Docstoc

Chapter 15.pptx - ViewpointAPES

Document Sample
Chapter 15.pptx - ViewpointAPES Powered By Docstoc
					           Chapter 15

Air Pollution and Stratospheric Ozone
               Depletion
                   Air Pollution
• Is the contamination of
  the atmosphere with
  chemicals, particulates, or
  pathogens that harm
  living things or alter
  ecosystems
• Can be natural or
  anthropogenic
• Can be indoors or
  outdoors
• Can come from point or
  nonpoint sources
               Major Pollutants
• Are also called criteria
  pollutants for their EPA
  allowable levels
• Include oxides
   – Sulfur dioxide
   – Nitrogen oxides
   – Carbon oxides
• Include particulates
• Include ozone
• Include lead
              Sulfur Dioxide (SO2)
• Is a gas caused by burning
  fossil fuels
   – Mostly coal and oil
   – Release sulfur into the
     atmosphere
   – Sulfur reacts with
     atmospheric oxygen to
     form SO2
• Is a respiratory irritant
• Can form other pollutants
   – Sulfuric acid H2SO4
   – Smog
• Can come from forest
  fires and volcanic
  eruptions
          Nitrogen Oxides (NOx)
• Can be nitrogen oxide
  (NO) or nitrogen dioxide
  (NO2)
   – Can transform from one
     to the other
• Are gases caused by the
  burning of fossil fuels
• Can come from forest
  fires and volcanic
  eruptions
            Carbon Oxides (COx)
• Can be carbon monoxide
  (CO) or carbon dioxide
  (CO2)
• Are gases caused by
  combustion of carbon
   – Fossil fuels, wood, manure
• Are asphyxiants in high
  doses
• Can come from forest fires
  and volcanic eruptions
                     Particulates
• Also called particulate matter
  (PM)
• Range from 0.01 μm to 100
  μm
• Can come from combustion of
  pretty much anything
• Can also come from pollen,
  dust, forest fires, and volcanic
  eruptions
• Scatter light and create haze
   – Large amounts can reduce
     sunlight and photosynthesis
         Particulate Health Risks
• Inhaled particles can
  cause respiratory
  diseases
• Particles smaller than 10
  μm (PM 10) are not
  filtered by the nose and
  throat
• Particles smaller than 2.5
  μm (PM 2.5) can settle
  deep in the lungs
   – Can come from aerosols
                           Lead (Pb)
• Comes from burning
  leaded gasoline
   – Lead is an additive that
     prevents engine knock
• No longer used in the
  US
   – Still used in other
     countries
• Can also be found in old
  paint
   – Do not eat paint chips!
                    Ozone (O3)
• Can be produced
  naturally
• Can be produced from
  photochemical
  reactions
  – Sunlight reacts with
    nitrogen oxides and
    sulfur dioxide
                          Smog
• Comes from combining
  the words smoke and
  fog
• Can be created from
  direct emissions from
  industries and homes
   – Industrial smog
• Can be created by
  reactions between
  sunlight and chemicals
   – Photochemical smog
                Industrial Smog
• Also called sulfurous
  smog
• Forms from combustion
   – Coal power plants are
     most common cause
• Has particulates,
  carbon, and sulfur
  released from burning
  fossil fuels and/or wood
           Photochemical Smog
• Also called brown smog
  – Atmospheric Brown
    Cloud
• Forms from sunlight
  breaking down nitrogen
  compounds
  – Mostly from vehicle
    emissions
• Has nitrogen
  compounds, ozone, and
  particulates
    Non-Criteria Major Pollutants
• Include volatile organic
  compounds (VOCs)
   – VOCs are targeted particularly
     because they contribute to
     photochemical smog
• Include metals other than
  lead
• Are also regulated by EPA
  standards
  Volatile Organic Compounds (VOCs)
• Are chemicals that
  become vapors at typical
  atmospheric
  temperatures and
  pressures
• Often have a strong smell
• Are often involved in
  photochemical reactions
• Are found in gasoline,
  paint and perfume
• Can come from plants
                       Metals
