Acid PrecipitationAcid PrecipitationSection 12.3Section 12.3

Objectives:1. Explain causes of acid

precipitation.2. Explain effects of acid

precipitation.

IntroIntro

1. Rainfall downwind2. Acid precipitation and cars

What Causes Acid What Causes Acid Precipitation?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.

pHpH: power of hydrogen: 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 ScalepH 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 Effects on Aquatic EcosystemsEcosystems

•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 Effects on Humans and LifestyleLifestyle•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 NeedleCleopatra’s Needle

Challenges in Controlling Challenges in Controlling Acid PrecipitationAcid 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 ConflictInternational Conflict

Know For TEST!Know For TEST!

•Section Review (p.317): 1-3, 6