Acid Precipitation Section 12.3 Objectives: Explain causes of acid precipitation. Explain effects of acid precipitation.

Intro Rainfall downwind Acid precipitation and cars

What Causes Acid Precipitation? Acid precipitation: any form of precipitation that contains a high concentration of acids Caused by burning fossil fuels Releases oxides of sulfur and nitrogen into the air (SO2 and NO2) These gases combine with water vapor in the atmosphere, forming sulfuric acid and nitric acid.

pH: power of hydrogen Acids: pH < 7 Bases: pH > 7 Pure water: pH =7.0 Normal rain: pH about 5.6 Acid precipitation: pH < 5.0 Varies by location: Eastern Europe: 4.3-4.5 Rest of Europe: 4.5-5.1 Eastern U.S.: 4.2-4.8 (Lake Ontario and Lake Erie: 4.2)

pH Scale

Effects on Soil and Plants Drop in pH of soil (acidification) Acidic soil: Some nutrients are dissolved Causes aluminum and other toxic metals to be released and absorbed by plants Aluminum causes root damage.

Effects on Aquatic Ecosystems Change in water’s pH can kill aquatic plants, fish, and animals. Acidic pH causes aluminum to leach out of soil and accumulate in fish gills so they can’t exchange oxygen and salt. (Fish suffocate!) Acid shock: sudden change in water pH due to excess runoff of acidic precipitation (mainly in Spring)

Effects on Humans and Lifestyle Toxic metals released in acidic soils (aluminum, mercury, etc.) become part of food crops, water, and fish, then we ingest them. Possible connection between acid precipitation and respiratory problems in children Damage to fishing and forestry industries Can damage buildings and monuments

Cleopatra’s Needle

Challenges in Controlling Acid Precipitation Pollutants may be released in one geographical area and fall to the ground in another. SE Canada’s acid precipitation is formed in Ohio, Indiana, Pennsylvania, Illinois, Missouri, West Virginia, and Tennessee! Acid precipitation falls downwind from where it is formed.

International Conflict

Know For TEST! Section Review (p.317): 1-3, 6