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ENV200H1 Lecture Notes - Electromagnetic Spectrum, Photosynthesis, Atmospheric Circulation

School of Environment
Course Code
Jack Parkinson

of 7
Fossil fuel = decomposition of living organisms --> liquid or gas, they're actually
fossils made through millions of years
We use them very quickly.
Water cycle: slide7
The earth = 97% water = ocean
Moves water around the globe,
water from ocean evaporates b/c of solar energy ends up in atmosphere
Makes up clouds
Precipitate in the form of rain/snow
Makes way back to the ocean
Complete recycle of water back to the eco system.
Nitrogen cycle: slide 8
Proteins and DNA, what makes who we are, requires nitrogen which is an
important element
78% of the atmosphere is made out of
We'd think that nitrogen wouldn't run out or have a shortage, but nitrogen in our
atmosphere is not in a biologically useable forms
Nitrogen in our atmosphere cannot be changed into proteins for us to use it,
biological useable form
Nitrogen cannot be used unless converted into useable forms , after it goes through
ammonification then it can be used in a biological way.
It has to go through a complicated five steps, details will be in the text book go
check it
In the past, b/c
nitrogen in the atmosphere isn't in a biologically useable form we relied on
bacteria to convert the nitrogen into the biological useable form which is called
nitrogen fixation
There're some plants that had this bacteria in their root structures that were able
to do this miraculous chemical transformation to convert it to ammonia, a more
usable form, which would take it through other four stages of chemical
Lots of nitrogen in the air, but not in useable form unless it's converted.
Understand how atmosphere affect nitrogen, go through the nitrogen fixation and
how it goes back to the cycle and how it gets back into the atmosphere.
Human activities significantly altered the nitrogen cycle , we saw how nitrogen
could be incorporated to our agricultural system.
From rarly 20th cen, our chemical advance allowed us to do what bacteria was
doing for us before , that is converting nitrogen into useable forms
This altered the landscape and how nitrogen was incorporated to the system
--> great growth in agriculture, fertilizers have high percentage of nitrogen
b/c it's needed for growth to happen
Nitrogen in the atmosphere will be doubled in 25 yrs, this is an enormous amount
Impact? Concept of Eutrophication, richness in the water body, an excessive
Many plants will grow, which will decompose and cause the problem creating
oxygen sucked up by decomposition process. Makes water less easy to clean up or
Smog, acid rain and formation of green house gases, would also be a factor other
than carbon dioxide.
Phosphorus cycle (another fertilizer)
Big diff b/t this and nitrogen, phosphorus is not in our atmosphere nor can be
altered to be created
Yet still an imp. Element in our dna and atp (chemical energy).
Basic understanding of how phosphorus works through food chain is, we don't get it
from atmosphere instead, we find it in the land.
It's in the earth's systems. Phosphates move through the food chain
Organism eat plant -> organism eat other organism -> -> organism dies ->
phosphorus goes back into the land
= Organisms making an access to phosphate
b/c it's not in our atmosphere it's in a patchy distribution
There're areas that doesn't have so much phosphorous this is why plants grow
abundantly when it has phosphorus in fertilizer
When it's trapped in the lithosphere it won't move like nitrogen that's in the
atmosphere but will stay there
Once it ends up in ocean, seabed that's very deep that phosphorus will be tied up
So the cycle can take a very long geological time
Although having an abundance of phosphorus is a good thing, over-abundance
causes\ similar things as things caused by over abundance of nitrogen.
MESSAGE: All these Cycles cycle through, they have varying length of time but
humans have disturbed these cycles and destroyed it
The atmosphere
Gaseous envelope surrounding the earth
Oxygen and nitrogen combined together makes up 99% of our atmosphere
Think of multi layer cake, it consists of four layers.
Troposphere (closes to us)
Average distance ground -> 12km above it
Thickness depends on where you are on the earth
16km thick in equator while 8km thick at the pole
As we go up troposphere it goes cold up to -52, this is why it gets colder in the
Ozone in troposphere is identified as smog, bad
Stratosphere ozone resides, jets fly
Layer of atmosphere that absorbs the most of sun's Damaging ultra violet ray
Starts roughly 11km and 50km up
Temp. Actually increases up, you'd think the that it Will go colder as we go up, but
it's not
Natural protective ozone layer, good: Blocks out nasty uv radiation, ozone holes ->
uv radiation come through
50-80km sea level
You can see meteor
Very low density, very thin
Temp. diff do not allow atmosphere layers to become mixed
As you go up, it goes closer to the sun = higher temp
Although same chemicals could appear in each layer, the chemical may be good or
bad depending on where they are. Like Ozone layer
Where it's nasty when it's in troposphere but good when it's in stratosphere
Atmosphere is not very impt, understand how gases between the layers can get
mixed there're concerns about concentration of gasses in one of each layers
If an earth was an orange was atmosphere would be as thin as an orange peel but
it's consisted of four layers
500km = atmosphere