1. Nitrogen Cycle
Thank – You Bacteria!

2. Why is Nitrogen so important?

3. 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.

4. What are the key parts?
On the next slide I would like you to observe the image of the Nitrogen Cycle.
Make note of:
Important Reservoirs
Roles played by bacteria
Important Processes –please note not all of the processes are described at the bottom of the image.

6. Nitrogen Cycle Reservoirs
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.

7. Nitrogen Cycle Video
As you watch this short clip, make additions to your previous observations.
PLUCLHk
Tech – please embed the above video. Thanks  You are rock stars!

8. 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.

9. 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.

10. Bacteria Mediated Processes
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.

11. Bacteria Mediated Processes
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.

12. 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

13. Human Participation Burning of fossil fuels
Industrial production of fertilizers – forms ammonia from N2 gas in the atmosphere.

14. 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?