The document discusses several important biogeochemical cycles on Earth:
- The water cycle describes the continuous movement of water across the planet through evaporation, condensation and precipitation.
- The carbon-oxygen cycle involves the release of oxygen by animals and absorption of carbon dioxide by plants during photosynthesis to regulate gas levels in the air.
- The nitrogen cycle is the process by which nitrogen and its compounds are converted between different forms through nitrogen fixation and decomposition in both the environment and living organisms.
- Other key cycles discussed include the sulfur cycle involving the movement of sulfur between minerals, waterways and living systems, and the phosphorus cycle governing the movement of phosphorus through the lithosphere, hydrosphere and bi
