Biogeochemical cycles

Science

Definition

Biogeochemical cycles are the pathways by which essential chemical elements and compounds move through the biotic (living) and abiotic (non-living) components of Earth's systems. The major cycles include the carbon, nitrogen, phosphorus, and water cycles.

Examples

  • The carbon cycle moves carbon through the atmosphere (CO₂), organisms (organic molecules), oceans, and rocks (fossil fuels, limestone)
  • The nitrogen cycle converts atmospheric N₂ into ammonia through nitrogen-fixing bacteria, making it available to plants
  • The phosphorus cycle is unique among major cycles because it has no significant gaseous phase—phosphorus moves mainly through rock, soil, and water

Related Terms

Water cycle Ecosystems Photosynthesis Climate change

Study This Concept

Practice biogeochemical cycles with free review games in these units:

AP Environmental Science Unit 1: The Living World: Ecosystems