Air Pollution

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Air Pollution

• Chapter 20

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Sections 20-1 20-2

• We live at the bottom of a thin layer of gases
  surrounding the earth
• Atmosphere
• The Atmosphere is made up of several layers
• We live in the troposphere
• Above the troposphere is the stratosphere

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• Troposphere
• 1st layer of atmosphere
• Extends 11 miles above Earth
• 78 N, 21 O
• Chemical cycling of nutrients happens here
• Weather Climate happen here
• Water vapor present

• Stratosphere
• 2nd layer of atmosphere
• Extends from 11 30 miles above Earths surface
• More ozone (O3) present here
• Less water vapor

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• Atmospheric Pressure
• A measure of the mass per unit of air
• Pressure of atmosphere increases at the density
  increases
• A volume of air with a high density has more gas
  molecules than air at a lower density (D m/v)
• Atmospheric pressure decreases with altitude
• Ex At sea level, your body is bombarded with
  more gas molecules than your body would be at the
  top of a mountain

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In the diagram, notice that as altitude
decreases, the atmospheric pressure increases.
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Another graph As altitude decreases, atmospheric
pressure increases.
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• Ozone (O3)
• Found in 2nd layer of atmosphere (stratosphere)
• Filters our most of the suns harmful UV rays
• Ultraviolet rays dangerous to organisms, can
  cause cancer
• Created when oxygen molecules interact with UV
  radiation emitted by the sun

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How ozone is created
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• Air Pollution
• Presence of chemicals in the atmosphere in
  concentrations high enough to affect climate and
  harm organisms
• Range from annoying to lethal
• Sources
• Majority of air pollution comes from natural
  sources
• Ex dust blowing across the land organic
  chemicals released by plants, forest fires,
  volcanic eruptions, and sea spray

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• Primary Pollutants
• Pollutants emitted directly into the troposphere
  in a potentially harmful form
• Ex soot, carbon monoxide (CO)
• Secondary Pollutants
• When some primary pollutants react with one
  another or with the air to form a new pollutant
• Ex SO2, H3SO4

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• U.S. cities typically have higher outdoor
  pollution levels than rural areas
• Due to prevailing winds, the city pollutants are
  spread to rural areas
• Indoor air pollutants come from infiltration of
  outdoor pollutions into the building

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• Most people believe CO2 is a pollutant
• EPA (Environmental Protection Agency)disagrees
• Too much pressure from oil and coal companies?
• Repercussions if listed as pollutant by EPA?

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• CO2 IS a pollutant because
• 1) Its found in high concentrations in the air
• ANY chemical in high concentrations in the air
  can become a pollutant
• 2) We have been increasing CO2 concentrations in
  the troposphere by burning fossil fuels
  clearing CO2-absorbing trees faster than they can
  grow back
• No way to get rid of CO2
• 3) The troposphere is warming there is
  considerable evidence that additional CO2 added
  by humans is the cause
• Greenhouse gas warms the Earth

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Videos

• UV Rays
• http//www.youtube.com/watch?vnp-BBJyl-go
• Air Pollution
• http//www.youtube.com/watch?ve19VoA2SApMfeature
  related

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Sections 20-3 20-4

• Photochemical reaction
• Any chemical reaction activated by light (photo
  light)
• Ex Photochemical smog

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• Photochemical smog
• A mixture of air pollutants formed by the
  reaction of nitrogen oxides (NO and NO2 )and
  volatile organic hydrocarbons
• Activated by light

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Photochemical Smog formation
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• Smog pollutants
• NO2, NO3 (nitrogen oxides)
• Ozone
• Nitric acid
• Aldehydes
• Peroxyacyl nitrates (PANs)
• Sources of smog pollutants
• Automobile engines
• Coal-burning plants
• Industrial plants
• Vegetation

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• Certain trees plants can contribute to
  photochemical smog
• Ex oak, sweet gums, poplars, kudzu
• They release volatile organic compounds (VOCs)
• Ingredient in smog

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• Trees planted in nonurban areas release their
  VOCs, which are dispersed into the atmosphere
• They do not make a significant contribution to
  the formation of photochemical smog
• Trees planted in / near urban areas with high
  levels of NOx (nitrogen oxides) and sunlight,
  will create high levels of VOCs
• Environmentalists view widespread planting of
  trees in urban areas BUT only those who emit low
  VOCs

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• Industrial smog
• A mixture of sulfur dioxide, droplets of
  sulfuric acid, and a variety of particles emitted
  by burning coal and oil
• When burned, carbon in coal and oil is converted
  to CO2 and CO
• Some of this ends up in atmosphere as ingredient
  of smog

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• Industrial smog
• Also known as gray-air-smog
• Not a big problem in developed countries
• Good pollution control when coal oil are burned
• It IS a big problem in industrialized urban areas
  of
• China, India, Ukraine, Slovakia, Poland, Hungary,
  and Czech Republic

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• Factors that decrease outdoor air pollution
• Precipitation
• Rain snow help to cleanse the air, lowering
  pollution
• Sea Spray
• Can wash out particulates water-soluble
  pollutants from air that flows from land onto the
  oceans
• Wind
• Can sweep pollutants away or dilute them
• Pollutants are blown somewhere else
• Can be deposited onto surface waters, soil,
  buildings

