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Atmospheric Pollution: Ozone Depletion (Sec. 18.8,18.9), Photochemical Smog (Sec. 17.3), Acid Deposition (Sec. 17.4), and Climate Change (Sec 18.1 - 18.6)

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Air Pollution Primary Pollutants Any substance that causes direct harm to the atmosphere and organisms Sulfur Oxides (SO x ) Nitrogen Oxides (NO x ) Particulates particles (Rocks) Volatile Organic Compounds (VOCs) Carbon Monoxide (CO) Lead Rocks, SO x, NO x,and VOCs COoperate to Lead to pollution.

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Sources of Primary Pollutants Burning Fossil Fuels Electrical Power Sulfur and Nitrogen Oxides Transportation Carbon monoxide VOCs Nitrogen Oxides Industrial Chemicals Cleaners, solvents, paints VOCs, CO and SO x Construction/Agriculture particulates

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Secondary Pollutants Created by the reaction of one or more primary pollutants Tropospheric Ozone Smog Acid Rain

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Good Ozone? GOOD Ozone Exists in the STRATOSPHERE Protects us from UV rays UV rays can cause damage to skin cells (cancers) Eye tissue (cataracts) Fish and amphibians phytoplankton

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Ozone Depletion Production of CFCs began in 1930s and were used as coolants, propellants in aerosols, cleaners for electronics, sterilants for hospitals, fumigants for granaries and cargo ships, and insulation and packaging production CFCs remain in the troposphere because they are not water soluable and are chemically unreactive Over 11-20 years, they rise to stratosphere

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Ozone Depletion CFCs break apart when exposed to ultraviolet radiation Halogen atoms break free and react with single oxygen atoms Slows the rate of ozone formation in upper atmosphere CFCs can last 65 385 years in the stratosphere (depending on type)

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Ozone Depletion Other halogenated organic gases also cause ozone depletion Halons and HBFCs (fire extinguishers) Methyl bromide (CH 3 Br) fumigants Carbon tetrachloride (CCl 4 ) toxic solvent Methyl chlorogorm (C 2 H 3 Cl 3 ) solvent for dry cleaning and propellant in consumer products N-propyl bromide solvent and cleaner Hexachlorobutadiene cleaning solvent Hydrogen chloride emitted by Space Shuttles

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Ozone Depletion Montreal Protocol, 1987 36 nations met and agreed to stop production of CFCs In London in 1990, and again in Copenhagen, Denmark in 1992, the representatives met again and agreed to phase out other ozone-depleting compounds

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Tropospheric Ozone BAD Ozone Created by the chemical reaction between nitrogen oxides (NO x ) from car exhaust, oxygen and sunlight Causes respiratory problems Wheezing, asthma, bronchitis, pneumonia Irritates eyes and throats BAD OZONE

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Tropospheric Ozone When fossil fuels are formed, pollutants are emitted: Hydrocarbons (from unburned fuel) Nitrogen oxide (NO) Nitrogen oxide reacts with oxygen to form nitrogen dioxide (NO 2 ) Brown gas contributed to urban haze NO 2 can also absorb sunlight and break up releasing oxygen atoms that react with diatomic oxygen gas (O 2 ) to form ozone (O 3 )

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Effects of Tropospheric Ozone Ozone is a toxic gas and oxidizing agent Damages crops and forests Irritates eyes and respiratory system Highly reactive with rubber materials and fabrics

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Photochemical Smog Photochemical smog is the mixture of about 100 primary and secondary pollutants formed under the influence of sunlight. Main pollutants: ozone, NO, NO 2, Volatile Organic Compounds (VOCs) (mostly hydrocarbons), Peroxyacetyl Nitrates (PANs) Occurs in cities with large populations (lots of vehicles), and sunny, warm, dry climates.

