Nitrogen Cycle

N’ Lyssa BullardKatherine FondeurPeriod: 03 AICE EM

● A cyclic movement of nitrogen in different chemical forms from the environment to organisms and then back to the environment.

● All organisms require large quantities nitrogen compounds (ex: proteins, vitamins, nucleic acids DNA)

● 78.08% of Nitrogen gas is the composition of dry air● N2 gas cannot be absorbed and used directly of its strong,

covalent, triple bond. ● Nitrogen fixation is the conversion of atmospheric nitrogen gas,

by lightning, bacteria, and cyanobacteria, into forms useful to plants; it is part of the nitrogen cycle.

● They’re two natural processes that convert, or fix, nitrogen into compounds in which the plants and animals can utilize as nutrients.

- Atmospheric fixation - Nitrogen-fixing bacteria

Atmospheric Fixation ● lightning breaks down N2 molecules and enables the atoms to combine with

O2 in the air forming nitrogen oxide: nitric oxide NO and nitrogen oxide NO2 ● nitrogen oxides dissolve in rain, forming nitrates NO3 on earth ● Lightning fertilizes the soil with nitrates● Nitrate is essential for every living organism.

Nitrogen-Fixing Bacteria

● Microorganisms able to convert atmospheric nitrogen into fixed nitrogen, the inorganic compounds used by plants

● Specialized bacteria in soil or cyanobacteria in aquatic environments combine with gaseous nitrogen with hydrogen to make ammonia NH3.

● The bacteria use some of the ammonia produced as a nutrient and release the rest into the soil or water.

● Some of the ammonia is converted to ammonium ions (NH4+) that plants can use a nutrient.

Nitrogen Fixing Bacteria - Nitrification● Ammonia not taken up by plants undergoes the process of nitrification● the process when specialized soil bacteria convert ammonia and ammonium into

nitrites NO2- and nitrate ions NO3-● They’re two steps into nitrification: ammonia oxidation (oxidation of ammonia to

nitrate) and nitrite oxidation (oxidation of nitrite to nitrate) ● The plants then use nitrites or nitrate ions to produce amino acids, proteins, nucleic

acids, and vitamins. ● Consumers, detritus feeders, and decomposers eventually consume the plants nitrogen

rich compounds. The nitrogen rich organic compounds, from plants and animals, is returned to the environment fas cast-off particles of tissues: leaves, skin, hair. The dead bodies are decomposed or eaten off by detrius feeders

● This process is very important to soil and aquatic ecosystems for its vital nutirents. ● It’s performed by very small groups of autotrophic bacteria.● Ammonia- and nitrite-oxidizers help to maintain healthy aquaria by facilitating the

removal of potentially toxic ammonium excreted in fish urine.

Human Impacts to Nitrification● There is an abundance of growth of algae because of the excess addition of

nitrates in aquatic ecosystems from agricultural runoff through of fertilizers, animal manure, and municipal sewage systems.

Nitrogen-Fixing Bacteria - Ammonification● Ammonification is the process when nitrogen is recycled.● Specialized decomposer bacteria convert this detritus into simpler nitrogen

containing inorganic compounds such as ammonia or ammonium ions● This process can be carried out by a diversity of many organisms. Some can’t use

ammonia directly which causes nitrate to be their main nutrient.● This can also be the time frame in the cycle when nitrogen can be returned back

into the soil.●

Human Impacts to Ammonification● In the aspect of big agricultural industries the use of fertilizers that contain

nitrogen can affect the soil.

Nitrogen Fixation - Denitrification

● In the denitrification process it is the complete opposite of the nitrification process.

● This process involves the reduction of nitrate ions to nitrite ions.● The reduction of nitrates to gaseous nitrogen by microorganisms in a series of

biochemical reactions is called “denitrification".

Human Impacts to Denitrification

The amount of fertilizer being used to help stimulate growth.

More Developed Countries vs Less Developed Countries● Agriculture is one of the major components in a more developed country due

to all of the fields and crops they may have.● As compared to a less developed country they don’t release as much nitrogen

as we due to them not having the ability to certain things we do.

Effects of Human Activities● The burning of fossil fuels causes Nitrogen to be released into the

environment.● Caused changes in the lives of plants and animals and contributed to the

process of eutrophication in the different bodies of water.● Reduce the amount of fertilzer that is being used● It can also speed the microbial breakdown of ammonium and nitrates in the

soil, enhancing the release of nitrous oxide.

How can we solve the problems dealing with the nitrogen cycle?● Reduce the amount of fertilizer being used● Reduce the amount of fossil fuels being burned.

Citationshttp://scifun.chem.wisc.edu/chemweek/pdf/airgas.pdf

http://www.biology-pages.info/N/NitrogenCycle.html#Nitrification

https://www.princeton.edu/nitrogen/publications/pdfs/Ward_2015_Nitrification.pdf

http://images.fineartamerica.com/images-medium-large/nitrogen-molecule-dr-tim-evans.jpg

http://agriinfo.in/?page=topic&superid=5&topicid=165

http://www.esa.org/esa/documents/2013/03/issues-in-ecology-issue-1.pdf

https://www.britannica.com/science/nitrogen-fixing-bacteria

http://www.nature.com/scitable/knowledge/library/the-nitrogen-cycle-processes-players-and-human-15644632