Acid precipitation forms when sulfur dioxide and nitrogen oxides from fossil fuel combustion react with water vapor to form acids. This acidic precipitation damages plants by leaching nutrients from soil and releasing aluminum, harms aquatic life by making waters too acidic for fish and frogs, and affects humans through respiratory irritation, loss of commercial fishing, and building corrosion. Countries have signed agreements to reduce emissions that cross borders and cause acid precipitation in downwind nations.

2.  Pure water has a pH of
7.0.
 Normal precipitation
has pH of 5.6
› Due to CO2 mixing
with water vapor to
make carbonic acid.
 Acid precipitation has
pH of less than 5.0
 Can be in the form of
rain, snow, sleet, hail,
fog

3.  SO2 & NOx released
when fossil fuels are
burned.
 SO2 & NOx combine
with water vapor in
atmosphere to make
sulfuric acid & nitric
acid.
 Can fall out of sky, run
along ground, and
enter water sources.

4.  Eastern U.S. (Lake Erie &
Lake Ontario) has pH of
4.2-4.8
 Most of Europe 4.5-5.1
 Eastern Europe and
parts of Scandinavia
4.3-4.5

5.  High Population-
› higher population,
more cars, more fossil
fuel usage
 More industry
› More factories putting
out SO2 & NOx
 Type of rocks in soil
can alter pH levels
› Marble/Limestone-
neutralize pH
› Granite- less
neutralizing power

6.  Acidification- soil pH
drops due to acid
precipitation
› Soil nutrients are
dissolved and washed
away
› Toxic metals (Al) are
released from soil
particles & taken up
by plants
› SO2 can clog
openings in leaves so
they can’t get CO2 to
make sugar
Adirondack mtns in New York

7.  Fish are adapted to
live at specific pH
 Acid precipitation
makes water too
acidic and many
aquatic organisms
can’t tolerate
changes
 Aluminum that
leaches out of soil can
enter water, attach to
fish gills, cause
suffocation.
Frogs can tolerate pH that is more
acidic (pH 4.0) than a fish like a
bass which can only live in water
that is around pH 5.5

8.  Acid snow will melt
rapidly causing pH of
river water to drop
rapidly resulting in acid
shock.
› Causes massive fish
kills
› Fish & frog may
produce fewer eggs
which may not hatch
› Many eggs that do
hatch have birth
defects.

9.  Toxic metals can be
leached out of soil by
acid & be taken up by
crops, water, fish which
can poison humans
 Irritate respiratory systems
 Less fish = decrease in
commercial fishing
(people lose jobs)
 Dissolves building
materials
› Marble, limestone easily
dissolved
› Metals can be tarnished
› Costly to repair these
things.

10.  Air pollution is released in
one location and falls
hundreds of miles away.
 Air pollution produced in
northeastern US falls in
southeastern Canada
› Created Canada-US Air
Quality Agreement
(1991) to reduce
emissions along border.
 China burns mostly coal
with few if any pollution
laws which affects many
nearby Asian countries.

11.  Explain how acid precipitation forms.
 Describe the harmful effects that acid
precipitation can have on plants, soil,
and aquatic ecosystems.
 Describe 3 ways in which acid
precipitation can affect humans.
 Describe a way in which countries are
working together to solve the problems
of acid precipitation.