EQ1 Carbon Cycle

• Atmospheric: CO2 in air
• Terrestrial: Biomass, soils, mantle
• Oceanic: Dissolved carbon in water, sedimentary rocks, calcium carbonate shells

Flows of carbon between stores

The exchange of carbon between the atmosphere, terrestrial biosphere, oceans and sediments.

• In petagrams
• 1 Pg = billion tonnes of carbon

• Inorganic: in rocks as bicarbonates + carbonate
• Organic: in plant material
• Gaseous: as CO2, CH4 and CO

The removal + long-term storage of carbon from the atmosphere.

• 1) Terrrestrial carbon in mantle is released into atmosphere when volcanoes erupt, called outgassing
• 2) Atmospheric CO2 + rainfall -> carbonic acid. Acid rain dissolves rocks, which releases bicarbonates, called chemical weathering
• 3) Rivers transport carbon + calcium to oceans
• 4) Organic carbon from plants/shells/skeletons sinks to ocean bed + builds up
• 5) Carbon rocks are subducted along plate boundaries, emerging during eruptions
• 6) Intense heating along plate boundaries metamorphoses sedimentary rocks, forming metamorphic rocks and CO2 is released

• 1) PS by phytoplankton takes in CO2 from atmosphere
• 3) Respiration by organisms releases CO2 + water into atmosphere
• 4) Decomposition of dead organisms releases CO2 into soil + sea floor
• 5) Combustion of FFs releases CO2 into atmosphere

Process by which living organisms transfer carbon from atmospheric store to the ocean floor sediment store

• CO2 from atmosphere dissolves in water (oceans hold 50x more carbon than atmosphere)
• Phytoplankton (microscopic organisms) photosynthesise and sequester this carbon and some CO2 is released by respiration (they sequester 2bn tonnes of carbon from atmophere to ocean)
• When eaten by zooplankton/larger organisms, carbon is passed through food chain
• Organisms turn carbon into calcium carbonate outer shells and inner skeletons
• They die and sink to sea floor
• Sedimentation/lithification occurs and they form limestone sediments as a carbon store

Terrestriaal part where plants sequester CO2 via PS and release it via respiration/decomposition (100-120Gt/yr)

• Ocean part where carbon is in dissolved form + ocean organisms, and held in sediment on ocean floor for a long time
• Long-held stores in earth's surface are moved when volcanic eruptions occur

Increased as less carbon sequestration via PS

• Ocean acts as carbon sink
• Seesters carbon via phytoplankton through PS, lowering atmospheric carbon
• Biological carbon pump

• Respiration
• Combustion
• Decomposition/decay

• PS
• Dissolution into ocean

• Bacteria
• Fungi
• Maggots

• Decomposers cause decay of dead plants/animals
• Releases carbon and nitrogen into soil to be taken by plants

Hydrocarbon fuel + oxygen = carbon dioxide/sulfur dioxide + water

• Limewater - turns cloud
• Bicarbonate indicator - yellow if above atmospheric CO2 level, orange if equal, purple if below

Carbon dioxide + water -> oxygen + glucose + energy

Oxygen + glucose -> carbon dioxide + water + energy

• Cellulose
• Starch
• Glycogen
• Glucose

Sedimentary rocks + fossil fuels

• Ocean current that produces vertical/horizontal circulation of cold + warm water around the world’s oceans. In addition to this, the
• atmospheric circulation creates large currents in the oceans which transfers water from the
• warmer tropical areas of the world to the colder polar regions.
• Cold currents upwell nutrients and ocean mixing removes zooplankton, so phytoplankton thrive

• Peat bogs
• Afforestation
• Wetland restoration (15% of world's soil carbon is in wetlands)