Definition - What does Oxygen Cycle mean?
Oxygen cycle refers to the movement of oxygen through the atmosphere (air), Biosphere (plants and animals) and the Lithosphere (the earth’s crust). The oxygen cycle demonstrates how free oxygen is made available in each of these regions, as well as how it is used.
Safeopedia explains Oxygen Cycle
Although the earth’s crust holds the largest reserve of oxygen, most of this oxygen is bound in mineral compounds and is unavailable. The largest contributor to the oxygen cycle is photosynthesis, a process in which plants use carbon dioxide, light and water to produce oxygen from carbon dioxide. As a result, the oxygen and carbon cycles are closely connected. The increased release of carbon dioxide through emissions has disrupted the carbon cycle, and plants are no longer able to produce enough oxygen to prevent atmospheric carbon dioxide concentrations from increasing.