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Ocean Acidification
The chemistry is known, the biological effects are not
16
Environmental Studies
Graduate
12/01/2010

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Cards

Term
Who cares about ocean acidification?
Definition

1. Marine microorganisms (corals, mollusks, crustaceans, sea urchins, and some algae) which build their calcareous shells or skeletons out of calcium carbonate-- shell is (only) protection against predation

2. Entire food chains (pelagic and coral reef ecosystems) and potentially fisheries (finfish and shellfish)

3. Climate (and us!): the biological, solubility and carbonate pumps

Term
Ocean Acidification
Definition
A marine expression of CO2 pollution-- a large level of misinformation since the research being done on this issue has largely taken place since 2004.
Term
Main anthropogenic sources of CO2
Definition
Deforestation, burning of fossil fuels, cement making = > 440 billion tonnes of CO2
Term
Emissions/year into oceans?
Definition
about 25%
Term
Monaco Declaration
Definition
15- leading scientists from 26 countries and Prince Albert II of Monaco called for immediate action to reduce CO2 emissions to avoid severe damage to marine ecosystems from ocean acidification
Term
What is pH?
Definition
pH is a measure of how acidic or basic a substance is, it stands for power of Hydrogen and is the negative log of the concentration of Hydrogen ions in a substance.
Term
The Ocean Acidification Reaction
Definition

CO2+H2O<->H2CO2(carbonic acid)<->H++HCO2-(bicarbonate ion)

 

This reaction increases acidity and lowers the availability of carbonate ions-- reduction in carbonate ions is needed for calcification.

Term
Calcite
Definition
A form a calcium carbonate which is found in the shells of coccolithophores, foraminifera, echinoderns-- relatively less soluble
Term
Aragonite
Definition
A more soluble form of calcium carbonate, found in corals, mollusks, pteropods, some algae.
Term
Solubility product constant of calcium carbonate
Definition
increases with decreasing temperature, and with increasing pressure, also increases with depth. the product of the two concentrations (saturated) -- it's a measure of how much can "fit" into solution. older water have higher solubility product constant because they have more respiration-- more carbon
Term
Saturation State
Definition
Most waters are not at equilibrium with respect to either calcite or aragonite. The saturation state reflects this, it is given by the observed concentration of teh carbonate ion over the concentration of the carbonate ion that "fits" i.e. the saturation concentration. If the saturation state is over 1, we are in a state of supersaturation and it will precipitate. If less thant 1, understaturation, more will dissolve
Term
Saturation Horizon
Definition
transition depth between the supersaturated upper ocean and the undersaturated deep ocean, when saturation state equals 1
Term
Calcite/Aragonite Compensation Depths
Definition
Depths below which the rate of supply of calcite/aragonite is equal to the dissolution rates, such that no calcite/aragonite is preserved
Term
Lysocline
Definition
Depth at which dissolution of calcite increases dramatically
Term
Le Chatelier's principle
Definition
A chemical system at equilibrium which experiences a change in concentration will experience an equilibrium shift to counteract the change and a new equilibrium will be established. In the case of ocean acidification, increasing carbon dioxide increases the dissolution of calcium carbonate
Term
Things we don't know
Definition
Sound propagation and olfactory cues (effects on), the biological response of organisms to known acidification is still new to study and therefore unclear
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