Where do we start?

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• Where do we start?
• Create the Universe
• Form the Earth and elements
• move the elements into their correct positions
• build the atmosphere and oceans

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The BIG BANG

• The Universe was created 15 billion years ago in
  one BIG BANG ...... How do we know?
• Start with the atom

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ENERGY
Nucleus
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ENERGY
E hv
Nucleus
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Wavelength
700 nm
400 nm
Elemental Absorption

• Every element has a characteristic absorption
  spectra - (ICP)

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Spectrum of the Sun
http//images.encarta.msn.com/xrefmedia/aencmed/ta
rgets/illus/ilt/T014334A.gif
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700 nm
Wavelength

• From the magnitude of the shift we can calculate
  the speed of the star.
• The more distant stars are moving the fastest.
• From distance and velocity information -gt TIME
  15 billion years!

400 nm
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At the Start
BANG
Protons and electrons
Big Blob of Neutrons (N)
12 Minutes
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• Now we are COOKING ........... Fusion produces
  heat
• E mc2
• 1 gram of hydrogen will produce 6.3x1011 j of
  heat.
• Enough heat to boil 2 million liters of H2O
• Compare this to our terrestrial energy
  consumption.

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C
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• This process stops at iron-56

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Supernovae
Second Generation Star
Elements H-1 through Fe-56
H through Fe and n
Explosion
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Supernovae
Second Generation Star
Elements H-1 through Fe-56
H through Fe and n
Explosion
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Beta Decay
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e-
14N
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Proton Number
14C
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5
6
7
8
9
Neutron Number
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Electron Capture
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e-
40K
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Proton Number
40Ar
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17
20
21
22
23
Neutron Number
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Alpha Decay
147
238U
146
Proton Number
145
4He
234Th
144
143
89
90
91
92
93
Neutron Number
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Review of Element Formation

• Big Bang
• Nuclear Cooking - Fusion
• Neutron Capture
• What is the end result?

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What about the Earth?
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Another look at the earth on a linear scale.

• Where did all the other elements go? H, He, C,
  N??
• They got BLOWN AWAY
• This leaves just Si, Mg, Fe, and O

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.....and just for fun
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Formation of the Earth

• The earth started as a hot molten blob of metal
  and oxygen
• As the blob cooled, density differences of the
  original components drove an elemental
  segregation.
• Metallic iron - The Earths core
• Mg, Fe, and Si oxides - The crust
• How do we know?
• We know from earthquake seismology

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A Slice of the Earth
Inner Core
Outer Core
Mantle
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A Slice of the Earth
Inner Core
2900 km
Outer Core
Mantle

• earthquakes travel as shear waves or
  compressional waves

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• shear waves only pass through SOLIDS (mantle)
• So we have a liquid iron core. This has
  important implications for other elements
• Ni, S, Au, Pt, Ag, Pb dissolve in the liquid
  iron
• What is left is Mg, Si oxide mantle.
• The mantle is not really solid, but really a
  putty that is kept warm by the radioactive
  decay of 40K, 235U, 238U, and 232Th.
• The heating of the mantle drives convection cells.

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Crust
Lower Mantle
Outer Core
Inner Core

• The mantle melt cycle (subduction/formation)
  enriches the crust further in Si, Na, K, Ca, and
  Al

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What about the Oceans and the Atmosphere?

• The Earth is about 0.5 water. Where did it come
  from?
• The source of water in the early Earth is poorly
  understood ...we are lucky that it arrived.
• The gravitational attraction of the Earth
  retained almost all of the water.
• Surface water puts important constraints on
  global temperature! 0 lt--gt 100 oC.

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Controls on CO2

• CO2 is controlled by a global scale feedback loop
  with a time scale of gt10,000 years
• Consider the following reactions

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Controls on CO2

• CO2 is controlled by a global scale feedback loop
  with a time scale of gt10,000 years
• Consider the following reactions

Generic Weathering Reaction
Generic Precipitation Reactions
Generic Mantle Reactions
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Atmosphere
Oceanic Crust
Continental Crust
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Lets work with units
CO2 (g) 0.0365 , This is a mixing
ratio O2 20.95 N2 78.08 Ar 0.93 PV nRT,
average mass gas 28.96 g/mol , 00/0, ppm,
ppb
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Pressure
Atmospheric Pressure is a force kg/m2 P0
Mass(atm g)/4(pi)r2 r 6.37x106 m P0
101325 Pa Ph Po e -Mgh/RT
M 0.029 kg/mol R 8.314 J/mol K g 9.81
m/s2 Scale height 5-6 km
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Unit Conversion