Oxygen Cycle Centrum

8/3/2019 Oxygen Cycle Centrum

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Respiration

Oxygen gas is poisonous to bacteria that causes

gangrene.

Human benefits

Pure oxygen is used to ensure the complete

combustion of different chemicals.

Oxygen is used to treat water and cut and weldmetals.


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Atmospheric oxygen

-is an important part of the

Earth's atmosphere and of the conditions that

allow for life on Earth.

Sources of oxygen:

(1.) break up of water vapour through process

driven by sunlight - water molecules disassociated


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(2.) Photosynthesis- is the process of converting light energy to

chemical energy and storing it in the bonds of sugar.- Oxygen is produced by plants

and cyanobacteria and phytoplankton in the ocean,.- photosynthesis and aerobic respiration involve

the alternate release and utilization of oxygen

Aerobic respiration-is a process of cellular respiration thatuses oxygen in order to break down molecules-creates a substance known as adenosine

triphosphate (ATP) * Photosynthesis accounts for 98% of the world's

atmospheric oxygen, while the break up of watermolecules by ultraviolet radiation composes the other1-2%.


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Nevertheless, at some time in Earths history,

the amount of oxygen introduced into the

atmosphere had to exceed the amount taken up in

respiration and geological processes. Part of theoxygen present in the atmosphere is from the past

imbalance between photosynthesis and

respiration in plants.


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Photosynthesis Respiration Requires sunlight Does not need sunlight Occurs in cells Occurs in cells

with chlorophyll

Uses water Gives off water Uses carbon dioxide Releases carbon dioxide Gets energy from sun Releases energy from

sugar Makes sugar Breaks down sugar

Releases oxygen Uses oxygen


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The main reservoirs of oxygen cycle:

Water ( H2O )

Carbon dioxide ( CO2 )

Atmosphere

Lithosphere


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Sources of atmospheric oxygen :

Most of the Hydrogen escapes intospace

Water molecules are disassociatedto produce hydrogen and oxygen

Water Vapor break-up

SUNLIGHT


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Exchange Pools

Plants-Take in carbon dioxide from the atmosphere

and then releases oxygen in the atmosphere

through the process ofPhotosynthesis


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The other main source of atmospheric

oxygen is photosynthesis, which

produces sugars and oxygen from

carbon dioxide and water


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Phytoplankton and Cyanobacteria


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Weathering processes initiated by organisms

can also free oxygen from the lithosphere.

Plants and animals extract nutrient mineralsfrom rocks and release oxygen in the process.


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Oxygen CyclesOxygen Cycles


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The Oxygen Cycle in the

Biosphere


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In the biosphere the main cycles are respiration andphotosynthesis.


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The OxygenThe Oxygen CCycle in theycle in the

HydrosphereHydrosphere


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OxygenOxygen in water is known asin water is known as dissolved oxygendissolved oxygen or DOor DO..

1. diffusion from the

surrounding air

2. aeration (rapid movement)

3. as a waste product of

photosynthesis.

How does oxygen get into water?


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When the water in a stream enters a pond,When the water in a stream enters a pond,

microorganisms in the pond begin to metabolizemicroorganisms in the pond begin to metabolize

(break down) organic matter, consuming oxygen in(break down) organic matter, consuming oxygen in

the process.the process.

In nature, oxygenIn nature, oxygen

enters water whenenters water whenwater runs over rockswater runs over rocks

and creates tremendousand creates tremendous

amountsamounts of surfaceof surface

area.area. The high surfaceThe high surface

area allows oxygen toarea allows oxygen totransfer from the airtransfer from the air

into the water veryinto the water very

quickly.quickly.


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TheThe OxygenOxygen CycleCyclein the Lithospherein the Lithosphere


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The lithosphere mostly

fixes oxygen in mineralssuch as silicates and

oxides. Most of the time

the process is

automatic all it takes is

a pure form of anelement coming in

contact with oxygen

such as what happens

when iron rusts.

An example of surface weathering chemistry

is formation of iron-oxides (rust):

4FeO + O2 2Fe2O3


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Marine organisms in the biosphere create calcium

carbonate shell material (CaCO3) that is rich in oxygen.

When the organism dies its shell is deposited on theshallow sea floor and buried over time to create the

limestone rock of the lithosphere.

Weathering processes

initiated by organisms

can also free oxygen

from the lithosphere.

Plants and animals

extract nutrient

minerals from rocksand release oxygen in

the process


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The Oxygen Cycle in theThe Oxygen Cycle in the

AtmosphereAtmosphere


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In the atmosphere Oxygen is freed by the process

called photolysis. This is when high

energy sunlight breaks apart oxygen bearing

molecules to produce free oxygen.

One of the most well known photolysis it the ozonecycle. O2 oxygen molecule is broken down to atomic

oxygen by the ultra violet radiation of sunlight. This

free oxygen then recombines with existing O2

molecules to make O3 or ozone. This cycle is

important because it helps to shield the Earth from

the majority of harmful ultra violet radiation turning it

to harmless heat before it reaches the Earths surface.


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Atmosphere

Surface Organic Matter

Reduced Constituentsof the Crust

Burial

Respirationand Decay

NetPrimary

Production

Weathering


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Several human activities yield adverse effects to the amount of

oxygen in the world. These would include:

o Production of ODS or ozone-depleting substances (i.e. CFCs)

o Denudation of forested areas

o Pollution and eutrophication


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In the past, chlorofluorocarbons or CFCs were used in

refridgerants and coolants.

These substances, along with brominated CFCs, undergo photo-

induced scission to produce chlorine or bromine free radicals.

e.g. CCl3FCCl2F. +Cl.


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This yields in a deficiency of ozone molecules which are

responsible for reflecting off harmful UV radiation.

As a result, photosynthetic organisms and other animals that take

part in the CO2-O2 interaction are greatly harmed.


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This pressing concern was addressed by the signing of the

Montreal Protocol on Substances That Deplete the Ozone Layer

It is an international treaty designed to protect the ozone

layer by phasing out the production of numerous substances

believed to be responsible for ozone depletion.


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This unilateral legislative attempt was successful in obtaining

ratification by over 191 countries.

Because of this, it was quick in gaining motion and ultimately

levelled off or decreased atmospheric ODS content.


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Plants, due to their photosynthetic process, contribute much to

the production of oxygen gas.

With the increase of forested areas being converted into

agricultural, commercial or residential land, the potential

photosythetic output of that specific area greatly reduces.


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Needless to say, the more trees that are cut down, the slower the

overall rate of oxygen synthesis becomes.

This also disrupts the equilibrium of the CO2-O2 interaction


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Pollutants in bodies of water also affect the amount of dissolved

oxygen. Some of these may include excess amounts of nitrogen

and sulfur.

This occurence is called eutrophication, which is an increase in

phytoplankton initiated by the addition of artificial or natural

substances such as nitrates and phosphates

through fertilizers or sewage, to an aquatic system.


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As the organisms in the said bloom die, they are acted upon by

bacteria and other decomposers. The presence of these

decomposers depletes the water of its dissolved oxygen and

increases the production of carbon dioxide.

As an adverse effect, hypoxia occurs, which is the depletion of

oxygen in the water, which induces reductions in specific fish and

other animal populations.


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Oxygen Cycle Centrum

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