The Nitrogen Cycle

1. The Nitrogen Cycle Or, “How do you eat air?”

2. What is Nitrogen? • Element #7 (7 Protons, 7 Neutrons, 7 Electrons) • 78% of the atmosphere is made of Nitrogen, one of the strongest bonding gases • Colorless, odorless, tasteless • Created by fusion in stars and is the 7th most common element in the Universe

3. Some Commercial Uses • Used in cheap light bulbs instead of argon • Food preservative • Fire suppression systems • Aircraft tires because of lack of moisture • Used in some paintball guns (makes it heavier and more expensive, though) • Refrigerant/cryogenic (liquid nitrogen) • Gunpowder • Fertilizer • Pharmaceutical Drugs

4. In the atmosphere, as N2 which forms about 78% of the air we breath. Take a deep breath, but it won’t matter… it is inert. There is a million times more nitrogen in the air than nitrogen in living things. • Essential for growth and reproduction in plants and animals… 3% of your body is Nitrogen. • Found in proteins, DNA/RNA, and many other compounds essential for life. • Amino acids which are used in muscle, tissues and organs. • Urea, a byproduct of protein digestion… yes, human waste.

5. So, how do we turn that gas to a usable substance? • Nitrogen in the atmosphere can be changed to make something that we can actually use. Atmospheric Nitrogen (N2) NITROGEN-CONTAINING COMPOUNDS Ammonia (NH3) Nitrogen combines with Hydrogen to make Ammonia Nitrates (NO3) Nitrogen combines with Oxygen to make Nitrates

6. Animation of Nitrogen Fixation

7. Recap • We can’t breathe Nitrogen gas. We need FIXATION • Bacteria either living on root of legumes: • Alfafa • Clover • Peas • Beans • Lentils • Lupins • Mesquite • Carob • Soy • Peanuts

8. Certain other bacteria that live “free” can convert Nitrogen gas into a usable nitrogen-containing compound, but the majority are made in nodules on roots.

9. Other less common ways to “fix” nitrogen are through lightning or by commercial means (making fertilizer)

10. When humans commercially make Nitrogen, it is sold as fertilizer We’ll come back to this in a bit.

11. However it is made, once we have nitrogen fixation, the plant can now use it. • Animals, when eating the plants, can now take in USABLE Nitrogen compounds. • These animals are eaten by other animals and so on, up the food chain.

12. Decomposition of organics • When plants and animals decompose or give off wastes, nitrogen is returned to the soil. • Bacteria and fungi break down the nitrogen-containing biotic factors and return the nitrogen compounds to the soil • During the process, some of the nitrogen compounds are converted back into NITROGEN gas, which is returned to the atmosphere. THIS COMPLETES THE CYCLE!!!

13. Nitrogen has a back door! • Nitrogen can also return to the atmosphere through emissions from cars and factories (nitrous oxides) • Volcanoes also emit nitrous oxides.

15. Now, back to the human factor Humans interfere in the Nitrogen Cycle by doing several things: 1. Burning fossil fuels and wood which releases nitrogen compounds into the air (nitric oxide which can combine with oxygen to form Nitrogen Dioxide and eventually acid rain)

16. 2. Dumping of untreated sewage and other wastewater. So much nitrogen in the waterways causes algal blooms and can quickly deplete waterways of oxygen.

18. 3. Use of inorganic fertilizers Currently uses about 5% of the world’s natural gas consumption (about 2% total energy in the world) The minerals used in fertilizers are limited. Phosphorus and Potassium come from mines and Nitrates are made with fossil fuels.

19. Overharvesting a land (stripping it of nitrogen richness) Quite frankly, take away the Nitrogen and plant life (and pretty much everything else) becomes difficult to support.