Saturday, July 26, 2008

The carbon cycle is the biogeochemical cycle by which carbon is exchanged between the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.The cycle is usually thought of as four major reservoirs of carbon interconnected by pathways of exchange.
These reservoirs are the atmosphere, the terrestrial biosphere, which is usually defined to include fresh water systems and non-living organic material, such as soil carbon, the oceans, including dissolved inorganic carbon and living and non-living marine biota and the sediments including fossil fuels.
Carbon is an element. It is part of oceans, air, rocks, soil and all living things. Carbon doesn’t stay in one place. It is always on the move! The Carbon Cycle is a complex series of processes through which all of the carbon atoms in existence rotate. The same carbon atoms in your body today have been used in countless other molecules since time began. The wood burned just a few decades ago could have produced carbon dioxide which through photosynthesis became part of a plant. When you eat that plant, the same carbon from the wood which was burnt can become part of you. The carbon cycle is the great natural recycler of carbon atoms. Unfortunately, the extent of its importance is rarely stressed enough. Without the proper functioning of the carbon cycle, every aspect of life could be changed dramatically.
Carbon moves from the atmosphere to plants
In the atmosphere, carbon is attached to oxygen in a gas called carbon dioxide (CO2). With the help of the Sun, through the process of photosynthesis, carbon dioxide is pulled from the air to make plant food from carbon.
Carbon moves from plants to animals
Through food chains, the carbon that is in plants moves to the animals that eat them. Animals that eat other animals get the carbon from their food too.
Example:
Plants absorb carbon dioxide from the atmosphere and use it, combined with water they get from the soil, to make the substances they need for growth. The process of photosynthesis incorporates the carbon atoms from carbon dioxide into sugars.
Animals, such as the rabbit pictured here, eat the plants and use the carbon to build their own tissues. Other animals, such as the fox, eat the rabbit and then use the carbon for their own needs.
Carbon moves from plants and animals to the ground
When plants and animals die, their bodies, wood and leaves decay bringing the carbon into the ground. Some becomes buried miles underground and will become fossil fuels in millions and millions of years.
Carbon moves from living things to the atmosphere
Each time you exhale, you are releasing carbon dioxide gas (CO2) into the atmosphere. Animals and plants get rid of carbon dioxide gas through a process called respiration.
Carbon moves from fossil fuels to the atmosphere when fuels are burned
When humans burn fossil fuels to power factories, power plants, cars and trucks, most of the carbon quickly enters the atmosphere as carbon dioxide gas. Each year, five and a half billion tons of carbon is released by burning fossil fuels. That’s the weight of 100 million adult African elephants! Of the huge amount of carbon that is released from fuels, 3.3 billion tons enters the atmosphere and most of the rest becomes dissolved in seawater.
Carbon moves from the atmosphere to the oceans.
The oceans, and other bodies of water, soak up some carbon from the atmosphere.
Ultimately, the same carbon atom can move through many organisms and even end in the same place where it began. Herein lies the fascination of the carbon cycle; the same atoms can be recycled for millennia!


Sources:
Environmentalist Blogged:9:05 PM