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					       ES 1111
Air Pollution and Acid Rain
 Section 11.2 in first text
             Pollutant
A  pollutant is anything that is
  hazardous to life or the environment
 Primary pollutant – one that is
  emitted directly into the atmosphere
 Secondary pollutant – one that not
  emitted directly, but is generated
  through chemical reactions over time
 Criteria pollutant – identified and
  monitored by the US EPA
  Important Criteria Pollutants
 Particulates (can be secondary too)
 Carbon monoxide

 Sulfur Compounds

 Nitric Oxide

 Volatile Organic Compounds

 Lead
Primary Pollutants and Sources


Figure showing the primary pollutants and their
                   sources
             Particulates
 Suspended solid or liquid particles
  (aerosols) in the air
 Sizes vary from 0.1 μm to 100 μm
 Sources are fires, volcanic eruptions,
  breaking sea waves, plants (pollen)
 Gravitational settling and precipitation
  removes particulates
 Reduce visibility
 Those smaller than 2.5 μm most readily
  enter the lungs and cause tissue damage
         Carbon Monoxide (CO)
   Colorless and odorless gas
   Most released naturally by volcanic eruptions, fires,
    bacteria, etc.
   Soil microorganisms consume it
   Poorly running automobiles emit large amounts by
    incomplete burning
   Extremely toxic – causes heart disease long-term, or
    death within an hour if concentration is 1600 ppm or
    more
   Hemoglobin in the blood is 200 times more attracted
    to carbon monoxide than oxygen (leading to oxygen
    starvation of the body)
   Most hazardous to human health of all criteria
    pollutants
        Sulfur Compounds
 2/3 comes from natural processes
  (volcanic eruptions, bacterial release
  of hydrogen sulfide (H2S), sea spray)
 Sulfur dioxide (SO2) is released by
  burning sulfur-based fossil fuels (coal
  and oil) and other industrial activities
 Sulfur dioxide is colorless but highly
  corrosive and irritates the lungs
           Nitric Oxide (NO)
 Nitric Oxide is toxic, highly reactive,
  colorless, and odorless
 Also considered a pollutant because
  it readily oxidizes into nitrogen
  dioxide (a toxic secondary pollutant)
 Created when high temperature
  combustion forces atmospheric
  oxygen (O2) and nitrogen (N2) to
  react to form NO
    Volatile Organic Compounds
 Also called hydrocarbons, entirely made of
  carbon and hydrogen atoms
 Examples include methane, butane,
  propane, and octane
 Most emitted naturally by plant and
  animal emissions and decomposition
 Industrial activities/automobiles are a
  source of anthropogenic VOCs
 No direct adverse health effects, but they
  react with other substances to form smog
                Lead
 Was  used as a fuel additive to make
  engines run smoother, and for
  plumbing pipes and in paints
 Can be inhaled or ingested

 Results in brain damage and memory
  loss, as well as low IQ in children
       Secondary Pollutants
 Particulates

 Nitrogen   Dioxide
 Ozone
              Particulates
 Secondary   particulates can be
  created by the coagulation of gases
 This happens when the humidity is
  high
 Hygroscopic aerosols are particularly
  effective at being secondary
  particulate pollutants
         Nitrogen Dioxide (NO2)
   Can be emitted directly as a primary
    pollutant, but most is created by the
    oxidation of Nitric Oxide (NO)
   Toxic gas that has a pungent odor and gives
    the air a yellow to reddish-brown color
   Corrosive and can react with other
    substances to produce other secondary
    pollutants
   Irritates the lungs and can reduce immunity
    to infection at high levels
   Breaks down readily, so at its highest levels
    when traffic levels are the highest
                  Ozone
 At the surface, ozone (O3) is a pollutant -
  it irritates the respiratory system and
  damages plants
 Created differently than it is produced in
  the stratosphere
 Nitrogen dioxide is created when nitrous
  oxide is oxidized. NO2 is broken down by
  sunlight back into NO and O. The loose O
  reacts with O2 to create ozone
 Because it is created by sunlight, ozone is
  at its highest levels in the afternoon
                 Smog
 A combination of the words ―smoke‖ and
  ―fog‖
 Two different types of smog occur

 London Smog: original meaning of smog;
  mixture of smoke, sulfurous particles and
  soot with a fog
 Los Angeles Smog: Photochemical smog;
  dry air smog with ozone, peroxyacyl
  nitrate (PAN) and formaldehyde
      Pollution Meteorology
 Meteorological  conditions can make
  the pollution issue better or worse
 ―The solution to pollution is dilution‖
 Meteorological conditions that inhibit
  the dispersion of air pollution will
  create a pollution problem
 Pollution can come from a point
  source (i.e., one smoke stack) or a
  distributed source (i.e., a city)
       Atmospheric Stability
 Recall that unstable conditions allow
  vertical motions of the air while
  stable conditions prevent vertical
  mixing
 Stable conditions will inhibit the
  pollution from dispersing aloft
 Changing profiles of stability with
  respect to the smoke stack can yield
  different results
      Atmospheric Stability
         Figure 11.8, Page 217
showing how variations in atmospheric
  stability in reference to smoke stack
      height will result in different
                 dispersions
               Winds
 The  stronger the wind, the more
  diffuse the pollution will be
 The more variable the winds
  (direction), the more diffuse the
  pollution will be
 Wind shear can induce turbulence
  that can aid in the diffusion
            Topography
 At  night, cold, dense surface air
  drains downhill into low-lying areas,
  making them susceptible to strong
  temperature inversions
 Hills and mountains can block flow
  (like Los Angeles)
 Sea breezes can trap pollution in its
  vertical circulation (like Houston)
  Other Meteorological Factors
 For the production of photochemical
  smog, clear skies will allow ample
  sunlight to begin those chemical
  reactions
 Rain will ―scrub‖ the atmosphere
  because many of the pollutants are
  condensation nuclei or dissolve easily
  in water
    Pollution Mitigation Strategies
 Tall smoke stacks
 Catalytic converters on automobiles (can
  reduce by 90% the CO, NO, and
  hydrocarbon emissions)
 Unleaded gas – US has seen a reduction
  of 90% of lead emissions
 Electrostatic precipitators (scrubbers) on
  power smoke stacks
 Using fuels low in sulfur content
 Alternate energy sources
 Mass transit
                Acids
 Acids are substances that, when
  dissolved in water, produce positively
  charged hydrogen ions
 Bases are substances that, when
  dissolved in water, produce
  negatively charged hydroxide ions
 Acidity is measured using the pH
  scale (potenz hydrogen)
              pH Scale
 The value of pure distilled water has
  a pH value of exactly 7.0
 Acids will have lower pH values

