Transcript The Phosphorus Cycle

The Phosphorus Cycle
Masta B Yoo, Devin Kim, Drew Li,
Justin Yun, Raymond Kim
Basic Chemistry
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Essential element of life
Phosphorus is a Group 15 (5A)
element
Symbol: P
Atomic number: 15
Atomic mass: 30.974
Color: colorless/ red/ silvery white
Basic Chemistry continued
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Nonmetal
Density: 1823 kg/m3
Atomic radius: 100 pm
Solid
Melting Point: 317.3 K
Boiling Point: 550 K
Basic Chemistry continued
Key ingredient to plants 
fertilizers
 In nature, Phosphorus exists in
form of Phosphate
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Basic Chemistry, cont.
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Formulas of rocks containing
phosphate are fluoroapatite
(3Ca3(PO4)2.CaF2),
chloroapaptite,
(3Ca3(PO4)2.CaCl2), and
hydroxyapatite
(3Ca3(PO4)2.Ca(OH)2)
Description of Phosphorus
 Most
common form of phosphorus is
red and white.
 Both are tetrahedral groups of four
atoms.
 White phosphorus burns on contact
with air and can change into red
phosphorus when exposed to light or
heat.
Description of Phosphorus Cont.
 White
phosphorus has two
modifications.
–Ordinary phosphorus is waxy
white solid.
–When pure it is colorless and
transparent.
Description, Cont.
 Pure
phosphorus is insoluble in
water but soluble in carbon
disulphide
–Catches fire spontaneously in air.
Background
 Very
poisonous
 Never found in free nature
 Essential ingredient of all cell
protoplasm, nervous tissue, and bones
 Most commonly found as phosphates
 Part of DNA materials and energy
distribution
Uses of Phosphorus
 Used
to make waterproof matches,
pyrotechnics, smoke screens, tracer
bullets, and incendiary shells.
 Used in fertilizer
 Used to produce special glasses,
for example sodium lamps
Uses, continued
 Calcium
Phosphate is used to create
fine Chinaware
 Monocalcium Phosphate used to
make baking powder
 Used in making steel, and Phosphor
Bronze
 Na3PO4 is used as a cleaning agent,
water softener, and also prevents
corrosion in pipes
Hazards and Risks
 Severely
toxic
 White form is more toxic than red form
 Chronic poisoning leads to necrosis of
jaw (phossy-jaw)
 Phosphate pollution comes from
detergents, insecticides, and fertilizers
 Inorganic phosphorus is harmless
Background
 The
phosphorus cycle does not
have a gas phase, but small
amounts of phosphoric acid rise
into the atmosphere, contributing
to acidic precipitation.
Background
 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
Description of 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
Description of Cycle
 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
Description, cont.
 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
Description, cont.
 Phosphate
is in backbone of DNA
and RNA
 When animals and plants die,
phosphates will return to the soils
or oceans again during decay
Description, cont.
 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
Description, cont.
 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
Description, cont.
 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
Description, cont.
 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.
Human Influences on Cycle
 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.
Influences cont.
 Phosphate
rock and sulfuric acid
are combined to make a fertilizer
called “super phosphate.”
 There are many negative effects of
using this fertilizer.
Influences cont.
 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.
Influences cont.
 In
some lakes & ponds the
phosphate can be recycled as a
problem nutrient.
 Other sources of phosphate are in
out flows from local sewage
treatment plans.
Interesting Facts
 Originally,
phosphorus was
extracted from urine.
 Highly energy intensive.
 Gr.  phosphoros, meaning “light
bearer”
Facts, cont.
 In
1669, German alchemist Henning
Brand discovered phosphorus from a
preparation from urine.
 The only correct spelling of the
element is phosphorus. There does
exist a word phosphorous, but it is the
adjectival form for the smaller valency
Bibliography
 “Nutrient
Cycling in Ecosystems.”
http://home.earthlink.net/~dayvdan
ls/ecosys4.htm 17 September 2004
 “Phosphorus.”
http://pearl1.lanl.gov/periodic/elem
ents/15.html 17 September 2004
Bibliography cont.
 “Web-Elements.”
http://www.webelements.com/webelem
ents/elements/text/P/key.html 17
September 2004
 http://en.wikipedia.org/wiki/Phosphoru
s 17 September 2004
 “Virtual Chembook.”
http://www.elmhurst.edu/~chm/vchem
book/308phosphorus.html 17
September 2004