Download Nitrogen Cycle

Nitrogen Cycle
Thank – You Bacteria!
Why is Nitrogen so important?
Nitrogen is important because:
It is required for the growth and
reproduction of all organisms.
 It is part of all amino acids, which are the
building blocks of proteins, like
chlorophyll and hemoglobin.
 Nucleic acids, the building blocks of
DNA and RNA also require nitrogen.
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What are the key parts?
On the next slide I would like you to
observe the image of the Nitrogen Cycle.
 Make note of:
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◦ Important Reservoirs
◦ Roles played by bacteria
◦ Important Processes –please note not all of
the processes are described at the bottom of
the image.
Nitrogen Cycle Reservoirs
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Atmosphere – 78% is made of N2 gas.
Ocean – 63% of dissolved gasses, but there are also
other forms which dissolve readily
Crust – it only forms a minor amount of minerals –
so it has an average of 20 ppm concentration in the
crust.
Rocks – especially sedimentary rocks. Why would
there be more in sedimentary rocks than igneous
rocks?
Soil – there are a variety of compounds, primarily
from the break down of organic compounds. This
can be considered the most active reservoir as it’s
where most reactions take placce.
Nitrogen Cycle Video
As you watch this short clip, make
additions to your previous observations.
 https://www.youtube.com/watch?v=VQAx
PLUCLHk

Tech – please embed the above video.
Thanks  You are rock stars!
Bacteria Mediated Processes
◦ Nitrogen fixation – Bacteria are the only
organisms who can access N2 from the
atmosphere. Through the process of
nitrogen fixation they turn it in to
ammonium (NH4+) which can be taken up
by plants and/or used by other bacteria.
Bacteria Mediated Processes
◦ Ammonification and decomposition Proteins and other compounds with amine
groups, such as nucleic acids and urea, are
decomposed by ammonifying bacteria, releasing
ammonia (NH3). This dissolves in water, and
usually forms ammonium (NH4+) ions, by
combining with hydrogen (H+) ions, which are
abundant in most soils.
Bacteria Mediated Processes
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Nitrification: Some bacteria can convert NH4+
to Nitrite (NO2-) and then in to Nitrate(NO3-).
This is important because
This step is important because Nitrate is easier for most plants to uptake.
Bacteria Mediated Processes
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Denitrification: Bacteria break Nitrate
(NO3-) down and N2 is formed.
Important
because it can
be used to
reduce nutrients
in human and animal waste, and it can have a
negative impact on agricultural soils.
Other Natural Processes
Nitrogen Fixation by Lightening –
provides the energy to break apart N2 –
reaction with oxygen to form NO3
 Assimilation – plants uptake nitrogen
compounds through their roots and
animals consume food.
 Leaching – compounds in the soil dissolve
in ground water and run off
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Human Participation
Burning of fossil fuels
 Industrial production of fertilizers – forms
ammonia from N2 gas in the atmosphere.
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How much do you remember?
Take a moment and see how much you
can remember. Draw out your version of
the Nitrogen cycle without looking at
your notes.
 When you are finished, share with your
partner to see if you have the same
information and to make any corrections.
 Finally, your teacher will share the full
cycle with you. How did you do?
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