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Introduc)on to Ocean Acidifica)on Arthur J. Spivack Graduate School - - PowerPoint PPT Presentation
Introduc)on to Ocean Acidifica)on Arthur J. Spivack Graduate School - - PowerPoint PPT Presentation
Introduc)on to Ocean Acidifica)on Arthur J. Spivack Graduate School of Oceanography University of Rhode Island Primary Driver of Ocean Acidifica)on Increasing atmospheric carbon dioxide due to fossil fuel use. Carbon Dioxide CO 2 Long term
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Carbon Dioxide CO2
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Long term
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Sources and Fate of Human Produced CO2
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The Ocean Acidifica)on Irony
- The Good News-
In the long run (> 1,000 years), the ocean and its sediment will neutralize most of the extra CO2 humans add to the atmosphere.
- The Bad News-
Ocean uptake of human-produced CO2 will,
- 1. lower the amount of the oceanic carbonate ion (CO3
- 2), an
essen)al component of the shells of many organisms and,
- 2. lower ocean pH which will adversely affect the metabolism
- f many marine organisms.
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What happens to carbon dioxide when it dissolves in the ocean?
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What happens to carbon dioxide when it dissolves in the ocean?
Fate 1: Acid Produc)on
acid
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A liYle chemistry background
Acidifica)on- increasing concentra)on of H+. The concentra)on of H+ symbolically is [H+ ].
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pH Scale measure of the [H+] concentra)on
pH=-log (H+) For every 10-fold increase in acid, pH decreases by 1.
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pH Scale measure of the acid [H+] concentra)on
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Common pH Values
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How Ocean pH Changes with CO2
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Fate 2: Neutraliza)on by carbonate ion (CO3
- 2)
What happens to carbon dioxide when it dissolves in the ocean?
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Shell Solubility and CO2
Clams, mussels, oysters and many other
- rganisms build shells of calcium carbonate
(CaCO3). This is called calcifica)on.
– How much energy it takes to make a shell depends on how much CO3
- 2 there is.
– Omega (Ω) is a quan)ta)ve measure of the solubility of CaCO3:
=
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Shell Solubility and CO2
Dissolved CO2 increases
CO3
- 2 decreases
Ω decreases More difficult for
- rganisms to make shells
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So what happens as we go into the future?
Prediction is very difficult, especially if it is about the future. Niels Bohr
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Ocean Acidifica)on: The Future
- The extent of acidifica)on will depend on:
– Fossil fuel use. – How much of the human produced CO2 dissolves in the ocean.
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Global Predicted Aragonite Satura)on 2100
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Inconvenient Facts
- In cold water, shells are more soluble.
- Coastal Rhode Island waters are cold during
the winter and early spring.
- Result: RI coastal waters are most sensi)ve to
aragonite dissolu)on in winter and early spring.
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NarraganseY Bay Carbonate Satura)on
Year 0.0 1.0 2.0 1950 2000 2050 2100 2150
Omega Winter
0.0 1.0 2.0 3.0 4.0 1950 2000 2050 2100 2150 Year
Summer Omega
Simple Idealized Model
Dissolved CO2 in equilibrium with the atmosphere
Trend due to projected increasing atmospheric CO2
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NarraganseY Bay and Carbonate Satura)on
The real Bay is more complicated: Not in equilibrium with the atmospheric CO2 Actual controls on Bay carbonate satura)on
- 1. Dissolved CO2 of inflowing water
- 2. Salinity
- 3. Respira)on/photosynthesis balance
- 4. Rate of gas exchange
- 5. Stra)fica)on and mixing
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Dissolved CO2 of Inflow
NarraganseY Bay circula)on
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Respira)on/photosynthesis balance
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Photosynthesis is highly influenced by the input of plant nutrients
Biological produc)on, photosynthesis, is ojen s)mulated by the input of nutrients (mostly nitrate). The respira)on of plant maYer leads to the produc)on of CO2 (and deple)on of O2).
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Stra)fica)on and Mixing
Respira)on
- here. CO2 will
build up. Photosynthesis here.
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