Nitrogen Cycle• Nitrogen is an important element for all living organisms• Covers up the 78% of Earth’s atmosphere• Nitrogen Cycle is the circulation of Nitrogen from

atmosphere [Abiotic] to soil [Biotic] and back to atmosphere

• Nitrogen from atmosphere is converted into:• Ammonia (NH3) • Nitrates (NO3)

• It is converted because most of living organisms can’t use the existing Nitrogen in atmosphere• Some organisms can utilize e.g.: Azotobacter.sp and

Rhizobium• Nitrogen is the component of DNA & Proteins• Not all plants can utilize Ammonia, thus it needs to

be processed

Rhizobium root nodules

• Ammonia that is not utilize by plants is absorbed into soil particles• Ammonia that’s in the soil is stored and change

into the useable form that plants can use• IT’S NOT THAT SIMPLE! The ammonia must

combine with oxygen to form nitrites, where the bacteria within the soil convert nitrites into nitrates• Plants can absorb and grow because of nitrates.

• Nitrates (NO3) from the soil is converted back into Atmospheric Nitrogen (N2)• This process helps the replenishing of Nitrogen• Bacteria that lives deep in soil use nitratres and the their product is nitrogen gas• The Nitrogen gas then circulate back through the atmosphere

Human activities on Nitrogen Cycle

• Emission from vehicles and factories which is nitrous oxide can make acid rain• Releasing nitrogen into the Troposphere through deforestation• Contaminating groundwaters from non-organic fertilizers which

contains nitrate ions

Phosphorous Cycle

• The circulation of of phosphorus through lithosphere, hydrosphere, and biosphere.• Phosphorus and phosphorus-based compounds are usually solids found on Earth.• Used as energy source for cell metabolism

Phosphorous Cycle

1. Phosphorous rocks that contains Phosphate ions (PO43-) are exposed to water,

the rock weathers out and become sediments (rock erosion)

2. Plants absorb this phosphorus sediments from groundwater and utilize it

3. Plants then eaten by animals thus obtaining phosphorus (through food chain)

4. Then it seep into the soil or groundwater, and as time goes by it forms into rocks

5. When rock erosion happens again, the cycle is repeated.

Human activities on Phosphorus Cycle• The removal of phosphate from earth for making fertilizers• Phosphorus reduction in tropical soils by clearing forests• Phosphate excession to aquatic systems from runoff of animal wastes

and fertilizers – caused algal blooms

• Algal blooms are the result of an excess of nutrients (particularly phosphorus and nitrogen) into waters and higher concentrations of these nutrients in water cause increased growth of algae and green plants.• As more algae and plants grow, others die.• Produce biotoxins that may have severe biological impacts on wildlife.

Sulfur Cycle

• Movement of sulfur from minerals and living organisms.• Essential for plants and bacteria

1. Plants absorbed sulfate (SO4) and then circulate through series of food chains

2. Dead animals will be degraded into components by bacteria

3. Bacteria reduce sulfate into sulfide (H2S) 4. The sulfide is then used by a photoautotroph bacteria to produce

sulfur and oxygen5. Sulfur is then oxidized into sulfate again.

Sulfur Cycle