1. Acid Precipitation
Chapter 12 Section 3

2. What Causes Acid Rain
Acid precipitation is precipitation such as rain, sleet, or snow that contains a high concentration of acids.
When fossil fuels a burned, they release oxides of sulfur and nitrogen. When these oxides combine with water vapor, they form sulfuric and nitric acid which fall as acid precipitation.
It can kill living things and cause decline or loss of plant and animal populations.

3. A pH number is a measure of how acidic or basic a substance is
A pH number is a measure of how acidic or basic a substance is. The lower the pH, the more acidic the substance is. The higher the pH the more basic a substance is. Pure water has a pH of 7.
Natural rain is slightly acidic because carbon dioxide dissolves into the precipitation forming carbonic acid. Normal rain has a pH of about Acid rain has a pH of less than 5.

4. How Acid Precipitation Affects Soil and Plants
Acid precipitation can cause a drop in the pH of soil and water. This increase is called acidification.
This changes the balance of a soil's chemistry. This causes some nutrients to dissolve and wash away. It also causes aluminum and other toxic metals to be released and absorbed by plant roots.

5. Acid Precipitation and Aquatic Ecosystems
Aquatic animals are adapted to live in an environment with a particular pH range. If the pH of the water changes, the fish and other organisms can die.
Acid precipitation causes aluminum to leech out of the soil, and aluminum in the gills of fish interferes with oxygen and salt exchange.
Effects are worst in the spring when snow melts and rushes into lakes and rivers.
The sudden influx of acidic water is called acid shock.

6. Acid Precipitation and Humans
Toxic metals like aluminum and mercury can be released into the environment when soil acidity increases. These metals find their way into crops, water, and fish; then they poison humans.
There is a correlation between acid rain and respiratory problems.
Decreases in the number of fish affects commercial fishermen. Forestry is affected when the trees are damaged.
Calcium carbonate can dissolve which affects many monuments and creates sink holes.

7. International Conflict and Cooperation
One problem is that pollutants released in one area may fall to the ground hundreds of miles away.
Acid precipitation is an international problem. Canada and the U.S. signed the Canada-U.S. Air Quality Agreement in Both countries agreed to reduce emissions that flow across the U.S. Canada border.
Sulfur dioxide emissions have reduced significantly because agreements like this.
China still burns large amounts of high- sulfur without pollution controls.

8. Copy now, answer later Explain how acid precipitation forms.
Describe the harmful effects that acid precipitation can have on plants, soils, and aquatic ecosystems.
Describe three ways in which acid precipitation can affect humans.
Describe a way in which countries are working together to solve the problem of acid precipitation.
Write a paragraph in which you discuss whether or not a country that releases significant amounts of pollutants into the air that falls as acid precipitation in another country should be expected to pay some of the costs of cleanup.