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Air composition & pollution

Air composition & pollution. Core Case Study: South Asia’s Massive Brown Cloud. South Asian Brown Cloud Causes Drought, burning of forests, automobiles, coal-plants, waste incinerators Chemical composition Dust, smoke, ash, soot, acidic compounds, mercury, lead Areas impacted

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Air composition & pollution

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  1. Air composition & pollution

  2. Core Case Study: South Asia’s Massive Brown Cloud • South Asian Brown Cloud • Causes • Drought, burning of forests, automobiles, coal-plants, waste incinerators • Chemical composition • Dust, smoke, ash, soot, acidic compounds, mercury, lead • Areas impacted • India, Bangladesh, China, W. Pacific Ocean • Air pollution connects the world • Affects west coast of the United States • China and India need stricter air pollution standards

  3. The Asian Brown Cloud Fig. 18-1, p. 465

  4. Air Pollution in Shanghai, China Fig. 18-2, p. 465

  5. The Atmosphere Consists of Several Layers • Density varies • Number of gas molecules/unit of volume • Decreases with altitude • Gravity pulls molecules towards earth • Atmospheric pressure • Mass per unit are • More collisions between molecules  more pressure • Decreases with altitude • Less molecules

  6. Atmospheric pressure (millibars) 0 200 400 600 800 1,000 120 75 Temperature 110 65 100 Thermosphere 90 55 80 Mesosphere 45 70 Altitude (miles) Altitude (kilometers) 60 35 50 Stratosphere 40 25 30 15 Ozone layer 20 10 Troposphere 5 Pressure Pressure = 1,000 millibars at ground level (Sea level) 0 –80 –40 0 40 80 120 Temperature (˚C) Fig. 18-3, p. 467

  7. Air Movements in the Troposphere Play a Key Role in Earth’s Weather and Climate • Troposphere • 75–80% of the earth’s air mass • Closest to the earth's surface • Chemical composition of air • 78% nitrogen • 21% oxygen • Traces of water vapor, argon, carbon dioxide, methane, ozone, nitrous oxide, particulates (dust/soot) • Rising and falling air currents: weather and climate • Involved in chemical cycling

  8. Case Study: The South Asian Brown Clouds, Melting Glaciers, and Atmospheric Cooling • 2008 UNEP study on South Asian Brown Clouds • Causing gradual melting of Himalayan glaciers • Particles absorb sunlight and warm air above the glaciers • Reflect some sunlight back to space • Overall cooling affect on earth’s atmosphere

  9. Atmospheric pressure (millibars) 0 200 400 600 800 1,000 120 75 Temperature 110 65 100 Thermosphere 90 55 80 Mesosphere 45 70 Altitude (miles) Altitude (kilometers) 60 35 50 Stratosphere 40 25 30 15 Ozone layer 20 10 Troposphere 5 Pressure Pressure = 1,000 millibars at ground level (Sea level) 0 –80 –40 0 40 80 120 Temperature (˚C) Fig. 18-3, p. 467

  10. The Stratosphere Is Our Global Sunscreen • Stratosphere • Similar composition to the troposphere, with 2 exceptions • Much less water (1/1000) • O3, ozone layer • Ozone layer • Reaction of O2 and UV Rays to produce Ozone • Filters 95% of harmful UV radiation • Allows us and other life to exist on land

  11. Air Pollution Comes from Natural and Human Sources (1) • Air pollution • Concentrations high enough to harm human health or alter climate • Natural sources • Dust blown by wind • Pollutants from wildfires and volcanoes • Volatile organics released by plants • Mostly removed through chemical cycling, precipitation, gravity.

  12. Air Pollution Comes from Natural and Human Sources (2) • Human sources: mostly in industrialized and/or urban areas • Stationary sources: power plants and industrial facilities • Mobile sources: motor vehicles

  13. Burning Fossil Fuels Causes Air Pollution Fig. 18-4, p. 468

  14. Some Pollutants in the Atmosphere Combine to Form Other Pollutants • Primary pollutants • Emitted directly into the air • Concentrations high enough to cause harm • Secondary pollutants • From reactions of primary pollutants • Air quality improving in developed countries • Less-developed countries face big problems • Indoor pollution: big threat to the poor • Burning wood, coal, dung, cigarette smoke

  15. Primary Pollutants Secondary Pollutants CO CO2 NO2 SO2 NO NO SO3 CH4 and most other hydrocarbons HNO3 H2SO4 O3 PANs Most suspended particles H2O2 Most NO3– and SO42– salts Natural Source Human Source Stationary Human Source Mobile Fig. 18-5, p. 469

  16. Indoor Air Pollution in Bangladesh Fig. 18-6, p. 469

  17. What Are the Major Outdoor Air Pollutants? (1) • Carbon oxides • Carbon monoxide (CO) • Incomplete combustion • Car exhaust, burning organic material/fossil fuels, tobacco smoke, inefficient stoves • Carbon dioxide (CO2) • Mostly clearing forests • Human health and environmental impact • Global warming • Heat exhaustion • Reduction of food supplies • Water shortages, drought in some areas • Excessive flooding in others

