AP Environmental Science

Advanced Placement Environmental Science examining environmental systems and human impact.

Basic Concepts

Biogeochemical Cycles

Essential Cycles in Nature

Biogeochemical cycles describe how important elements—like carbon, nitrogen, and water—move through the environment.

The Water Cycle

  1. Evaporation: Water turns into vapor and rises.
  2. Condensation: Vapor cools and forms clouds.
  3. Precipitation: Water falls as rain or snow.
  4. Runoff: Water flows back to oceans and lakes.

The Carbon Cycle

Carbon moves from the atmosphere into plants through photosynthesis, then into animals, and finally returns to the air via respiration or decay.

The Nitrogen Cycle

Nitrogen-fixing bacteria turn nitrogen gas into forms plants can use. Animals eat plants, and decomposers return nitrogen to the soil.

Why Cycles Matter

Disrupting these cycles can cause problems like climate change or water shortages.

Examples

  • Burning fossil fuels increases atmospheric carbon, contributing to global warming.

  • Fertilizer runoff leads to excess nitrogen in lakes, causing algal blooms.

In a Nutshell

Biogeochemical cycles move elements through the environment, supporting all life.

Biogeochemical Cycles - AP Environmental Science Content | Practice Hub