Oxygen Cycle Facts

The Oxygen Cycle moves oxygen through the Earth in three main areas, including the Lithosphere, the Biosphere, and the Atmosphere. The area that has the freest oxygen is the atmosphere, which is the area that is located directly above the surface of the Earth.

The oxygen cycle is connected with the carbon cycle.

Global Oxygen Cycle

Oxygen Cycle Facts for Kids:

  • All living creatures breathe in Oxygen
  • Plants take in carbon dioxide and release Oxygen
  • Oxygen is produced by plants using photosynthesis
  • Oxygen in the Earth’s atmosphere is around 21%.
  • The biggest element of the body is oxygen.
  • Plants replace 99% of the oxygen that is used.
  • Fish under the water breath oxygen.
  • The Earth’s crust has many minerals that are made of oxygen, but it does not help people to breathe.
  • Phytoplankton is small plants and they produce the most oxygen.
  • One interesting thing about oxygen is it is cycled from plant to animal and back to plant.  It is a continuous circle.
  • When animals or people breathe in oxygen, it is called respiration.
  • Oxygen is used when dead things decompose.
  • When the sun hits water vapor, oxygen is released into the atmosphere.
  • When a lot of trees and plants are cut down, our oxygen level decreases.
  • The oxygen that humans breathe goes in like oxygen, but it mixes with the carbon from the food we eat and that is why it comes out as carbon dioxide.
  • The sun is made up of 1% oxygen.

The Lithosphere

Most of the oxygen is found in the Lithosphere but a lot of this type of oxygen is what makes things rust.

The Biosphere

The Biosphere is all of the ecosystems put together.  This helps to make oxygen through photosynthesis and other ways that life changes.

The Atmosphere

The atmosphere is the place that is above the Earth’s surface.  It has the least amount of oxygen compared to other parts of the Earth.

How Does Oxygen Cycle Work?

Plants and animals use oxygen.  The plants are the ones that create the most oxygen in the atmosphere when they use photosynthesis.

When a plant or a tree uses sunlight for photosynthesis, it takes in the carbon dioxide to make energy and then it releases oxygen back into the atmosphere.

Animals then breathe in the oxygen and they breathe out the carbon dioxide.  The plants use the carbon dioxide that the animal’s breath out and this completes the oxygen cycle.

What Processes Help to Use Oxygen?

There are different processes that use oxygen such as:

  • Combustion-combustion happens when things burn.  Oxygen is used with combustion because as things burn, they use up oxygen.  Oxygen is then replaced with carbon dioxide.  In order for combustion to work, it has to have heat, fuel, and oxygen.
  • Decomposing-When something decomposes, it means it dies.  When a plant or animal begins to decompose, it uses up oxygen and then releases carbon dioxide into the atmosphere.
  • Rusting-things use up oxygen to rust.  Rusting is also called oxidation.
  • Breathing-animals and people use oxygen to breathe.  They breathe in oxygen and release carbon dioxide into the atmosphere.

What Processes Make Oxygen?

There are different ways that oxygen is made such as:

  • Sunlight-sunlight is produced when it mixes with water vapor in the Earth’s atmosphere.
  • Plants-plants help to make most of the oxygen that is in the atmosphere.  Photosynthesis is used to create the oxygen that people and animals breathe.  The plant uses sunlight and carbon dioxide to make energy and then when they make energy, they make oxygen that is released into the atmosphere.

All About Oxygen

Oxygen is one of the biggest elements that is found in the atmosphere.  The only other element that is higher in nitrogen.


Water helps to make a lot of the oxygen that goes into the atmosphere.  Algae replace a lot of the oxygen into the atmosphere.


Plants and trees are important because they help to replenish the oxygen into the air.  Since there are so many plants and trees on the Earth, the oxygen is pretty strong and continues to move in the atmosphere.

Remember, plants make their own food and they absorb the carbon dioxide that is found in the water, soil, and the air.

The leaves on the plants have chlorophyll and this helps to break down the carbon dioxide to make food for the plant.  Oxygen is then released, and this is all of the stages of photosynthesis.

What Affects the Oxygen Cycle?

When carbon dioxide is released in the atmosphere it affects the oxygen cycle.  When people burn fossil fuels and other pollution is released into the air, oxygen can be replaced by carbon dioxide and it can change the way that oxygen is cycled.

What Did You Learn?

  • What is the oxygen cycle?  The oxygen cycle is when oxygen forms in the atmosphere and is circulated through different types of nature.
  • How does oxygen help people?  Oxygen is important because it helps people and animals to be able to breathe.
  • How do plants and trees help people breathe?  Plants and trees help people to breathe because they take in carbon dioxide and use it to make energy and then the energy releases oxygen into the air.  The oxygen that plants and trees release is what we breathe.
  • What other sources produce oxygen?  Oxygen is found in both water and in plants.  Oxygen in the water helps fish to breathe.
  • Where are the three areas that oxygen is found?  Oxygen is found in the biosphere, the lithosphere, and the atmosphere.