The percentages of gases like oxygen, nitrogen, and carbon dioxide in the atmosphere remain relatively constant due to continuous natural cycles that balance the processes of their release and consumption. These cycles involve interactions between biotic (living) and abiotic (non-living) components of the biosphere, transferring matter and energy.
Here’s a more detailed explanation:
Oxygen Cycle:
Oxygen is released into the atmosphere through photosynthesis by plants and consumed through respiration by living organisms and the combustion of fuels.
Nitrogen Cycle:
Nitrogen is converted between different forms (e.g., gas, nitrates) through various biological and physical processes, including fixation by microorganisms, decomposition, and denitrification.
Carbon Cycle:
Carbon dioxide is released into the atmosphere through respiration, decomposition, and volcanic activity, while it’s absorbed by plants during photosynthesis and dissolved in the oceans.
These cycles continuously replenish and remove gases, ensuring a relatively stable atmospheric composition. For example, plants take in carbon dioxide during photosynthesis, and animals and plants release it through respiration, maintaining a balance.