• Include some of the
  same metals found in
  water pollution
   – Mercury and
     cadmium
• Come from the
  burning of fossil fuels
  and metal smelting
             Primary Air Pollutants
• Come directly from the
  emission source
• Include the following:
  –   SO2
  –   COx
  –   NOx
  –   VOCs
• Can become secondary
  pollutants
        Secondary Air Pollutants
• Are primary pollutants
  that have undergone
  chemical transformation
• Can be caused by
  photochemical reactions
  and interactions with
  oxygen
• Include ozone, smog, and
  acids
• Are best controlled by
  reducing the primary
  pollutants that create
  them
   Natural Sources of Air Pollution
• Are not regulated or controlled
• Can range from 30-80% of total
  air pollution
• Forest Fires
   – Particulates, NOx, CO
• Volcanoes
   – Particulates, SO2, CO, NOx
• Lightning
   – Creates NOx
• Plants
   – VOCs, particulates (pollen)
• Dust
   – Particulates
            Thermal Inversions
• Are the opposite of normal
  atmospheric conditions
• Occur when a warm layer of
  air traps a layer of cold,
  dense air
• Traps pollutants in the cold
  layer underneath
• Occur more frequently in
  valleys or areas bounded by
  mountains
                   Acid Deposition
• Forms from NOx and SO2
   – Create nitric and sulfuric acid
• Occurs when atmospheric acids dissolve in rain or are
  deposited in dry form onto surfaces
• Is pH 4.5 and below
• Can occur far from the source of the primary pollutants
            Pollution Prevention
• Regulates
  anthropogenic pollution
• Is mandated through
  the Clean Air Act
   – National Ambient Air
     Quality Standards
     (NAAQS)
• Includes reducing
  emissions
             Pollution Prevention
• Requires newer and
  better technology
   – Chemicals
   – Scrubbers
• Requires legislation and
  enforcement
• Treats persistent and
  non-persistent pollution
  differently
• Can involve economic
  incentives
   – Cap and trade, tolls
        Reducing SO2 Emissions
• Involves changing how
  coal is burned
• Uses fluidized bed
  combustion
  – Calcium carbonate is
    added to coal as it is
    burned
  – Heated calcium
    carbonate absorbs sulfur
    and forms calcium
    sulfate
         Reducing NOx Emissions
• Involves reducing the
  heat and/or oxygen
  used in combustion of
  any fuel that contains
  nitrogen
   – Reducing heat can lower
     the efficiency of the
     combustion process
   – Creates less electricity
     and more waste
          NOx Emissions and Cars
• Have been reduced
  through the use of
  catalytic converters
   – Convert NOx emissions to
     N2 gas, H2O, and CO2
   Reducing Particulate Emissions
• Can use gravity
   – Larger particles fall to the
     bottom of a smokestack
• Can use baghouse filters
   – Emissions are passed
     through a series of bags that
     filter out particles
   Reducing Particulate Emissions
• Can use scrubbers
   – Water is sprayed on
     emissions to trap
     particles
• Can use electrostatic
  precipitators
   – Use electrically charged
     electrodes to attract
     charged particles
  Unique Pollution Control Legislation
• Regulating businesses
  that generate VOCs
• Allow car driving every
  other day
• Tiered toll systems
   – Costs more to drive at
     peak traffic times
• Location-based toll or
  permit systems
   – Costs more to drive in
     high-traffic areas
                    Cap and Trade
• Is how the US has
  reduced sulfur emissions
• Sulfur emitters get a
  number of allowances for
  sulfur emissions
   – Each allowance is for 1 ton
     of sulfur
• Sulfur emissions must be
  equal to or less than the
  allowances or a fine is
  levied
• Unused allowances can
  be sold or traded
          Do The Math p. 424
• Calculate total percentage reduction of sulfur
  emissions
  23.5 million metric tons – 10.3 million metric
  tons = 13.2 million metric tons total reduction

