1. Nutrient Cycles

2. NITROGEN MOLECULES TO KNOW
N2 - Nitrogen Gas
NO2 – Nitrite
NO3 – Nitrate
NH4 – Ammonia

3. Nitrogen Cycling

4. Nitrogen Fixation aka nitrification
To be useful to plant organisms nitrogen must be supplied in the form of the Nitrate ion NO3 –
NITROGEN FIXATION is a series of processes when Nitrogen gas from the atmosphere (N2) is converted into Nitrate ions
Nitrogen fixation can occur through lightning or through special bacteria

5. Fixation by Lightning
Energy in lightning causes Nitrogen gas to combine with Oxygen gas to for Nitrates
The Nitrates dissolve in rain and move into plants through their roots
Plants use these nitrates to make amino acids (proteins)

6. Nitrogen Fixation by Bacteria
Special bacteria are responsible
for creating most of the Nitrates
plants need.
Bacteria nodules form on the roots of legumes (beans, peas, alfalfa) to supply them with usable nitrogen
Excess nitrates move into the soil to help other plants

7. Decomposing Nitrogen
When organisms die decomposers break Nitrogen containing molecules into simpler chemicals like ammonia (NH3) AMMONIFICATION
Some bacteria convert Ammonia into nitrites
(Nitrification)
Some bacteria can turn nitrites into nitrates (Nitrification)
With the right bacteria decaying matter like manure can be turned into usable nitrates

8. Denitrification
When there is low oxygen in the soil bacteria can remove oxygen turning nitrates (NO3) back into nitrites (NO2) and then back into Nitrogen Gas (N2)
Denitrification usually occurs in bogs leaving the soil low in usable nitrogen.

9. Phosphorous Cycle
Phosphorous is a key element in ATP, DNA and the Calcium Phosphate in bones.
Phosphorous is cycled between living organisms by decomposers
Phosphorous is also found in Bedrock in Phosphate ions. Phosphates can dissolve out of rocks and can be absorbed by plants

10. Human Effects on Cycling
Fertilizers are materials used to restore nutrients like nitrogen and phosphorous that have been removed from the soil.
Runoff from fields carries extra nutrients into streams. This can cause Eutrophication
Eutrophication is the over concentration of nutrients in an ecosystem
Eutrophication can also be caused by municipal or industrial sewage deposit.

11. Eutrophication (to much of a good thing)
Causes overgrowth of algae (Algal Bloom) which may block out sunlight
Nitrates in water are dangerous for animals that have hemoglobin in their blood
Increased numbers of decomposing algae and animals reduces the amount of oxygen in the water causing even more species death

17. Sea of Azov
In Ukraine

18. Caspian Sea