet differentiation between sources remains a major challenge in atmospheric, geochemical, and biological investigations.  While, carbon (13C/12C) and hydrogen (D/H) isotope ratios can tell the origin of carbon and hydrogen, abundance of doubly-isotope substituted “clumped” methane isotopologue, 13CH3D, may inform us the origin of C-H bonds.

Our research with the newly developed tunable laser mid-infrared spectroscopy has demonstrated a wealth of additional information that can be inferred from clumped isotopologues. For example, methane samples from sites supporting active microbial methanogenesis (such as wetlands and cow rumens) and laboratory methanogen cultures carry unique non-statistical 13CH3D abundance, while most geologic methane follows expected thermodynamic abundance.  I will discuss application of the technique to test the origin of methane in various environments, including sites of serpentinization and marine hydrates.

Background Reading:

Ono_clloq_background_reading.pdf281 KB