Oxidants on Small Icy Bodies and Snowball Earth
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Transcript of Oxidants on Small Icy Bodies and Snowball Earth
Oxidants on Small Icy Bodies and Snowball Earth Yuk L. Yung (Caltech)
Mao-Chang Liang (Academia Sinica)
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet al., ., Oxidants on Small Icy Bodies and Snowball Earth
Parkinson et al., A&A 463, 353–357 (2007)
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet al., ., Oxidants on Small Icy Bodies and Snowball Earth
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet al., ., Oxidants on Small Icy Bodies and Snowball Earth
Initiation of Snowball
Hoffman, 2000
Paleoclimate Dim Sun Greenhouse by CH4 (Kasting et al.) Loss of CH4: Oxidized by O2 produced by oxygen-synthetic bacter
ia
ice
albedo(reflectance)
Runaway ice-house
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet al., ., Oxidants on Small Icy Bodies and Snowball Earth
Atmospheric Photochemistry during Snowball?
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet 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)Invited Talk (AGU 2007) Yung Yung et alet 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)Invited Talk (AGU 2007) Yung Yung et alet al., ., Oxidants on Small Icy Bodies and Snowball Earth
Principal Results
O3
H2O
H2O2
O2
H2CO
CO2
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet al., ., Oxidants on Small Icy Bodies and Snowball Earth
H2O2
ice
H2O2
H2O2
H2O2H2O2
H2OHO2
HO2 H2O2
OH
H2O2
H2O2 H2O2
H2O2
H2O2H2O2
1 km
diffusion
Schematic Diagramh (<200 nm)
h (<350 nm)
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet 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)Invited Talk (AGU 2007) Yung Yung et alet 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)Invited Talk (AGU 2007) Yung Yung et alet al., ., Oxidants on Small Icy Bodies and Snowball Earth
Farquhar et al., (2000)
SO2 + h → SO + O
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet al., ., Oxidants on Small Icy Bodies and Snowball Earth
Karhu & Holland, 1996Karhu & Holland, 1996
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet al., ., Oxidants on Small Icy Bodies and Snowball Earth
Kirschvink Kirschvink et alet al., 2000., 2000
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet al., ., Oxidants on Small Icy Bodies and Snowball Earth
Impact on the Evolution of Life?
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet 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 & Runega
r, 1992) Neoproterozic (~0.7 Ga)
multi-cellular life Cambrian explosion
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet al., ., Oxidants on Small Icy Bodies and Snowball Earth
Ages in Millions of Years
Oldest Stromatolite and Prokaryote Body Fossil
Oldest Eukaryote Body FossilIntroduction of OxygenSnowball Earth (Paleoproterozoic)
Cambrian ExplosionSnowball Earth (two?) (Precambrian)
3500
3000
2000
1000
Archaean
Proterozoic
CenozoicMesozoic
Paleozoic
Courtesy of Hyman Hartman
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet al., ., Oxidants on Small Icy Bodies and Snowball Earth
Role of H2O2
Touati, 2000
Invited Talk (AGU 2007)Invited Talk (AGU 2007) Yung Yung et alet al., ., Oxidants on Small Icy Bodies and Snowball Earth