Sulfur Chemistry of Cinder Pool, YNP: Implications for a Chemical Origin of Life ☆

Abstract One chemical origin of life theory posits the abiotic formation of alkyl thiols as an initial step to forming biomolecules and eventually simple chemoautotrophic cells. Alkyl thiols have not previously been identified in terrestrial hot springs as unequivocally abiogenic, but they have been synthesized in the laboratory under hydrothermal conditions in the presence of a catalyst. We found methanethiol as well as other sulfur gases in Cinder Pool, Yellowstone National Park in gas samples collected using the bubble strip method. Laboratory microcosm experiments were performed using synthetic Cinder Pool water in serum bottles containing different iron-sulfur minerals, including cinders collected from the pool itself, as catalytic surfaces for the CH 3 SH generating reaction. The bottles were charged with H 2 , and CO 2 , with CS 2 added to some and incubated from 60 to 100°C. In bottles without introduced CS 2 , only the cinder material produced detectable CH 3 SH. While CH3SH is central to the autotroph-first theory and has been synthesized in the laboratory 1 , it has not previously been observed to form abiotically in natural systems. We have identified abiogenic CH 3 SH in a terrestrial hydrothermal feature using natural catalytic surfaces consistent with the Autotroph-First origin theory.