Mark Ewoldsen, Ph.D.

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Acid Rain

• Mark Ewoldsen, Ph.D.
• Advanced Placement Environmental Science Teacher
• La Cañada High School

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This is the Island known as Earth
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Background Information
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Atmosphere
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Earths 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
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• If the Earth is compared to this Orange
• the Earths atmosphere would be thinner than the
  layer of pesticide on this Oranges surface

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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)

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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.

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Two Forms

• Wet
• Refers to acid rain, fog, sleet, cloud vapor and
  snow.

• Dry
• Refers to acidic gases and particles.

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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.

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• When gas pollutants e.g. sulphur dioxide,
  nitrogen dioxide dissolve 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)
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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
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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 acid
ic
Ocean
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Wet Acid Rain

• Acidic water flows over and through the ground,
  it affects a variety of plants and animals.

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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
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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.ht
ml
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• 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/s
w10_thumb.jpg
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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.

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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.

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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.

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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.

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Mongolia
Germany
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Great Smoky Mountains, NC
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http//nadp.sws.uiuc.edu/amaps2/
Sulfate Ion Concentrations 1985-2004
1985
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Sulfate Ion Concentrations 1985-2004
1986
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Sulfate Ion Concentrations 1985-2004
1987
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Sulfate Ion Concentrations 1985-2004
1988
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Sulfate Ion Concentrations 1985-2004
1989
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Sulfate Ion Concentrations 1985-2004
1990
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Sulfate Ion Concentrations 1985-2004
1991
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Sulfate Ion Concentrations 1985-2004
1992
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Sulfate Ion Concentrations 1985-2004
1993
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Sulfate Ion Concentrations 1985-2004
1994
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Sulfate Ion Concentrations 1985-2004
1995
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Sulfate Ion Concentrations 1985-2004
1996
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Sulfate Ion Concentrations 1985-2004
1997
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Sulfate Ion Concentrations 1985-2004
1998
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Sulfate Ion Concentrations 1985-2004
1999
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Sulfate Ion Concentrations 1985-2004
2000
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Sulfate Ion Concentrations 1985-2004
2001
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Sulfate Ion Concentrations 1985-2004
2002
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Sulfate Ion Concentrations 1985-2004
2003
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Sulfate Ion Concentrations 1985-2004
2004