Nitrogen Cycle

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Nitrogen Cycle

• By Kristen Wendt

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Nitrogen

• Gas Cycle
• Reservoir Earths Atmosphere
• contains 78 nitrogen
• Most abundant element in the atmosphere
• In proteins, DNA, and all amino acids

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Nitrogen Fixation

• Nitrogen gas in the atmosphere needs to be
  converted to a form that is usable by plants and
  animals
• Converted to Ammonia -gt Ammonium Ions (which can
  used by plants)
• Some ways to convert N2
• Biological fixation
• Industrial fixation
• Combustion of fossil fuels
• Lightning
• Bacteria

http//www.lightningsafety.noaa.gov/images/purple
20lightning.jpg
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Nitrogen Assimilation

• Occurs in algae and plants that are unable to
  perform nitrogen fixation independently
• Nitrates and ammonia are digested by the algae or
  plants (exchange pool)
• Animals digest algae or plants, therefore
  receiving the nitrogen

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Ammonification

• Animals or plants (exchange pools) die/decompose
• Nitrogen rich organic compounds return to the
  soil (reservoir)
• Amount of nitrogen in soil negligible (less than
  1)
• Microorganisms convert the nitrogen organisms
  during decomposition
• becomes ammonia, ammonium ions

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Nitrification

• Ammonia is converted to nitrites
• Performed by bacteria (Nitrosomonas )
• Bacteria gains energy from the process
• Nitrites are converted to nitrates
• Performed by bacteria (Nitrobacter )
• The bacteria are the exchange pools

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Nitrification, cont.
http//www.dnr.state.md.us/Bay/monitoring/eco/nitr
ification.gif
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Denitrification

• Nitrogen leaves the soil as bacteria
• Bacteria exchange pool
• Oxidized forms of nitrogen (nitrates, nitrites)
  are converted back to nitrogen gas and nitrous
  oxide gas
• Gases are put back into the atmosphere (reservoir)

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http//en.wikipedia.org/wiki/FileNitrogen_Cycle.j
pg
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Effects of Human Activities

• Burning fuel at high temperatures
• N2 and O2 combine during the burning
• Puts a lot of nitric acid into the atmosphere
• Turns into nitrogen dioxide gas and nitric acid
• Leads to acid
• desposition
• Damages trees
• Deadly to fish

http//www.sciencenewsforkids.org/articles/2004120
8/a610_3857.jpg
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Effects of Human Activities

• Use of Inorganic Fertilizers
• Leaching of Nitrate Ions
• Contaminates groundwater
• Puts nitrous oxide into the atmosphere
• Heats up the atmosphere
• Destroys the ozone

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Nitrogen Fixation
Humans have more than doubled the amount of
fixed nitrogen is pumped into the biosphere every
year.
http//www.visionlearning.com/library/module_viewe
r.php?mid98
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Effects of Human Activities

• Destruction of forests, grasslands, etc.
• Plants and soils release a large amount of their
  stored nitrogen during the destruction
• Changes into gaseous compounds
• Released into
• the troposphere

http//www.hancock.forests.org.au/images/8-02/8o-0
2.jpg
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Effects of Human Activities

• Agricultural Runoff, Dumping from untreated
  sewage systems
• Increased nitrates are put into the water
• Disturbs aquatic ecosystems
• Creates too much algae
• Algae depletes all
• oxygen in the water

http//www.johnstown-redevelopment.org/RAW/overflo
w.jpg
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Sources

• http//library.thinkquest.org/11353/nitrogen.htm
• http//www.biology.ed.ac.uk/research/groups/jdeaco
  n/microbes/nitrogen.htm
• http//www.britannica.com/EBchecked/topic/416268/n
  itrogen-assimilation
• http//science.jrank.org/pages/4690/Nitrogen-Cycle
  -Ammonification-nitrification.html
• http//science.jrank.org/pages/4690/Nitrogen-Cycle
  -Ammonification-nitrification.html
• http//www.visionlearning.com/library/module_viewe
  r.php?mid98
• http//www.absoluteastronomy.com/topics/Nitrogen_c
  ycle
• http//www.ext.colostate.edu/pubs/crops/00550.html