unit four: the global carbon cycle

Question 1

what are the 4 main carbon stores?

Answer 1

• biosphere = stored within plants and animals
• hydrosphere = stored in oceans
• litosphere = fossil fuels, like coal and iron
• pedosphere = buried underneath, like peat

Question 2

what is the important of carbon?

Answer 2

• 50% of the planet’s biomass is made from carbon
• 18% of the human body is made from carbon
• carbohydrates are created when carbon and hydrogen bond together
• humans obtain carbon from the air

Question 3

what is the importance of the bioshpere?

Answer 3

• photosynthesis creates carbohydrates
• 560 billion metric tonnes of carbon is stored in this store
• 0.0012% of carbon is stored here
• rainforests contain most carbon due to photosynthesis

Question 4

what is the importance of the atmosphere?

Answer 4

• stores 750 billion metric tonnes
• stores 0.0017% of planet’s carbon
• carbon dioxide and methane are two main gases in store that contain carbon (greenhouse gases)
• amount of carbon in store increased by 36% during last 100 years due to emissions from vehicles, power stations burning fossil fuels and deforestation

Question 5

what is the importance of the pedosphere?

Answer 5

• contains 0.0031% of planet’s carbon
• peat is dead organic material and made from 60% carbon
• dead organic matter becomes fossil fuels over millions of years (0.004% of all planet’s carbon)

Question 6

what is the importance of the hydrosphere?

Answer 6

• stores 0.038% of global carbon
• stores 38,000 billion metric tonnes
• size is 18 times more than all other spheres combined
• 90% of oceans in the form of bicarbonate

Question 7

what is the importance of the litosphere?

Answer 7

99.9% of world’s carbon is stored in marine sediment and sedimentary rock

Question 8

the slow carbon cycle operates over what time period?

Answer 8

100-200 million years

Question 9

how and where does carbonic acid form?

Answer 9

• carbon dioxide + water vapour = carbonic acid
• in the atmosphere

Question 10

when carbonation weathering occurs, some carbon is released to the atmosphere as carbon dioxide, which store does other carbon en up in?

Answer 10

the hydrosphere

Question 11

the carbon in the oceans is used by what organisms and for what purpose?

Answer 11

• goes into the shells and skeletons of marine creatures as calcium carbonate
• when they die, they sink and compact, to form sedimentary rock, like limestone
• under heat and pressure = fossil fuels

Question 12

what is the name of the process in which atmospheric carbon is stored in a liquid or solid form in the litosphere?

Answer 12

sequestration

Question 13

what are the key process of the slow carbon cycle?

Answer 13

• chemical weathering of rocks (carbonation)
• carbon storage (sequestration) on the ocean floor
• tectonic process and volcanic activity

Question 14

what is the process of chemical weathering in the slow carbon cycle?

Answer 14

• atmospheric carbon dioxide is dissolved in water vapour and forms carbonic acid. precipitation is naturally acidic (carbonic acid)
• carbonic acid, reacts with rocks containing calcium carbonate through carbonation weathering and created calcium bicarbonate
• calcium bicarbonate is soluble in water and is carried away in solution by runoff and percolating water
• soluble calcium bicarbonate is transferred to the ocean by river runoff

Question 15

what happens at the bottom of the ocean, where carbonate rich sediments accumulate?

Answer 15

at bottom of ocean carbonate rich sediments accumulate:
- bicarbonate being transferred by rivers to oceans
- biological carbon from accumulation of dead marine organisms
- sediments will compact to make up the upper layer of oceanic crust

Question 16

what happens to the carbon stored on the ocean floor?

Answer 16

• at convergent plate
• some carbon sediments are converted into magma = volcanic eruptions = carbon dioxide into atmosphere
• 200 million tons of carbon dioxide are released into the atmosphere

Question 17

what are the other effects of plate tectonics on carbon cycle?

Answer 17

• fold mountains at convergent boundaries
• force carbonate-rich sediments and rocks
• e.g. the himalayas
• carbonation weathering will occur

Question 18

what is the process by which plants use sunlight and carbon dioxide to produce carbohydrates?