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Photochemical Smog Occurrence depends on topography, climate, population density, and fossil fuel use. Precipitation cleans the air and winds disperse smog Thermal inversions trap smog in valleys In valleys, cold air slides down valley sides to bottom, but traps warm air layer above it A layer of warm air prevents mixing of air

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Acid Deposition The pH scale pH is a measure of acidity of a solution. It is a literal abbreviation of potential of hydrogen, meaning that it measures the amount of hydrogen ions in solution. The amount of H + determines if it is a base or an acid. Scale of 0-14, with 0 = acid, 7=neutral, 14=base logarithmic scale

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Acid Deposition Formation Can be wet (acid rain) or dry (particulate matter) Acid deposition comes from pollutants put out by vehicles and industrial and power- generating plants Primary pollutants are sulfur oxides and nitrogen oxides Sulfur oxides released from burning coal Nitrogen Oxides release from car exhaust

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Acid Deposition Formation Acid Deposition does not always fall where the pollutants are released The areas of greatest acidity (lowest pH values) are located in the Northeastern United States. caused by the large number of cities, the dense population, and the concentration of power and industrial plants in the Northeast. In addition, the prevailing wind direction brings storms and pollution to the Northeast from the Midwest soil and rocks in the NE United States is less likely to neutralize the acidity

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Acid Rain in the US Why are The acid Rain Concentrations Higher in the East than in The west?

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Chemical reactions natural rain fall has a pH of 6 because of the interaction of CO 2 and water vapor, forming weak carbonic acid. CO 2 + H 2 0 H 2 CO 3 Acid Rain has a pH below 5.6 because or reactions between water vapor and SO X and NO X.

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Chemical reactions Acid Rain from Sulfur Compounds: Sulfur dioxide reacts with water to form sulfurous acid: SO 2 + H 2 0 H 2 S0 3 Sulfur dioxide can be oxidized to sulfur trioxide 2SO 2 + 0 2 2SO 3 Sulfur trioxide reacts with water to form sulfuric acid: SO 3 + H 2 0 H 2 SO 4 Acid Rain from Nitrogen Compounds: 2NO 2 + H 2 O HNO 2 + HNO 3

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Effects of Acid Rain Damages buildings and marble statues by reacting with calcium carbonate to form soluble calcium bicarbonate CaCO 3 + acid rain Ca(HCO 3 ) 2 Leaches aluminum and calcium from soil into groundwater, lakes, and rivers poisoning fish and plant roots. Aluminum reacts with gill causing an increase in mucous, and suffocation Reduces production of chlorophyll in plants, and sulfuric acid kills the plant.

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Acid Rain Process

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Transboundary Air Movement Sulfur dioxide can remain in the atmosphere 3-4 days before reacting to form acid Therefore, it can travel for hundred or thousands of miles (depending on the winds) before becoming acid rain. Nitrogen oxides only remain in the air for about 12 hours, enabling them to travel only tens or hundreds of miles.

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Transboundary Air Movement Acid Deposition is a regional problem not a local one In the US, the prevailing winds come from the southwest traveling towards the northeast. Nine largest coal burning states are in the Midwest and Ohio River Valley causing much of the acid rain to fall in the NE US and eastern Canada.

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Reducing Acid Deposition coal containing less sulfur scrubbers on smokestacks (limestone) natural gas instead of coal catalytic converters (remove NO X from cars) use alternative energy sources Full cost accounting cradle to grave accounting costs of clean-up, restoration, reforestation, remediation, etc. coal, hydropower, and nuclear power seem cheap, but do not account for all cost

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Reducing Acid Deposition Restoring acidified soils and waters: Liming adding lime or limestone to acidic lakes to neutralize the acidity expensive, only treats the symptom not the cause, can affect plant productivity temporary must be repeated regularly dredging expensive and temporary

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Climate Change

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Global Warming Caused by increased carbon dioxide and other greenhouse gases in the troposphere that increase the natural greenhouse effect Increased greenhouse effect raises the average global temperature Increased temperature affects numerous aspects of global climate system

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Past Climate Change Changes in climate have happened numerous times over the past 400,000 years. Each time the world entered a new ice age it was after a significant increase in Carbon Dioxide in the atmosphere and an increase in global temperatures. Current data shows our CO 2 levels to be higher than at any time in earths history.

