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Phosphorus Cycle

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Phosphorus isn't very common in the biosphere! ... Strictly a lithosphere-hydrosphere-biosphere cycle (not in Atmosphere!) Phosphorus Cycle ... – PowerPoint PPT presentation

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Title: Phosphorus Cycle


1
Phosphorus Cycle
  • http//www.wwtlearn.org.uk/factfile/images/phospho
    rous-cycle.jpg

2
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!

3
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

4
Phosphorus Cycle
  • Strictly a lithosphere-hydrosphere-biosphere
    cycle (not in Atmosphere!)

5
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.

6
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. ?

7
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
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