Transcript Section 2.1 Monitoring Chemicals in the Environment

What do you know about water quiz: True or False
1. Rain, hail, and snow provide Earth with new sources of water.
2. Humans eat more water than they drink.
3. Water can dissolve more substances than any other liquid.
4. Water is the only naturally occurring substance that is found
on Earth as a solid, a liquid, and a gas.
5. Falling raindrops are shaped like tears.
6. The purest possible water is what aquatic life depends upon
for health.
7. The greatest home use of water in Canada is for drinking.
8. Like most other liquids, water contracts (gets smaller) when it
freezes.
9. Approximately 3% of the water on Earth is fresh water.
10. The largest fresh water lake entirely in Canada is Lake
Superior, located in Ontario.
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Monitoring – keeping track of chemicals or
populations in the environment to ensure
they stay at safe and healthy levels.
Various chemicals in the environment must be
monitored so that water and air quality can be
protected.
The ozone layer - the function of the ozone layer
is to shield the Earth from damaging ultraviolet
radiation from the sun.
Q: How would increased UV rays affect humans?
Q: What do the satellite photos indicate on
p.212? ( use a ruler )
2.1 Monitoring water Quality
Water Quality
Clarity, or how clear the water is, is not a good
indicator of water quality since acidic lakes are
often clear and lifeless. Water quality is
determined by what the water is to be used for.
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Guidelines exist for 5 categories of water:
 Human drinking water
 Recreation
 Livestock drinking water
 Irrigation
 Protection of aquatic life
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Scientists monitor water quality with both
biotic and chemical indicators.
A. Biological indicators – organisms that live in
water help determine its quality.
1. Microbiological – samples are taken from
water sources people use to determine the
number and type of microscopic organisms,
such as bacteria, that are there in order to
avoid illness.
2. Aquatic - invertebrates (animals without
backbones) such as insects, crustaceans,
worms and mollusks can be used as
indicators of water quality since different
invertebrates prefer different living
conditions, such as dissolved oxygen, pH
and temperature.
In Aquatic Environments, the diversity of all
organisms decreases as acidity increases and
dissolved oxygen decreases.
B. Chemical Factors that Affect Organisms
1. Measuring Chemicals – the concentration of
chemicals is measured in parts per million
(ppm) or milligrams per litre (mg/L).
1 ppm means there is 1 unit of that chemical in
1 million units of solution.
Eg. How many ppm is 0.02 mL juice in 100 mL
solution?
0.02mL
= x (ppm) = 200 ppm
100mL
1 000 000
2. Dissolved Oxygen – the amount of oxygen
dissolved in a body of water depends upon:
a. water temperature - more oxygen in cold
water
b. Turbulence - more oxygen in turbulent water
c. amount of photosynthesis
d. number of organisms living in it - they
consume oxygen.
5 ppm of oxygen will support most
organisms.
See Figure 2.4, p.217.
3. Phosphorus and Nitrogen Content – these
nutrients are added to water by sewage and
runoff from fertilized fields.
 Higher concentrations leads to increased
growth of algae and green plants and
eventually a buildup of dead matter.
 This encourages a decomposer bloom, then
bacteria increases to decompose the algae,
then, dissolved oxygen decreases.
 As a result, many fish and insects die. See
Figure 2.7, p. 219.
4. Acidity – as the pH of a water system drops the
diversity of plants and animals that can live in the
water decreases. Below 4.5, most fish
disappear. Acid deposition is a problem in areas
where soil and water lack bases to neutralize it.
(eg, Canadian Shield)
 Spring acid shock occurs when acid builds up
in the snow and then is released into the
waterways as the snow melts, causing a
dramatic drop in pH that seriously affects water
organisms.
5. Pesticides – some have long term toxic
effects because they don’t degrade and
become trapped in the tissues of animals.
Many today are engineered to decompose
after 1 season so they are no longer toxic.
 One problem: resistance.
 As pests become resistant to pesticides,
more must be developed and more chemicals
are added to the soil. As this happens, one
or more pesticides may combine to form
even more toxic substances.
6. Measuring Toxicity – different chemicals
affect organisms in different ways, so it can
be difficult to compare the toxicity of a
substance to other substances.
 A measurement called LD50 indicates the
amount of the substance that will cause 50%
of the population to die
(LD = lethal dose).
The greater the toxicity of a substance
the lower the LD50 is.
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LD50 testing is done on rats and mice and is
given either orally or applied to the skin. See
table, p. 221.
