1. The Nitrogen Cycle By Kristen Keech March 22, 2003

2. What is the Nitrogen Cycle? The nitrogen cycle consists of nitrogen in the atmosphere or soil that go through many complex changes. The changes are combined into living and non living materials. They turn back to the soil and air. The cycle continues.

3. More about the Nitrogen Cycle The largest amount of nitrogen is in the atmosphere. Other places that nitrogen is found are oceans and soils. Plants use nitrogen to grow and to make seeds to reproduce.

4. Follow the tour

5. Another way to look at the Nitrogen Cycle

6. Nitrogen Cycle Facts Nitrogen can be lost in the cycle. Nitrogen gas takes up 79% of our atmosphere! Living things need nitrogen to make proteins.

7. FORMS OF NITROGEN 1. Ammonia- (NH3) Waste product of animals during respiration, released during excretion. It is usually found as a liquid, but it can volatilize (definition on next page) into a gas. Ammonia is toxic to most organisms. 2. Ammonium- (NH4+) When ammonia is mixed with water, it grabs another hydrogen from the water molecules and makes ammonium. This is the only way you will ever see ammonia in nature. Also, it tends to stick to soil and clay particles instead of being washed away like nitrate. 3. Dinitrogen- (N2) This is a gas and is one of the most abundant gases in the atmosphere. 4. Nitrate- (NO3-) This is usually found as a liquid and is very easily washed out of the soil and into groundwater or streams. Farmers don't like when their fertilizer gets turned into this, because it washes away too easily and isn't always in the soil long enough to help their plants. 5. Nitric Acid- (HNO3) This is the form of nitrogen in acid rain. It is also made by lightning. 6. Nitrite- (NO2-) This is a middle step during the process of nitrification. It is very toxic to organisms. In a new fish tank, nitrite can build up because the next step of nitrification can't continue until all the ammonium is gone, so you have to carefully measure NO2- when you first add fish to a tank. 7. Nitrogen oxides- (N2O and NO) These are greenhouse gases and are a middle step (intermediate) between nitrate and N2 gas. 8. Organic Nitrogen- (CaHbNcOd) Organic molecules containing nitrogen come in many forms from amino acids to proteins to lipids.

8. LETS DO A FUN ACTIVITY Instructions for FISH (2 initially in each round) These instructions are for EACH person acting as a fish Your job is to eat organic nitrogen (JELLY BEANS) and make new fish. You also exude nitrogen. 1. You eat the 3 Organic Nitrogen the "farmer" gives you. 2. Every 30 seconds, you EXUDE 1 NH3 and 1 Organic N (put them on the WATER table) 3. If you have 5 Nitrogen EACH, then you "reproduce" and make a new fish-grab another student out of the class to be a fish and put the 10 total nitrogen aside.