carbon cycle

Question 1

what is the carbon cycle?

Answer 1

biogeochemical process by which carbon flows between the atmosphere, land and ocean.

Question 2

what is the origin of carbon

Answer 2

• comes from the earth’s interior
• stored in the mantle when the Earth formed
• escapes from mantle at constructive and destructive plate boundaries as well as hot spot volcanoes
• much of CO2 at destructive margins is derived from metamorphism of carbonate rocks subducting with the ocean crust
• some carbon remains as CO2 in atmosphere, some dissolved in oceans, some is held as biomass in living or dead and decaying organisms and some is bound in carbonate rocks

Question 3

how is carbon removed into long-term storage

Answer 3

burial of sedimentary rock layers, especially coal and black shales and carbonate rocks like limestone

Question 4

outline hydrosphere as a store of carbon

Answer 4

HYDROSPHERE
- surface layer = sunlight causes photosynthesis
- intermediate and deep layer
- living organic matter e.g. fish
When organisms die, their dead cells, shells and other parts sink into deep water. Decay releases carbon dioxide into the water and some sink to bottom creating rich sediments which can be turned into rocks

Question 5

what is a net carbon sink

Answer 5

if more carbon enters a store than leaves it

Question 6

what is a net carbon source

Answer 6

if more carbon leaves a store than enters it

Question 7

lithosphere as a store of carbon

Answer 7

LITHOSPHERE
- organic and inorganic forms
- organic = litter, organic matter, humic substances found in soils
- inorganic = fossil fuels, oil, gases, coal, natural gases
The largest amount of carbon on Earth is stored in sedimentary rocks within the earth’s crust. These are rocks produced either by the hardening of mud (containing organic matter) into shale over geological time periods, or by the collection of calcium carbonate particles, from the shells and skeletons of marine organisms, into limestone and other carbon containing sedimentary rocks.

Question 8

outline biosphere as a store of carbon

Answer 8

BIOSPHERE - terrestrial store - biggest carbon store
Plants, animals, soils and microorganisms, such as bacteria and fungi.
Soils are by far the largest stores.
Unlike the other stores most of the carbon in this store is ‘organic’ carbon - compounds produced by living things such as leaves, roots, dead plant material and soil humus.
Plants absorb CO2 through photosynthesis and release some back to the atmosphere through respiration.
The most prevalent form of carbon in soil is organic carbon derived from dead plant material and microorganisms. Most of the carbon enters soil in the form of dead plant matter that is broken down by microorganisms during decay. The decay process also releases carbon back to the atmosphere.

Question 9

outline atmosphere as a store of carbon

Answer 9

ATMOSPHERE
- atmospheric carbon levels at an all time high due to human activity e.g. industrial revolution - important as carbon is being released as carbon dioxide = greenhouse gas - meant to regulate warming of the earth - contributing to global climate change - carbon in atmosphere lowest in the Quaternary glaciation - stored as ice