Oxygen Cycle

The oxygen cycle is the cycle that helps move
oxygen through the three main regions of the
Earth, i.e. the Atmosphere, the Biosphere, and
the Lithosphere. The Atmosphere is of course the
region of gases that lies above the Earth’s surface
and it is one of the largest reservoirs of free
oxygen on earth. The Biosphere is the sum of all
the Earth’s ecosystems. This also has some free
oxygen produced from photosynthesis and other
life processes? The largest reservoir of oxygen is
the lithosphere. Most of this oxygen is not on its
own or free moving but part of chemical
compounds such as silicates and oxides.
In the atmosphere Oxygen is freed by the
process called photolysis. This is when high
energy sunlight breaks apart oxygen bearing
Chronicle IAS Academy [8]
molecules to produce free oxygen. One of the
most well known photolysis it the ozone cycle.
O2 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
radiations turning it to harmless heat before it
reaches the Earth’s surface.
In the biosphere the main cycles are
respiration and photosynthesis. Respiration is
when animals and humans breathe consuming
oxygen to be used in metabolic process and
exhaling carbon dioxide. Photosynthesis is the
reverse of this process and is mainly done by
plants and plankton.
The lithosphere mostly fixes oxygen in
minerals such as silicates and oxides. Most of the
time the process is automatic, all it takes is a pure
form of an element coming in contact with
oxygen such as what happens when iron rusts.
A portion of oxygen is freed by chemical
weathering. When a oxygen bearing mineral is
exposed to the elements a chemical reaction
occurs that wears it down and in the process
produces free oxygen.