Air Pollution (Ch 18 & 19) Earth’s atmosphere: 1) provides essential oxygen 2) moderates climate via insulative properties 3) provides medium for sound 4) shields solar radiation & incoming particulate matter 5) has been neglected
Major Pollutants 1) Carbon monoxide (CO) – by-product of converting organic compounds * > majority in atmosphere from natural sources * problem with small quantity (humancaused) condensed into small area (cities have 50X > conc.) * Clean Air Act of 1970 – helped reduce these emissions via fuel-efficient engines
3) Particulates – suspended particles/liquid * industry & autos (combustion) * wind erosion * slash & burn farming in tropics * respiratory dysfunction * toxins & particulates
Two Sources of Atmospheric (Air) Pollution 1) Natural Sources - forest fires (CO2, ash) - volcanic eruptions (sulfur, mercury) 2) Human Origin - primarily since Industrial Revolution in late 18th century
2) Sulfur Oxides (SOx) – by-product of burning sulfur-rich coal & oil * vehicles, energy industry, factories * “raw material” for acid deposition * respiratory irritant/reduced function Reducing Sox Emissions (Industry): • Use low-sulfur coal • Coal cleaning – separating out fool’s gold (fig 18.16, p 493) • Desulfurize flue gas in smoke stacks with scrubbers (fig 18.17, p 493)
4) Hydrocarbons * methane, benzene * concentrations in urban areas; autos & VOCs 5) Nitrogen Oxides (NOx) -- combustion NO NO2 O2 hydrocarbon + NOx = photochemical smog
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photochemical smog: hydrocarbon + NOx
O3 (ozone)
solar energy • Hot, humid summer days & cars – ozone warnings • Respiratory irritant, damage to lung tissue
• Air pollution changing precipitation patterns • Air pollution (particulates) changing temperature • Air pollution impacting human & ecosystem health
Controlling Air Pollution (input vs. output control) Particulates: 1) filter bag house -traps/collect material 2) electrostatic precipitator – charged small pollutant particles collected 3) cyclone filter – heavy dust filter removed with cyclone air stream
Filter Bag House
Filter Bag House
Electrostatic Precipitator
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Cyclone Filter
Controlling Air Pollution SOx: review notes relative to input vs. output control Auto Emissions: catalytic converters: attached along exhaust system of car; “cleaning” exhaust of CO, hydrocarbons, and NOx What about input controls for auto emissions? > fuel efficiency; < volume; alternative fuels; alternative engines; mass transit; mgt of urban sprawl
Reduction Catalyst vs. Oxidation Catalyst (located in honeycomb structure which is coated with metal catalysts)
Reduction Catalyst (A) & Oxidation Catalyst (B) Honeycomb Structure (C) or ceramic beads;
• Reduction – platinum & rhodium metals NOx N2 + 02 • Oxidation – platinum & palladium metals 02 + CO CO2
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Ozone damage to plants e.g., necrosis of plant tissue (O3 via gas exchange)
Global Impacts of Air Pollution Global Climate Change (“Greenhouse Effect”) * CO2, H2O, O3, NO, methane (CH4), and chlorofluorocarbons (CFCs) • greenhouse gases trap infared radiation (IR) from leaving atmosphere • CO2 concentrations on the rise correlated with rise in temperatures
Global Climate Change • 1990 – 2100 projected 2oC increase Do the Pros Outweigh the Cons? Some “Pros” < heating costs , > growing season? > crop production? Some “Cons” > ocean level (> 50 cm) , > variation in weather patterns, salt water intrusion, > species extinction, redistribution of ag., disease, species…..
Reducing the Threat of Global Warming • Reactive vs. Proactive Management • Optimism vs. Pessimism 1) Reduce auto emissions 2) Alternative fuels 3) Fuel taxes 4) Genetically engineered fuel crops 5) Stopping Deforestation & Increase Restoration 6) Population Growth Management * Tenets of Sustainable Development
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Global Impacts of Air Pollution Acid Deposition (“Acid Rain”) * acidic rain, snow, or dust * SO2 (sulfur dioxide) -- sulfuric acid * NO2 (nitrogen dioxide) – nitric acid * Differential acid precipitation patterns (Fig 19.5, p 514) & role of weather patterns (Fig 19.6, p 516) in spreading acid precursors
Acid Deposition
Acid Deposition
* But don’t volcanoes produce SO2 emissions?
* Differential vulnerabilities of ecosystems dependent on buffering ability (limestone vs. granite)
• Remember it’s a question of (relative to nutrient cycling, concentration, and dispersion): - Spatial & Temporal Scale - Frequency & Intensity
• Impacts of acid deposition on northern lake systems - relation to heavy metals
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Acid Deposition
Reducing Acid Deposition
Harmful Effects
• Reactive vs. Proactive Management
• > acidity of soil • defoliation of vegetation • fish reproduction impaired (chemotaxis) • altered trophic structure of aquatic community • > heavy metal availability • abnormal development
1) Low-Sulfur Coal (S) 2) Scrubbers (S) 3) Energy Conservation (S & N) 4) Renewable Energy Resources (S & N) * Tenets of Sustainable Development
Global Impacts of Air Pollution Ozone Depletion * in the stratosphere (25-50 km) * absorbs ultraviolet (UV) radiation (Fig 19.13, p 523) * naturally, dynamic equilibrium * chlorofluorocarbons (CFCs) – propellant & coolant (Fig. 19.14, p 523) – escape to stratosphere & react with ozone (persistant)
Ozone Depletion CFCl3 + UV O3 + Cl
Ozone Depletion Cl (free radical) ClO + O2
Harmful Effects (next 10-100+ yrs) • • • •
exasperate global warming UV radiation = > skin cancer < amphibian populations, > extinction altered trophic structure of communities
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Reducing Ozone Depletion • Reactive vs. Proactive Management 1) Montreal Protocol 1987 2) CFC substitutes
Sustainable Waste Management (Ch 17) • municipal solid waste (mainly paper & yard waste) of which only 25% reused/recycled • Reduce Waste • Reuse & Recycle Waste • composting • Landfill & Incineration as the last option Read Case Study 17.2, p465-466
Read: • Case Study 11.1, p.264-266 • Case Study 18.2, p. 489-490 * Case Study 18.3, p. 498-499 * A Closer Look 18.1 – Clean Air Act, p. 480
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