Download Chemistry in the Environment: Atmosphere

Earth’s
atmosphere
as seen from
space
Photo: NASA
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78 % Nitrogen
21 % Oxygen
1 % Argon
and other
trace gases
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Troposphere
◦ Most of our weather
occurs in this layer
closest to the
Earth’s surface
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Stratosphere
◦ Where ozone (O3)
absorbs harmful UV
radiation from the
Sun and prevents it
from reaching
Earth’s surface
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Atmosphere contains the air we breathe
Protects us from the Sun’s radiation
Keeps Earth balanced  traps and releases
heat
Atmospheres of other planets are different
◦ Mars very thin atmosphere made of mostly CO2
◦ Venus denser and hotter than Earth’s atmosphere
◦ Jupiter large, turbulent atmosphere made of H
and He
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Fossil fuels are fuels formed by natural
resources such as anaerobic decomposition
of buried dead organisms.
Fossil fuels are non-renewable resources
because they take millions of years to form,
and reserves are being depleted much faster
than new ones are being made.
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We burn fossil
fuels to produce
useful energy
This fuel provides
gas for our cars,
electricity for our
homes, and runs
factories and
powerplants
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The burning of fossil fuels produces around
21.3 billion tons (21.3 gigatons) of carbon
dioxide (CO2) per year
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A type of air pollution that comes from internal
combustion engines and industrial fumes that
react with sunlight to form photochemical smog
The word ‘smog’ comes from a combination of
smoke and fog
Mixture of air pollutants, including gases and
particles that are too small to see
Smog is also caused by large amounts of coal
burning in an area caused by a mixture of smoke
and sulfur dioxide
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Type: Particulate Matter - or PM. This is the name
given to microscopic particles that pollute the air.
They vary in size and chemical make-up.
Sources:
Industrial and vehicle emissions, road dust,
agriculture, construction and wood burning.
Type: Ground-level Ozone. This gas is the result of a
chemical reaction when certain pollutants are
combined in the presence of sunlight. Ground-level
ozone shouldn't be confused with the ozone layer in
the sky, which protects us from ultraviolet
radiation.
Sources: Ground-level ozone comes mostly
from burning fossil fuels for transportation and
industry. Ozone levels peak between noon and 6 p.m.
during the summer months.
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Type: Sulfur dioxideSources: Coal-fired power
plants and non-iron ore smelters
Type: Carbon monoxideSources: Mostly from
burning carbon fuels (e.g. motor vehicle
exhaust)
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Acid rain is a rain or any other form of
precipitation that is unusually acidic (has a
low pH)
Acid rain is caused by emissions of sulfur
dioxide and nitrogen oxides which react with
the water molecules in the atmosphere to
produce acids
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Asthma
Lung Cancer
Can cause coughing, chest pains, throat
irritation
Colds and pneumonia
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Can damage buildings and historic monuments,
especially those made of rocks such as limestone
and marble containing large amounts of calcium
carbonate
Soil biology and chemistry can be damaged
because microbes cannot tolerate changes in pH
As lakes and river become more acidic,
biodiversity is reduced
◦ Because of low pH, fish eggs may not hatch and some
adult fish are killed
◦ Eliminates insect life and some fish species (brook trout)
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Founded in 1990 by US Environmental
Protection Agency (EPA)
Goal is to reduce overall atmospheric levels of
sulfur dioxide and nitrogen oxides, which
cause acid rain.
The program is an implementation of
emissions trading that targets coal-burning
plants, allowing them to buy and sell
emission permits.
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There are several options for reducing SO2
emissions, including using coal containing
less sulfur, washing the coal, and using
devices called “scrubbers” to chemically
remove the SO2 from the gases leaving the
smokestack
Powerplants can use different fuels  burn
natural gas instead of coal
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Nuclear power
Hydropower
Wind energy
Geothermal energy
Solar energy
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Takes many years for ecosystems to recover
from acid rain even after emissions are
reduced and rain pH is back to normal
“Liming” = a process in which limestone or
lime is added to acidic lakes to cancel out the
acidity
◦ Disadvantage: expensive and short-term solution
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Reducing and controlling the emissions from
powerplants and cars
Implement cost-effective mechanisms to
reduce emissions
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Turn off lights, computers, and other appliances when
you're not using them.
Use energy-efficient appliances: lighting, air conditioners,
heaters, refrigerators, washing machines, etc. For more
information, see EPA’s ENERGY STAR Program.
Only use electric appliances when you need them.
Keep your thermostat at 68°F in the winter and 72°F in the
summer. You can turn it even lower in the winter and
higher in the summer when you are away from home.
Insulate your home as best you can.
Carpool, use public transportation, or better yet, walk or
bicycle whenever possible
Buy vehicles with low NOx emissions, and properly
maintain your vehicle.
Be well informed.
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Gases which absorb and emit radiation
Greenhouse Gases (GHG):
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Water Vapor
Carbon Dioxide
Methane
Nitrous Oxide
Ozone
Chlorofluorocarbons (CFCs)
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The greenhouse effect is a process by which
thermal radiation from a planetary surface is
absorbed by atmospheric greenhouse gases,
and is re-radiated in all directions
The greenhouse effect keeps our planet warm
If we had no atmosphere, our Earth would be
32°C colder than it is today
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Plants need CO2 to survive, and plants
exposed to more CO2 could grow up to 50%
faster than normal
Increased global temperature due to
greenhouse effect
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Treaty signed in which banned the use of
CFCs and HFCs