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LD50 DOSE WHICH KILLS 50% OF TEST
ANIMALS
Dose, mg/Kg
LD50 = 1.0 mg/Kg
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ORAL LD50 VALUES
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nicotine
0.3 mg/Kg (mice)
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2,3,7,8-TCDD
0.002 mg/Kg (guinea pig)
0.3 mg/Kg (mouse)
5 mg/Kg (hamster)
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1,3,6,8-TCDD
>1500 mg/Kg (guinea pig)
>3000 mg/Kg (mouse)
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octa-CCD
>4000 mg/Kg (mouse)
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2,3,7,8-TCDF
0.1 mg/Kg (guinea pig)
>6 mg/Kg (mouse)
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PCBs
1295 mg/Kg (rat)
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Aspirin
1100 mg/Kg (mouse)
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sodium cyanide
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caffeine
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methylisocyanate
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ethanol
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sodium chloride
6.4 mg/Kg (rat)
127 mg/Kg (mouse)
305 mg/Kg (rat)
1200 mg/Kg (rat)
3750 mg/Kg (rat)
7. Heavy Metals – metals such as copper, lead,
zinc, mercury, cadmium and nickel have
densities greater than 5 g/cm3 and are
therefore called heavy. They occur naturally
in the environment but not usually in large
amounts.
 Human activities can increase the amount of
these metals – acid water can dissolve lead
pipes, cadmium can be found in fertilizer as
an impurity and garbage can contain many of
these metals.
 These metals are toxic to many organisms,
but are very harmful for children. Their use
in products is now limited and waste
disposal is closely monitored to keep these
metals from entering the environment.
Section 2.2
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Air Quality
Air is made up of 78% nitrogen, 21% oxygen,
less than 1% argon and other trace gases
(0.03%).
It’s quality is determined by
1) measuring the pollutants
(more accurate)
2) estimating the amount of emissions from
pollution sources.
1. Sulfur Dioxide (SO2(g)) – this pollutant comes
from industrial processes, like the oil and gas
industry in Alberta, and from the burning of
fossil fuels (coal, oil and gas).
 It contributes to smog and acid rain and can
affect your respiratory system.
 Scrubbers are used to remove up to 99% of
sulfur from industrial emission by using
limestone (calcium carbonate) to convert it to
a useful product called gypsum, and carbon
dioxide.
2. Nitrogen Oxides (NOX(g)) – the X indicates
either NO or NO2. These pollutants are
formed mainly by fossil fuel emissions and
by combustion at generating plants and
industrial processes.
NO is formed first and then it combines with
oxygen in the air to form NO2, which is a
brown gas that gives smog its color.
These pollutants also affect the respiratory
system and eyes and contribute to acid rain.
3. Carbon Monoxide (CO(g)) – ‘the silent killer’,
colorless and odorless, it is a deadly gas that
is produced by the burning of fossil fuels and
can be produced when anything containing
carbon is burned (wood like when heating
homes or in forest fires, natural gas,
cigarettes and industrial processes).
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Catalytic converters make CO2 out of CO
since it is very toxic when inhaled – it leads to
headaches, sleepiness, brain damage and
death.
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Catalytic converters use Platinum and Palladium
to remove pollutants from vehicle exhaust.
4. Ground-Level Ozone (O3(g)) – a colorless,
odorless gas in the upper atmosphere that
protects the earth from harmful UV radiation.
At the earth’s surface, ozone is formed by
reactions between oxygen, nitrogen and
volatile organic chemicals (VOCs – emitted
from solvents and gasoline).
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Ozone at the earth’s surface is a pollutant
because it affects the respiratory systems of
people with asthma, lung disease and colds.
It also negatively affects crops such as
wheat, soybeans and onions and causes
plastics to deteriorate.
Section 2.3
Monitoring the Atmosphere
1. Carbon Dioxide - A Greenhouse Gas
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We live in a natural greenhouse, where gases
in the atmosphere trap heat from the sun’s
radiation. These greenhouse gases include
water, methane, nitrogen oxides and carbon
dioxide.

CO2 is released naturally into the air by
people breathing, driving vehicles and
combusting materials.
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With the large amount of people doing all of
these things, what effect will the increased
amount of carbon dioxide have on the
planet?
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Many scientists support the theory that
human activities enhance the greenhouse
effect which increases the global temperature
(global warming).
This trend can lead to climate change,
increase the amount of violent storms and
flooding, and increase the spread of disease.
Behind water, carbon dioxide contributes
most to the greenhouse effect.
See Figure 2.17, p. 231 for the upward trend
of CO2 concentration in our atmosphere from
1960 until today.
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Global warming is increasing due to natural
processes such as volcanic eruptions and
forest fires, but also because of human
activities.
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Some countries have begun to reduce CO2
emissions by turning to alternate energy
sources such as wind and are also investing
in forest projects to increase the amount of
CO2 absorbed.
2. The Ozone Layer
 The ozone layer is 15 to 50 km above the
earth and protects us from UV rays.
Scientists have found that this layer has
become thinner over the years, some places
so thin that they are called holes.
 As a result, more UV rays are getting to the
earth’s surface and many effects are being
seen, from skin cancer, to cataracts, to death
of plankton.
 CFCs, or cholorfluorocarbons, are thought to
cause thinning of the ozone layer. They were
used in refrigerators, aerosol cans, and fire
extinguishers.
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UV causes CFCs to break down into
substances (like chlorine) that breakdown
ozone into O2(g).
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One chlorine molecule can break down 100 000
ozone molecules. In colder regions (south
pole), ice particles in the atmosphere speed up
this reaction. Many countries have signed
international agreements to reduce the use of
CFCs.
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global warming link