Oxygen Cycle

Table of Contents
What is Oxygen Cycle?	Stages of the Oxygen Cycle
Uses of Oxygen	Production of Oxygen
Facts about oxygen	Importance of Oxygen

As we all know, the air is a mixture of gases. The air in the atmosphere is composed of different gases, namely nitrogen (78%), oxygen (21%), argon and other trace gases (1%).

According to the earth’s history, oxygen gas was first introduced by cyanobacteria through the process of photosynthesis. Earlier, around 4.6 billion years ago, there was no life on planet earth because the atmosphere was devoid of oxygen. Later, there was a gradual increase in the oxygen levels and by the Carboniferous Period- 299 million years ago, oxygen reached the levels that were similar to today’s estimates.

Today, oxygen is freely available in the air and also dissolved in water. It is the second most abundant gas present in the atmosphere and also the most common element of the human body. It plays an essential role in most life forms on earth and also serves as an essential element in biomolecules like proteins and nucleic acids.

Read on to explore more about oxygen, its uses, production and how it is recycled in a cyclic pattern.

A Diagrammatic Representation of the Oxygen Cycle

Oxygen cycle, along with the carbon cycle and nitrogen cycle plays an essential role in the existence of life on the earth. The oxygen cycle is a biological process which helps in maintaining the oxygen level by moving through three main spheres of the earth which are:

• Atmosphere
• Lithosphere
• Biosphere

 This biogeochemical cycle explains the movement of oxygen gas within the atmosphere, the ecosystem, biosphere and the lithosphere. The oxygen cycle is interconnected with the carbon cycle.

The atmosphere is the layer of gases presents above the earth’s surface. The sum of Earth’s ecosystems makes a biosphere. Lithosphere is the solid outer section along with the earth’s crust and it is the largest reservoir of oxygen.

Also Read: Biogeochemical Cycle

The  four main processes that use atmospheric oxygen are:

Breathing – It is the physical process, through which all living organisms, including plants, animals and humans inhale oxygen from the outside environment into the cells of an organism and exhale carbon dioxide back into the atmosphere.

Decomposition: It is one of the natural and most important processes in the oxygen cycle and occurs when an organism dies. The dead animal or plants decay into the ground, and the organic matter along with the carbon, oxygen, water and other components are returned into the soil and air. This process is carried out by the invertebrates, including fungi, bacteria and some insects which are collectively called as the decomposers. The entire process requires oxygen and releases carbon dioxide.

Read more: Decomposition

Combustion: It is also one of the most important processes which occur when any of the organic materials, including fossil fuels, plastics and wood, are burned in the presence of oxygen and releases carbon dioxide into the atmosphere.

Rusting: This process also requires oxygen. It is the formation of oxides which is also called oxidation. In this process, metals like iron or alloy rust when they are exposed to moisture and oxygen for an extended period of time and new compounds of oxides are formed by the combination of oxygen with the metal.

Plants: The leading creators of oxygen are plants by the process of photosynthesis. Photosynthesis is a biological process by which all green plants synthesize their food in the presence of sunlight. During photosynthesis, plants use sunlight, water, carbon dioxide to create energy and oxygen gas is liberated as a by-product of this process.

Sunlight: Sunlight also produces oxygen. Some oxygen gas is produced when the sunlight reacts with water vapour in the atmosphere.

Also Refer: Exchange Of Gases

• Phytoplankton is one of the most significant producers of oxygen, followed by terrestrial plants and trees.
• Oxygen is also produced when the sunlight reacts with water vapour present in the atmosphere.
• A large amount of oxygen is stored in the earth’s crust in the form of oxides, which cannot be used for the respiration process as it is available in the combined state.