1. Nutrient Cycles Nitrogen & Phosphorus

2. Why Nitrogen is Important
Nitrogen is important for a number of reasons
DNA and Protein
Protein for Muscle
Nitrogen for plant growth

3. Stores of Nitrogen 78% of our atmosphere is Nitrogen!
Also in oceans and organic matter in soils
Small amounts in terrestrial systems

4. The Nitrogen Cycle Cycle involves plants and bacteria
1 – Nitrogen Fixation
- The process by which atmospheric N2 is converted into NH4 or NO3-
2 – Nitrification
- The process by which NH4 is converted into NO3- or NO2- (by Nitrifying Bacteria)
3 – Uptake
- Plants incorporating Nitrates into their tissues

5. Nitrogen Fixation (3 places)
1 – Atmosphere 2 –Soil - legumes - free soil bacteria 3 – Oceans -cyanobacteria

6. Nitrification and Uptake
Nitrification (by nitrifying bacteria)
NH4 (ammonium) NO2- (nitrite)  NO3- (nitrate)
Uptake – Nitrates enter plants  Animals
Denitrification
Bacteria return
NO3-  N2

8. Human Impact
In WWI a German scientist discovered how to fix atmospheric nitrogen artificially (we haven’t looked back) we have added 50% more nitrogen to ecosystems
Fossil Fuels & Sewage
Leeching and Eutrophication (write definitions)

9. The Phosphorus Cycle Important for plant growth Energy metabolism
Roots/Stems
Animals (Humans)
Energy Metabolism
Bones

10. Stores
Trapped as phosphates(PO43–, HPO42–, H2PO4–) found in rocks and ocean sediments.
Weathering
Chemical – acids and lichens
Physical – wind, water, freezing…
Uptake by plants and animals

12. Human Impact
We are adding excess phosphorus to the environment through mining for fertilizer components
We are pouring it into ecosystems faster than natural stores can be replenished (non-renewable)
Reducing Supply
Slash-and-burn of forests removes phosphorus from ecosystems