Title: Oxidants on Small Icy Bodies and Snowball Earth
1Oxidants 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
2Parkinson et al., AA 463, 353357 (2007)
Invited Talk (AGU 2007)
Yung et al., Oxidants on Small Icy Bodies and
Snowball Earth
3Invited Talk (AGU 2007)
Yung et al., Oxidants on Small Icy Bodies and
Snowball Earth
4Initiation 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
5Atmospheric Photochemistry during Snowball?
Invited Talk (AGU 2007)
Yung et al., Oxidants on Small Icy Bodies and
Snowball Earth
6Atmosphere 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
7Photochemical 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
8Principal Results
O3
O2
CO2
CO
H2
H2O2
H2O
Invited Talk (AGU 2007)
Yung et al., Oxidants on Small Icy Bodies and
Snowball Earth
9Schematic Diagram
h? (lt200 nm)
H
H2O
HO2
H2O2
O2
h? (lt350 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
10Result 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
11Evidence 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
12SO2 h? ? SO O
Farquhar et al., (2000)
Invited Talk (AGU 2007)
Yung et al., Oxidants on Small Icy Bodies and
Snowball Earth
13Karhu Holland, 1996
Invited Talk (AGU 2007)
Yung et al., Oxidants on Small Icy Bodies and
Snowball Earth
14Kirschvink et al., 2000
Invited Talk (AGU 2007)
Yung et al., Oxidants on Small Icy Bodies and
Snowball Earth
15Impact on the Evolution of Life?
Invited Talk (AGU 2007)
Yung et al., Oxidants on Small Icy Bodies and
Snowball Earth
16Biological 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
17Ages 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
18Role of H2O2
Touati, 2000
Invited Talk (AGU 2007)
Yung et al., Oxidants on Small Icy Bodies and
Snowball Earth