1. What Causes Acid Precipitation?
Acid precipitation-precipitation that contains a high concentration of acids because of the pollution of the atmosphere
Burning fossil fuels releases oxides of sulfur and nitrogen
Oxides combine with water in the atmosphere forming sulfuric acid and nitric acid, which falls as acid precipitation.

2. What Causes Acid Precipitation?

3. Effects of Acid Precipitation?
Acidic water flows over and through the ground, and into lakes, rivers, and streams.
Results
Decline in plant and animal populations

4. pH- What is it?
A pH number is a value that is used to express the acidity or alkalinity (basicity) of a system.
Each whole number on the scale indicates a tenfold change in acidity.
pH of 7 is neutral
pH less than 7 is acidic,
pH greater than 7 is basic.
Pure water has a pH of 7.0, while normal precipitation has a pH of about 5.6.

5. pH Examples

6. Why is normal precipitation acidic?
Normal precipitation is slightly acidic because atmospheric carbon dioxide dissolves into the precipitation and forms carbonic acid.
Precipitation is considered acid precipitation if it has a pH of less than 5.0
PH of precipitation varies in different geographic areas.
pH of precipitation in the eastern U.S. and Canada ranges from 4.2 to 4.8, the most acidic precipitation occurs around Lake Erie and Lake Ontario.

7. How Acid Precipitation Affects Soils and Plants
Acid rain can drop the pH of soil and water.
Acidification- increase in the concentration of acid
Acidification of soil
Dissolves nutrients allowing rain to wash them away
Releases harmful nutrients allowing them to be taken into plants
Aluminum
Toxic metals
Sulfur dioxide in water vapor clogs the openings on the surfaces of plants.

8. Acid Precipitation and Aquatic Ecosystems
Aquatic animals are adapted to live in a particular pH range.
Acid precipitation can change lakes/rivers pH, killing aquatic plants and animals.
Acid precipitation causes aluminum to leach out of the soil and into a lake
Aluminum accumulates in the gills of fish and interferes with oxygen and salt exchange suffocating the fish

9. Acid Precipitation and Aquatic Ecosystems
Acid shock -sudden runoff of large amounts of highly acidic water into lakes and streams when snow melts or when heavy rains follow a drought.
Effects
kills large numbers of fish
affects the reproduction of fish and amphibians
birth defects

10. Acid Precipitation and Humans
Toxic metals such as aluminum and mercury can be released when soil acidity increases.
May be a correlation between large amounts of acid precipitation received and an increase in respiratory problems in a community’s children.

11. Acid Precipitation and Humans
Acid precipitation can decrease standard of living
Affects commercial fishing
Affects plant growth
Acid precipitation also dissolves the calcium carbonate in common building materials, such as concrete and marble
Damaging to buildings, sculptures and monuments

12. International Conflict
Difficult to control
pollutants may be released in one geographical area and fall to the ground hundreds of kilometers away.
For example, much of the acid precipitation that falls in southeastern Canada results from pollution produced in the northeastern United States.

13. International Conflict

14. International Cooperation
Because acid precipitation falls downwind, the problem of solving acid precipitation has been difficult, especially on the international level.
Air Quality Agreement in Canada and U.S. agreed to reduce acidic emissions that flowed across the Canada-U.S. boundary.
Similar agreements in Europe have significantly reduced sulfur dioxide emissions.

15. Objectives Explain the causes of acid precipitation.
Explain how acid precipitation affects plants, soils, and aquatic ecosystems.
Describe three ways that acid precipitation affects humans.
Describe ways that countries are working together to solve the problem of acid precipitation.