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Mark Ewoldsen, Ph.D.Mark Ewoldsen, Ph.D.Advanced Placement Environmental Science Teacher

La Cañada High SchoolLa Cañada High School

Acid Acid RainRain

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Background Background InformationInformation

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AtmosphereAtmosphere

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Earth’s AtmosphereEarth’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

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If theIf the EarthEarth is is compared to thiscompared to this

OrangeOrange

the Earth’s the Earth’s atmosphere atmosphere would be would be

thinner than the thinner than the layer of layer of

pesticide onpesticide on this this Orange’s Orange’s surfacesurface

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Two Atmosphere Two Atmosphere LayersLayers

• Stratosphere is above Stratosphere is above Troposphere Troposphere –Ozone Layer blocks UV radiation Ozone Layer blocks UV radiation

• Troposphere is where we liveTroposphere is where we live–Weather & Global WarmingWeather & Global Warming

• 72% of all air is below the 72% of all air is below the cruising altitude of commercial cruising altitude of commercial airliners (33000 ft)airliners (33000 ft)

Measuring Acid RainMeasuring 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 H2CO3

•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…Two Forms…

Wet

Refers to acid rain, fog, sleet,

cloud vapor and snow.

• Dry

Refers to acidic gases and particles.

CompoundsCompounds

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. 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)

Fossil fuelsPower plants

Industrial emissions

Auto emissions

Primary PollutantsSO2

NO2

Secondary Pollutants

H2SO4 HNO2

sulfuric acid nitric acid

soilsleaching of minerals

vegetationdirect toxicity

indirect health effects

water

sedimentsleaching

aluminum

acidic precipitation

““Wet” Acid Wet” Acid RainRain

Acidic water flows over and

through the ground

Affects a variety of plants and

animals.

““Dry” Acid RainDry” 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/into buildings, cars, homes, and trees.

http://svr1-pek.unep.net/soechina/images/acid.jpg

NutrientsNutrients• 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 Effects on WildlifeWildlife

• 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 Effects on WildlifeWildlife

• 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 ForestsAcid 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.

GermanyGermanyMongoliaMongolia

Great Smoky Mountains, NC

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Sulfate Ion Concentrations1985-2004

1985 19861984

http://nadp.sws.uiuc.edu/amaps2/

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1986 19871985

Sulfate Ion Concentrations1985-2004

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1987 19881986

Sulfate Ion Concentrations1985-2004

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1988 19891987

Sulfate Ion Concentrations1985-2004

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1989 19901988

Sulfate Ion Concentrations1985-2004

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1990 19911989

Sulfate Ion Concentrations1985-2004

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1991 19921990

Sulfate Ion Concentrations1985-2004

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1992 19931991

Sulfate Ion Concentrations1985-2004

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1993 19941992

Sulfate Ion Concentrations1985-2004

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1994 19951993

Sulfate Ion Concentrations1985-2004

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1995 19961994

Sulfate Ion Concentrations1985-2004

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1996 19971995

Sulfate Ion Concentrations1985-2004

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1997 19981996

Sulfate Ion Concentrations1985-2004

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1998 19991997

Sulfate Ion Concentrations1985-2004

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1999 20001998

Sulfate Ion Concentrations1985-2004

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2000 20011999

Sulfate Ion Concentrations1985-2004

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2001 20022000

Sulfate Ion Concentrations1985-2004

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2002 20032001

Sulfate Ion Concentrations1985-2004

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2003 20042002

Sulfate Ion Concentrations1985-2004

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2004 20052003

Sulfate Ion Concentrations1985-2004