1 Mark Ewoldsen, Ph.D. Advanced Placement Environmental Science Teacher La Cañada High School Acid Rain

2 Background Information

3 Atmosphere

4 Earth’s Atmosphere Compared to the size of the Earth (12000 km) The atmosphere is very thin (120 km)

5 If the Earth is compared to this Orange the Earth’s atmosphere would be thinner than the layer of pesticide on this Orange’s surface

6 Two Atmosphere Layers Stratosphere is above TroposphereStratosphere is above Troposphere – Ozone Layer blocks UV radiation Troposphere is where we liveTroposphere is where we live – Weather & Global Warming 72% of all air is below the cruising altitude of commercial airliners (33000 ft)72% of all air is below the cruising altitude of commercial airliners (33000 ft)

Measuring Acid Rain Acid rain is measured using a "pH" scale. – The lower the pH, the more acidic Pure water has a pH of 7.0 – Normal rain is slightly acidic and has a pH of about 5.6 because of H 2 CO 3 Rainfall with a pH less than 5.6 is acid rain As of the year 2010, the most acidic rain falling in the US has a pH of about 4.3.

Two Forms… Wet Refers to acid rain, fog, sleet, cloud vapor and snow. Dry Refers to acidic gases and particles.

Compounds Two main contributers to acid deposition: Sulfur Dioxide (SO 2 ) Nitrogen Oxides (NO x ) * 66% of all sulfur dioxides and 25% of all nitrogen oxides comes from electric power generation that produces energy by burning fossil fuels.

When gas pollutants e.g. sulphur dioxide, nitrogen dioxide dissolve in rain water, various acids are formed. CO 2 + H 2 O  H 2 CO 3 (carbonic acid) SO 2 + H 2 O  H 2 SO 3 (sulphorous acid) NO 2 + H 2 O  HNO 2 (nitrous acid) + HNO 3 (nitric acid)

Fossil fuels Power plants Industrial emissions Auto emissions Primary Pollutants SO 2 NO 2 Secondary Pollutants H 2 SO 4 HNO 2 sulfuric acidnitric acid soils leaching of minerals vegetation direct toxicity indirect health effects water sediments leaching aluminum acidic precipitation

“ Wet” Acid Rain Acidic water flows over and through the ground Affects a variety of plants and animals.

“Dry” Acid Rain Dry deposition refers to acidic gases and particles. About half of the acidity in the atmosphere falls back to earth through dry deposition. The wind blows these acidic particles and gases onto/into buildings, cars, homes, and trees.

Nutrients Acidic water – dissolves the nutrients and helpful minerals in the soil – washes nutrients away before plants can use them to grow. Acid rain also causes the release of substances, such as aluminum, that are toxic to plants

Effects on Wildlife Generally, the young of most species are more sensitive to environmental conditions than adults. At pH 5, most fish eggs cannot hatch. At lower pH levels, some adult fish die. Some acid lakes have no fish.

Effects on Wildlife Both low pH and increased aluminum levels are directly toxic to fish. Chronic stress that leads to lower body weight smaller size

Acid Rain and Forests Acid rain does not usually kill trees directly Weakens trees – Damaging leaves – Limiting nutrients available – Toxic substances slowly released from the soil.

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Great Smoky Mountains, NC

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