Transcript 8. CYCLING OF PHOSPHORUS ATOMS

Life on Earth
depends upon
one–way flow
of high–quality
energy from
sun & cycling
of crucial
elements.
Nitrogen and Phosphorus…These
elements are essential to function and
productivity of ecological systems.
Importance of Phosphorus (P)

Like nitrogen, phosphorus (P) is an
essential part of the process of
photosynthesis.

Involved in the formation of all oils,
sugars, starches, etc.

Helps with the transformation of
solar energy into chemical energy;
proper plant maturation;
withstanding stress.
Importance of Phosphorus (P)
Effects rapid growth.
 Encourages blooming and
root growth.
 Phosphorus originates from
rocks

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Hydrosphere- water layer. Liquid, Ice, Vapor.
Lithosphere- Earth’s crust and upper mantle.
- Fossil fuels, minerals, soil chemicals.
Biosphere- biotic & abiotic factors.
Phosphorous Cycle
Never enters the atmosphere
Atmosphere
Biosphere
Absorption
Waste &
Decomposition
Weathering & Erosion
Hydrosphere
Lithosphere
Absorption
Sedimentation
Human
Impacts
Phosphorous Cycle
Net Effect:
Increase in phosphorous in water &
“algal blooms”; Depletion in soils
Biosphere
Mining, use (fertilizer, detergent, etc.)
& increased runoff
Lithosphere
Hydrosphere
More Phos. for organisms
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The phosphorus cycle does not
have a gas phase, but small
amounts of phosphoric acid rise
into the atmosphere,
contributing to acidic
precipitation.
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The water, carbon, and sulfur
cycles all include at least one
phase in which the element is in
its gaseous state.
The largest reservoir of
phosphorus is in sedimentary
rock.
The Cycle
 Simplest
of the cycles
 Phosphorus has only one form
– phosphate
◦Always part of an organism,
dissolved in water, or in the
form of rock
 Phosphorus
enters
environment from rocks or
deposits
 Apatite is the phosphate rock
where phosphate is available
 Weathering and erosion
releases phosphate ions that
are soluble in water
 Phosphate
then acts as
fertilizers or nutrients for land
plants
 It gets incorporated into
molecules essential for life like
ATP, adenosine triphosphate –
this is important in storage
and use of energy
 Phosphate
is in backbone of
DNA and RNA
 When animals and plants die,
phosphates will return to the
soils or oceans again during
decay
 Phosphorus
cycles through
plants and animals much faster
than it does through rocks and
sediments..
 A lot of phosphate goes into the
water from erosion and leaching
 Water plants use this phosphate
as nutrients
 Phosphate
is the limiting agent
in growth of plants and algae
 If there is a lack of phosphate,
plants grow slowly or are
stunted
 If too much, excess growth
may occur
 Phosphate
in water is precipitated
from water as ion phosphate
(insoluble)
 Phosphate in shallow sediment
may be recycled into water
 In deep sediment in water, it is
available as part of as part of rock
formations for cycle to repeat
 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.
Major components of aquatic ecosystems.
Fig. 4–11
Major components of terrestrial ecosystems.
Fig. 4–12
Human
influences on
phosphate cycle mostly
comes from introduction &
use of commercial synthetic
fertilizers.
Phosphate obtained by
mining at certain deposits of
calcium phosphate called
apatite.
Phosphate
rock and sulfuric
acid are combined to make a
fertilizer called “super
phosphate.”
There are many negative
effects of using this
fertilizer.
A
lot of the fertilizer is lost
through the water run-off
because plants aren’t able to
use up all of it.
Eventually the wasted
phosphate in the water is
precipitated as it settles at the
bottom of the body of water.
Component
Input to soil
Loss from soil
The Phosphorus Cycle
Crop
harvest
Animal
manures
and biosolids
Atmospheric
deposition
Mineral
fertilizers
Plant
residues
Organic phosphorus
•Microbial
•Plant residue
•Humus
Leaching
(usually minor)
Plant
uptake
Soil solution
phosphorus
•HPO4-2
•H2PO4-1
Primary
minerals
(apatite)
Runoff and
erosion
Mineral
surfaces
(clays, Fe and
Al oxides,
carbonates)
Secondary
compounds
(CaP, FeP, MnP, AlP)
Phosphorus Cycle
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How and in what form(s) does phosphorus
enter and leave the cycle?
How do the roles of autotrophs and
heterotrophs differ?
What are the human impacts on the cycle?