Why is the phosphorus cycle important
The Phosphorus Cycle
okay so in this video we're going to
look at the phosphorous cycle now one
thing I want to mention is that even
though phosphorous cycles through the
environment there is no phosphorous in
the atmosphere so it's not like the
carbon cycle where there's carbon
dioxide in the atmosphere it's not like
the nitrogen cycle where there's
nitrogen in the atmosphere the
phosphorous cycle begins with rocks and
we're going to go through that in just a
moment well first of all why do we need
phosphorous well phosphorous if you
recall is one of the one of the atoms
that makes up the molecule called ATP
adenosine triphosphate in the picture
here here's a mitochondria and through
the process of cellular respiration the
mitochondria will make this molecule
adenosine triphosphate you can see there
are peas for phosphorus in the diagram
another important molecule that that
requires phosphorus is DNA and not just
DNA but RNAi nucleic acids so here's a
double helix now if we if we look at the
molecular structure of DNA remember that
DNA is made from small parts called
nucleotides and you can see the
nucleotide is a sugar molecule nitrogen
base and then a P the P stands for a
phosphate molecule the reason it's
called phosphate is there's phosphorus
in it and one nucleotide combined with
another with another with another like
you see in the picture makes up DNA a
nucleic acid so DNA the genetic heredity
the genetic molecule of life requires
phosphorus and a third reason why
phosphorus is really important in the
animation here we have a phospholipid
bilayer basically we have the cell
membrane of all of our cells
phospholipid phospho implies there's
phosphorus in the lipids that make up
the cell membrane well let's go ahead
and get on in to the stages of the cycle
now
so here we have on a rain cloud and it's
raining and so what we're going to show
you is really the first stage of the
phosphorous cycle and it comes from the
breaking down in the weathering of rocks
you know rocks are just lumps of
minerals and one of the minerals that
rocks are commonly made from is
phosphorous and so when it rains
phosphorus little chips of rocks break
off and crack and crumble and this is
what we mean by the weathering of rocks
and so phosphorous is released as rocks
weather and break down and erode and the
phosphorous has now entered the soil
well once the phosphorous is in the soil
now it becomes pretty straightforward
the flowers representing their producers
in this animation will absorb the
phosphorous through their roots and once
the phosphorous is in the roots of
plants I hope you can figure out how
animals can obtain the phosphorous
so now that the phosphorus is in the
plants the phosphorus simply moves up
the food chain in our animation we have
phosphorus going from the flowers to the
snail well that's because stales eat
leaves and flowers and plants in the
next part of the animation we have
phosphorus going from the snail into the
frog well that's because frogs can eat
snails phosphorus is simply moving up
the food chain and then we come to area
four represented by our mushrooms in the
animation it says decomposers will
obtain phosphorus as they feed on dead
remains in the animation there's a peak
coming from the flowers there's a pea
coming from the snail and there's a pea
coming from the frog and they're all
going to the mushrooms representing the
decomposers I'm not implying that
mushrooms hunt frogs and snails and
flowers but when frogs and snails and
flowers die they're dead remains which
still contain phosphorous are fed on by
default or such as fungus decomposers
such as bacteria well if we notice here
also there is a pee coming out of the
mushroom because again all organisms
give off waste and fungus and other
decomposers will give off phosphorous in
their waste and so if you just pause and
look at the animation we have a cycle
here we have a continuous loop of
phosphorous throughout the ecosystem
throughout the environment well there's
one little twist I want to add to this
before the video is finished
we have to focus on the human
contribution to the phosphorus cycle so
humans will often use fertilizers and
phosphorus is a very common ingredient
as well as nitrogen phosphorus and
nitrogen are very common to fertilizers
well we add fertilizers to help our
crops and plants grow better and so here
we have a picture of a farmer using a
tractor and pulling a trailer that is
dispensing fertilizers over their crops
and so the problem with this is that the
phosphorus when it's sprayed on the
crops will often run off with rain into
bodies of water
so in this picture right here you can
see that water is running off of this
farm and so often the fertilizers are
simply being carried away with this rain
water here
so in my animation here here we have a
farmer adding peas a bunch of peas for
phosphorus so the farmers adding
phosphorus to their crops to the plants
and so their fertilize the farm is
fertilizing the crops well unfortunately
the phosphorus that's accumulating in
the animation won't just stay there
often the phosphorus is carried with
weather and rain so when it rains when
it rains often the phosphorus is simply
carried downstream or downriver down
down the slope of the land and you can
see in the animation the phosphorus is
accumulating in this body of water well
this is going to lead to another problem
this often causes what are called algal
blooms an extreme growth of algae in the
animation you see the water in the pond
is turning green because of all the
algae that is now being stimulated to
grow from all the phosphorus phosphorus
is a fertilizer it stimulates the growth
of algae as well as stimulating the
growth of crops well why is this bad
well first of all before we address why
is that bad here's a couple photographs
of algal blooms you can see this watery
area is just as a layer of green slime
growing on it and here we have a lake or
a river that's completely been turned
green because of the extreme growth of
algae well what the problem that this
causes is something called
eutrophication off often and ultimately
what happens to this little body of
water it becomes a dead zone the algae
is so dense and so thick it will often
block sunlight to plants that live
deeper in the water and they start to
die often oh the next step that happens
is the algae themselves will begin to
die and bacteria will feed on the dead
remains of the algae
well the bacteria are using all of the
oxygen in the water to break down and
decompose the algae that the the water
almost becomes action oxygen lists
becomes void of oxygen because the
bacteria are using it all
so therefore snails die fish die
organism other animals that live in this
water begin to die because there's no
oxygen the extreme growth of algae often
causes the pH of the rivers and the
lakes to change and so that's another
reason why the lake can become a dead
zone so the point is is that the
phosphorus cycles out of balance and you
know human contributions are some of the
reasons for that so if you're if you
have a bit of a green thumb at home and
you're interested in landscaping and
gardening you know perhaps you can go
down to you know the local supply store
and look for safer non-chemical ways to
perhaps fertilize your lawn and
fertilize your garden
so here we go that was the there we go
that was the phosphorous cycle go ahead
and pause this video it's a very quick
practice quiz then the video was pretty
quick so go ahead and pause the video
answer these questions if you're in my
class I'd be happy to check them for
accuracy before school or after school
good luck
