Oxygen Cycle: Definition, Diagram, Examples, Uses, Production And Facts About Oxygen

Oxygen Cycle Definition

The oxygen cycle is a biogeochemical process through which oxygen exchanges between the atmosphere, biosphere, lithosphere, and hydrosphere.

What is the Oxygen Cycle?

The oxygen cycle in Biology is a biogeochemical process through which oxygen exchanges between the atmosphere, biosphere, lithosphere, and hydrosphere. Oxygen is of fundamental importance for life, it accounts for one-half of the molecules produced in cellular respiration and sustains life on Earth. The cycle thus maintains an equilibrium level of oxygen availability in the environment, supporting life on Earth.

Components of the Oxygen Cycle

The components of the oxygen cycle are:

Atmospheric Oxygen

• Constitutes 21% of Earth's atmosphere.

• Synthesised primarily through photosynthesis.

• Oxygen is consumed by all organisms for respiration.

Biosphere Oxygen

• Includes all living organisms- plants, animals, and microbes.

• All living organisms take oxygen for respiration and release during photosynthesis.

• Serves as a basis for aerobic respiration.

Oxygen in Water (Hydrosphere)

• Existent as dissolved oxygen which is used by aquatic living organisms.

• In oceanic phytoplanktons, tremendous amounts of oxygen are produced.

Oxygen in the Lithosphere

• They are found in the crust of Earth as oxides and silicates.

• Released into the atmosphere via natural processes such as weathering.

Oxygen Cycle Stages

The stages of the oxygen cycle include:

Photosynthesis

• Phototropic organisms, including plants, algae, and cyanobacteria, convert carbon dioxide and water into glucose and oxygen.

• Oxygen is released into the atmosphere and replenishes the reserve.

Respiration

• Organisms (plants inclusive breathe in oxygen to liberate energy associated with glucose.

• Oxygen is used and carbon dioxide is emitted.

Decomposition

• Lifeless organisms and waste are broken down by decomposers - bacteria, and fungi.

• Oxygen is taken in by releasing carbon dioxide.

Combustion

• The combustion of fossil fuels or organic matter takes in oxygen and produces carbon dioxide.

• It provides atmospheric CO₂ and reduces oxygen concentration.

Oxidation and Weathering

• Rocks, primarily iron-containing, are being oxidised (rust).

• Oxygen reacts with minerals, slowly giving it out or taking it in the process.

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Production of Oxygen

Oxygen is both naturally produced and industrially produced:

Natural Production

Plants, algae, and cyanobacteria generate oxygen as a byproduct of photosynthesis.

Industrial Production

• Oxygen is industrially produced by fractional distillation of liquid air, which separates it from nitrogen and others like argon.

• Water can also be separated into oxygen and hydrogen through electrolysis, which is an electrolytic technique that uses electric current.

Significance of the Oxygen Cycle

The oxygen cycle holds great significance due to the following factors:

Balances Oxygen Concentration

Maintains oxygen concentration in the atmosphere and aquatic ecosystems.

Helps Support Life

Provides oxygen for aerobic respiration in plants, animals, and microorganisms.

Ecosystem Processes

Decomposers, producers, and consumers must maintain the energy flow and nutrient cycles.

Oxygen Control in The Atmosphere

Prevents depletion of oxygen and aids in sustaining the continuation of life on Earth.

Oxygen Cycle Examples

Some common examples of the oxygen cycle are:

Photosynthesis: Plants and cyanobacteria, respectively, convert sunlight, water, and carbon dioxide into glucose, generating oxygen.

Respiration: Oxidation of glucose for energy by animals and plants produces carbon dioxide.

Decomposition: Decomposers, such as fungi and bacteria, use oxygen to decompose dead plants and animals and organic material, releasing CO₂.

Combustion: Combustion of fossil and organic fuels burns oxygen and emits carbon dioxide.

Oxidation: Iron-rich rocks weather as well as rust in contact with oxygen in the air.