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INDUSTRIAL REVOLUTION CURRENT LEVEL HISTORICAL LEVEL

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Interpretation of Graphics Carbon Dioxide levels and temperature correlate The carbon dioxide level never exceeded 290 ppm until after the industrial revolution (around 1800s) Current Carbon Dioxide levels exceed historical levels by nearly 70 ppm or 25% of historical records

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Greenhouse Gases 1992 Earth Summit Rio de Janeiro, Brazil UN Framework Convention on Climate Change approved by 106 nations, establishing two basic principles: Scientific uncertainty must not be used to avoid precautionary action. Industrial nations, the greatest historical contribution to climate change, must take the lead in reducing greenhouse gases and slowing global warming.

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Greenhouse Gases Nations committed to reduce CO 2 levels to 1990 levels by 2000. But, it did not require them to reach the goal.

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Greenhouse Gases 1997 Conference of Parties Kyoto, Japan 161 nations were represented to negotiate a new treaty to slow global warming. Three agreements: 38 developed countries required to reduce GHG emissions to 1990 levels by 2012. Developing countries not bound to requirement of treaty Emission Trading allowed between participating countries.

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Ways to reduce greenhouse gas emissions: Reduce use of fossil fuels increase use of renewable energy sources hydrogen fuel cells, tidal, geothermal, solar, wind, biomass, hydroelectric, nuclear

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Ways to reduce greenhouse gas emissions: Energy efficiency use more energy efficient cars, lighting, heating, cooling and other machinery, better building insulation Increase use of public transportation (trains, buses, etc.) uses less energy less pollution environmental benefits: traffic, noise, road building

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Ways to reduce greenhouse gas emissions: Implement ideas such as: carbon tax carbon credits use carbon and nitrogen filters in power station collect all the methane that leaks from land fill sites (methane can be used as a fuel) reduce deforestation, increase reforestation

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Impacts of Global Climate Change Present day Predicted Distribution forest grassland arid woodland shrub land shrub land woodland grassland Arid deserts in Southwestern U.S. will shrink as precipitation increases Savanna/shrub/woodland systems will replace grasslands in the Great Plains Eastern U.S. forests will expand northerly weather conditions will become more severe Southeastern U.S. increasing droughts will bring more fires triggering a rapid change from broadleaf forests to Savannas

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Impacts of Global Climate Change Increases in evaporation in tropical areas Results in a change in global rain patterns Increased precipitation resulting in increased flooding Decreased precipitation may result in drought, crop failures and famine

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Impacts of Global Climate Change Increased melting of land ice raises ocean levels Increases flooding of coastal areas Inundates groundwater systems with salt water

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Impacts of Global Climate Change Coastal residents forced to migrate inland Results in overcrowding of inland cities Lack of infrastructure to support population Result in shortages of resources

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Impacts of Global Climate Change Increase in sea temperatures Results in more intense hurricanes and typhoons Results in melting sea ice which changes the density of sea water

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Impacts of Global Climate Change Increased spread of disease Increased temperatures create higher incidence of heat related illness and death Increased precipitation increases mosquito population and spread of diseases Increases flooding and chances for drinking water contamination from sewage

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Impacts of Global Climate Change Migration of people causes overcrowding Breeding ground for diseases such as typhoid, cholera and diarrheal diseases

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Impacts of Global Climate Change Increased temperature also changes the density of ocean water Affects the upwelling of deep ocean water Affects the global conveyor belt that moves the heat energy around the planet This could ultimately push the world climate into another ice age

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Solutions to Global Warming Changes in human consumption of fossil fuels is essential to reducing the carbon dioxide emissions Integration of alternative forms of energy for electrical power must be done soon: Wind/Biomass/Geothermal/Solar/Hydro Mass acceptance and use of alternative energy for transportation Distribution of alternative energy technology to developing countries so that they can transition their economy without creating additional carbon dioxide problems.