Download The Nitrogen Cycle

The Nitrogen Cycle
Created by Ted Park, Akshay Patel, and Sang Lee
What is nitrogen and why is it needed?
●
●
●
●
●
Nitrogen is a chemical element that is needed by living organisms
Nitrogen is a component of amino acids in proteins and bases in nucleic acids
Without nitrogen, organisms would not be able to grow or reproduce
Nitrogen (in the form of N2) makes up approximately 80 percent of the air in
the atmosphere
The triple bond in the nitrogen molecule (N2) makes the molecule inert
(unreactive) and stable
What is the nitrogen cycle and why is it important?
●
●
●
●
●
The nitrogen cycle is the transformation and movement of nitrogen between the
geosphere and biosphere
Although there is an abundance of nitrogen in the atmosphere, most plants cannot
use this form of nitrogen
Instead, nitrogen must be in its “fixed” form, or in a compound, for it to be usable by
plants
To get to this “fixed” form, nitrogen must first go through the cycle
The steps of the nitrogen cycle are the following:
○
○
○
○
○
○
Nitrogen Fixation
Nitrification
Denitrification
Ammonification
Assimilation
Eutrophication
Nitrogen Fixation
●
●
●
●
Nitrogen fixation is the process in which nitrogen (N2 ) from the atmosphere is
converted to ammonia (NH3) and then to ammonium (NH4+)
Ammonia is an organic form of nitrogen, so it can not be absorbed by plants
Ammonium is created when ammonia combines with a hydrogen ion (H+)
Natural or industrial processes (such as lightning and bacteria) cause free
nitrogen to combine with other elements to form these nitrogen compounds
Nitrification
●
●
●
Nitrification is the two-step process in which ammonia is converted to nitrites
(NO2-) and then to nitrates (NO3-).
Two different species of bacteria that are present in the soil oxidize the
ammonia into inorganic forms of nitrogen
The rate of nitrification is determined by these factors:
○
○
○
○
temperature dependency: rapid changes in temperature do not produce rapid changes in growth
oxygen intake: nitrifying bacteria are sensitive to low oxygen concentrations
pH dependency: nitrification occurs the fastest when the pH is between 8 and 9
prevention substances- many substances can prevent nitrification reactions such as metals
Assimilation
●
●
●
Assimilation is the is the process by which living organisms incorporate NO3and NH4+ ammonium formed through nitrogen fixation and nitrification
Plants take in this form of nitrogen via the roots and incorporate them into
nucleic acids and plant protein
Animals are then able to receive and utilize the nitrogen from plant tissues
through consumption
Ammonification
●
●
●
●
Ammonification occurs when a plant or animal dies or excretes waste
Decomposers, such as bacteria and fungi, first break down the proteins in the
organic matter
This releases ammonia, which dissolves with the water in the soil
Ammonia then combines with a hydrogen ion to create ammonium
Denitrification
●
●
Denitrification is the process in which microorganisms, such as bacteria, break
down nitrates to metabolize oxygen
This releases nitrogen gas back into the atmosphere, completing the cycle
Eutrophication
●
●
Eutrophication, which comes from the Greek word eutrophıa, meaning healthy,
adequate nutrition, development, is an ecosystem’s response to the addition of
artificial/natural nutrients through detergents, fertilizers, or sewage
Eutrophication occurs when nitrate leaches into a body of water
How do humans affect the nitrogen cycle?
Humans affect the nitrogen cycle mainly
in four different ways. Nitrogen fertilizer,
deforestation, burning of fossil fuels, and
the growth of human population.
-
Nitrogen Fertilizer
- Each year, humans produce approximately 80 teragrams of nitrogen fertilizer.
For scale, one teragram is 2,204,622,621.85 lbs, 80 teragrams is
176,369,809,748 lbs,
- This immense amount of nitrogen enters the ecosystems of the planet and as of
now, it is the largest contribution of new nitrogen into our planet by human
race.
Deforestation
- Forests and the plants within them have the ability to retain nitrogen.
Therefore when the trees are cut, the amount of nitrogen retained decreases
and the amount being put out into the air increases.
Burning of Fossil Fuels
- Transportation vehicles, power plants, industrial factories, and other man-made
devices/buildings that rely on a combustion process to function increase the amount
of nitrogen because the burning of fossil fuels sends back nitrogen that was trapped
inside, thus causing an increase in the amount of nitrogen. This affects the nitrogen
cycle.
Human Population Growth
- Ultimately, with the growth of the human population comes come an increase in
demand. Therefore, more trees will be cut down, more factories will be made,
more vehicles will be driven, and more fertilizer will be used.
- Therefore, there will evidently be an exponential increase in nitrogen as the
population on Earth continues to grow.
Are they any solutions to this issue?
●
Reduce your usage of fossil fuels in your daily lives
○
○
○
●
●
●
Reduce, Reuse, and Recycle
Carpool, walk, or bike to get around places
Conserve power and electricity when possible
In 2014, the United States consumed 6.97 billion barrels of petroleum alone
Another possible solution to this problem is to reduce the usage of nitrogen
fertilizer for agriculture
This will then reduce eutrophication and damage in our ecosystems
Sources
●
●
●
●
●
http://www.visionlearning.com/en/library/Earth-Science/6/The-NitrogenCycle/98
http://www.nature.com/scitable/knowledge/library/the-nitrogen-cycleprocesses-players-and-human-15644632
http://archive.bio.ed.ac.uk/jdeacon/microbes/nitrogen.htm
http://www.wisegeek.org/what-is-ammonification.htm
http://www.fondriest.com/news/nitrogencycle.htm