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Origins of the Elements

Origins of the Elements. From: Jacobson. Production of Heavier Elements. Cosmic Composition of Elements. From: Jacobson. Composition of the Earth. 93% - iron, oxygen, silicon, and magnesium 6.5% - nickel, sulfur, calcium, and aluminum 0.5% - 84 other elements. Composition of the Earth.

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Origins of the Elements

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  1. Origins of the Elements From: Jacobson

  2. Production of Heavier Elements

  3. Cosmic Composition of Elements From: Jacobson

  4. Composition of the Earth • 93% - iron, oxygen, silicon, and magnesium • 6.5% - nickel, sulfur, calcium, and aluminum • 0.5% - 84 other elements

  5. Composition of the Earth • Core – iron and nickel • Mantle – iron, magnesium, silicon • Crust – oxygen, silicon • Atmosphere – nitrogen, oxygen • Elements of life – carbon, hydrogen, oxygen, nitrogen, phosphorous, sulfur

  6. Elements of Life • Carbon – structure, energy storage • Hydrogen – water, electron transport • Oxygen – aerobic respiration, water • Nitrogen – amino acids, nitrogenous bases • Phosphorus – ATP • Sulfur – amino acids • Others (Fe, Mg) – enzyme cofactors

  7. The Water Cycle From: Schlesinger

  8. Potential Human Influence on theWater Cycle • Restricted run-off • Groundwater depletion • Reduction in ice-pack • Climate (increased evaporation, increased precipitation, increased run-off, sea level rise)

  9. Calculating Lifetime • If we assume that reservoirs are in steady state, the lifetime, τ, is the quantity in the reservoir divided by the sum of all sinks. • The average τof water in the atmosphere:

  10. Chemical cycle diagrams are only for equilibrium conditions

  11. From: Jacob

  12. Pre-industrial Carbon Cycle From: Jacob

  13. The Human InfluencedCarbon Cycle From: http://dilu.bol.ucla.edu/home.html

  14. Increase of Atmospheric CH4 From: http://www.ipcc.ch/present/graphics.htm

  15. Increase of Atmospheric CO2 created by Robert A. Rohde from NOAA published data From: http://www.ipcc.ch/present/graphics.htm

  16. The Missing Carbon Sink • Not all the ‘extra’ carbon emitted to the atmosphere remains there: • Sources: fossil fuel and tropical forest burning = (6.0 + 1.6) Pg yr-1 • Increase in atmosphere = 4.0 Pg yr-1 • Missing sink = 3.6 Pg yr-1 • Possible sinks: ocean and terrestrial biosphere.

  17. Atmosphere/OceanCarbon Exchange • CO2 partitions into water according to Henry’s Law: H = 3x10-2 M/atm • The ocean’s buffer system: pKa1 = 6.1; pKa2 = 9.2 The ocean’s pH is 8.2

  18. Effects of Rising CO2 onOcean Storage • However, complete ocean mixing can take hundreds of years. • Is ocean mixing the only way carbon is mixed into the ocean? – No, it is assisted by a biological pump.

  19. The Ocean’s Biological Pump From: http://calspace.ucsd.edu/virtualmuseum/images/OceansBiologicalPump.html

  20. Effects of Rising CO2 onOcean Storage From: Jacob

  21. Biosphere/Atmosphere Exchange of Carbon • Source – burning, decay, and respiration • Sink – photosynthesis, dissolution into ocean

  22. The Nitrogen Cycle From: Jacob

  23. Lifetime of N2 in the Atmosphere • Atmospheric reservoir = 3.9 x 109 Tg • Sinks = (80+160+80+30+20) Tg yr-1 • Lifetime (τ) = 1.0 x 107 yr (10 millions yrs) • However, the N2 cycle is heavily disturbed by human activities.

  24. Active Nitrogen • Nitrogen Fixation: bacteria lightning, combustion • Nitrification: • Denitrification:

  25. Increase of Atmospheric N2O From: http://www.ipcc.ch/present/graphics.htm

  26. Global Phosphorus Cycle From: Schlesinger

  27. What Controls Atmospheric O2? • Remember the reactions: • These control carbon in the atmosphere, but do they control oxygen? photosynthesis respiration, decay

  28. The Coupled Carbon/Oxygen Cycle From: Jacob

  29. What Controls Atmospheric O2? • What if photosynthesis stopped? • 0.8% decrease of O2 • 470% increase of CO2 • What if respiration and decay stopped? • 0.1% increase of O2 • 100% decrease of CO2

  30. What Controls Atmospheric O2? • Sources (photosynthesis, anaerobic metabolism) • Sinks (sedimentary rock weathering)

  31. What Controls Atmospheric O2? From: Jacob

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