Air%20Pollution

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Air Pollution
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THE AIR AROUND US

• Air pollution-physical or chemical changes
  brought about by natural processes or human
  activities that result in the decrease of air
  quality
• 147 million metric tons annually in US
• Worldwide 2 billion metric tons.
• Improving air quality in developed countries,
  developing getting worse.

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NATURAL SOURCES OF AIR POLLUTION

• Natural Fires - Smoke
• Volcanoes - Ash and acidic components
• Sea Spray - Sulfur
• Bacterial Metabolism - Methane
• Dust
• Pollen

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HUMAN-CAUSED AIR POLLUTION

• Primary Pollutants emitted directly into air
  from a point source
• Secondary Pollutants formed in air when primary
  pollutants react or interact

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Major Sources of Primary Pollutants

• Stationary Sources
• Combustion of fuels for power and heat Power
  Plants
• Burning wood, crops, and/or forest fires
• Industry
• Solvents and aerosols
• Mobile Sources
• Highway cars, trucks, buses and motorcycles
• Off-highway aircraft, boats, locomotives, farm
  equipment, RVs, construction machinery, and lawn
  mowers

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Major Air Pollutants

• Carbon monoxide (CO)
• Nitrogen dioxides (NO2)
• Ozone (O3)
• Particulate matter (PM-10, PM-2.5)
• Sulfur dioxide (SO2)
• Lead (Pb)
• Greenhouse gases (CO2 and others)

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Carbon Monoxides

• Properties colorless, odorless, 0.0036 of
  atmosphere
• Effects reduces ability of blood to bring oxygen
  to body cells and tissues, mental functions and
  visual acuity, even at low levels
• Sources incomplete combustion of fossil fuels
  and combustion of waste
• 60 - 95 from auto exhaust

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Sulfur Dioxides

• Properties colorless gas with irritating odor
• Effects
• reacts in atmosphere to create SO3 and H2SO4
• breathing difficulties
• Sources
• Natural sea spray, volcanic fumes
• Human sources burning high sulfur coal or oil,
  smelting or metals, paper manufacture

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Particulate Matter

• Properties particles suspended in air (lt10 um)
• Effects Inhalation causes respiratory diseases,
  ranging from asthma to respiratory distress and
  lung cancer, reduces visibility
• Sources
• Natural dust, volcanic ash, pollen, spores
• Human sources Smoke, dust, soot, asbestos,
  factories, unpaved roads, plowing, lint, burning
  fields

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Particulate Matter

• Impacts Visibility at Shenandoah Natl Park

Source Ref. (2)
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Nitrogen Dioxides

• Properties reddish brown gas, strong oxidizing
  agent, forms Nitric acid in air
• Effects lung and heart problems, component of
  photochemical smog and acid deposition,
  suppresses plant growth
• Sources
• Natural forest fires, volcanoes, lightning,
  bacteria in soil
• Human sources fossil fuels combustion and power
  plants

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Lead

• Properties grayish metal
• Effects accumulates in tissue affects kidneys,
  liver and nervous system (children most
  susceptible) mental retardation possible
  carcinogen 20 of inner city kids have high
  levels
• Sources particulates, melting smelting,
  batteries

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Ground Level Ozone

• Properties colorless, unpleasant odor, major
  part of photochemical smog
• Effects lung irritant, damages plants, rubber,
  fabric, eye, reduces visibility
• Sources Created by sunlight acting on NOx and
  VOCs NOx VOCs sunlight -gt NOx O3
• cars, industry, gas
  vapors, chemical solvents,
• incomplete fuel combustion
  products
• 10,000 to 15,000 people in US admitted to
  hospitals each year due to ozone-related illness
• Children more susceptible

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VOCs

• Properties organic compounds (hydrocarbons) that
  evaporate easily, usually aromatic
• Effects eye and respiratory irritants
  carcinogenic liver, CNS, or kidney damage
  damages plants lowered visibility due to brown
  haze global warming
• Sources vehicles (largest source), evaporation
  of solvents or fossil fuels, aerosols, paint
  thinners, dry cleaning
• Concentrations indoors up to 1000x outdoors

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Formation Intensity

• Factors
• Local climate (inversions, air pressure,
  temperature, humidity)
• Topography (hills and mountains)
• Population density
• Amount of industry
• Fuels used by population and industry for
  heating, manufacturing, transportation, power
• Weather rain, snow,wind
• Buildings (slow wind speed)
• Mass transit used
• Economics

