• involve the movement of matter via biological, chemical, and geological processes

• sources

  • anything that releases more of the biogeochemical substance than it absorbs

• sinks

  • anything that absorbs more of the biogeochemical substance than it releases

Hydrologic (water) cycle

• powered by the sun

• movement of water between sources and sinks

• water can move in its three phases (gas, liquid, or solid)

• solar heating

• evapotranspiration

• cool/cloud formation

• precipitation

  • form of rain

• plant uptake/runoff/infiltration

Carbon cycle

• movement of atoms and molecules containing the element carbon between sources and sinks

• some reservoirs hold carbon for long and short periods of time

• cycles between photosynthesis and cellular respiration in living organisms

• decomposition: storage of carbon over millions of years

• the 7 processes that drive the carbon cycle

  • photosynthesis & respiration

    • producers uptake CO2 and respire some back through cellular respiration or death

  • exchange, sedimentation & burial

    • c exchanged between atmosphere and ocean

  • extraction & combustion

    • human activities (fossil fuels)

    • fires & volcanoes

Nitrogen cycle

• movement of atoms and molecules containing nitrogen between sources and sinks

• nitrogen reservoirs hold compounds for a (relatively) short amount of time

• nitrogen fixation: the process in which atmospheric nitrogen is converted into a form of N (usually ammonia) that is available for uptake by plants

• the atmosphere is a major reservoir of N

Phosphorus cycle

• movement of atoms and molecules containing phosphorus between sources and sinks

• major reservoirs of phosphorus are rocks and sediments (no atmosphere component)

• phosphorus is naturally scarce in aquatic & terrestrial ecosystems - limiting factor