- Slides: 39
AIR POLLUTION POINT SOURCES Sources that release large quantities of pollutants in concentrated amount. Paper mills, oil refineries, chemicalprocessing industries, and industrial and sewage treatment plants. NON-POINT SOURCES Sources that release pollutants in a diffused manner. Smoke emission from vehicles, burning of garbage, and using aerosol sprays and insecticides.
PHOTOCHEMICAL SMOG • A brown smog, the gray-brown haze that hovers over many cities. It is especially a problem in warm, sunny regions where lots of cars burn gasoline. • It involves the blending of nitrogen oxides, hydrocarbons, and solar energy in the form of UV light. • This forms ozone at ground level. • Photochemical smog can cause eye irritation and poor visibility.
• Higher amounts of ozone in the Earth’s surface causes damage to the respiratory system, loss of immune function, nausea, eye and throat irritation, and fatigue. • Oxidants, like ozone, can also kill plant cells, causing leaves to develop brown spots, reduce plant growth, and make plants susceptible to damage.
THERMAL INVERSION • It creates a layer of warm air (an inversion layer) lies over a layer of cool air, trapping harmful chemicals near the ground. It heightens air pollution because smoke are trapped in the surface by the layer of cool air.
RADIATION INVERSION • It develops at night when the ground cools and gives off long wave radiation. The air near the ground is cooled when it comes in contact with the ground, this layer of air gets cooler than the air above
ACID DEPOSITION • It describes how acid can fall back to the Earth.
POLLUTANTS IN THE ATMOSPHERE
CARBON DIOXIDE Released mainly from fossil fuels. major contributor to air pollution. Burning of coal, oil, and gas, and deforestation. Volcanic outgassing.
GREENHOUSE GASES • Gases that trap heat in the atmosphere. • • • Carbon dioxide Methane Nitrous oxide Ozone Water Vapor
GREENHOUSE EFFECT • These gases do not allow heat to escape earth easily, causing the heat energy to be trapped and raise the temperature of air near the surface.
NITROGENBASED COMPOUNDS nitric oxide and nitrogen oxide come from burning fossil fuels. contributes to the thinning of the ozone layer. nitrous oxide comes from fertilizers, deforestation, and burning of biomass.
SULFUR DIOXIDE produced by burning sulfur-containing fuels – coal and crude oil; production of sulfuric acid and metallurgical applications. can irritate the upper human respiratory tract and makes breathing difficult.
CHLOROFLOUROCARBONS CFCs are used as coolants in refrigerators and air conditioning units. CFC trap more heat than any other greenhouse gases. causes the thinning of the ozone layer. Can last in the atmosphere between 70 and 110 years.
OZONE LAYER – situated in the atmosphere about 30 -40 km above the surface. Composed of high content of ozone (O 3), a triatomic form of oxygen. As cfc enter the layer, a strong ultraviolet radiation from the sun breaks the bond between the chlorine atom and carbon. Chlorine will act as a catalyst, pulling out one oxygen from the O 3 molecule, thus making the oxygen ready to react with another oxygen atom in the atmosphere. the single chlorine atom does this in this cycle, damaging thousands of ozone molecules before decomposing.
THE OZONE CYCLE
OZONE DEPLETION • Tropospheric or ground ozone is a pollutant. Nitrogen oxide emitted by supersonic jets and other vehicles react with the ozone molecules in the stratosphere to form nitrogen dioxide and oxygen. The nitrogen dioxide then reacts with free oxygen atoms to form nitrogen oxide, which reacts with another ozone molecule.
• The ozone layer is continually damaged as nitrogen oxides break down and reform in the atmosphere.
• Image of the largest Antarctic ozone hole ever recorded (September 2006), over the Southern pole
Ozone hole in North America during 1984 (abnormally warm reducing ozone depletion) and 1997 (abnormally cold resulting in increased seasonal depletion). Source: NASA
• Human health is affected due to extreme heat and cold • Melting of glaciers will raise sea levels • Occurrence of more violent storms • Extinction of species • Decreased food production • Shifts in flow and water supply • Increased susceptibility of forest fires, disease and insect damage
HUMAN-CAUSED CLIMATE CHANGE • The world’ climate had changed significantly over the past century. • This significant change had human influence. • Using climate models, if the trend continues, the global mean surface temperatures will increase between 1°C and 3. 5°C by 2100.
? WHAT CAN YOU DO ABOUT IT
• • • • Unplug electronics from the wall when not in use Don't use regular incandescent light bulbs Switch to compact fluorescent lightbulbs Follow 3 R Rule - Recycle, Reduce, and Reuse Avoid heavily packaged products Carpool, bike, or walk instead of driving alone Buy fresh produce at you local farmer's market Use energy efficient appliances Prefer buying energy-efficient appliances like fluorescent bulbs. Plant trees, as they absorb UV rays greatly and thus protect the environment. Replace your old refrigerators and air conditioners as they are the major contributors of CFC in the atmosphere. Avoid or restrict the use of insecticides and pesticides. Use paper when lighting stove or grill. Mowing the lawn after 6 pm