Biogeochemical Cycle - The Oxygen Cycle

The oxygen cycle refers to the continuous circulation and recycling of oxygen within the biosphere, including the atmosphere, hydrosphere, and lithosphere. Oxygen forms 21% of the atmosphere and exists in various forms like molecular oxygen (O₂), water (H₂O), and carbon dioxide (CO₂).

Oxygen is released into the atmosphere through photosynthesis by plants and is used up in processes such as respiration, combustion, decomposition, and corrosion. It is highly reactive and readily combines with other elements and compounds. This cycle ensures a balance of oxygen in the environment and supports life by continuously cycling oxygen between biotic and abiotic components.

• Plants produce oxygen during photosynthesis by absorbing carbon dioxide (CO₂) from the atmosphere and converting it into food (sugar molecules).
• Animals breathe in oxygen produced by plants and use it to break down sugar molecules for energy during respiration.
• Animals release CO₂ as a by-product of respiration, which is absorbed by plants to perform photosynthesis.
• The cycle continuously exchanges oxygen and carbon dioxide between plants and animals, maintaining the balance of gases in the environment.

The Oxygen Cycle