L 17 air pollution
- 2. Ahh Fresh Clean Air
- 3. Air Pollution Any undesirable changes in air that adversely affect the health, survival, or activities of humans or other organisms Primary air pollutants emitted directly into the atmosphere Primary pollutants that account for nearly all air pollution problems are carbon monoxide, particulates, hydrocarbons, nitrogen oxides, and sulfur oxides Secondary pollutants Produced through reactions between primary pollutants and normal atmospheric compounds, e.g. ozone, peroxy-acyl nitrate (PAN), photochemical smog, sulfur trioxide, acid rain
- 4. Tehran Air Pollution Polluted Air/ Mexico City
- 5. Sources of Air Pollution Stationary sources are those that have a fixed location Emit most of the particulate matter, sulfur oxides, nitrogen oxides, hydrocarbons, and carbon oxides Include point sources, fugitive sources, and area sources Point sources are stationary sources that emit air pollutants from one or more controllable sites, e.g., smokestacks of power plants Fugitive sources generate air pollutants from open areas exposed to wind processes, such as dirt roads, construction sites, farmlands, surface mines, etc Area sources are locations from which air pollutants are emitted from a well-defined area having several sources, e.g., agricultural areas sprayed with herbicides and pesticides Mobile sources are emitters of air pollutants that move from place to place while yielding emissions, include automobiles, trucks, buses, aircraft, ships, trains
- 6. Sources of Air Pollution Combustion of fossil fuels release significant quantities of nitrogen oxides, carbon oxides, particulate matter, and hydrocarbons Each year over a billion tons of these pollutants enter the atmosphere from human-related processes About half is carbon monoxide Power plant Smokestacks
- 7. Tank farm Smokestacks from (N) power plant
- 8. Factory chimneys, Cologne, Germany Mobile Source
- 9. Natural Sources of Air Pollution Volcanoes discharge ash, acid mist, and H2S Natural forest fires Trees and bushes emit millions of tons of volatile organic compounds (terpenes & propenes), pollen, spores, virus, bacteria in the air cause wide spread suffering from allergies and airborne infections Dust storm Various chemicals used in buildings Both inside and outside pollutants create a high risk for the human health
- 10. General Effects of Air Pollutants Affects many aspects of environment: Visually aesthetic resources, vegetation, animals, soil, water quality, structures, and human health Affect visual resourcesAffect visual resources by discoloring atmosphere,by discoloring atmosphere, reducing visual range,reducing visual range, atmospheric clarity, etcatmospheric clarity, etc Effects on vegetationEffects on vegetation Damage to leaf tissue, needles,Damage to leaf tissue, needles, or fruitor fruit Suppression of growthSuppression of growth Increased susceptibility to aIncreased susceptibility to a variety of diseasesvariety of diseases Disruption of reproductiveDisruption of reproductive processesprocesses
- 11. General Effects of Air Pollutants Effects on human health Toxic poisoning causing cancer Eye irritation Irritation of respiratory system Increased susceptibility to viral infections Causing pneumonia & bronchitis Heart disease Aggravation of chronic diseases, such as asthma Effect on vertebrate animals Impairment of respiratory system Damage to eye, teeth bones Increased susceptibility to disease, pests Decreased availability of food sources Decreased ability to reproduce Effects on Soil & Water Degrades soil and water quality; may become toxic from the deposition of various pollutants Effects on structures include discoloration, erosion, and decomposition of building materials
- 12. Potential for Urban Air Pollution Q The potential for air pollution in urban areas is determined by the following factors: Population density The rate of emission of pollutants per unit area The distance downwind that a mass of air may move through an urban area Temperature inversion The average speed of the wind The height to which pollutants may be thoroughly mixed in the lower atmosphere Stronger the wind and the higher the mixing layer, the lower the pollution Hills, mountains, tall buildings Rain helps clean the air pollutants
- 13. Acid rain Pure rainfall has a pH (a numeric value to describe the strength of an acid) of about 5.6 Acid rain is defined as the precipitation in which the pH is below 5.6 (Acid rain is rain consisting of water droplets that are unusually acidic because of atmospheric pollution - most notably the excessive amounts of sulfur and nitrogen released by cars and industrial processes) Acidic deposition occurs in two ways: wet and dry Wet deposition refers to acidic rain, fog, and snow Dry deposition : In areas where the weather is dry, the acid chemicals may become incorporated into dust or smoke and fall to the ground through dry deposition, sticking to the ground, buildings, homes, cars, and trees Dry deposited gases and particles can be washed from these surfaces by rainstorms
