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GEOLOGICAL CARBON CYCLE - Coggle Diagram
GEOLOGICAL CARBON CYCLE
NATURAL CARBON CYCLE is the movement and storage of carbon between the land, ocean and the atmosphere.
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BALANCE There is generally a balance between production and absorption (or sources and sinks) of carbon in the natural carbon cycle. Sometimes, it takes a long time for equilibrium to be reached e.g. after a volcanic eruption.
STORES
STORES e terrestrial, oceanic or atmospheric
CARBON SINK A carbon sink is any store which takes in more carbon than it emits , so an intact tropical rainforest is an example. A carbon source is any store that emits more carbon than it stores so a damaged tropical rainforest is an example.
TYPES
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▪ The lithosphere as carbonates in limestone and fossil fuels like coal, gas and oil
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CARBON SEQUESTRATION Carbon Sequestration is the transfer of carbon from the atmosphere to other stores and can be both natural and artificial. For example. a plant sequesters carbon when it photosynthesises and stores the carbon in its mass.
MAIN STORES
Marine Sediments and Sedimentary Rocks - Lithosphere - Long-term ○ Easily the biggest store. 66,000 - 100,000 million billion metric tons of carbon. The rock cycle and continental drift recycle the rock over time, but this may take thousands, if not millions of years.
● Oceans - Hydrosphere - Dynamic ○ The second biggest store contains a tiny fraction of the carbon of the largest store. 38,000 billion metric tons of carbon . The carbon is constantly being utilised by marine organisms, lost as an output to the lithosphere, or gains as an input from rivers and erosion.
● Fossil Fuel Deposits - Lithosphere - Long-term but currently dynamic ○ Fossil fuel deposits used to be rarely changing over short periods of time, but humans have developed technology to exploit them rapidly, though 4000 billion metric tons of carbon remain as fossil fuels.
● Soil Organic Matter - Lithosphere - Mid-term ○ The soil can store carbon for over a hundred years, but deforestation, agriculture and land use change are affecting this store. 1500 billion metric tons of carbon stored.
● Atmosphere - Dynamic ○ Human activity has caused CO ₂ levels in the atmosphere to increase by around 40% since the industrial revolution , causing unprecedented change to the global climate. 750 billion metric tons of carbon stored
. ● Terrestrial Plants - Biosphere - Mid-term but very dynamic ○ Vulnerable to climate change and deforestation and as a result carbon storage in forests is declining annually in some areas of the world. 560 billion metric tons of carbon.
LITHOSPHERE
main store of carbon , with global stores unevenly distributed. For example, the oceans are larger in the southern hemisphere, and storage in the biosphere mostly occurs on land. Terrestrial plant storage is focussed in the tropics and the northern hemisphere.
FLUXES
FLUX movement and trasfter of carbon between stores
The transfers in the carbon cycle act to drive and cause changes in the carbon cycle over time. They all have impacts of varying magnitude over different lengths of time . Biological and chemical processes determine how much carbon is stored and released. The role of living organisms is very important in maintaining the system running efficiently.
PHOTOSYTHESIS
Living organisms convert Carbon Dioxide from the atmosphere and Water from the soil, into Oxygen and Glucose using Light Energy. By removing CO ₂ from the atmosphere, plants are sequestering carbon (see below) and reducing the potential impacts of climate change. The process of photosynthesis occurs when chlorophyll in the leaves of the plant react with CO ₂, to create the carbohydrate glucose. Photosynthesis helps to maintain the balance between oxygen and CO ₂ in the atmosphere. The formula is shown below: Carbon Dioxide + Water → Light Energy → Oxygen + Glucose
RESPIRATION
- Respiration occurs when plants and animals convert oxygen and glucose into energy which then produces the waste products of water and CO ₂. It is therefore chemically the opposite of photosynthesis:
Oxygen + Glucose → Carbon Dioxide + Water During the day, plants photosynthesise, absorbing significantly more CO ₂ than they emit from respiration. During the night they do not photosynthesise but they do respire, releasing more CO ₂ than they absorb. Overall, plants absorb more CO₂ than they emit, so are net carbon dioxide absorbers (from the atmosphere) and net oxygen producers (to the atmosphere).
COMBUSTION - When fossil fuels and organic matter such as trees are burnt, they emit CO ₂ into the atmosphere , that was previously locked inside of them. This may occur when fossil fuels are burnt to produce energy, or if wildfires occur.
DECOMPOSITION When living organisms die, they are broken down by decomposers (such as bacteria and detritivores ) which respire, returning CO₂ into the atmosphere. Some organic matter is also returned to the soil where it is stored adding carbon matter to the soil.
DIFFUSION - The oceans can absorb CO ₂ from the atmosphere, which has increased ocean acidity by 30% since pre-industrial times . The ocean is the biggest carbon store, but with carbon levels increasing seawater becomes more acidic which is harming aquatic life by causing coral bleaching. Many of the world’s coral reefs now under threat.
SEDIMENTATION This can happen on land or in the sea. For example, when shelled marine organisms die, their shell fragments fall to the ocean floor and become compacted over time to form limestone. Organic matter from vegetation and decaying marine organisms is compacted over time, whether on land or in the sea, to form fossil fuel deposits.
WEATHERING AND EROSION - Inorganic carbon is released slowly through weathering: rocks are eroded on land or broken down by carbonation weathering. Carbonation weathering occurs when CO ₂ in the air mixes with rainwater to create carbonic acid which aids erosion of rocks such as limestone . The carbon is moved through the water cycle and enters the oceans. Marine organisms use the carbon in the water to build their shells . Increasing carbon dioxide levels in the atmosphere, may increase weathering and erosion as a result, potentially affecting other parts of the carbon cycle
METAMORPHOSIS Extreme heat and pressure forms metamorphic rock, during which some carbon is released and some becomes trapped.
VOLCANIC OUTGASSING There are pockets of CO2 found in the Earth’s crust. During a volcanic eruption or from a fissure in the Earth's crust, this CO2 can be released.
VARIATIONS The quickest cycle is completed in seconds as plants absorb carbon for photosynthesis and then they release carbon when they respire. This cycle can slow down when levels of light or CO2 drop. Dead organic material in soil may hold carbon for hundreds of years. Some organic materials may become buried so deeply that they don’t decay, or are buried in conditions unfavourable to decayers (potent low-lying gas, too much water). This material will become sedimentary rocks or hydrocarbons by geological processes.