The Carbon Cycle

http://www.ucar.edu/communications/gcip/m2ccycle/m2pdf.pdf http://www.ucar.edu/communications/gcip/m2ccycle/m2pdf.pdf The Carbon Cycle
Importance of Carbon Cycle
Carbon (C) is the fourth most abundant element in the universe and is found in all living substances as well as in many inorganic materials and is also the key element for life. The carbon cycle is the exchange of carbon among three reservoirs or storage places: the land, the oceans, and the atmosphere
The atmosphere has the least amount of carbon, followed by the land with it plants and animals, also called the terrestrial biosphere and the ocean being the largest carbon reservoir.

The carbon cycle is important as carbon-containing gases such as carbon dioxide affects and regulates the earth’s climate. It is also vital during the processes photosynthesis and respiration. It helps breakdown matter through decomposition.
The Atmosphere and the Greenhouse Effect
Carbon forms less than 1% of the atmosphere, in comprising mainly of Carbon Dioxide (CO2) and smaller amounts of Methane (CH4), Carbon Monoxide (CO) and Chlorofluorocarbons (CFCs). These gases traps heat and thus called greenhouse gases
Short wavelength radiation from the sun passes through the earth’s atmosphere and is absorbed by the earth’s surface. Some of this absorbed energy is re-radiated back toward space as infrared radiation or heat. The greenhouse gases in the atmosphere absorb the heat energy and keep it from escaping back to space thus warming the earth.
With the exponential increase in greenhouse gases over the years, it has led to higher amounts of heat being trapped in the earth’s atmosphere, leading to a phenomenon called global warming.

Photosynthesis and Respiration
Photosynthesis is the process in which plants make food by combining carbon dioxide and water in the presence of light energy to form carbohydrates, giving out a by-product oxygen, which is released into the atmosphere.
CO2 + H2O + Light Energy -> C6H12O6 + O2
Respiration is the chemical process which carbon-containing compounds such as carbohydrates are broken down within the cells of organisms to produce energy, giving carbon dioxide and water as a by-product
C6H12O6 + O2 -> CO2 + H2O + Energy

The processes photosynthesis which requires the intake of CO2 and the process respiration which require the release of CO2 keeps the level of CO2 fairly constant
Photosynthesis and Respiration plays a part in the short-term carbon cycle.
The Ocean
The ocean absorbs and stores more than 60 times as much carbon as the atmosphere. Usually found in the form of dissolved inorganic carbon such as dissolved carbon dioxide, bicarbonates and carbonate ions. The remaining comprises of organic carbon such as living organic matter and dissolved organic carbon.
The Terrestrial Biosphere
The largest pool of carbon within this reservoir is in the form of sedimentary rocks such as limestone and organic sediments which contains fossil fuel.
Plants and soil stores and releases carbon on time scales ranging from season to thousands of years and contains 3 times more carbon than the atmosphere.

Exchange between Reservoirs

Exchange between the Atmosphere and the terrestrial Biosphere
The exchange between the atmosphere and the terrestrial biosphere has great impact on the carbon cycle due to human intervention. The burning of fossil fuels releases large amounts of carbon dioxide into the atmosphere, becoming part of the active carbon cycle, as the fossil fuels have been inert and essentially not part of the active carbon cycle. This adds to the greenhouse effect and the balance of the carbon cycle is disrupted
Exchanges between the Oceans and the Atmosphere
The oceans play a great role in the carbon cycle. Firstly, it absorbs excess atmospheric carbon dioxide and secondly, changes in physical, chemical and biological state of future atmospheric carbon dioxide.
The ocean absorbs excess carbon dioxide as the gas passes through the air sea interface, and reacts chemically with dissolved inorganic carbon in the ocean’s surface water and is then transported into deeper waters.
Oceanic Circulation
Oceanic circulation affects carbon storage in the ocean, and is affected by wind, salt concentration and difference in water temperature.

Chemical Processes | Biological Processes | When CO2 enters the ocean, it reacts chemically with the water to form carbonate and bicarbonate ions. As more of these ions are formed, more atmospheric CO2 can enter the ocean | Driven by the marine plants and animals, phytoplankton take up dissolved inorganic carbon through photosynthesis | Exchanges between the terrestrial biosphere and the oceans This is accomplished in two ways, via the hydrological cycle (through evaporation and rain) and via rivers into the ocean