Answer 18

photosynthesis

Question 19

what is the name of the organisms in the ocean that use photosynthesis?

Answer 19

phytoplankton

Question 20

what is the name of the process in which organisms release carbon dioxide as a by-product of using carbohydrates to release energy?

Answer 20

respiration

Question 21

apart from carbon dioxide, what other carbon containing gas do animals release?

Answer 21

methane

Question 22

what is the name of the process when dead organic matter is broken down by bacteria, fungi and detritivores?

Answer 22

decomposition

Question 23

what is the process when fire burns organic matter and carbon dioxide is released?

Answer 23

combustion

Question 24

how much carbon typically moves through the fast carbon cycle each year?

Answer 24

1000 million to 100,000 million metric tonnes

Question 25

what are the key processes in the fast carbon cycle?

Answer 25

• diffusion of carbon dioxide between atmosphere and ocean
  -photosynthesis, respiration and decomposition
• combustion: forest fires and fossil fuels

Question 26

how much more carbon does the ocean store compared to the atmosphere?

Answer 26

• 50 times more
• 7% is dissolved carbon dioxide
• 93% within organisms that live there

Question 27

how does diffusion through a physical (inorganic) pump occur?

Answer 27

• carbon dioxide is moved in oceans by thermohaline ocean currents (form due to variations in ocean temperature and salinity)
• carbon transferred from surface to deep ocean where cold dense water sinks = downwelling (polar regions)
• carbon transferred from deep ocean to surface where deep waters rise = upwelling (equatorial regions)

Question 28

how does diffusion through a biological (organic) pump occur?

Answer 28

1) diffusion of carbon dioxide in to ocean surface
2) phytoplankton photosynthesise and use the diffused carbon dioxide, storing it in new biomass
3) phytoplankton eaten by zooplankton, which is then eaten by other marine organisms, passing carbon
4) when organisms respire, they release carbon dioxide (some will pass to atmosphere)
5) marine organisms die and sink to seafloor
6) over millions of years, organic carbon rich sediments can form fossil fuels

Question 29

what is the equation for photosynthesis?

Answer 29

carbon dioxide + water > glucose + oxygen

Question 30

how do earthworms affect infiltration rates of a soil?

Answer 30

increase infiltration rates by making burrows and tunnels which is a clear pathway for water to infiltrate into the ground, so it helps flood prevention

Question 31

why would decomposition rates be different between a tropical rainforest and a periglacial region?

Answer 31

• tropical rainforests are wet, warm and have a lot of vegetation = worms and bacteria can get into the soil easily
• periglacial regions are cold, dry and have less biodiversity, leading to the accumulation of organic matter

Question 32

what are 3 key components to initiate a wildfire?

Answer 32

• fuel
• climate and recent weather
• source of ignition

Question 33

what are the natural and human causes of wildfires?

Answer 33

natural
- lightning
- hot, volcanic material

human
- cleared land for agriculture
- dropped cigarette
- camp fire
- fireworks
- arson

Question 34

what were the causes and impacts of the austrailian wildfires in 2019?

Answer 34

causes
- extreme and persistant drought = land tinder-dry
- temperatures in high 30s
- federal government’s refusal to discuss role of climate change

impacts
- 3 people dies
- 1300 volunteer firefighters from across the country
- 150 homes hazed

Question 35

what were the causes and impacts of the lincolnshire, uk wildfire in 2022?

Answer 35

causes
- crop, grassland and woodland blazes
- hottest temperature in the uk (july 19th = 40.3 degrees)

impacts
- funds raised to attach firefighter pumps to farmers’ water tanks
- over 6 months, 1000 farmers attended fire training
- double amount of forest fires that summer than previous year

Question 36

what are the risks and solutions to wildfires?

Answer 36

risks
- plantations = can spread easier
- reducing biodiversity = forest more vulnerable
- fewer but more intense fires
- change in water cycle = land drying out more frequently

solutions
- natural defenses
- reduce carbon emissions = buys more times to look for solutions and spreads out impact

Question 37

how much of global energy is derived from fossil fuels?

Answer 37

85%