  (13.2 million metric tons /23.5 million metric
  tons) x 100 = 56%
           Do The Math p. 424
• Calculate annual percentage reduction of
  sulfur emissions
• 2008 – 1982 = 26 years (reductions began in
  1982, latest year for which data is available is
  2008)
• 56% / 26 years = 2.2% per year
              Stratospheric Ozone
• Is beneficial as it absorbs
  UV radiation
• Constantly breaks down
  and re-forms
• Can be destroyed by
  chlorofluorocarbons
  (CFCs)
   – Chlorine permanently
     bonds to oxygen,
     disrupting the ozone
     formation cycle
   – CFCs are persistent in the
     upper atmosphere
                 The Ozone Hole
• Forms at the South Pole,
  where ozone
  concentrations are
  thinnest
• Forms from springtime
  release of Cl2 that is
  bound to ice crystals in air
  during winter
• Results from the overall
  thinning of the ozone
  layer
   – Allows more UV radiation
     through to the
     troposphere
         The Montreal Protocol
• Was signed in 1987
• Targeted chemicals that
  deplete ozone
• Aimed to reduce CFC
  emissions by 50% by
  2000
• Addendum required
  production of CFCs to
  stop by 1996
           The Montreal Protocol
• Succeeded because:
   – There was a clear cause to
     the problem that could be
     eliminated
   – Developers of substitutes
     for CFCs stood to gain
     financially
• Has reduced CFC
  emissions to 5 ppb/year,
  and these levels will
  continue to drop
   – We should see the ozone
     layer begin to rebuild
     around 2080 - 2100
                Indoor Air Pollution
• Can come from combustion
   – Particulates
   – Carbon monoxide
   – This is more often found in
     developing countries
• Can come from chemicals
  used in construction and
  consumer goods
   – Asbestos
   – Radon
   – VOCs
• Is a problem in developed
  countries because of better-
  insulated buildings
                 Indoor Particulates
• Can come from cooking
  and heating fires
• Can be biological
   – Hair, dander, dust mites,
     bacteria, viruses
   – 95% of dust is dead skin
       • A human generates 1.5 lbs of
         skin cells a week
   – Bioaerosols
       • Sweat, skin oil, urine, feces
• Cause respiratory diseases
   – Cancer, emphysema,
     asthma, bronchitis
                         Asbestos
• Is a thin fiber made of
  silicates
• Is an excellent insulator
   – Was common in many building
     materials
   – Now banned in the US
• Individual fibers are usually
  less than 10 μm in diameter
   – Cause asbestosis (scarring of
     lungs) and cancer if they are
     inhaled
• Is only dangerous when
  exposed or disturbed
   – Cleanup must be carefully
     monitored and contained
                     Radon (Rn)
• Is a colorless, odorless,
  radioactive gas
• Decays into polonium
• Forms from breakdown of granitic
  rock
• Often found in rock layers and soil
• Can seep into a home through
  cracks in the foundation
   – Basements can accumulate it
• Causes lung cancer
   – Second leading cause behind
     smoking
                   Indoor VOCs
• Are found in plastics,
  building materials,
  furniture, paint, glue,
  dry cleaning solvent,
  deodorizers
• A good example is
  formaldehyde
   – Biological fixative
   – Suspected carcinogen
           Sick Building Syndrome
• Results from sealing
  drafts and increasing
  insulation to maintain
  energy efficiency
• Can cause diseases in its
  occupants
• Can be caused by:
   – Poor ventilation
   – Indoor chemicals
   – Outdoor contaminants
     transferred inside
   – Buildup of mold or bacteria

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:0
posted:5/20/2013
language:English
pages:63
yan tingting yan tingting
About