1. moving through the nitrogen cycle
Of Microbes and Men
moving through the nitrogen cycle
Katya Hafich
BSI Science Squad 2012
University of Colorado at Boulder

2. A little about the author.

3. Explore the world with science!
In college, I got to travel to Costa Rica with 10 other students to study soils in the rainforest. I learned all about how to conduct research, and actually got paid by the National Science Foundation to do so!

4. Exploring our backyard…
Now I work right here in Colorado at the CU Mountain Research station, 45 minutes west of Boulder, where CU students collect water samples and dig snow pits to learn more about our water supply.

5. What is Nitrogen? Where do you find it?
Does it move from place to place or stay still?
Who needs it?

6. Who needs Nitrogen? All living things!
All living things!

7. Approximately 80% of the Earth’s atmosphere is nitrogen
Two nitrogen atoms bond together to form a gas, N2
All living things need nitrogen to make amino acids, proteins, and DNA, but N2 is not in a form they can use
N2 can become usable when the molecules are broken apart during lightning strikes or fires, or by bacteria

8. Nitrogen is stored in reservoirs
The Nitrogen Cycle
Nitrogen is stored in reservoirs

9. You need a microscope to see them!
Wait! What are microbes?
Microbes (microorganisms) are tiny living life forms, like bacteria or fungi.
You need a microscope to see them!
on.com/wp-content/uploads/2011/11/microorganism-1lg.jpg
Microbes are so small that hundreds of thousands of bacteria could fit onto a pinhead. Microorganisms in and on our bodies are protozoa, algae, fungi, bacteria, and viruses. Most of them are beneficial, some are dangerous. Microbes also serve a valuable purpose, transforming elements into valuable nutrients.
Nitrogen Fixation
The conversion of atmospheric nitrogen (N2) into usable forms for use by living things (NO3- and NH4+).
MICROBES
HUMANS
LIGHTNING

10. The Nitrogen Cycle

11. Nitrification
Bacteria convert ammonium (NH4+) to nitrite (NO2-) to nitrate (NO3-), a more usable form of nitrogen for plants.

12. The Nitrogen Cycle

13. Assimilation
Nitrogen compounds in various forms are taken up from soils by plants which are then used in the formation of plant and animal proteins.

14. The Nitrogen Cycle

15.
Mineralization
When nitrogen is excreted in animal waste, microbes process nitrogen through the process decay, returning nitrogen to the soils.

16. The Nitrogen Cycle

17. Denitrification
Some nitrogen returns to the atmosphere through denitrification, thanks to bacteria called Pseudomonas and Clostridium.

18. The Nitrogen Cycle

19. Leaching
Excess nitrogen in soils can be carried away by runoff (water), which then enters surface waters downstream.
Leaching leads to high levels of nitrogen in surface waters, causing algal blooms. Algal blooms cause anoxic conditions, which lead to fish kills and other environmental damage.

20. The Nitrogen Cycle

21. The Nitrogen Cycle

22. Let’s play the game…

23. The Nitrogen Cycle Discussion Questions:
How many stops can you make on your trip?
Will your journey ever end?
Was everyone’s journey the same? Why not?
Can someone give an example of nitrogen fixation on their journey?
Nitrification? Assimilation? Mineralization? Denitrification? Leaching?
What would happen if a farmer used too much fertilizer?
Would would happen if we burnt too many fossil fuels?
Livestock farming creates a large amount of animal waste. How would this affect the nitrogen cycle?

24. Humans are changing the Nitrogen cycle…

25. The orange arrows represent nitrogen added into the system by humans.
Gruber, N. and Galloway, J. N. (2008) An Earth-system perspective of the global nitrogen cycle. Nature, 451(7176),
The orange arrows represent nitrogen added into the system by humans.

26.
The Dead Zone!
Increased fertlizer use has resulted in too much leaching, releasing high levels of nitrate in surface waters to the ocean.
High nutrient loads lead to algal blooms, which use up all the oxygen, resulting in waters with low oxygen, so fish can’t live!

27. Closer to home… Changes in alpine vegetation Changes in water quality
Even some fish kills!

28. Nitrogen Deposition in the Front Range
to the Green Lakes 4 watershed (part of Niwot Ridge LTER) is equivalent to dumping lb. sacks of nitrogen fertilizer each year.
Nitrogen deposition has increased significantly since the 1980s due to anthropogenic causes.
Currently, the amount of nitrogen deposited

29. Alpine N Cycling