1.3 - Thermohaline Pump

Question 1

Where is warmer water found?

Answer 1

• at surface
• colder/polar water sinks deeper and stays there
• cold + warm water do not mix

Question 2

How does the temperature of water affect how much gas it stores?

Answer 2

• Cold water holds more gas than warm water
• gas molecules move more slowly at lower temperatures
  
  • thus diffuses out of solution more slowly, resulting in more gas being stored at any given time
• at room temperature, molecules are moving faster, thus not as much gas stays dissolved in the water

Question 3

What happens to the warm water in the thermohaline pump?

Answer 3

• as warm water moves towards poles, it evaporates
  
  • leaving saltier, colder water, which is able to absorb more CO₂ behind
  • sinks

Question 4

What happens as a result of the colder water sinking?

Answer 4

• forces deep water that is already at the bottom to move elsewhere
  
  • movement is dictated by landmasses
• results in cold water circulating around Antarctica
  
  • 25% of CO₂ diffusion occurs here
• thermohaline cycle is recharged by cold Antarctic water

Question 5

What are the two tracks of the thermohaline cycle?

Answer 5

• Indian Ocean, into Atlantic Ocean, towards Arctic and then back to Antarctica
  
  • warm water rises in Indian Ocean
• 2^nd path: Pacific Ocean and back to Antarctica
  
  • warm water rises in Pacific

Question 6

What are the 3 types of oceanic pumps + general function?

Answer 6

• Pumps circulate and store carbon
• Biological
• Physical
• Carbonate

Question 7

What is the biological pump?

Answer 7

• Moves carbon dioxide to ocean surface to phytoplankton through photosynthesis
• as organisms die, shells sink
  
  • carbon transported to deep water
  • decay occurs here, resulting in carbon dioxide dissolving into deep/intermediate water
  • since is so deep, carbon dioxide does not vent back into atmosphere

Question 8

What is the carbonate pump?

Answer 8

• organisms die, resulting in carbonate sediment sinking to ocean floor
• gradually transformed into limestone
• carbon remains stored here for many many years

Question 9

What is the physical pump?

Answer 9

• moves carbon compounds to different parts of the of ocean via downwelling and upwelling currents

Question 10

When does downwelling and upwelling occur?

Answer 10

• cold water sinks, due to absorption of more CO₂
• warmer water can also cause downwelling of cold water to occur
• Upwelling occurs when water is displaced from deep water by denser, colder water sinking

Question 11

How can surface winds affect the physical pump?

Answer 11

• Surface winds can push water from tropics to take place of cold water where downwelling is occurring
• Results in additional diffusion of carbon into ocean (not more than cold water though)

Question 12

What happens in the physical cycle?

Answer 12

• The ocean moves around dissolved CO₂
  
  • CO₂ diffuses into ocean
  • Downwelling currents move water from surface ocean to deep oceans

Question 13

What happens in the solubility cycle?

Answer 13

• Ocean absorbs CO₂
  
  • Hydrogen ions break carbonic acid apart
    
    • form bicarbonates
    • used by organisms to make carbonate shells/skeletons

Question 14

What happens in the biological cycle?

Answer 14

• Phytoplankton sequester CO₂
  
  • do so through photosynthesis, carbon is now in form of organic matter

Question 15

What do the physical, solubility and biological cycle acheive?

Answer 15

• increase amount of CO₂ that can enter the oceans from the atmosphere
• allows for regulation of carbon cycle

Question 16

How can the thermohaline cycle be weakened?

Answer 16

• heating poles
  
  • reduces temp difference between polar water and water at equator
  • reduces the force associated with downwelling, weakening pump
• changing salinity
  
  • reduction in salinity reduces density of water
  • force of downwelling decreased
  • pump is weakened

Question 17

Where does the thermohaline cycle split?

Answer 17

• Paths split in South Ocean