the carbon cycle

Question 1

where is carbon found in the lithosphere

Answer 1

-over 99.9% of the carbon on earth is stored in sedimentary rocks
- about 0.004% of the carbon on Earth is stored in fossil fuels in the lithosphere

Question 2

where is carbon found in the atmosphere

Answer 2

-stored as carbon dioxide and in smaller quantities as methane in the atmosphere
- the atmosphere contains 0.001% of the earths carbon

Question 3

where is carbon found in the hydrophere

Answer 3

• carbon dioxide is dissolved in rivers, lakes and oceans
• the oceans are the second-largest carbon store on Earth, containing approximately 0.04% of the earths carbon. the majority of the carbon here is found deep in the ocean in the form of dissolved inorganic carbon
• a small amount is found at the ocean surface where it is exchanged with the atmosphere

Question 4

where is carbon found in the biosphere

Answer 4

-stored in the tissues of living organisms, it is transferred to the soil when living organisms die and decay

• the biosphere contains approximately 0.004% of the Earths total carbon

Question 5

where is carbon found in the cryosphere

Answer 5

• contains less than 0.01% of the earths carbon
• most of the carbon in the cryosphere is in the soil in areas of permafrost where decomposing plants and animals have frozen into the ground

Question 6

what are the flows in the carbon cycle that change carbon stores

Answer 6

photosynthesis, respiration, combustion, decomposition, ocean uptake and loss, weathering, sequestration

Question 7

how does photosynthesis change the size of carbon stores

Answer 7

-photosynthesis transfers carbon stored in the atmosphere to biomass
-plants and phytoplankton use energy from the sun to change carbon dioxide and water into glucose and oxygen, this enables plants to grow

Question 8

how does respiration change the size of carbon stores

Answer 8

-respiration transfers carbon from living organisms to the atmosphere
-plants and animals break down glucose for energy, releasing carbon dioxide and methane in the process

Question 9

how does combustion change the size of carbon stores

Answer 9

-combustion transfers carbon stored in living, dead or decomposed biomass to the atmosphere by burning
-wildfires cause carbon flow

Question 10

how does decomposition change the size of carbon stores

Answer 10

-decomposition transfers carbon from dead biomass to the atmosphere and the soil
-after death, bacteria and fungi break organisms down, co2 and methane are released
-some carbon is transferred to the soil in the form of humus

Question 11

how does ocean uptake and loss change the size of carbon stores

Answer 11

-co2 is directly dissolved from the atmosphere into the ocean, it is also transferred to the oceans when it is taken up by organisms that live in them
-carbon is also transferred from the ocean to the atmosphere when carbon-rich water from deep in the oceans rises to the surface and releases co2

Question 12

how does weathering change the size of carbon stores

Answer 12

-chemical weathering transfers carbon from the atmosphere to the hydrosphere and biosphere
-atmospheric carbon reactes with water vapour to form acid rain. when the acid rain falls it dissolves rocks

Question 13

how does sequestration change the size of carbon stores

Answer 13

-carbon held from the atmosphere can be sequestered in sedimentary rocks or as fossil fuels. rocks and fossil fuels form over millions of years when dead animal and plant material in the ocean falls to the floor and is compacted
-carbon in fossil fuels is sequestered until we burn them.

Question 14

what are fast carbon flows

Answer 14

photosynthesis, respiration, combustion and decomposition

Question 15

what are slow carbon flows

Answer 15

sequestration

Question 16

what natural processes can change the carbon cycle

Answer 16

wildfires and volcanic activity

Question 17

how do wildfires cause change in the carbon cycle

Answer 17

-wildfires rapidly transfer large quantities of carbon from biomass to the atmosphere. loss of vegetation decreases photosynthesis, so less carbon is removed from the atmosphere
-in the longer term fires can encourage the growth of new plants, which take in carbon from the atmosphere for photosynthesis, depending on the amount and type of regrowth, fires can have a neutral effect on the amount of atmospheric carbon

Question 18

how does volcanic activity cause change in the carbon cycle

Answer 18

-carbon stored within the earth in magma is released during volcanic eruptions, the majority enters the atmosphere as co2
-recent volcanic eruptions have released much less co2 than human activities
-volcanic eruptions cause about 130-380 million tonnes of carbon to be released each year whereas human activity releases 50 billion tonnes per year
-silicates in lava turn into co2
-sulfur is released, creating sulfur dioxide which acts as an aerosol and blocks out sun

Question 19

what human factors can impact on the carbon cycle

Answer 19

fossil fuel extraction and use, deforestation, farming practices, land use changes

Question 20

how does fossil fuel extraction and use impact on the carbon cycle

Answer 20

-extracting and burning of fossil fuels releases co2 into the atmosphere
-without human intervention the carbon would remain sequestered in the lithosphere for thousands or millions of years to come

Question 21

how does deforestation impact on the carbon cycle

Answer 21

-forests may be cleared for agriculture, logging or to make way for developments
-clearance reduces the size of the carbon store, and if the cleared forest is burnt there is a rapid flow of carbon to the atmosphere

Question 22

how does farming practice impact on the carbon cycle

Answer 22

-animals release co2 and methane when they respire and digest food
-ploughing can release co2 stored in soil
-growing rice in rice paddies releases a lot of methane
-mechanisation of farming has increased co2 emissions

Question 23

how do land use changes impact on the carbon cycle

Answer 23

-concrete production releases lots of co2
-vegetation is removed which reduces carbon storage in the biosphere

Question 24

how does the carbon cycle affect the atmosphere

Answer 24

-the carbon cycle affects the amount of gases containing carbon in the atmosphere. these are greenhouse gases which trap some of the suns energy
-as the concentration of greenhouse gases in the atmosphere increase, temperature is expected to rise
-changing temps will affect areas of the climate, like storm intensity

Question 25

how does the carbon cycle affect land

Answer 25

-carbon cycle allows plants to grow, if there was no carbon then plants could not photosynthesis, if there was no decomposition dead plants would remain where they fell and their nutrients would never be recycled
-changes in the carbon cycle can reduce the amount of carbon stored in the land
-an increase in global temperatures could also increase the frequency of wildfires

Question 26

how does the carbon cycle affect oceans

Answer 26

-as part of the carbon cycle, carbon dioxide is dissolved directly into the oceans from the atmosphere
-co2 in the oceans is used by organisms such as phytoplankton and seaweed during photosynthesis and by other marine organisms to form calcium carbonate shells and skeletons
-increased levels of co2 in the atmosphere can increase the acidity of the oceans because the oceans initally absorb more co2. this can have adverse effects to marine life
-global warming can also affect oceans as it can affect marine life which is sensitive to heat
-warmer water is also less able to absorb co2 so as temps rise the amount of co2 that could potentially be dissolved in the sea decreases