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Acid Rain. Mark Ewoldsen, Ph.D. Advanced Placement Environmental Science Teacher La Cañada High School. Background Information. Atmosphere. Earth’s Atmosphere. Compared to the size of the Earth (12000 km) The atmosphere is very thin (120 km). - PowerPoint PPT Presentation
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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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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.
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Sulfate Ion Concentrations1985-2004
1985 19861984
http://nadp.sws.uiuc.edu/amaps2/