Acid Precipitation Environmental Science Spring 2010

What is Acid Precipitation? Rain, sleet, or snow that contains a high concentration of acid because of pollution in the atmosphere Rain, sleet, or snow that contains a high concentration of acid because of pollution in the atmosphere SO 2 and NO 2 combine with water in the atmosphere to create acid precipitation SO 2 and NO 2 combine with water in the atmosphere to create acid precipitation

How is acidity measured? pH is a number that indicates the acidity of a solution pH is a number that indicates the acidity of a solution A pH of 7 is neutral, a pH of less than 7 is acidic, and a pH of greater than 7 is basic. A pH of 7 is neutral, a pH of less than 7 is acidic, and a pH of greater than 7 is basic.

How is acidity measured? Normal precipitation is slightly acidic because atmospheric carbon dioxide dissolves into the precipitation and forms carbonic acid. 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 Precipitation is considered acid precipitation if it has a pH of less than 5.0

How acid precipitation effects plants and soil Acid precipitation can cause a drop in the pH in soil or water – called acidification Acid precipitation can cause a drop in the pH in soil or water – called acidification Nutrients in the soil are dissolved and wash away Nutrients in the soil are dissolved and wash away Aluminum and other toxic metals are more easily absorbed by plants – causes root damage Aluminum and other toxic metals are more easily absorbed by plants – causes root damage SO 2 in water vapor can clog openings in plant leaves SO 2 in water vapor can clog openings in plant leaves

Acid Precipitation and Aquatic Ecosystems If the water’s pH changes, it can kill aquatic organisms If the water’s pH changes, it can kill aquatic organisms Acid precipitation also can cause aluminum to leach out of the soil and into a lake. Acid precipitation also can cause aluminum to leach out of the soil and into a lake. The aluminum accumulates in the gills of fish and interferes with oxygen and salt exchange so the fish slowly suffocate. The aluminum accumulates in the gills of fish and interferes with oxygen and salt exchange so the fish slowly suffocate.

Acid Precipitation and Aquatic Ecosystems Acid shock – when large amounts of highly acidic run off enters an aquatic ecosystem Acid shock – when large amounts of highly acidic run off enters an aquatic ecosystem Most often happens when snow melts in the spring or heavy rains after a drought Most often happens when snow melts in the spring or heavy rains after a drought Causes fish to die and those that don’t die lay fewer eggs and most of the eggs don’t hatch Causes fish to die and those that don’t die lay fewer eggs and most of the eggs don’t hatch The offspring that do hatch often have birth defects and cannot reproduce The offspring that do hatch often have birth defects and cannot reproduce

Acid Precipitation and Humans Acid Precipitation releases aluminum and toxic metals into the soil that gets into crops, water and fish. Acid Precipitation releases aluminum and toxic metals into the soil that gets into crops, water and fish. Research also indicates a relationship between large amounts of acid precipitation and respiratory problems in children Research also indicates a relationship between large amounts of acid precipitation and respiratory problems in children

International Cooperation One problem in controlling acid precipitation is that pollutants can be release in one place and fall hundreds of miles away One problem in controlling acid precipitation is that pollutants can be release in one place and fall hundreds of miles away It can be especially difficult to solve on an international level It can be especially difficult to solve on an international level Canada and the United States signed the Canada-U.S. Air Quality Agreement in Canada and the United States signed the Canada-U.S. Air Quality Agreement in 1991.