Ocean Carbon Sequestration

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Ocean Carbon Sequestration

• John Nowoslawski
• Fall 2003

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Today

• Basics of CO2 in the atmosphere and how it gets
  into the ocean
• What the increase in atmospheric CO2 has done to
  ocean chemistry
• Possibility of the ocean to safely sequester CO2
  from the atmosphere while reversing the negative
  effects on ocean chemistry from increased
  atmospheric CO2
• Experiments
• Where it could go

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Follow the Carbon
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Carbon in the Ocean
The entire system is in equilibrium
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Anthropogenic Effects

• As the atmospheric CO2 concentration increases
  more CO2 dissolves into the ocean as carbonic
  acid
• The buffer system of the ocean activates in order
  to prevent a large swing in pH
• CO3-- ions pick up H ions and convert to HCO3-
  ions
• Bottom Line the pH of the ocean has decreased
  and will continue to decrease. The concentration
  of carbonate ions (CO3--) is decreasing.

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Solution?

• Increase the CO3-- concentration. But how?
• Add CO3-- ions by throwing rocks into the ocean.
• What will this do?

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Throwing Stuff into the Ocean
If we add CO3-- ions, the buffer system of the
ocean will pull CO2 out of the atmosphere to make
HCO3- ions to keep the system in equilibrium
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Throwing Stuff into the Ocean

• What happened?
• The dwindling carbonate ion (CO3--) concentration
  has increased.
• The negative effects from the lowering of the pH
  are reversed
• The buffer system of the ocean is strengthened
• The total amount of carbon the ocean can store
  has increased
• CO2 is naturally pulled out of the atmosphere
  (sequestered) and is in a stable form in one of
  the earths largest carbon sinks.

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Experiments

• Made Artificial Seawater in the laboratory
• Figuring out which minerals dissolve into
  seawater and what problems arise
• Ocean chemistry is very unstable because the
  upper 100m of the ocean is supersaturated with
  respect to Calcite (CaCO3)
• Building a dissolution rate calculator
• Whatever mineral added to the water must dissolve
  in the upper 100m of the ocean, or it is too far
  from the atmosphere to pull out CO2

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Dissolution Rate Calculator
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Conclusion

• It is possible that the addition of alkaline
  minerals will decrease atmospheric CO2
  concentration and safely sequester it while
  having other positive effects on ocean chemistry.
• Experiments are being performed to determine if
  the dissolution will happen and if the effects
  are beneficial.