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Carbon Cycle
Carbon Cycle - Photosynthesis:
- Photosynthesis is a complex series of reactions carried out
by algae, phytoplankton, and the leaves in plants, which utilize
the energy from the sun. The simplified version of this chemical
reaction is to utilize carbon dioxide molecules from the air
and water molecules and the energy from the sun to produce a
simple sugar such as glucose and oxygen molecules as a by product.
The simple sugars are then converted into other molecules such
as starch, fats, proteins, enzymes, and DNA/RNA i.e. all of the
other molecules in living plants. All of the "matter/stuff"
of a plant ultimately is produced as a result of this photosynthesis
reaction.
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- An important summary statement is that during photosynthesis
plants use carbon dioxide
and produce oxygen.
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Carbon Cycle - Combustion/Metabolism Reaction:
- Combustion occurs when any organic material is reacted (burned)
in the presence of oxygen to give off the products of carbon
dioxide and water and ENERGY. The organic material can be any
fossil fuel such as natural gas (methane), oil, or coal. Other
organic materials that combust are wood, paper, plastics, and
cloth. Organic materials contain at least carbon and hydrogen
and may include oxygen. If other elements are present they also
ultimately combine with oxygen to form a variety of pollutant
molecules such as sulfur oxides and nitrogen oxides.
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- Metabolism occurs in animals and humans after the ingestion
of organic plant or animal foods. In the cells a series of complex
reactions occurs with oxygen to convert for example glucose sugar
into the products of carbon dioxide and water and ENERGY. This
reaction is also carried out by bacteria in the decomposition/decay
of waste materials on land and in the water.
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- An important summary statement is that during combustion/metabolism
oxygen is used and carbon dioxide is
a product. The whole purpose of both processes is to convert
chemical energy into other forms of energy such as heat.
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Carbon Cycle - Sedimentation:
- Carbon dioxide is slightly soluble and is absorbed into bodies
of water such as the ocean and lakes. It is not overly soluble
as evidenced by what happens when a can of carbonated soda such
as Coke is opened. Some of the dissolved carbon dioxide remains
in the water, the warmer the water the less carbon dioxide remains
in the water.
- Some carbon dioxide is used by algae and phytoplankton through
the process of photosynthesis.
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- In other marine ecosystems, some organisms such as coral
and those with shells take up carbon dioxide from the water and
convert it into calcium carbonate. As the shelled organisms die,
bits and pieces of the shells fall to the bottom of the oceans
and accumulate as sediments. The carbonate sediments are constantly
being formed and redissolved in the depths of the oceans. Over
long periods of time, the sediments may be raised up as dry land
or into mountains. This type of sedimentary rock is called limestone.
The carbonates can redissolve releasing carbon dioxide back to
the air or water.
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Human Impacts on the Carbon Cycle
- Fossil Fuels:
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- In the natural carbon cycle, there are two main processes
which occur: photosynthesis and metabolism.
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- During photosynthesis, plants use carbon
dioxide and produce oxygen.
- During metabolism oxygen is
used and carbon dioxide is a product.
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- Humans impact the carbon cycle during the combustion of any
type of fossil fuel, which may include oil, coal, or natural
gas. Fossil Fuels were formed very long ago from plant or animal
remains that were buried, compressed, and transformed into oil,
coal, or natural gas. The carbon is said to be "fixed"
in place and is essentially locked out of the natural carbon
cycle. Humans intervene during by burning the fossil fuels. During
combustion in the presence of air (oxygen), carbon dioxide and
water molecules are released into the atmosphere.
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- The question becomes as to what happens to this extra carbon
dioxide that is released into the atmosphere. This is the subject
of considerable debate and about it possible effect in enhancing
the greenhouse effect which may than result in global warming.
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