[U-11] CO環境の生命惑星化学

[U11-06] Atmospheric UV synthesis of organics from CO₂ and CO

*上野 雄一郎¹、藏 暁鳳¹、毛利 晃大¹ (1.東京工業大学大学院地球惑星科学系)

キーワード：生命起源、惑星大気

Photochemistry is important for origin of life and the early Earth’s environment. Based on previous experiments, CO atmosphere is favorable for the synthesis of simple organic compounds irrespective to energy source, though the factors controlling the amount and speciation of the product organics is largely uncertain. We have conducted a series of UV experiments and demonstrated that the speciation and production rate are depending on starting carbon source (CO₂/CO/CH₄) with or without co-existing reducing agent mainly H₂. In contrast to previous reports, the results demonstrated that solar UV irradiation into CO atmosphere produces not only formaldehydes, but also various C2 compounds, including acetaldehyde, glycolate, and glyoxylate, with smaller amount of some C3 compounds, including lactate and pyruvate. Furthermore, some of the aldehydes and carboxylic acids were formed even started from CO₂ atmosphere under the presence of H₂. The modeling of the experimental results indicated that atmospheric UV synthesis is largely mediated via CO. Total production rate of organics could depend largely on a total redox state of the whole atmosphere and ocean system. Consequently, CO-mediated UV chemistry could play a major role for abiotic synthesis in early atmosphere of terrestrial planets like Earth and Mars.