  18. What Are the Major Outdoor Air Pollutants? (2) • Nitrogen oxides (NO) and nitric acid (HNO3) • Sources • Oxygen reacting with nitrogen at high temp. • Automobiles, coal-burning plants • Lightning, soil • Fertilizers, animal wasters • Acid deposition • Nitric acid and water vapor • Photochemical smog • Mixture of chemicals under sunlight in cities with heavy traffic • Human health and environmental impact • Irritate eyes, nose, throat • Asthma, bronchitis • Suppress plant growth

  19. What Are the Major Outdoor Air Pollutants? (3) • Sulfur dioxide (SO2) and sulfuric acid (H2SO4) • Sources • Coal-burning, oil-refining • Human health and environmental impact • Major component of acid deposition (sulfur dioxide react with water vapor) • aerosols • Breathing problems • Damage plants, crops, • Increase pH of water and soil • Damage paint, leather, stone • Particulates • Suspended particulate matter (SPM) • Variety of solid and liquid particles that remain in the air for long periods of time. • Fine – less than 10 micrometers in diameter • Ultrafine – less than 2.5 micrometers in diameter • Sources • 62% natural-Dust, wildfires, sea salt • 38% human induced • Indoor – cigarette smoke, open fires • Human health and environmental impact • Irritate nose, throat, lungs • Genetic mutation (toxic metal particulates)

  20. What Are the Major Outdoor Air Pollutants? (4) • Ozone (O3) • Major ingredient in photochemical smog • Sources • Troposphere ozone – bad • Stratosphere ozone -good • Human and environmental impact • Breathing problems, heat disease • Reduce resistance to colds/pneumonia • Damages plants, fabrics, paints • Volatile organic compounds (VOCs) • Hydrocarbons • Methane • benzene • Sources • 1/3 from natural sources • Rice paddies, landfills, oil/nature gas wells, cows • Solvents, dry-cleaning fluids, gasoline, plastics • Human and environmental impact

  21. Chemical Reactions That Form Major Outdoor Air Pollutants Table 18-1, p. 470

  22. Statue Corroded by Acid Deposition and Other Forms of Air Pollution, RI, U.S. Fig. 18-7, p. 471

  23. Case Study: Lead Is a Highly Toxic Pollutant (1) • In air, water, soil, plants, animals • Does not break down in the environment • Human health and environmental impact • Neurontoxin – affects nervous system • Children most vulnerable • Can cause death, mental retardation, paralysis • Sources • Lead-based paint, water pipes, waste incinerators, leaded gasoline

  24. Case Study: Lead Is a Highly Toxic Pollutant (2) • Reduction of lead (Pb) • Unleaded gasoline • Unleaded paint • Still problems • 15-18 million children have brain damage • Need global ban on lead in gasoline and paint

  25. Solutions Lead Poisoning Control Prevention Replace lead pipes and plumbing fixtures containing lead solder Phase out leaded gasoline worldwide Remove leaded paint and lead dust from older houses and apartments Phase out waste incineration Ban use of lead solder Sharply reduce lead emissions from incinerators Ban use of lead in computer and TV monitors Remove lead from TV sets and computer monitors before incineration or land disposal Ban lead glazing for ceramicware used to serve food Test for lead in existing ceramicware used to serve food Ban candles with lead cores Test existing candles for lead Test blood for lead by age 1 Wash fresh fruits and vegetables Fig. 18-8, p. 472

  26. Science Focus: Detecting Air Pollutants • Chemical instruments • Satellites • Lasers and remote sensors • Biological indicators • Lichens

  27. Natural Capital: Lichen Species, Vulnerability to Air Pollutants Fig. 18-A, p. 473

  28. Burning Coal Produces Industrial Smog • Chemical composition of industrial smog • Sulfur dioxide, particulate sulfuric acid and soot • Reduction of this smog in urban cities of the United States • Pollution controlled plants • High smoke stacks • China and smog • 16/20 world’s most polluted cities • Human deaths – 750,000 death annually • Need strong standards, especially for coal burning

  29. How Pollutants Are Formed from Burning Coal and Oil, Leading to Industrial Smog Fig. 18-9, p. 474

  30. Ammonium sulfate [(NH4)2SO4] Ammonia (NH3) Sulfuric acid (H2SO4) Carbon monoxide (CO) and carbon dioxide (CO2) Water vapor (H2O) Sulfur trioxide (SO 3 ) Oxygen (O2) Sulfur dioxide (SO2) Burning coal and oil Oxygen (O2) Carbon (C) in coal and oil Sulfur (S) in coal and oil Stepped Art Fig. 18-9, p. 474

  31. Industrial Smog in India Fig. 18-10, p. 474

  32. Sunlight Plus Cars Equals Photochemical Smog • Photochemical Smog • Chemical composition • Sources • VOCs + NOx + Heat + Sunlight yields • Ground level O3 and other photochemical oxidants (NO2, O3) • Aldehydes • Other secondary pollutants

