Download nitrogen cycle - Alliance Gertz

Earth Science/Biology Standard
7a. Students know the carbon cycle of
photosynthesis and respiration and the nitrogen
cycle.
What is nitrogen?
Chemical element
N, atomic number=7


Colorless, odorless,
tasteless, inert gas

Makes up 78% of the
atmosphere

N2,Dinitrogen gas,
(Diatomic )
Why is it important?

Proteins and nucleic acids (DNA, RNA)
in living organisms

Nitrogen gas (N2)-> cannot be used
directly.
* Animals get nitrogen from plants or
animals that ate plants
Forms of nitrogen

Atmospheric Nitrogen: N2

Nitrate :NO3

Nitrite: NO2

Ammonia: NH4
What is the
nitrogen cycle?
•The
process by
which nitrogen is
converted between
its chemical forms
•It
can be carried out
by both biological and
non-biological
processes
•Bacteria
are key
element of the cycle
Where does it go?
Air
Soil
Microbes
Animals
Soil
•Microbes
Plants
Nitrogen fixation
break apart N2

Atmospheric: lightning

Biological: bacteria

Industrial: great pressure and
temperature
Atmospheric Nitrogen and Nitrogen Fixation
Triple bond is very stable
Nitrogen gas- ammonia
Mainly through bacteria
Bacteria
•Single
•Very
celled
small,
microscopic
Nitrogen fixing bacteria
Bacteria living in root
nodules of LEGUMES
(soybeans, peanuts, alfalfa)
Bacteria living in soil and
water
Assimilation
Plants
 Nitrate->nitrite-> ammonium-> amino
acids, nucleic acids
 Ammonium-> amino acids, nucleic acids
(in legumes)

Animals eat plants
amino acids, nucleotides

Mineralization (ammonification)

Plant or animal dies, animal excretes
waste

Bacteria convert organic nitrogen to
ammonium
Nitrification
Bacteria convert ammonium to nitrate
 nitrite-> nitrate->ammonium
 Nitrate-> ammonium

Can seep into groundwater
 Health problems
 Environmental problems

Denitrification

Bacteria convert Nitrate to Nitrogen
gas

Completes the cycle by returning
nitrogen to the atmosphere
Increased Nitrogen emissions

Cultivation of legumes

Artificial fixation of nitrogen
Nitrogen oxide from cars and factories
(greenhouse gas, destroys ozone layer)

In water…

Acidification
Eutrophication
Too much nitrogen in the water (mostly
due to runoff from land) -> more algae
(algal blooms) -> take up oxygen->
affects other organisms (animal lives
die)

Earth Science/Biology Standards
7c. Students know the movement of matter among
reservoirs is driven by Earth's internal and external
sources of energy
What powers the water cycle?
What drives photosynthesis?
(Carbon transfer: atmosphere->biomass)
The sun!
What type of energy is produced
during cellular respiration and
*decomposition?
What powers subduction zones?
Energy transfer between hot interior and cool exterior
How?
Convection
movement of molecules in liquids and gases, “flowing”
Coal Formation?
Plants that died millions of years ago
*Pressure by sedimentary rocks
video
http://video.google.com/videoplay?docid=7538120906762340500#