Ocean Equilibria

Question 1

Why is there a difference between the pH of the ocean and freshwater?

Answer 1

• Increased salinity causes a decreases solubility of gases, and as it is the dissolution of CO2 that causes decreased pH, saltwater will have a greater pH than freshwater (more alkeline)
• Through the presence of the carbonate buffering system the equilibrium releases more H+ ions when the pH is too high and removes them when the pH is too low

Question 2

Why is there a difference between the pH of the ocean and freshwater?

Answer 2

• Increased salinity causes a decreases solubility of gases, and as it is the dissolution of CO2 that causes decreased pH, saltwater will have a greater pH than freshwater (more alkeline)
• Through the presence of the carbonate buffering system the equilibrium releases more H+ ions when the pH is too high and removes them when the pH is too low

Question 3

How is the carbonate system linked to geological processes and times?

Answer 3

The carbonate system is affected by changes in CO2 which is affected by events such as volcanic eruptions or the industrial revolution

Question 4

What factors do increases in atmospheric CO2 influence?

Answer 4

• Global temeprature (greenhouse effect)
• pH (Ocean acidification)

Question 5

What are 4 sources of carbon dioxide in the atmosphere?

Answer 5

• Burning coal
• Burning forests
• Organic decomposition
• Cement production

Question 6

How does carbon dioxide in the atmosphere affect ocean chemistry?

Answer 6

• Carbon dioxide dissolves into the water producing carbonic acid
• carbonic acid dissociates producing bicarbonate ions and hydrogen ions
• When pH is too low, carbonate ions and hydrogen ions form bicarbonate ions

Question 7

How does ocean acidification affect sea water in terms of ocean chemistry?

Answer 7

As CO2 is dissolved in sea water, it mostly forms bicarbonate which releases a free hydrogen ion hence increasing the acidity of the water. In order to try and reverse or reduce this change in pH, carbonate mixes with the H ion to form more bicarbonate hence taking away carbonate for marine organisms and their calcium carbonate skeletons.

Question 8

Expain how the carbonate compensation depth (CCD) varies due to depth, location and oceangrpahic processes

Answer 8

Deeper water has lower temperatures and higher pressure.
CCD is shallower with lower temeprature (upwellings bring cold water up) and more pressure.
CCd is shallower with greater CO2 in the atmosphere as less carbonates are available

Question 9

How does temperature affect the capacity of water to hold CO2?

Answer 9

The colder the water is the more CO2 that can be absorbed in the water