Transcript Slide 1 - Cloudfront.net

14.4
The Air We Breathe
Name some sources of air
pollution.
Air pollution
• The contamination of atmosphere by the
introduction of pollutants from human and
natural sources.
Primary Pollutants
• Pollutants that are put
•
directly into the air by
human or natural
activity.
Natural sources: dust,
sea salt, volcanic gases
and ash, pollen
• Other examples:
vehicle exhaust
Smog
• Forms when the ozone and vehicle
exhaust react with sunlight.
Secondary Pollutants
• Pollutants that form
•
when primary
pollutants react with
other primary
pollutants or with
naturally occuring
substances, such as
water vapor.
Example: ozone,
smog
Smog
How does the burning of gasoline by cars
contribute to air pollution?
The burning of gasoline releases exhaust,
which reacts with sunlight to form ozone and
smog.
Industrial Air Pollution
• Industrial plants burn
•
fossil fuels, coal, to
produce energy which
can cause large
amounts of air
pollutants.
Other plants pollute
the air with chemicals
(oil refineries,
chemical
manufacturing plants)
How does burning of fuels to produce energy
affect air quality?
The burning of fossil fuels releases smoke and
other pollutants.
Indoor Air Pollution
• Ventilation and limit the use of chemical
cleaners can lower indoor air pollution.
Acid Precipitation
• Precipitation such as
rain, sleet, or snow
that contains acids
from air pollution.
Acid Rain
What causes acid precipitation?
When pollutants that are released when fossil
fuels are burned combine with water in the
atmosphere, acid rain forms.
Acid precipitation and Plants
• Acidification – the
process where acid
precipitation can
cause the acidity of
soil to increase. (
some nutrients
dissolves)
Acid Precipitation and Aquatic
Ecosystems
• Acid shock
– a rapid change in a body of water’s acidity
– can cause fish to die
– Some communities spray powdered lime on
acidified lakes to reduce the effects of acid
precipitation.
What effects can the burning of fossil fuels
have on aquatic ecosystems?
The burning of fossil fuels can cause acid
precipitation. When acid precipitation falls on
lakes or streams, it may cause a rapid change
in the acidity of the lake or stream. This
process, called acid shock, can kill or damage
large numbers of organisms.
The Ozone Hole
• The ozone layer is thinning
• Chemicals called CFCs are causing the
ozone to break down into oxygen which
doesn’t block the sun’s harmful rays.
The Ozone Hole
Clean Air Act
• A law that allows the Environmental Protection
•
Agency the authority to control the amount of air
pollutants that can be released from any source.
Scrubber – a device that is used to remove some
pollutants before they are released by smokestacks
Allowance Trading System
• EPA establishes allowances for the amount
of a pollutant that companies can release.
• Companies can sell some of their
allowances or buy more.
Controlling Pollution
Review Questions
1. How does smog form?
2.
* Vehicle exhaust reacts with sunlight and
ozone to create smog.
What is the difference between primary and
secondary pollutants?
* Primary pollutants are pollutants that are
put into the air directly by human or natural
activity. Secondary pollutants form when
primary pollutants react with other substances.
3. How are fossil fuels related to air pollution and acid
precipitation?
* When fossil fuels are burned, they release
pollutants such as sulfur dioxide and nitrogen oxide.
These chemicals react with water in the atmosphere
to cause acid precipitation. They can also react with
sunlight and ozone to form smog.
4. Is all air pollution caused by humans? Explain your
answer.
* No, some air pollutants, such as volcanic ash and
gases, pet dander, and plant pollen, come from
natural sources.