Nutrient Cycles

NITROGEN MOLECULES TO KNOW

N2 - Nitrogen Gas

NO2 – Nitrite

NO3 – Nitrate

NH4 – Ammonia

Nitrogen Cycling

Nitrogen Fixationaka 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

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)

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

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

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.

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

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.

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

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• Sea of Azov

In Ukraine

Caspian Sea