Human Activities Involving Oxygen Cycle

Human beings both create and destroy the oxygen cycle through human activities. From clear-cutting and industrialisation, these activities may otherwise affect the balance of oxygen in the atmosphere, land, and water, bringing about environmental consequences such as global warming, oxygen depletion, and destruction of habitats.

Deforestation

• Reduces the number of trees that undergo photosynthesis.

• The atmospheric oxygen is depleted with time.

Fossil Fuel Combustion and Industrialisation

• Combustion uses up plenty of oxygen and releases CO₂.

• Contributes to global warming and climate change.

Water Body Pollution

• The presence of fertilizers leads to eutrophication and therefore algal blooms. When these algae decompose, the dissolved oxygen level in the water is depleted.

• Gives rise to "dead zones" in the ocean and lakes that do not support aquatic life.

Reusing and Recycling Activities

• Enhances the levels of oxygen through afforestation.

• Eliminates the use of fossil fuels by the use of renewable energy resources.

• Reduces water pollution from the fertilizers runoff.

Oxygen Cycle in Aquatic Ecosystems

Aquatic ecosystems are the core of the oxygen cycle of the world because water bodies, such as oceans, lakes, and rivers, form large reservoirs of dissolved oxygen. Oxygen flux between the atmosphere and the aquatic environment is important to life in the ocean and the stability of marine ecosystems.

Importance of Dissolved Oxygen

• Dissolved oxygen is necessary for the respiration of aquatic life, such as fish.

• Low concentrations of oxygen can lead to large-scale death of fish.

Factors Limiting Dissolved Oxygen

• Temperature: Warm water holds less dissolved oxygen.

• Salinity: Salinity greater than 35 ppt decreases levels of dissolved oxygen.

• Pollution: Organic waste and nutrient enrichment from agriculture decreased levels of dissolved oxygen.

Role of Phytoplankton

• Small, photosynthetic organisms release much of Earth's oxygen.

• Involved in the oxygen cycle in marine ecosystems.

Dead Zones

• Regions in oceans that are too anoxic to support a significant percentage of living organisms.

• Attributed to nutrient pollution and eutrophication.

Uses of Oxygen

Oxygen has vital applications in biological, industrial, and medical use as described below:

Biological Use

• Essential for cellular respiration in humans, animals, and most microorganisms.

• Release of food energy in cells.

Industrial Use

• Applicable in the process of manufacturing steel through oxidation and cutting metals.

• Oxygen is very relevant for the chemical reactions that produce materials such as plastics and chemicals.

Medical Use

• Used in oxygen therapy treatment of patients with respiratory failure.

• Vital for life support systems in hospitals and people suffering from lung diseases.

Role of Oxygen in the Regulation of Global Climate

Oxygen is one of the major factors that help to balance Earth's climate. This occurs because oxygen directly impacts the carbon cycle and the amount of greenhouse gases held within the atmosphere. The interaction between oxygen and both photosynthesis and respiration promotes the stability of atmospheric composition and minimises the impacts of climate change.

Interrelationship with the Carbon Cycle

• Photosynthesis and respiration are interlinked in the sense of oxygen and carbon cycles.

• Carbon dioxide produced by respiration is used in photosynthesis, and oxygen produced is used by respiration.

Regulation of Greenhouse Gases

• Oxygen facilitates the removal of CO₂ by supporting plant growth.

• Reduced photosynthesis from trees will, however, upset the balance increase in atmospheric CO₂ and enhanced Greenhouse effect.

Oxygen Cycle Facts

Oxygen is one of the most common elements present in the world, yet there are so many interesting facts about it. Here are some of them.

• 21% of the atmosphere consists of oxygen.

• Oxygen is the third most abundant element present in the universe.

• It is one of the most reactive elements which forms compounds with almost all other elements.

• The level of oxygen in the Earth's atmosphere was once at very low levels but began to increase remarkably about 2.4 billion years ago.

• A person cannot survive more than a few minutes without breathing oxygen.

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