How Does Nature Recycle Nutrients?

What is the Nitrogen Cycle?

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Facts:

► Nitrogen (N) is an essential constituent of protein, DNA, RNA, and chlorophyll.

► Nitrogen is the most abundant gas in the atmosphere (78%), but it must be fixed or converted into a usable form.

How is Nitrogen Fixed?

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Nitrogen Fixation Methods:

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High energy fixation-

nitrogen is fixed by lightening. The high energy combines N and H 2 a small amount of atmospheric O resulting in ammonia (NH 3 ) and nitrates (NO 3 ). These forms are carried to Earth in precipitation. ►

Biological fixation

(NH 3 ). : achieves 90% of the nitrogen fixation. Atmospheric nitrogen (N 2 ) is split and combined with hydrogen (H) atoms to eventually form ammonia

Who Performs Nitrogen Fixation?

    Symbiotic bacteria association with leguminous (plants in the pea/bean family).

(eg. Rhizobium spp.) living in - free-living anaerobic bacteria - blue-green algae (cyanobacteria ) Ammonification : Once NH 3 is in the soil it combines with 4 ), or without it to form NO 3 . NH 4 + and NO 3 are readily absorbed by plants. Nitrification : is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of these nitrites into nitrates (bacteria) Denitrification : Bacteria reduces nitrates and nitrites back into gaseous nitrogen (N 2 )

The Nitrogen Cycle

What is the Carbon Cycle?

► ► ► ► All life is based on the element

carbon

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Carbon is the major chemical constituent of most organic matter, from fossil fuels to the complex molecules (DNA and RNA) that control genetic reproduction in organisms. Yet by weight, carbon is not one of the most abundant elements within the Earth's crust. In fact, the lithosphere is only 0.032 % carbon by weight. In comparison, oxygen and silicon respectively make up 45.2 % and 29.4 % of the Earth's surface rocks.

The Carbon Cycle

Where is Carbon Stored ► Living Organisms (organic molecules) ► Sedimentary Rock (limestone, dolomite) ► Shells of marine organisms (calcium carbonate) ► Fossil Fuels ► Carbon Dioxide in our atmosphere ► Organic matter in our soils

What is the Phosphorus Cycle?

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Component of DNA, RNA, ATP, proteins and enzymes

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Cycles in a sedimentary cycle - A good example of how a mineral element becomes part of an organism.

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The source of Phosphorus (P) is rock.

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It is released into the cycle through erosion or mining.

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It is soluble in H 2 O as phosphate (PO 4 )

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It is taken up by plant roots, then travels through food chains.

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It is returned to sediment

The Phosphorus Cycle

What is the Oxygen Cycle?