1.11. The Carbon Cycle: Transfers

Question 1

Combustion

Answer 1

• transfers carbon stored in living, dead or decomposed biomass to atmosphere by burning
• organic material can be any vegetation or fossil fuel

Question 2

Photosynthesis

Answer 2

• transfers atmospheric carbon into biomass
• plants and phytoplankton use energy from sun to change co2 and water into glucose and oxygen
• Carbon then passed through food chain

Question 3

Respiration

Answer 3

• transfers carbon from living organisms to atmosphere
• plants and animals break down glucose for energy
• oxygen + carbohydrate -> energy + glucose + carbon dioxide

Question 4

Decomposition

Answer 4

• transfers carbon from dead biomass to atmosphere and soil - after death, bacteria and fungi break organism down
• co2 and methane released
• some carbon transferred to soil in form of hummus
• important elements continually recycled

Question 5

Sequestration

Answer 5

• carbon from atmosphere can be captured and held in sedimentary rocks or used as fossil fuels
  E.g. when coccoliths die, they fall to ocean floor to create carbon-rich sediments which form carbonate rocks over time

Question 6

Weathering

Answer 6

• chemical weathering transfers carbon from atmosphere to hydrosphere and biosphere
• Atmospheric carbon reacts with water vapour to form carbonic acid
• acid rain falls onto calcium carbonate rocks and chemical reaction occurs to create weaker rocks
• carbon molecules washed into sea, react with co2 dissolved in water to form calcium carbonate- used by sea creatures to make shells

Question 7

Ocean uptake and loss

Answer 7

• co2 directly dissolved from atmosphere into ocean
• warm tropical water cooled and sinks to ocean floor, transferring carbon dioxide to deep ocean waters
• carbon-rich water rises to surface and releases co2 (oceanic pump)
• Co2 released to atmosphere near tropics
• carbon transferred to oceans when taken in by organisms that live in euphotic zone
• organisms photosynthesise and consumed
• carbon incorporated into marine organisms or structural calcium carbonate
• when organisms die, dead cells sink deep into water, forming layers of carbon rich sediment which turn into sedimentary rock
• biological pump