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Air and Air Pollution
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Outdoor Air Pollution Primary pollutants Secondary pollutants Sources:
Natural Stationary CO CO2 SO2 NO NO2 Most hydrocarbons Most suspended particles SO3 HNO3 H2SO4 H2O2 O3 PANs Most and salts NO3 – Mobile SO4 2 Sources: Natural Mobile Stationary Fig. 17.4, p. 422 See Table 17-1 p. 421 See Table 17-2 p. 422
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Natural Pollutants Dust and other suspended particles from soil
Sulfur oxides and particulate matter from volcanoes Carbon oxides, nitrogen oxides and particulates from forest fires Hydrocarbons and pollens from plants Methane and hydrogen sulfide from decaying plants Salts from the ocean
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Primary Pollutants SOx, NOx, VOCs and Rocks,
Produce direct harm to environment and organisms Sulfur Oxides (SOx) Nitrogen Oxides (NOx) Carbon Monoxide (CO) Particulates (Rocks) Volatile Organic compounds (VOCs) Lead SOx, NOx, VOCs and Rocks, COoperate to lead to pollution.
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Criteria Pollutants Pollutants monitored by EPA Ozone Lead
Sulfur Oxides Nitrogen Oxides Carbon Monoxide Particulate Matter Handout on the sources, health effects, Environmental effects and property damage caused by these – KNOW THIS!!
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Air 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 SOx Construction/Agriculture particulates
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Carbon monoxide Sulfur Oxide Nitrogen Oxide Volatile Organic Compounds (VOC) Particulate Matter (PM)
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Types of Sources Stationary Sources Mobile Sources Point vs Area
Those sources that have a fixed location such as power plants and factories Mobile Sources Those sources that can move from place to place such as automobiles, trucks, planes, boats Point vs Area Points sources are ones that have specific origin whereas Area sources are ones that do not have a specific origin. These are similar to point and non-point sources of water pollution.
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Outdoor Air Pollution Emission Sources –
Automobiles (and other mobile sources): tailpipe is the primary source however the engine itself can also emit pollutants and is the primary source of waste heat. Tires can emit pollutants as they wear against the road surface
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Emission Sources con’t
Manufacturing plants Primarily emit pollutants through exhaust stacks and heat exchangers Some may produce pollutants within the building that are released through windows and doors. Pollutants can be released directly into the air from mining and processing plant.
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Emission Sources Storage Tanks
A variety of storage facilities emit air pollutants: Fuel Tanks Chemical Tanks Nuclear Waste facilities
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Primary Pollutants Pollutant Source Environmental Impacts
Human Impacts Prevention or control Contribute to Secondary Pollution?
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Secondary Pollutants Created by a reaction between one or more primary pollutants Tropospheric Ozone Photochemical smog Industrial Smog Acid precipitation
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How Tropospheric Ozone is formed
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Ultraviolet radiation
Photochemical Smog Brown-air smog Solar radiation Ultraviolet radiation NO Nitric oxide Photochemical smog H2O Water NO2 Nitrogen dioxide Hydrocarbons O2 Molecular oxygen HNO3 Nitric acid PANs Peroxyacyl nitrates Aldehydes (e.g., formaldehyde) O3 Ozone O Atomic Photochemical reaction Any reaction activated by light Photochemical oxidants NO2, O3 and PANs Fig. 17.5, p. 424
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Industrial Smog (Gray-Air Smog)
Created by the burning of coal which creates CO2 and CO and particulates Coal burning also releases sulfur S+O2 SO2 which reacts with oxygen SO2 + O2 SO3 Sulfur trioxide reacts with water SO3 + H2O H2SO4 Sulfuric acid reacts with ammonia particles creating ammonium sulfate which gives the smog its gray appearance
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Factors Influencing formation of photochemical smog
Local climate and topography Population density Amount of industry Fuels used in industry, heating and transportation Low air flow High temperatures
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Particulate size Particulates Contribute to Photochemical
Ultra Fine Particles Fine Large Sea salt nuclei Fly ash Particulates Contribute to Photochemical And industrial smog And are a criteria pollutant Carbon black Paint pigments Pollens Tobacco smoke Cement dust Milled flour Combustion nuclei Coal dust Oil smoke Metallurgical dust and fumes Photochemical smog Insecticide dusts 0.001 0.01 2.5 10.0 100.0 Average particle diameter (micrometers or microns)
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Temperature Inversions
Subsidence temperature inversion Warmer air Inversion layer Cool layer Mountain Valley Decreasing temperature Increasing altitude Fig. 17.9, p. 427 Radiation Temperature Inversion occurs at night when air At the surface cools faster than air above it. Typically dissipates in the morning as the sun rises and warms the air.
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Regional Outdoor Air Pollution from Acid Deposition
Forms when sulfur oxides (SOx) and to a lesser degree nitrogen oxides (NOx) react with water to form sulfuric/Nitric acid (H2SO4/HNO3) SO2 + H2O H2SO4 Deposition can occur in dry form where sulfuric acid particles attach to dust in the air Deposition occurs in wet form as rain, snow, sleet, or fog
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Acid Deposition Wet deposition Dry deposition Fig. 17.9, p. 428 Wind
Transformation to sulfuric acid (H2SO4) and nitric acid (HNO3) Nitric oxide (NO) Acid fog Ocean Sulfur dioxide (SO2) and NO Windborne ammonia gas and particles of cultivated soil partially neutralize acids and form dry sulfate and nitrate salts Dry acid deposition (sulfur dioxide gas and particles of sulfate and nitrate salts) Farm Lakes in deep soil high in limestone are buffered Lakes in shallow soil low in limestone become acidic Wet acid deposition (droplets of H2SO4 and HNO3 dissolved in rain and snow) Fig. 17.9, p. 428
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Acid Deposition in the US
Acid deposition is greater in the Eastern US due to: Higher concentration of coal fired power plants Larger population concentrations Westerly flow of air Fig , p. 428
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Acid Deposition and Aquatic Systems
Water boatman Whirligig Yellow perch Lake trout Brown trout Salamander (embryonic) Mayfly Smallmouth bass Mussel 6.5 6.0 5.5 5.0 4.5 4.0 3.5 pH Fish declines Undesirable species Aluminum toxicity Acid shock Fig , p. 430
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Acid Deposition, Plants, and Soil
Emissions Effects of Weather Acid deposition Dry weather Low precipitation Increased evapotranspiration transpiration Lake Groundwater SO2 NOX H2O2 O3 PANs Others susceptibility to frost, pests, fungi, mosses, and disease Dead leaves or needles Reduced photosynthesis and growth Tree death Damage to tree crown Water deficit Nutrient deficiency Bark damage Direct damage to leaves and needles Leaching of soil nutrients Acids and soil nutrients Damage to fine roots Disturbance of water uptake of nutrient Soil acidification Kills certain essential soil microorganisms Release of toxic metal ions Nitrate Sulfate Magnesium Aluminum Calcium Potassium Nutrient leaching Heavy metal release Weakens trees Fig , p. 432 See Connections p. 431
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Acid Deposition and Humans
Respiratory diseases Toxic metal leaching Decreased visibility Damage to structures, especially containing limestone Decreased productivity and profitability of fisheries, forests, and farms
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