Japan Geoscience Union Meeting 2016

Presentation information


Symbol B (Biogeosciences) » B-CG Complex & General

[B-CG09] Interrelation between Life, Water, Mineral, and Atmosphere

Mon. May 23, 2016 1:45 PM - 3:00 PM A02 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Kentaro Nakamura(Department of Systems Innovation, School of Engineering, University of Tokyo), Tsubasa Otake(Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University), Yohey Suzuki(Graduate School of Science, The University of Tokyo), Ken Takai(Extremobiosphere Research Center, Japan Agency for Marine-Earth Science & Technology), Yuichiro Ueno(Department of Earth and Planetary Sciences, Tokyo Institute of Technology), Takeshi Naganuma(Graduate School of Biosphere Science), Takeshi Kakegawa(Graduate School of Science, Tohoku University), Tadashi Yokoyama(Department of Earth and Space Science, Graduate School of Science, Osaka University), Fumito Shiraishi(Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University), Chair:Fumito Shiraishi(Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University)

2:30 PM - 2:45 PM

[BCG09-04] A role of ferruginous ocean in photochemical synthesis of organic compounds

*Waka Kawade1, Yuichiro Ueno1, Norio Kitadai2, Yayoi Hongo2 (1.Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2.ELSI)

Keywords:origin of life

Photochemistry is important for the origin of life and the early earth’s environment. Previous photochemical experiments suggest that the reaction initiated by UV in CO-rich atmosphere can produce simple organic compounds mainly formaldehyde and methanol (Bar-Nun and Chang, 1983). The amount and speciation of organic molecules are known to depend on the redox state of the atmosphere. The reducing ocean containing ferrous iron may also control the redox state of the ocean-atmosphere system, though the role of ferruginous ocean for abiotic UV synthesis is poorly understood. We have conducted photochemical experiments simulating the reducing atmosphere and Fe(II)-bearing ocean. The results of our experiment suggest that formate, acetate, propionate, and normal alkanes are synthesized under CO-atmosphere. When irradiating UV under the presence of Fe(II)-bearing water, the production rate of formate is about three times faster than the simple CO-H2O system without ferrous iron. Furthermore, formate is formed even when the gas phase is pure CO2 when liquid-phase contains Fe(II). These results suggest that the production rate and speciation of organic matter depends on the availability of H2O as well as total redox state of the whole atmosphere and ocean system. Based on the results, we have modeled the reaction pathway and estimate the flux of each organic compounds supplied to early ocean.