2. What is nitrogen?

3. Nitrogen is in the Nonmetals Group
Periodic Table

4. Where is nitrogen found in the environment?

5. The largest single source of nitrogen is in the atmosphere.
Nitrogen makes up 78% of our air!

6. What happens to atmospheric nitrogen (N2) in the nitrogen cycle?

7. Atmospheric nitrogen is converted to ammonia or nitrates.
Atmospheric Nitrogen (N2) N N
Ammonia (NH3)
Nitrogen combines with Hydrogen to make Ammonia
Nitrates (NO3)
Nitrogen combines with Oxygen to make Nitrates

8. Why does atmospheric nitrogen need to be converted?

9. It is one of nature’s great ironies…
Nitrogen is an essential component of DNA, RNA, and proteins—the building blocks of life.
Although the majority of the air we breathe is nitrogen, most living organisms are unable to use nitrogen as it exists in the atmosphere!

10. How does atmospheric nitrogen get changed into a form that can be used by most living organisms?

11. There are three ways that nitrogen gets “fixed”!
(a) Atmospheric Fixation
(b) Industrial Fixation
(c) Biological Fixation
Bacteria

12. Lightning “fixes” Nitrogen!
Atmospheric Fixation (5 to 8% of the Fixation Process) The enormous energy of lightning breaks nitrogen molecules apart and the nitrogen atoms combine with oxygen forming nitrogen oxides (N2O). Nitrogen oxides dissolve in rain, forming nitrates. Nitrates (NO3) are carried to the ground with the rain. N N O
Nitrogen combines with Oxygen
Nitrogen oxides forms
(N2O)
Nitrogen oxides dissolve in rain and change to nitrates
(NO3)
Plants use nitrates to grow!

13. N N H
Industrial Fixation Atmospheric nitrogen (N2) and hydrogen are combined to form ammonia (NH3). Ammonia can be used as a fertilizer. N H3
Industrial Plant combines nitrogen and hydrogen
Ammonia is formed
(NH3)
Ammonia is used a fertilizer in soil

14. Symbiotic Relationship Bacteria
Biological Fixation (where MOST nitrogen fixing is completed) There are two types of “Nitrogen Fixing Bacteria”
Free Living Bacteria
(“fixes” 30% of N2)
Symbiotic Relationship Bacteria
(“fixes” 70% of N2)

15. Free Living Bacteria Highly specialized bacteria live in the soil and have the ability to combine atmospheric nitrogen with hydrogen to make ammonia (NH3). N N H N H3
Free-living bacteria live in soil and combine atmospheric nitrogen with hydrogen
(NH3)
Nitrogen changes into ammonia
Bacteria

16. Symbiotic Relationship Bacteria Bacteria live in the roots of legume family plants and provide the plants with ammonia (NH3) in exchange for the plant’s carbon and a protected home.
Legume plants N
NH3 N
Roots with nodules where bacteria live
Nitrogen changes into ammonia.

17. Decomposers break down amino acids from dead animals and wastes into nitrogen and ammonium(NH4).

18. Plants cannot use the organic forms of nitrogen that are in the soil as a result of: (1) wastes (manure and sewage) (2) compost and decomposing roots and leaves

19. Microorganisms convert organic nitrogen to ammonium
Microorganisms convert organic nitrogen to ammonium. Ammonium in the soil is later changed into inorganic nitrogen, the kind of nitrogen that most plants can use.
Bacteria converts organic nitrogen to ammonium (NH4)
Ammonium (NH4) is used by some plants
Bacteria
Ammonium (NH4) is stored in soil.

20. What happens to ammonium (NH4) stored in the soil?

21. Nitrifying bacteria in the ground first combine ammonia with oxygen to form nitrites. Then another group of nitrifying bacteria convert nitrites to nitrates which green plants can absorb and use!
Nitrifying bacteria in soil combine ammonia with oxygen
Ammonia changes to nitrites
Nitrifying bacteria in soil convert nitrites to nitrates
Ammonia
Nitrites
Nitrates
Plants absorb nitrates and grow!
(NH3)
(NO2)
(NO3)

22. How does nitrogen reenter the atmosphere in the nitrogen cycle?

23. Denitrification converts nitrates (NO3) in the soil to atmospheric nitrogen (N2) replenishing the atmosphere.
Nitrogen in atmosphere (N2)
Nitrates (NO3) in Soil

24. Other ways that nitrogen returns to the atmosphere…
Emissions from industrial combustion and gasoline engines create nitrous oxides gas (N2O).
Volcano eruptions emit nitrous oxides gas (N2O).

25. Human activities and the nitrogen cycle -
burning of both fossil fuels and forests releasing nitrogen in the atmosphere
fertilizing crops with nitrogen-based fertilizers which then enter the soil and water
livestock waste releases ammonia into the soil and water
* allowing sewage and septic tanks to leach into streams, rivers, and groundwater

26. decomposition by bacteria & fungi
Nitrogen in
the air
nitrogen fixing plants - pea, clover
animal protein
plant made
protein
denitrifying
bacteria
root nodules
(containing nitrogen
fixing bacteria)
dead plants & animals
decomposition by bacteria & fungi
nitrates absorbed
nitrates
ammonia
bacteria
nitrites
bacteria
(nitrifying bacteria)

27. The End