Biochemical cycles.

Biochemical cycles.

1. Hydrological cycle

   • Water
     • Principally from Oceans
     • Radiant energy evaporates water into the atmosphere
       • Winds distribute it over the surface of the globe
         • Precipitation brings it down to Earth's surface
           • Stored
             • Soil
             • Lakes
             • Icefields
   • Loss
     • Evaporation
     • Transpiration
     • Liquid flow through stream channels
       • Sea
   • Pools of water
     • Oceans, ice of polar icecaps, deep ground water, rivers and lakes
     • Proportion in transit
       • Requirements for survival and productivity, nutrients
   • Terrestrial vegetation
     • Modify fluxes, intercept water, moving it back into the atmosphere
       • Catching in foliage
       • Taking it up via the roots

2. Phosphorus cycle

   • Stocks
     • Waters of soil, rivers, lakes, rocks, ocean sediments
   • Sedimentary cycle
     • Tendency to be carried from land, to the oceans, gets incorporated in sediments
   • Released from rock (chemical weathering)
     • Cycle within the terrestrial community for years
       • Carried via the ground water into a stream
         • Carried to the ocean
           • Trips between surface and water
             • Taken up by surface dwelling organisms
             • Enters the bottom sediment in particulate form
               • Ocean floor is lifted
                 • Dry land
                   • Find its way back

3. Nitrogen cycle

   • Atmospheric phase
     • Nitrogen fixation and denitrification
   • Nitrogen may be significant in fueling productivity
     • Terrestrial and freshwater communities
   • Small magnitude of flux
     • Significant to aquatic systems
       • Nitrogen limits plant growth
   • Small annual loss of nitrogen to ocean sediments

4. Sulfur cycle

   • Release sulfur
     • Seaspray aerosol formation
     • Anaerobic respiration by sulfate-reducing bacteria
       • H2S
         • Waterlogged bog, marsh, tidal mudflats
     • Volcanic activity
   • Weathering of rocks
     • Sulfur draining
   • Proportion taken up by plants
   • Small fraction in terrestrial and aquatic communities
     • Loss to ocean sediments.

5. Carbon cycle

   • Photosynthesis and respiration
   • Gaseous cycle
     • Carbon dioxide
       • Vehicle of flux (atmosphere, hydrosphere and biota)
       • Fossil fuels as reservoirs (until human intervention)
       • Into inland waters and oceans as bicarbonate
       • Respiration releases carbon back to its compartments
   • Aquatic plants use dissolved carbonates.