Plenary Lecture
Day 2, June 11（Thu.） 13:05-13:55 Room A (5F 503)
- 2A-PL-1305
Intramolecular Isotope Geochemistry of Light Hydrocarbons (and Beyond)
(Texas Tech)
oJuske Horita
Since the advent of modern mass spectrometry in the 1920s-30s, it has become a routine to determine natural variations of stable isotope compositions of light elements. The invention of GC – isotope ratio mass spectroscopy (IR-MS) in the 1970s provided greater isotope resolutions on individual organic/biological compounds. Recent advances for intramolecular isotope compositions have opened up a new frontier of stable isotope geochemistry and other closely related fields. For a group of the simplest organic compounds such as light hydrocarbons position-specific (PS) carbon and hydrogen isotope compositions of propane (C3) and butane isomers (n/i-C4) generated to date clearly show that 13C/12C and 2H/1H ratios between the different C and H positions within these molecules vary widely, ranging from -9 to +42 ‰ (13C/12C) and -200 to +150 ‰ (2H/1H). These data suggest that 13C and 2H do not distribute randomly within parental macromolecules of biogenic origins (kerogens), reflecting their biosynthesis and early diagenesis processes. Armed with ever-developing IR-MS, synergistic efforts of natural studies, laboratory simulations, and theoretical/molecular simulations of key reactions and processes are expected to significantly improve our understanding of organic/biological molecules, including possible abiotic signatures of various organic molecules in terrestrial and extraterrestrial environments.