Carbon can be found in multiple reservoirs on Earth and beyond:
- Rocks and Sediments: The majority of Earth's carbon is stored in rocks and sediments, especially in carbonate rocks like limestone, dolomite, and marble, which contain carbon from biological origins such as marine organisms' shells and skeletons
. Coal, rich in carbon, is another significant mineral source
- Oceans: The ocean holds a large amount of carbon dissolved in water, estimated at around 36,000 gigatonnes of carbon, making it the largest active carbon store
- Atmosphere: Carbon exists primarily as carbon dioxide (CO2) in the atmosphere, with about 900 gigatonnes of carbon present. Atmospheric carbon is dynamic, constantly exchanged with other reservoirs through the carbon cycle
- Living Organisms and Soil: Carbon is a fundamental component of all living things, including plants, animals, and microorganisms, and is also found in soils and organic matter
- Fossil Fuels: Carbon is stored in fossil fuels such as coal, oil, and natural gas, which are concentrated carbon deposits formed from ancient organic matter
- Other Sources: Carbon is also found in methane hydrates under the sea and polar regions, in diamonds within certain rocks, and in extraterrestrial sources like meteorites and carbon-rich asteroids
In summary, carbon is widely distributed in the Earth's geosphere (rocks, sediments), hydrosphere (oceans), atmosphere, biosphere (living organisms), and fossil fuel deposits, as well as in extraterrestrial materials
