研究目的
Understanding the origins of methane is crucial for predicting the methane atmospheric budget, locating natural gas deposits for energy production, and for exploring the potential for extraterrestrial life. The origins of methane have traditionally been studied based on the analysis of its carbon (13C/12C) and hydrogen (D/H) stable isotope ratios. These ratios reflect both the origin of carbon and hydrogen and the isotope fractionation during its formation. In addition to traditional bulk isotope ratios, abundances of methane isotopologues (molecules with different isotope configurations) that contain more than one rare isotope, 13CH3D and 12CH2D2, have recently been explored as novel proxies.
研究成果
The combined measurements of Δ13CH3D and Δ12CH2D2 for methane from working reference cylinders, isotopologue spiked, and natural samples highlight the application space of these novel measurements to distinguish between methane carrying isotopologue abundances characterized by near-equilibrium distributions. TILDAS instruments provide an alternative means to high-resolution mass spectrometers, offering the benefits of speed of analysis and a smaller size and lower cost although TILDAS requires larger sample size than the high-resolution mass spectrometer.
研究不足
The accuracy of the measurements is limited by non-linearity in the δ12CH2D2 scale due to an imperfect line profile to describe the baseline. This is critical, in particular, for samples with low δD values. The instrument requires larger sample size than high-resolution mass spectrometers.
