The water cycle

• the movement of water through ecosystems and atmosphere

Anthropogenic components

• Major water pools (in 10³ km³)

• Major water fluxes (in 10³km³yr^-1)

Forests and Rainfall

• The Biotic Pump

  • 

The carbon cycle is closely tied to the movement of energy

• Six main transformations:

  • photosynthesis

  • respiration

  • exchange

  • mineralization

  • sedimentation/burial

  • combustion

• 

The carbon cycle

• Methane production:

  • Ch4

  • A greenhouse gas

  • Produced under anaerobic conditions

Nitrogen cycles through ecosystems in many different forms

• Concepts

  • Nitrogen fixation: the process of converting atmospheric nitrogen into forms producers can use

  • Nitrification: the final process in the nitrogen cycle, which converts ammonium to nitrite (NO2-) and then from nitrite to nitrate (NOe-)

  • Mineralization: the process of breaking down organic compounds into organic compounds

  • Denitrification: the process of converting nitrates into nitrogen gas

Phosphorus cycles between land and water

• Mostly in the soil

• Eutrophication: an increase in the productivity of aquatic ecosystems

In terrestrial ecosystems, most nutrients are generated from organic matter in the soil

• Weathering

  • in terrestrial systems, nutrients are mostly in the soil

    • main source of P

• Breakdown of organic matter

• Decomposition

• Aquatic: Sediments and nutrients

  • nutrients tend to sink to deep waters or sediments

In aquatic ecosystems, most nutrients are generated from organic matters in the sediments

• Allochthonous inputs

• Rio Piedras, Puerto Rico

  • leaf litter decomposition rates decrease with increasing urbanization

  • Important factors

    • channelization/substrate

    • Macroinvertebrates