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Processes of carbon cycle - Coggle Diagram
Processes of carbon cycle
Carbon exchanges
Precipitation
Atmospheric CO2 dissolves into rainwater to create a weak carbonic acid and rising concentrations of atmospheric CO2 due to anthropogenic emissions have increased the acidity.
Photosynthesis
Amount of carbon to land plants and phytoplankton averages 120 gigatonnes (GT) a year. Plants then release C02 in respiration.
Weathering
Most weathering involves rainwater, containing dissolved CO2, derived from the soil and atmosphere.
Estimated that chemical weathering transfers 0.3 billion tonnes of carbon to the atmosphere and ocean per year
Respiration
Important process in the fast carbon cycle. The volume of carbon transferred via respiration and photosynthesis is 1000 x more than in the slow carbon cycle.
Decomposition
Bacteria and fungi breakdown dead organic matter, releasing CO2 into the atmosphere and mineral nutrients into the soil.
Rates of decomposition depend on climatic conditions - fastest rates in warm, humid environments like the tropical rainforest.
Combustion
This process releases CO2. Wildfires can be essential to the health of some ecosystems. Winters slow the decomposition of forest litter and so it builds up on the forest floor. Fire shifts this accumulation and frees carbon.
Human activities: deliberate firing of forestry or grassland, combustion of fossil fuels (this transfers 10 GT of CO2 a year to the atmosphere, oceans and biosphere)
Physical (inorganic) pump
CO2 diffuses into the ocean
CO2 is then moved polewards by ocean currents, where it cools, becomes denser, and finally sinks
This is called downwelling and downwelling carries dissolved carbon to the depths so that carbon molecules may remain for centuries.
Eventually, deep ocean currents transport the carbon to areas of upwelling and there, cold, carbon-rich water rises to the surface and CO2 diffuses back into the atmospheric store.
Biological (organic) pump
Carbon also exchanged between oceans and atmosphere through marine organisms
Around 50 GT of carbon is drawn from the atmosphere by the biological pump every year.
Phytoplankton combines sunlight, water and dissolved CO2 to produce organic material.
Then, whether this phytoplankton is consumed by animals or naturally die, the carbon locked in the phytoplankton either accumulates as sediment on the ocean floor or is decomposed and released into the ocean as C02.
Vegetation
Land plants, especially trees in rainforests and boreal forests, contain huge stores of carbon, most of it extracted from the atmosphere through photosynthesis is locked away