17_00CO.JPG Ch. 17 Atmosphere and Air Pollution

Rules/Regulations px?aid=17963&xtid=35562&loid=31344

New York City – Congestion pricing??

The atmosphere’s composition Composition

17_02.JPG Thermosphere Up to 500km (300 mi) High temp – would feel cold Mesosphere 50-80km (31-56mi) Low pressure, temp. drops Stratosphere km (7-31 mi) Drier/less dense Temp. increases with altitude due to O3 (17-30kim or mi) Troposphere Avg. thickness 11km (7 mi) Weather Temperature/density decline with altitude

17_03.JPG Atmospheric Pressure= force per unit area produced by a column of air Sea Level = 1013 mb (14.7 lb/in 2 ) ft (Everest top) = 300mb

Atmospheric properties Relative humidity = the ratio of water vapor a given volume of air contains to the amount it could contain at a given temperature. Expressed as percent

Temperature = average kinetic energy in molecules Thermometer = molecular speedometer

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Equator – Angle of incident radiation perpendicular, greatest concentration of energy Poles – Angle of incident radiation obtuse, less concentrated ***The troposphere is warmed primarily by convection

17_05.JPG Seasons

Weather: local physical properties of the troposphere over short time periods: temp, pressure, cloud cover, wind, humidity Climate: patter of atmospheric conditions found across large geographic regions over long periods of time

17_06.JPG Convective Circulation

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Air Pollutants removed by: –Precipitation –mixing

17_08a.jpg Mixing removes pollutants

17_08b.jpg Pollutants trapped

17_09.JPG Large scale convective cells determine global patterns of humidity and aridity

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17_09b.jpg Coriolis Effect – apparent deflection of air from straight path as globe moves beneath

17_10a.jpg Outdoor Air Pollution (Ambient) Natural Sources: Dust Storms Carry fungal and bacterial spores

17_10b.jpg Volcanoes: Particulates including ash, aerosols of SO 2 can cool atmosphere

17_10c.JPG Fires: Particulates and gases

Types of outdoor air pollution Point Sources = specific spots where large quantities of pollutants are discharged (power plants and factories) Nonpoint Sources = more diffuse, consisting of many small sources (automobiles) Primary Pollutants = directly harmful,and can react to form other harmful substances Secondary Pollutants = form when primary pollutants interact with components of the atmosphere Anthropogenic Sources

Primary Pollutants Stationary Mobile Sources Natural Most hydrocarbons Most suspended particles SO 2 NO NO 2 CO CO 2 Secondary Pollutants SO 3 HNO 3 H 2 SO 4 H2O2H2O2H2O2H2O2 O3O3O3O3 PANs Most NO 3 – SO 4 2– salts

Successful legislation Clean Air Act of 1970 –standards for air quality –limits on emissions –funds for pollution-control research –Allows citizens to sue parties violating the standards The Clean Air Act of 1990 –Strengthens standards for auto emissions, toxic air pollutants, acidic deposition, stratospheric ozone depletion –Introduced emissions trading for SO 2

6 Criteria Pollutants

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What is the good news????

Air pollution has decreased since 1970

17_14.JPG Remove up to 90% particulates and SO 2

Reasons for the decline in U.S. pollution Cleaner-burning vehicles and catalytic converters decrease carbon monoxide Permit-trading programs and clean coal technologies reduce SO 2 emissions Scrubbers = technologies that chemically convert or physically remove pollutants before they leave the smokestacks Phaseout of leaded gasoline Improved technologies and federal policies

17.16 Industrial smogPhotochemical smog

17_16a.jpg Photochemical Smog

Photochemical (brown air) smog Produced by a series of reactions –Hot, sunny cities surrounded by mountains –Light-driven reactions of primary pollutants and normal atmospheric compounds –Morning traffic exhaust releases pollutants –Irritant – eyes, throat, nose –decreased due to emissions testing Photochemical Smog

1. 2NO+ O 2  2NO 2 2. NO 2 + UV  NO + O 3. O 2 + O  O 3 Typical Daily Patterns Air Quality Guide for Ozone

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17_SBS01-02.JPG Stratospheric Ozone

The hole in the ozone Ozone hole = ozone levels over Antarctica had declined by 40-60% –Depletion also in the Arctic and globally –Causes skin cancer, harms crops and decreases ocean productivity

The Montreal Protocol addressed ozone depletion Montreal Protocol = 180 nations agreed to cut CFC production in half –Follow-up agreements deepened cuts –ozone-depleting chemicals has decreased 95% –The ozone layer is beginning to recover –Success story included industry adaptive management strategy –Model for international cooperation

Sources of acid deposition Originates from burning fossil fuels that release sulfur dioxide and nitrogen oxides –These compounds react with water to form sulfuric and nitric acids Acid Deposition

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Acid deposition has not been greatly reduced Scrubbers have helped SO 2 emissions are lower (cap and trade) But, NO x emissions are higher Acid Deposition not Greatly Reduced

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17_23.JPG Indoor Air Quality

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