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Oxidants on Small Icy Bodies and Snowball Earth

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Title: Production of Oxidants in the Atmosphere of a Snowball Earth Author: Danie Liang Last modified by: Yuk Yung Created Date: 2/8/2005 7:47:58 PM – PowerPoint PPT presentation

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Title: Oxidants on Small Icy Bodies and Snowball Earth


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