  33. A Model of How Pollutants That Make Up Photochemicals Are Formed Fig. 18-11, p. 475

  34. PANS and other pollutants Volatile organic compounds (VOCs) Ozone (O3) Oxygen (O2) Nitric oxide (NO) + Oxygen atom (O) Water vapor (H2O) Hydrocarbons UV radiation Peroxyacyl nitrates (PANs) Nitrogen dioxide (NO2) Oxygen (O2) Nitric oxide (NO) Oxygen (O2) Burning fossil fuels Nitrogen (N) in fossil fuel Fig. 18-11, p. 475

  35. Global Outlook: Photochemical Smog in Santiago, Chile Fig. 18-12, p. 475

  36. Several Factors Can Decrease or Increase Outdoor Air Pollution (1) • Outdoor air pollution may be decreased by • Settling of particles due to gravity • Rain and snow • Salty sea spray from the ocean • Winds • Chemical reactions

  37. Several Factors Can Decrease or Increase Outdoor Air Pollution (2) • Outdoor air pollution may be increased by • Urban buildings • Hills and mountains • High temperatures • Emissions of VOCs from certain trees and plants • Grasshopper effect • Tropical areas to poles in winter • Temperature inversions • Warm air above cool air prevents mixing • City surrounded by mountains • City, 3 sides mountain, 1 side ocean, lots of cars

  38. A Temperature Inversion Fig. 18-13, p. 476

  39. Acid Disposition Is a Serious Regional Air Pollution Problem • Acid deposition, acid rain • Chemical sources • Coal burning, industrial plants burning things that contain nitrous oxides or sulfides • Local versus regional problems • Tall smokes stacks • Effects of prevailing winds • Move pollution to other parts of the region • Buffers • Basic substances (soils with carbonates) that neutralize the acidic precipitation • Where is the worst acid deposition? • China- cause…affects China, Japan, N. & S. Korea

  40. Natural Capital Degradation: Acid Deposition Fig. 18-14, p. 477

  41. Wind Transformation to sulfuric acid (H2SO4) and nitric acid (HNO3) Windborne ammonia gas and some soil particles partially neutralize acids and form dry sulfate and nitrate salts Wet acid deposition (droplets of H2SO4 and HNO3 dissolved in rain and snow) Nitric oxide (NO) Dry acid deposition (sulfur dioxide gas and particles of sulfate and nitrate salts) Sulfur dioxide (SO2) and NO Acid fog Lakes in shallow soil low in limestone become acidic Lakes in deep soil high in limestone are buffered Fig. 18-14, p. 477

  42. Current and Possible Future Acid Rain Problem Areas Fig. 18-15, p. 478

  43. Acid Deposition Has a Number of Harmful Effects (1) • Human health • Respiratory disorders • Toxins in fish (biomagnification) • Release of toxic metals • Cause leaching of soils and rocks • Aquatic ecosystems affected • Lowers pH and kills organisms • Releasing aluminum ions that attract minerals and clog gills

  44. Acid Deposition Has a Number of Harmful Effects (2) • Leaching of soil nutrients • Lower crop yields • Low soil pH • Forest damage • Leaching nutrients • Releasing ions that damage tree roots (toxic metals) • Damage to buildings, statues, and monuments

  45. Natural Capital Degradation: Air Pollution Damage to Trees in North Carolina, U.S. Fig. 18-16, p. 479

  46. Emissions SO2H2 O2 NOx Acid deposition O3 PANs Others Reduced photosynthesis and growth Direct damage to leaves and bark Increased susceptibility to drought, extreme cold, insects, mosses, and disease organisms Tree death Soil acidification Leaching of soil nutrients Root damage Release of toxic metal ions Reduced nutrient and water uptake Acids Lake Groundwater Fig. 18-16a, p. 479

  47. Solutions Acid Deposition Prevention Cleanup Reduce coal use Add lime to neutralize acidified lakes Burn low-sulfur coal Increase use of natural gas and renewable energy resources Add phosphate fertilizer to neutralize acidified lakes Remove SO2 from smokestack particulates and NOx gases and remove vehicular exhaust NOx from motor Tax emissions of SO2 Fig. 18-17, p. 480

  48. Indoor Air Pollution Is a Serious Problem (1) • Developing countries • Indoor burning of wood, charcoal, dung, crop residues, coal • Poor suffer the greatest risk

  49. Indoor Air Pollution Is a Serious Problem (2) • Developed countries • Indoor air pollution is greater than outdoor air pollution • Why? • Levels of 11 of the common air pollutants higher inside than outside • Greater in vehicles than outside • Health risks magnified: people spend 70–98% of their time is indoors or in cars

  50. Indoor Air Pollution Is a Serious Problem (3) • Who is at greatest risk from indoor air pollution? • Children under 5 and the elderly • Sick • Pregnant women • People with respiratory disorders or heart problems • Smokers • Factory workers

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