- 14. Acid rain Causes (Q) Acid deposition can occur via natural sources like volcanoes but it is mainly caused by the release of sulfur dioxide and nitrogen oxide during fossil fuel combustion When these gases are discharged into the atmosphere they react with the water, oxygen, and other gases already present there to form sulfuric acid and nitric acid About 70% of the acidity of acid rain is due to sulfur oxides emissions 30% is due to nitrogen oxides emissions These acids may travel long distances with prevailing winds to be deposited as acid precipitation
- 15. Emission from power plant in New Mexico contained excessive amounts of SO2
- 16. Acid rain Harmful effects on Terrestrial ecosystems 1. Damages leaves and needles 2. Decrease ability of trees to tolerate cold 3. Weakened trees either are killed or become susceptible to diseases 5. Causes leaching of basic essential elements 6. Causes dissolution of Fe, Al, Mn from minerals Can cause human respiratory diseases such as bronchitis and asthma Aquatic ecosystemsAquatic ecosystems 1.1. Loss of essentially all fishLoss of essentially all fish populationspopulations below a pHbelow a pH of 4.5of 4.5 2.2. Dissolution and release ofDissolution and release of aluminum ions (aluminum ions (AlAl3+3+ ) from) from minerals can kill manyminerals can kill many kinds of fishkinds of fish 3. Accumulation in fish of3. Accumulation in fish of heavy metals pose healthheavy metals pose health hazards to humans,hazards to humans, mammals, and birdsmammals, and birds
- 17. Consequences of acid rain
- 18. Fish kill
- 19. Solution to Acid Rain Problem Liming periodically, though not satisfactory over a long period Also expensive & requires continuing effort Long-term practical solution is to ensure that the production of acid-forming components in the atmosphere is minimized Best strategy Increasing energy efficiency and conservation measures that result in burning less coal Alternative energy sources Pollution abatement technology to lower the emission
- 20. Solution to Acid Rain Problem The only way to fight acid rain is by curbing the release of the pollutants that cause it This means burning fewer fossil fuels But even if acid rain could be stopped today, it would still take many years for its harmful effects to disappear Individuals can also help prevent acid rain by conserving energy The less electricity people use in their homes, the fewer chemicals power plants will emit Vehicles are also major fossil fuel users, so emissions can be reduced by using public transportation, carpooling, biking, or simply walking wherever possible
- 21. Smog Air pollution that is localized in urban areas, where it reduces visibility Formation of smog depends on local climate, topography, population density, industry, fuels used in industry, heating, and transportation Two types Photochemical smog (brown air) Solar radiation is important Directly related to automobile use Involve both N- oxides & HCs Sulfurous smog (gray air/ Industrial smog ) Produced primarily by burning coal or oil at large power plants Affects human health and comfort Damage to materials Affects atmosphere Toxic to plants
- 22. Smog over California Looking from the Hollywood hills, air pollution is visible in downtown Los Angeles
- 23. Smog in Cairo Smog over a city
- 24. Pollution Control Most reasonable strategies are to reduce, collect, capture, or retain the pollutants before they enter the atmosphere The reduction of emissions via energy efficiency and conservation measures is the preferred strategy Particulates emitted from fugitive, point, or area stationary sources are much easier to control than released from mobile sources Settling chambers or collectors are may be used to control emissions of coarse particulates from power plants and industrial sites Particulates from fugitive sources (waste pile) must be controlled on-site so that the wind does not blow them into the atmosphere
- 25. Pollution Control Control of pollutants such as carbon monoxide, nitrogen oxides, and hydrocarbons in urban areas is best achieved through control measures for automobiles Control of nitrogen oxides from automobile is accomplished by recirculating exhaust gas Carbon monoxide and hydrocarbons from automobile is reduced by using catalytic converter which converts carbon monoxide to carbon dioxide, hydrocarbons to carbon dioxide and water by passing exhaust gases over a catalyst Sulfur dioxide emission can be reduced by abatement measures performed before, during, or after combustion
- 26. End of Slides Thank You