APES 1: Biogeochemical Cycles

• 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

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