Self-Shielding Enhanced Organics Synthesis in an Early Reduced Earth’s Atmosphere
Joint press release (in Japanese) by Tohoku University, The University of Tokyo, Hokkaido University
Abstract
Earth is expected to have acquired a reduced proto-atmosphere enriched in H2 and CH4 through the accretion of building blocks that contain metallic Fe and/or the gravitational trapping of surrounding nebula gas. Such an early, wet, reduced atmosphere that covers a proto-ocean would then ultimately evolve toward oxidized chemical compositions through photochemical processes that involve reactions with H2O-derived oxidant radicals and the selective escape of hydrogen to space. During this time, atmospheric CH4 could be photochemically reprocessed to generate not only C-bearing oxides but also organics. However, the branching ratio between organic matter formation and oxidation remains unknown despite its significance on the abiotic chemical evolution of early Earth. Here, we show via numerical analyses that UV absorptions by gaseous hydrocarbons such as C2H2 and C3H4 significantly suppress H2O photolysis and subsequent CH4 oxidation during the photochemical evolution of a wet proto-atmosphere enriched in H2 and CH4. As a result, nearly half of the ….
Read the original article on Astrobiology
Article inforamation
Tatsuya Yoshida, Shungo Koyama, Yuki Nakamura, Naoki Terada, and Kiyoshi Kuramoto
Self-Shielding Enhanced Organics Synthesis in an Early Reduced Earth’s Atmosphere, Astrobiology Vol.24, No.9 September 2024
DOI：10.1089/ast.2024.0048
