AP Environmental Science

Acid Rain AP Environmental Science

This is the Island known as Earth

Background Information

Atmosphere

Earth’s Atmosphere Compared to the size of the Earth (12000 km) The atmosphere is very thin (120 km) http://www.gsfc.nasa.gov/gsfc/earth/pinatuboimages.htm

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

Two Atmosphere Layers • Stratosphere is above Troposphere • Ozone Layer blocks UV radiation • Troposphere is where we live • Weather occurs here • 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 a substance's pH, it is more acidic • Pure water has a pH of 7.0 • Normal rain is slightly acidic and has a pH of about 5.6 • Any rainfall has a pH value less than 5.6 is defined as acid rain • As of the year 2000, 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 (SO2) • Nitrogen Oxides (NOx) * 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. sulfur dioxide, nitrogen dioxidedissolve in rain water, various acids are formed. CO2 + H2O  H2CO3 (carbonic acid) SO2 + H2O  H2SO3 (sulphorous acid) NO2 + H2O  HNO2 (nitrous acid) + HNO3 (nitric acid)

Secondary Pollutants H2SO4 HNO2 sulfuric acid nitric acid Primary Pollutants SO2 NO2 acidic precipitation vegetation direct toxicity indirect health effects water Fossil fuels Power plants Industrial emissions Auto emissions soils leaching of minerals sediments leaching aluminum

Acidic Precipitation Wind Transformation to sulfuric acid (H2SO4) and nitric acid (HNO3) Windborne ammonia gas and particles of cultivated soil partially neutralize acids and form dry sulfate and nitrate salts Wet acid deposition (droplets of H2SO4 and HNO3 dissolved in rain and snow) Dry acid deposition (sulfur dioxide gas and particles of sulfate and nitrate salts) Sulfur dioxide (SO2) and NO Nitric oxide (NO) Acid fog Farm Lakes in deep soil high in limestone are buffered Lakes in shallow soil low in limestone become acidic Ocean

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

“Dry” Acid Rain • Dry deposition refers to acidic gases and particles. • About half of the acidity in theatmosphere falls back to earth through dry deposition. • The wind blows these acidic particles and gases onto buildings, cars, homes, and trees. http://svr1-pek.unep.net/soechina/images/acid.jpg

Effects of Acid Rain • Has a variety of effects, including damage to forests and soils, fish and other living things, materials, and human health. • Also reduces how far and how clearly we can see through the air, an effect called visibility reduction. • Effects of acid rain are most clearly seen in the aquatic environments • Most lakes and streams have a pH between 6 and 8 http://cica.indiana.edu/projects/Biology/movies.html

In areas where buffering capacity is low, acid rain also releases aluminum from soils into lakes and streams • Aluminum is highly toxic to many species of aquatic organisms. http://home.earthlink.net/~photofish/fish_photos/sw10_thumb.jpg

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

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. • In addition, low pH and increased aluminum levels cause chronic stress that may not kill individual fish, but leads to lower body weight and smaller size and makes fish less able to compete for food and habitat.

Acid Rain and Forests • Acid rain does not usually kill trees directly. • Instead, it is more likely to weaken trees • Damaging their leaves • Limiting the nutrients available to them • Exposing them to toxic substances slowly released from the soil.

Mongolia Germany

Great Smoky Mountains, NC

1984 1986 http://nadp.sws.uiuc.edu/amaps2/ Sulfate Ion Concentrations 1985-2004 1985

1985 1987 Sulfate Ion Concentrations 1985-2004 1986

AP Environmental Science