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Photochemical Smog Forms
...when polluted air is stagnant (weather
conditions, geographic location)
Los Angeles, CA
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Primary Pollutants
CO
CO2
Secondary Pollutants
SO2
NO
NO2
SO3
Most hydrocarbons
HNO3
H2SO4
Most suspended particles
H2O2
O3
PANs
Most
Natural
Sources
Stationary
Mobile
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Photochemical Smog
UV radiation H2O O2
Primary Pollutants NO2 Hydrocarbons
Auto Emissions
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Temperature Inversions

• Occurs when a stable layer of warm air overlay
  cooler air near the ground
• Usually happens at night since ground loses heat
  quickly

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Heat Islands

• Heat islands-Urban development creates warm,
  stable air masses over large cities.
• Sparse vegetation and dark surfaces
• Concentrates pollutants in a dust dome.
• Rural areas downwind have decreased visibility
  and increased rainfall.

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Acid Deposition

• Occurs when sulfur dioxide and nitrogen oxides
  are emitted into the atmosphere
• Coal burning plants
• Automobiles
• Absorbed by water droplets in clouds

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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
sediments leaching aluminum
soils leaching of minerals
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2 Forms of Acid Deposition

• Wet deposition-acidic rain, fog, snow and cloud
  vapor
• Falls in downward winds areas within 4-14 days
• Dry deposition-acidic particles and gases
• Falls near the emission sources within 2-3 days

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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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Factors that effect

• The strength of the effects depend on many
  factors
• How acidic the water is
• The chemistry and buffering capacity of the soils
  involved
• The types of fish, trees, and other living things
  that rely on the water

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Effects of Acid Rain

• Damages forests and soils, fish and other
  organisms, materials, and human health.
• most clearly seen in the aquatic environments
• young of most species are more sensitive
• At pH 5, most fish eggs cannot hatch.
• At lower pH levels, some adult fish die.

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Effects of Acid Rain

• Acidic water
• dissolves the nutrients and helpful minerals in
  the soil
• washes them away before uptake from plants

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Buffering Capacity

• Acid rain primarily affects sensitive bodies of
  water
• soils have a limited buffering capacity
• Lakes and streams become acidic
• When low, acid rain also releases aluminum from
  soils into lakes and streams
• Aluminum is highly toxic to many species of
  aquatic organisms.

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Mongolia
Germany
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Great Smoky Mountains, NC
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Ozone Two Faces

• Stratosphere Good Ozone
• Blocks UV radiation
• Hole caused by depletion due to CFCs
• Troposphere Bad Ozone
• Pollution
• Photochemical smog
• Eye irritant

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Ozone Formation
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Destroying Good Ozone

• Chloroflourocarbons created in 1928 as non-toxic,
  non-flamable refrigerants
• first produced commercially in the 1930's by
  DuPont
• In 1974, a laboratory study demonstrated the
  ability of CFC's to breakdown Ozone in the
  presence of high frequency UV light
• Cl O3 -gt ClO O2 ClO O3 ---gt 2 O2 Cl
• In a 1985, a study summarized data that had been
  collected by the British Antartic Survey showing
  that ozone levels had dropped to 10 below normal
  January levels for Antarctica.
• http//www.nas.nasa.gov/About/Education/Ozone/hist
  ory.html

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Destruction of Stratospheric Ozone

• CFCs persist up in the atmosphere for decades
• Models indicate that 75-85 of the observed ozone
  losses in the stratosphere since 1976 are the
  result of ozone depleting chemicals released in
  the early 1950s

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http//www.mmscrusaders.com/newscirocks/ozone/cfc.
jpg
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Stratospheric Ozone

• Winds isolate Antarctic air and allows
  stratospheric temperatures to drop and create ice
  crystals at high altitudes.
• ozone and chlorine molecules are absorbed on the
  surfaces of these ice particles.
• When sun returns in the spring and provides
  energy chlorine molecules are released

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Harmful effects of UV radiation

• Skin cancer
• Cataracts and sun burning
• Adverse impact on crops and animals
• Alters photochemical reaction rates
• Increases smog and surface layer ozone
• Degradation of paints and plastic material

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Montreal Protocol

• An international treaty designed to protect the
  ozone layer
• Phasing out production of number of substances
  believed to be responsible for ozone depletion
• Effective January 1, 1989
• Five revisions
• 1990 (London)
• 1992 (Copenhagen)
• 1995 (Vienna)
• 1997 (Montreal)
• 1999 (Beijing)
• As a result CFC production fell 85