Transcript Unit C: Topic 6 - Greater St. Albert Catholic Schools

Unit C: Topic 6
NIMBY: Not In My Back Yard
Producing Wastes
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Since the industrial revolution,
the amount of wastes being
produced has been increasing.
More wastes means more
landfills but no one wants a
landfill in their neighborhood.
The Movement of Pollution
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Pollution can be produced in one
area but transported to other places
in the world.
There are three stages of transport
of pollutants:
1. Release of chemicals at the
source.
2. Dispersion of the chemical into the
atmosphere.
3. Deposition of the chemical in soil
or water.
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The direction and distance of
airborne pollutants depends on
various factors including:
1. The type of pollutant.
2. The wind speed.
3. The direction of the winds.
4. The speed and direction of
ocean currents.
Natural Vs. Man-Made Wastes
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Natural wastes include volcanic
ash, forest fires, animal and
plant wastes.
Man-made wastes include toxic
chemicals, airborne pollutants,
etc.
CFCs and the Ozone Layer
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CFCs = chlorofluorocarbons.
They are produced by
refrigerant coolants and aerosol
cans as well as in Styrofoam.
One chlorine atom from a CFC
molecule can break up 100’000
ozone molecules (O3).
International agreements have
been signed to limit the
production of CFCs.
Surface Water Pollution
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Most comes from clothes
washing which pollutes the
water with nitrates and
phosphates.
Sewage treatment involves
removing harmful levels of these
chemicals.
Septic Tank
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Underground tank that traps
grease and solid wastes.
The remaining liquid waste are
pumped into a field where
bacteria can break down the
waste products leaving water for
irrigation and the waste as
fertilizers.
Treating Sewage – A 3 Step
Process
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Primary Treatment – Physically
separating large solids and
sediments
Secondary Treatment – Removing
organic compounds by bacterial
decomposition. UV light or chlorine is
used to kill germs.
Tertiary Treatment – Chemicals such
as phosphates and nitrates are
removed from water which is passed
into soil as ground water.
Ground Water
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Water that filters down through
soil. It moves average 15 m/a.
The more permeable the soil,
the faster the flow rate of ground
water.
Impermeable bedrock and clay
prevent ground water from
moving.
Aquifers
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Underwater pools which serve
as supplies of spring water.
Water here is filtered naturally
and free from bacteria
contamination.
However as ground water
becomes polluted so do aquifers
and water contamination here is
nearly irreversible.
Biodegradable
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Organic substances which can
be broken down naturally by
organisms or common
chemicals (eg. water, air).
In order for biodegradation to
occur, the waste must be mixed
in with water, organisms, and
air; conditions that aren’t met in
most landfills.
Sanitary Landfills
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Most common
Waste is buried daily under dirt.
Clay lines the bottom to prevent
contamination of groundwater.
Liquid waste, Leachate, is sent
to water treatment center.
Hazardous by-products such as
methane are produced
anaerobically.
Secure Landfills
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Used for toxic wastes.
Clay lining is backed up with
gravel, plastic layers and drain
pipes to collect toxic seepage.
When filled, the waste are
capped by layer of clay, plastic,
and soil.
The landfill is forever monitored
for toxic leaks through the
drilling of wells.
The (Second) Last Slide
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Bioremediation – The use of
living things instead of
synthetics to fix a problem. Eg.
Using plants to remove heavy
metals from soils, and ladybugs
as pesticides.
Bioreactors – Using bacteria
holding tanks as natural sanitary
landfills. Bacteria break down
organic wastes in the presence
of air and water.
Phytoremediation and
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Phytoremediation: a technique that
can be used to reduce the
concentration of harmful chemicals
in the soil or groundwater. Plants
have been used to clean up metals
and other pollutants. The plants are
able to absorb and accumulate large
amounts of these chemicals. When
the plants have matured, they are
harvested, burned or composted.
Other plants can then be grown in
the healthier soil.
Photolysis
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Photolysis is the breakdown of
compounds by sunlight. The formation
of ozone is an example of this process
Another example is photodegradable
plastic. This plastic is made of
chemicals that react when exposed to
sunlight. In 3 months, the plastic
becomes a fine powder that is easier
to dispose of. (This type of plastic will
only degrade if it is exposed to
sunlight – if it is buried, it will last in its
original shape for hundreds of years.)