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Oxidants on Small Icy Bodies and Snowball Earth. Yuk L. Yung (Caltech) Mao-Chang Liang (Academia Sinica). Invited Talk (AGU 2007). Yung et al ., Oxidants on Small Icy Bodies and Snowball Earth. Parkinson et al. , A&A 463 , 353 – 357 (2007). Invited Talk (AGU 2007).
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Oxidants on Small Icy Bodies and Snowball Earth Yuk L. Yung (Caltech) Mao-Chang Liang (Academia Sinica) Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Parkinson et al., A&A 463, 353–357 (2007) Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Initiation of Snowball • Paleoclimate • Dim Sun • Greenhouse by CH4 (Kasting et al.) • Loss of CH4: Oxidized by O2 produced by oxygen-synthetic bacteria ice Runaway ice-house albedo (reflectance) Hoffman, 2000 Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Atmospheric Photochemistry during Snowball? Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Atmosphere of Snowball • Oxygen poor • Cold • Surface temperature -40 C • Low water vapor abundance • Weak hydrological cycles (~1 mm/yr) • 100 Myr to get rid of the Snowball, by assuming present CO2 outgassing rate Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Photochemical Calculation • One-dimensional calculation • Continuity of mass • ni/t + i/z = Pi Li • Close to present-day vertical mixing profile • Temperature profiles • Surface temperature of 210, 240, 273 K • Lapse rate of 6.5 and 10 K km-1 • Deposition rate of ~109 molecules cm-2 s-1 for H2O2 Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Principal Results O3 O2 CO2 CO H2 H2O2 H2O Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Schematic Diagram h (<200 nm) H H2O HO2 H2O2 O2 h (<350 nm) H2O2 H2O2 H2O2 H2O2 H2O2 1 km OH diffusion ice H2O2 H2O2 H2O2 H2O2 H2O2 H2O2 Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Result Summary • High ratio of H2O2 and H2O • ~1019 mole of H2O2 could be deposited • ~0.1 bar of O2 • Decomposition of H2O2 • Release O2 into the atmosphere • Global oxidation on the planetary surface Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Evidence of the Rise of Oxygen/Oxidants • Farquhar et al. (2000) • Mass-independent of sulfur isotopes • Karhu, J. A. & Holland (1996) • 13C anomaly • Kirschvink et al. (2000) • Large deposition of MnO2 Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
SO2 + h → SO + O Farquhar et al., (2000) Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Karhu & Holland, 1996 Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Kirschvink et al., 2000 Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Impact on the Evolution of Life? Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Biological Evolution Associated with Snowball • Paleoproterozic (~2.4 Ga) • global oxidation event • first clear fossil of eukaryotic cell (Han & Runegar, 1992) • Neoproterozic (~0.7 Ga) • multi-cellular life • Cambrian explosion Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Ages in Millions of Years Cenozoic Mesozoic Cambrian Explosion Snowball Earth (two?) (Precambrian) Paleozoic 1000 Proterozoic Oldest Eukaryote Body Fossil Introduction of Oxygen Snowball Earth (Paleoproterozoic) 2000 3000 Archaean 3500 Oldest Stromatolite and Prokaryote Body Fossil Courtesy of Hyman Hartman Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
Role of H2O2 Touati, 2000 Invited Talk (AGU 2007) Yung et al., Oxidants on Small Icy Bodies and Snowball Earth
