The Carbon Cycle Flashcards
What is the importance of the Carbon Cycle
- Used by humans for energy
- ‘building blocks of life’
- used for photosynthesis to be turned to O2 as CO2 is toxic to humans.
Consequences of disruptions to the Carbon Cycle
- Sea level rises (80cm by the end of the century)
- Forest fires become more frequent and areas losing the amazon could feel the greatest impact
- Food shortages - wheat yields have decreased by 40% in Africa
How much carbon is stored in the atmosphere?
720GT
How much carbon is stored in the Ocean (Surface and Deep Layers)
Surface - 670GT
Deep - 37,000
How much carbon is stored in the Lithosphere (Sedimentary and Kerogens)?
Sedimentary - >60.000,000GT
Kerogens - 15,000,000GT
How much carbon is stored in the Biosphere (dead and alive)?
Dead - 1,200GT
Alive - 600-1,000GT
How much carbon is stored as Fossil Fuels?
5330GT
Is the Global carbon cycle an open or closed system?
Closed - The amount of carbon on the earth doesn’t change, it only changes form.
What is an example of an open carbon system?
Forest - Trees can be cut down or die, and leave the carbon system. Any system that carbon can leave or enter is open.
What are the 3 largest global carbon stores?
1st: Lithosphere - stored as fossil fuels and in rocks, the lithosphere stores most of the carbon on Earth
2nd: Oceans - stored as dissolved carbon and calcium carbonate in the shells of marine life. Only 4% of carbon is stored near the surface
3rd: Biosphere - stored in organic molecules in living or dead plants and animals. Decaying releases CO2 to the atmosphere.
4th: Atmosphere - Stored as the gas CO2.
What are key fluxes in the carbon cycle?
- Precipitation
- Respiration
- Carbon sequestration
- Photosynthesis
- Weathering
- Decomposition
- Combustion
Explain Precipitation - CC
An increase in CO2 levels have led to a dramatic increase in the acidity of seawater and therefore rainfall.
Explain Respiration - CC
- 6 O2 + C6H12O6 —> 6 CO2 + 6 H2O + ATP
- Plants and animals absorb oxygen to provide energy which is needed for metabolism and growth.
- The volume of carbon exchanged by respiration and photosynthesis each year is 1000x higher than through the slow carbon cycle.
- Stays in balance with photosynthesis (biosphere -> atmosphere -> biosphere.)
Explain Carbon Sequestration Physical Pump - CC
Physical inorganic pump:
- CO2 enters the ocean from the atmosphere by
diffusion.
- Surface ocean currents then transport the water
and dissolved CO2 towards the poles where it
cools, becomes more dense and sinks.
- Downwelling carries dissolved carbon to the
oceans depths where individual carbon
molecules remain for centuries.
- Eventually deep ocean currents transport the
carbon to areas of upwelling causing the water to
rise and CO2 to diffuse into the atmosphere.
Explain Carbon Sequestration Biological Pump - CC
Biological pump:
- Marine organisms (phytoplankton) combine
sunlight, water and dissolve CO2 to produce
organic material.
- This causes carbon to be locked in the
sediment on the ocean floor or decomposed to
release CO2 into the ocean.
- Some crustaceans extract carbon and calcium
ions from sea water to manufacture shells and
skeletons.
- Most carbon-rich material ends up on the
seafloor undergoing lithification to form chalk or
limestone.
Explain Photosynthesis - CC
- 6 CO2 + 6H2O —> 6O2 + C6H12O6
- Using the sun’s energy to cover the light energy into chemical energy for the formation of glucose and growth in plants.
- O2 is released balancing respiration.
Explain Weathering - CC
Chemical: Carbonation - rainwater (weak carbonic acid) dissolves limestone & chalk slowly. This releases carbon from linestomes to streams or rivers or the atmospheres. This transfers 0.3 billion tonnes of carbon a year. Increased rate in colder temps.
Physical: Freeze-thaw breaks rocks down into smaller particles with no chemical change releasing carbon. Increased rate at fluctuating temps.
Biological: Chelation - rainwater mixed with dead and decaying organic matter to form humid acids which attack rock minerals.
Roots can destroy rocks. Increased rate at warmer moist temperatures.
Explain Decomposition - CC
Bacteria or fungi break down dead organic matter, extracting energy and releasing CO2 into the atmosphere.
This occurs faster in warm humid environments (places with rainforest).
Explain Combustion - CC
Organic material earths or burns in oxygen, releasing CO2 as well as sulphur dioxides and nitrogen oxides.
Usually occurs from human activity (deliberate firing of forest & combustion of fossil fuels) but occurs naturally in forest fires.
This increases the amount of CO2 in the oceans and atmosphere adding to the greenhouse gas effect.
How does temperature influence carbon moving between the atmosphere and oceans?
Increase in temperature - speeds up diffusion of CO2 out of the ocean but slows absorption into the ocean from the atmosphere.
As temperatures increase due to global warming more carbon will be released from pumps resulting in a downwards spiral.
What processes does the fast carbon cycle include?
Includes the processes of photosynthesis, respiration, combustion, decomposition & air-sea gas exchange.
Carbon moves between the atmosphere, oceans and biosphere.
Phytoplankton are key components in absorbing CO2 from the atmosphere.
What processes does the slow carbon cycle include?
Includes the processes of chemical weathering, fixing dissolved carbon, volcanic activity & subduction.
Marine organisms fix dissolved carbon with calcium to form calcium carbonate.
Decomposed organic material is buried beneath younger sediments.
Lithification
What is the total carbon circulation for the slow carbon cycle?
10-100 million tonnes a year
What is the total carbon circulation for the fast carbon cycle?
10,000 to 100,000 million tonnes a year