Carbon Cycle

Question 1

Carbon cycle on land:

Answer 1

• Dominated by photosynthesis of plants absorbing CO2
• Stored within biomass, such as tropical and temperate forests
• Transferred to soil through decomposition
• Bacterial action in decomposition releases co2 back to atmosphere
• Carbon is cycled through quite rapidly through organic systems between atmosphere, vegetation and soils (Fast Carbon Cycle)

Question 2

Carbon Cycle in Oceans:

Answer 2

• Carbon stored in Oceans as dissolved CO2, bicarbonate ions + tissues of marine organisms
• Inputs of carbon are from the atmosphere in a direct exchange with ocean surfaces through bicarbonate ions brought by rivers
• Phytoplankton in surface waters absorb co2 in photosynthesis
• Carbon pump operates within oceans transferring carbon from upper layers to sea bed

Question 3

Carbon Cycle in Atmosphere:

Answer 3

• Atmospheric carbon is usually in the form of co2 or methane (CH4)
• CO2 combines with water molecules in clouds to form carbonic acid, and naturally acidic rain
• Outputs from the atmosphere include absorption by surface vegetation and by oceans in the atmosphere-ocean gas exchange

Question 4

Key processes in the Fast Carbon Cycle:

Answer 4

• Photosynthesis, the absorption of CO2 from the atmosphere and from oceans to produce organic carbon structures
• Respiration, the release of CO2 into atmosphere
• Digestion, the release of carbon compounds by animals after feeding on carbon-rich material
• Combustion, natural fires release carbon compounds from vegetation into atmosphere

Question 5

Slow Carbon Cycle:

Answer 5

• 1. Transfer of carbon into oceans from atmosphere + land surface
• 2. The deposition of carbon compounds on the ocean floor
• 3. The conversion of ocean sediments into carbon-rich rock
• 4.The transfer of carbon rocks to tectonic margins
• 5. Return of carbon compounds to the atmosphere in volcanic eruptions

Question 6

Describe the slow carbon cycle:

Answer 6

• 1. CO2 in the atmosphere reacts with water to form carbonic acid
• 2. Carbonic acid then reacts with some rocks to form bicarbonate ions which get carried away by rivers
• 3. Bicarbonate is used by animals to form shells
• 4. Shells accumulate on the seabed + eventually form carbonate rocks
• 5. When heated to the point of melting during subduction these rocks will emit CO2 back into the atmosphere in volcanic regions during eruptions

Question 7

Biological Ocean Pumps:

Answer 7

• Involves the uptake of marine organisms, and its eventual transfer to the deeper ocean levels
• Phytoplankton in the oceans water surface photosynthesise reducing CO2 from the surface levels
• Allows continuation of more CO2 to be absorbed from atmosphere
  -Phytoplankton die or are eaten, Carbon enters food chain

Question 8

Carbonate Ocean Pump:

Answer 8

• Involves the production + dissolution of calcium carbonate, these organisms use carbonate + calcium ions to form calcium carbonate for seashells and skeletons
• When organisms die their shells can either dissolve in the upper ocean or fall to the sea floor to become sediment

Question 9

Physical Ocean Pump:

Answer 9

• Oceans ability to absorb CO2 from the atmosphere
• CO2 dissolves more in colder seawater
• Once dissolved CO2 reacts with water to form bicarbonate acid
• Ocean currents rich in CO2 are transported to the deep ocean through processes such as downwelling in cold regions