1. The Biogeochemical Cycles

2. © 2003 John Wiley and Sons Publishers Idealized diagram of the geologic cycle, which includes the tectonic, hydrologic, rock and biogeochemical cycles.

3. Ecosystem Biotic and abiotic components are required for proper ecosystem functioning.

4. Nitrogen Cycle Vocabulary Nitrification Denitrification Nitrogen fixation Decomposition Absorption Consumption N 2 Nitrogen NH 3 Ammonia NH 4 + Ammonium Ion NO 2 - Nitrite NO 3 - Nitrate N 2 O Nitrous Oxide

5. © 2003 John Wiley and Sons Publishers Fig 4.5 Periodic table of the elements.

6. Vocabulary Nitrification- Chem rxn that converts Ammonium (NH 4 + ) to Nitrate (NO 3 - ) and Nitrite (NO 2 - ) Denitrification- Chem rxn that converts Nitrate and Nitrite ions into Nitrogen gas (N 2 ) and Nitrous Oxide (N 2 O) Nitrogen fixation- Conversion of N 2 from atmosphere into ammonia and ammonium ions for plants and animals Decomposition- Plants and animals decompose and break down supplying the soil with Nitrogen Absorption- Plants absorb nitrogen from the soil Consumption- Animals eat plants that have nitrogen in them

7. Figure 36.16 Nitrogen (N 2 ) in atmosphere Amino acids and proteins in plants and animals Consumption Absorption by plants Denitrifying bacteria Denitrification Nitrates (NO 3 – ) Nitrifying bacteria Nitrifcation Detritus Detritivores Decomposition Ammonium (NH 4 + ) Nitrogen fixation Nitrogen-fixing bacteria in soil Nitrogen-fixing bacteria in root nodules of legumes Nitrogen fixation

8. Nitrogen Fixation Convert N 2 from atmosphere to a usable form: NH 4 +1 or NO 3 -1 Ammonia or Nitrate Three methods of Nitrogen Fixation: 1.atmospheric fixation by lightning 2.biological fixation by certain microbes - alone or in a symbiotic relationship with plants

9. The nitrogen cycle relies heavily on bacteria Nitrogen is plentiful in the atmosphere as N 2 –But plants cannot use N 2 Various bacteria in soil (and legume root nodules) convert N 2 to nitrogen compounds that plants can use –Ammonium (NH 4 + ) and nitrate (NO 3 – ) Nitrogen Fixation continued…

10. Nitrogen fixation by lightning Nitrates are produced by forest fires and lightning.

11. Nitrogen fixation by bacteria Atmospheric nitrogen (78% of atmosphere) is chemically fixed by bacteria to ammonium (NH 4 +1 ), which is used by plants as a fertilizer.

12. Nitrogen cycle

13. © 2003 John Wiley and Sons Publishers Critical Thinking Issue – How are Human Activities Affecting the Nitrogen Cycle? Increased nitric acid in soil: Leaching of magnesium and potassium Increased aluminum levels Plant root damage Changes in microbe communities Fish kills Eutrophication of water bodies Nitrates in drinking water Effects of increased use of nitrogen fertilizer:

14. The Nitrogen Cycle Copyright © McGraw-Hill Companies Permission Required for Reproduction or Display

15. A single atom of nitrogen can have sequential effects in various parts of the environment after it has been converted from non-reactive N2 to a reactive form during energy or food production. N Cascade