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• Factors that increase outdoor air pollution
• Urban buildings
• Slow wind speed
• Reduce dilution / removal of pollutants
• Hills and Mountains
• Reduced the flow of air in valleys below them
• Allows pollutants to build up at ground level
• High temperatures
• Promote chemical reactions leading to
  photochemical smog
• Grasshopper effect
• Transfers air pollutants from tropical /
  temperate areas to the earths poles
• Reason for high levels of pollutants, decreasing
  ozone in poles

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Grasshopper Effect
Keep in mind that the warm air rises in the
temperate / tropical areas and will condense once
it reaches the colder temperatures (earths
poles).
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• Temperature Inversion
• Occurs when cool, dense air is trapped under a
  warm, less dense air
• These two air masses do not mix
• As a result, pollutants in the air can be
  concentrated in the lower layer of cool air
  (closest to the earth)

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Effects of temperature inversion
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Case Study S. Asias Brown Cloud

• Asian brown cloud (industrial smog)
• 2 miles thick
• Caused by huge emissions of ash, smoke, dust,
  acidic compounds (from burning coal), burning
  trees (to plant crops), dust blowing from
  desserts
• As the cloud travels it picks up many pollutants

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Case Study S. Asias Brown Cloud

• Impacts
• Effects the amount of solar energy hitting earth
• Impacts of crop production
• Damage trees
• Can kill organisms in lakes
• Illnesses premature deaths
• Respiratory diseases
• Particles in cloud are causing climate change
• Changes temperature pattern, rainfall shifts
• Can effect El Nino (which could affect North
  South America)

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South Asias Brown Cloud
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• Acid deposition / acid rain
• Mixture of wet deposition dry deposition
• Wet deposition acid rain, snow, fog, cloud vapor
• pH is less than 5.6
• Dry deposition acidic particles
• Composed of
• Sulfur dioxide (SO2)
• Nitrogen oxides (NO2 and NO)
• Particulates

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Acid Deposition / Rain
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• Some soils contain chemicals which buffer acidic
  deposition / rain
• Calcium carbonate (CaCO3)
• Limestone
• Chemicals neutralize acids
• Bring pH closer to 7

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• Harmful effects of acid deposition / rain
• Human respiratory diseases
• Bronchitis, asthma
• Can leach toxic chemicals into drinking water
• Lead, copper
• Damages statues, monuments, buildings, metals
• Including car finishes, eats away / dissolve
  certain types of rock
• Can kill aquatic life if pH drops too low
• Acid shock
• Damage to aquatic life due to runoff of large
  amounts of highly acidic water

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• Effects of acid rain on plants and soil
• Can deplete soil nutrients
• Calcium and Magnesium
• Release toxic ions into the soil
• Weaken plants
• If pH of soil drops below 5.1
• Calcium deficiencies in plants can be passed to
  the organisms who eat them
• Ex birds eating these plants could have problems
  with egg production (shell made of calcium)

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• Synergistic effect
• When the interaction of two or more factors
  combined effect is greater than the sum of their
  separate effects

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• Clean Air Act
• Has helped reduce some of the harmful impacts of
  acid deposition

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• Solutions to acid deposition
• Prevention (BEST solutions)
• Improve energy efficiency
• Reduce coal use or burn low-sulfur coal
• Increase natural gas use and renewable energy
• Remove SO2 particulates and NOx from smokestack
  gases
• Fees for SO2 emissions
• Cleanup
• Add lime or phosphate fertilizer to neutralize
  acidified lakes

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• Controlling acid deposition / rain is a
  challenge
• The people who cause acid rain and the people or
  ecosystems affected by it are quite distant
• Countries with large supplies of coal (which
  produces acid rain) want to use coal for energy
• Coal-burning power plants say its too costly to
  install equipment to reduce harmful emissions
• Environmentalists idea- Use alternative energy
  sources (wind turbines, natural gas)

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• Cleanup of acid rain in lakes soil
• Add limestone (or lime) to neutralize
• Called liming
• Problems
• Expensive
• Needs to be repeated annually (temporary fix)
• Can kill some aquatic plants, plankton, wetland
  plants
• Possible solution
• Add phosphate fertilizer to neutralize
• Effectiveness still being evaluated

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Video Clips

• Thermal Inversion demonstration
• http//www.youtube.com/watch?vLPvn9qhVFbM 
• Thermal Inversion in the real world
• http//www.youtube.com/watch?vpkOuBUXwiyA
• Asias Pollution Super Cloud
• http//www.youtube.com/watch?vqYYK-2sDN4U
• Coal combustion Acid Rain
• http//www.youtube.com/watch?vHE6Y0iEuXMQ

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Hippocampus Videoshttp//www.hippocampus.org/

• Go to hippocampus link
• On the left-hand side of the screen click Earth
  Science
• Click Environmental Science for AP
• Scroll down the middle of the page
• Watch the following videos
• Earths atmosphere
• Ozone
• Photochemical smog
• Air pollution