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BIOGEOCHEMICAL CYCLES

LECTURER:

Mr. Faisal Arrieta Alonto Jr., M.S. Biology

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Nitrogen Cycle

All life requires nitrogen-compounds, e.g., proteins andnucleic acids.

Air, which is 79% nitrogen gas (N2), is the majorreservoir of nitrogen.

But most organisms cannot use nitrogen in this form. Plants must secure their nitrogen in "fixed" form, i.e.,incorporated in compounds such as:nitrate ionsammoniaurea

Animals secure their nitrogen (and all other) compoundsfrom plants (or animals that have fed on plants).

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5 Processes in Nitrogen Cycle

nitrogen fixation

Ammonification Assimilation

nitrification

denitrification

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Three processes are responsible for most of

the nitrogen fixation in the biosphere:

atmospheric fixation by lightning

biological fixation by certain microbes

alone or in a symbiotic relationship withsome plants and animals

industrial fixation the use of fertilizers

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Symbiosis.htmlhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Symbiosis.html

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Assimilation

The process of convertingammonium ions (NH3

-) into organicnitrogen (amino acids and protein)

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Ammonification

When plants or animals die orproduce wastes their nitrogencontaining molecules are brokendown and the nitrogen is released inthe form of ammonia.

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Nitrification

The process where ammonium isconverted into nitrite (NO2

-) theninto nitrate (NO

3

-)by nitrogen-fixingbacteria

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Denitrification

The process wherein nitrate (NO3-)

is converted into atmosphericnitrogen (N

2) by the denitrifying

bacteria and return it to theatmosphere

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Atmospheric fixationby Lighting

Biological fixationBy: microorganisms

(nitrogen-fixing bacteria)

Assimilation

AmmonificationBy: Ammonifying bacteria

Nitrification

By: nitrifyingbacteria

DenitrificationBy: Denitrifying

bacteria

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http://upload.wikimedia.org/wikipedia/commons/d/de/Nitrogen_Cycle.jpg

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WATER CYCLE or Hydrologic Cycle

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Processes involved in water cycle

Evaporation (vapor)

Condensation (water)

Transpiration (plants) Sublimation (ice and snow)

Precipitation (rain)

Infiltration (underground water)

Run-off (directed in the bodies ofwater)

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Carbon Cycle

Major processes involved

1. Photosynthesis2. Respiration

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Carbon cycle

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Processes in Phosphorus Cycle

Decomposition converting the organiccompound into inorganic compound whichmay contain phosphate

Leaching

bringing the phosphatecompound in bodies of water

Sedimentation deposition of sedimentswith phosphate materials at the bottom ofthe ocean

Weathering phosphate becomesavailable from the breakdown of rocks forplant use

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PHOSPHORUS CYCLE

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Sulfur Cycle

The storage of sulfur in the variouscompartments of Earth and its biosphere,and the many transfers occurring among

them, is referred to as the sulfur cycle. Sulfur (S) occurs in the environment in

many chemical forms, including organicand mineral compounds, either of which

can be chemically transformed by bothbiological and inorganic processes.

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Sulfur Cycle