 Bases will have higher pH values

 Logarithmic scale; a decrease of 1 in
  pH means an increase by a factor of
  10 in acidity (hydrogen ions)
               pH Scale



Figure showing the pH scale and the values of
             various substances
              Acid Rain
 Note  that ―clean‖ rain is naturally
  acidic (pH of 5.6) due to carbon
  dioxide in the atmosphere dissolving
  in the water to create carbonic acid
          H2O + CO2 —> H2CO3
 Other acids are created when
  pollution aerosols dissolve in water
 Important acids created due to
  man’s activities are sulfuric acid and
  nitric acid
            Sulfuric Acid
 Sulfur dioxide dissolves in water to
  create a weak acid, sulfurous acid
             SO2 + H2O —> H2SO3
 Sulfurous acid then can react with
  oxygen to create sulfuric acid
         H2SO3+ O2 —> H2SO4
 Once again, sulfur dioxide is emitted
  primarily by coal-burning power
  plants
               Nitric Acid
 Nitric acid is created when nitric oxide
  (NO) oxidizes, yielding nitrogen dioxide
  (NO2). The nitrogen dioxide then
  dissolves in water creating nitric acid
  (HNO3) and nitrous acid (HNO2)
       2NO2 + H2O—> HNO3 + HNO3
 High temperature combustion, such as
  automobiles, produced the nitric oxide
  that began this process
     Regional Acid Rain




Figure showing regional pH values of rain
           Regional Acid Rain
   The northeastern United States has the
    worst acid rain problem
    – Midwestern industry located along the Great
      Lakes
    – Prevailing winds blowing eastward
 The southwestern United States has an
  enhanced acidity due to Mexico
 pH values have improved overall in recent
  decades, especially in the northeast
 pH values have worsened slightly in the
  southwest
    Acid Rain Consequences
 Crop  and forest damage was feared
 Increase in acidity for lakes, rivers

 Death of fish and wildlife

 Weathering of monuments and
  buildings
 Health impacts for those prone to
  respiratory ailments
           Forest Damage
 Fears that forests would die worldwide
  were prevalent in the 80s
 Further studies have shown that the trees
  in most regions are growing better, and
  studies have supported the fact that trees
  can see an increase in growth
 Areas where tree deaths have been
  observed are a result of smoke falling
  directly on the trees from the source
      Damage to Monuments
 Marble structures are especially prone to
  decay due to acid rain
 Marble is made of calcium carbonate
  (CaCO3), and it weathers in sulfuric acid to
  produce gypsum (plaster), carbon dioxide
  gas, and water
  CaCO3 + H2SO4 -> CaSO4 + H2O + CO2
 Cleopatra’s Needle stood for 3000 years in
  Egypt, but has experienced significant
  erosion in New York over just 100+ years
  (symbols barely visible now)
        Cleopatra’s Needle



Picture of Cleopatra’s Needle, showing obvious
    weathering due to acid rain in New York
 Acid Rain Mitigation Strategies
 Sinceacid rain results from pollution,
 the same pollution mitigation
 strategies will also aid in reducing
 the acid rain problem
  – Emissions testing and scrubbing
  – Cleaner fuels
  – Mass transit
  – Alternate Energy
        Indoor Air Pollution
 As bad as the outdoor air pollution
  can be, indoor air pollution is much
  more harmful to our health
 Many of us spend 90% of our time
  indoors
 Air flow is restricted in our homes
  and businesses, so pollutants can
  build up
           Oxygen Deficits
 We breathe in 21% oxygen and 0.03%
  carbon dioxide
 We exhale approximately 16% oxygen
  and 4% carbon dioxide
 About 25% of oxygen has been removed
  and a 100-fold increase in carbon dioxide
  has been added in your breath
 Over time, headaches and drowsiness can
  occur if fresh air does not circulate in
               Radon
 Radon  is itself harmless
 Results from the radioactive decay of
  uranium and thorium in bedrock
 However, radon is radioactive and
  the daughter products are dangerous
 Estimated that 20,000 lung cancer
  deaths are due to radon decay
 Fresh air circulation is the key to
  prevention
              Smoking
 Hazards of smoking have been
  shared with the public over the past
  few decades
 Heart and lung disease results, even
  with second-hand smoke
 Smoking can make individuals 15 x
  more prone to radon-related cancer
        Household Products
 Many of the substances contained in
  carpet molds, paint, insulation, and
  pressed wood furniture are harmful
 Such substances include asbestos,
  benzine, and formaldehyde
 Inefficient stoves and furnaces may emit
  carbon monoxide
 Dispose of harmful materials properly

 Ventilation is vital

				
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posted:2/23/2010
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