Acid Rain- environmental problem - affects large parts of the US and Canada- damaging to lakes, streams, and forests and

the plants and animals that live in these ecosystems.

Effects of Acid Rain

• Damage to plants• Damage to animals• Damage to buildings

Effects of Acid Rain on Marble(marble is calcium carbonate)

George Washington:BEFORE acid rain

George Washington:AFTER acid rain

Where is Acid Rain?Acid rain affects the whole world –

no part of the world is safe.

Causes of Acid Rain

Natural Sources:•volcanoes •decaying vegetation•Forest fires•lightning

Man-Made Sources:•emissions of sulfur dioxide (SO2) •Emissions of nitrogen oxides (NOx)

• In the United States, roughly 2/3 of all SO2 and 1/4 of all NOx come from electric power generation that relies on burning fossil fuels, like coal.

• Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds.

• The result is a mild solution of sulfuric acid and nitric acid.

2 Types of Acid Rain1. wet deposited material 2. dry deposited material

Wet Deposition• acidic rain, fog, and snow• If the acid chemicals in the air are blown into

areas where the weather is wet, the acids can fall to the ground in the form of rain, snow, fog, or mist.

• The strength of the effects depends on several factors:• how acidic the water is• the chemistry of the soils involved• the types of fish, trees, and other living things that

rely on the water.

Dry Deposition• In areas where the weather is dry, the acid chemicals

may become incorporated into dust or smoke and fall to the ground sticking to the ground, buildings, homes, cars, and trees.

• Dry deposited gases and particles can be washed from these surfaces by rainstorms, leading to increased runoff.

• This runoff water makes the resulting mixture more acidic.

• About half of the acidity in the atmosphere falls back to earth through dry deposition.

Measuring Acid Rain• Normal rain is slightly acidic because carbon dioxide

(CO2) dissolves into it forming weak carbonic acid, giving the resulting mixture a pH of approximately 5.6 at typical atmospheric concentrations of CO2.

• As of 2000, the most acidic rain falling in the U.S. has a pH of about 4.3.

Reducing Acid Rain• Societal changes

• Use Alternative Energy Sources• Restore a Damaged environment

• Individual action• Turn off lights, computers, and other appliances when

you're not using them. • Use energy-efficient appliances• Keep your thermostat at 68°F in the winter and 72°F in

the summer.• Insulate your home as best you can. • Carpool, use public transportation, or better yet, walk

or bicycle whenever possible • Buy vehicles with low NOx emissions, and properly

maintain your vehicle.

Clean Air Act Amendments – 1990

• imposes emission restrictions on fossil fueled power plants