APES All Biogeochemical Cycles

Carbon Cycle

Movement of carbon through the atmosphere, biosphere, hydrosphere, and geosphere via processes like photosynthesis, respiration, and combustion.

Photosynthesis (Carbon Cycle)

Plants use CO₂ and sunlight to produce glucose, removing CO₂ from the atmosphere.

Cellular Respiration (Carbon Cycle)

Organisms break down glucose and release CO₂ back into the atmosphere.

Decomposition (Carbon Cycle)

Dead organisms are broken down, releasing carbon into the soil and atmosphere.

Combustion (Carbon Cycle)

Burning of fossil fuels or biomass releases stored carbon as CO₂.

Nitrogen Cycle

The cycling of nitrogen through the atmosphere, soil, and living organisms; critical for proteins and DNA.

Nitrogen Fixation

Bacteria or lightning convert atmospheric N₂ into ammonia (NH₃) or ammonium (NH₄⁺).

Nitrification

Bacteria convert ammonia into nitrites (NO₂⁻) and then into nitrates (NO₃⁻).

Assimilation (Nitrogen Cycle)

Plants absorb nitrates from the soil and incorporate them into biological molecules.

Ammonification

Decomposers convert nitrogen from organic matter into ammonia or ammonium.

Denitrification

Bacteria convert nitrates into nitrogen gas (N₂), returning it to the atmosphere.

Phosphorus Cycle

Movement of phosphorus through rocks, soil, water, and organisms; does not cycle through the atmosphere.

Weathering (Phosphorus Cycle)

Breakdown of rocks releases phosphate into the soil and water.

Assimilation (Phosphorus Cycle)

Plants absorb phosphate from soil and use it for growth.

Decomposition (Phosphorus Cycle)

Organic phosphorus in dead organisms returns to the soil as inorganic phosphate.

Sedimentation (Phosphorus Cycle)

Phosphate settles in water bodies and becomes rock over time.

Water Cycle (Hydrologic Cycle)

Continuous movement of water through evaporation, transpiration, condensation, precipitation, infiltration, and runoff.

Evaporation

Liquid water becomes water vapor and rises into the atmosphere.

Transpiration

Plants release water vapor into the air through their leaves.

Condensation

Water vapor cools and forms clouds.

Precipitation

Water falls from the atmosphere to Earth as rain, snow, sleet, or hail.

Infiltration

Water seeps into the ground and recharges groundwater.

Runoff

Water flows over land into rivers, lakes, or oceans