Phosphorus Cycle

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Phosphorus Cycle

• http//www.wwtlearn.org.uk/factfile/images/phospho
  rous-cycle.jpg

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Phosphorus

• Phosphorus is essential to living organisms
  because it forms DNA , RNA , ATP molecules and
  fats of cell membranes.
• Phosphorus isnt very common in the biosphere!
• Phosphorus, unlike C, O2 N2, remains mostly on
  land in rock soil minerals and in ocean
  sediments. As rocks minerals wear down,
  phosphate is released!

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More on Phosphate

• Phosphate must be weathered out of
  phosphate-bearing rock
• PO43- is an important nutrient in coastal
  upwelling zones in the oceans
• Humans are doubling the rate of transport of
  PO43- into the environment through application of
  fertilizers

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Phosphorus Cycle

• Strictly a lithosphere-hydrosphere-biosphere
  cycle (not in Atmosphere!)

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Phosphorus Cycle

• Phosphorus moves slowly from deposits on land and
  in sediments, to living organisms, and than much
  more slowly back into the soil and water
  sediment. The phosphorus cycle is the slowest one
  of the matter cycles that we will talk about.
• Because the quantities of phosphorus in soil are
  generally small, it can be the limiting factor
  for plant growth. That is why humans often apply
  phosphate fertilizers on farmland.
• Phosphates are also limiting factors for
  plant-growth in marine ecosystems, because they
  are not very water-soluble.
• Animals absorb phosphates by eating plants or
  plant-eating animals.

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Phosphorus Cycle

• Phosphorus cycles through plants and animals much
  faster than it does through rocks and sediments.
• When animals and plants die, phosphates will
  return to the soils or oceans again during decay.
  
• After that, phosphorus will end up in sediments
  or rock formations again, remaining there for
  millions of years.
• Eventually, phosphorus is released again through
  weathering and the cycle starts over. ?

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Human Impacts on Phosphorus Cycle

• Phosphorus is used by humans as a fertilizer in
  farmlands .
• On farmland where phosphates are applied as
  fertilizers, plants do not absorb all phosphate.
  The phosphates end up in water and stream towards
  lakes and reservoirs.
• Eutrophication occurs when the water is so rich
  in nutrients that it causes algae, to grow
  extensively to bloom. As a result the oxygen
  supply in the water depletes, causing fish to die
  and bacteria that are not oxygen dependent
  (anaerobic) to take over
• http//www.unep.or.jp/ietc/Publications/TechPublic
  ations/TechPub-15/2-2/img/img2-5.gif