Presentation on theme: "Global Issues: Ozone Depletion, Global Warming and Acid Rain"— Presentation transcript:
1 Global Issues: Ozone Depletion, Global Warming and Acid Rain IntroductionAbout ozone depletionCauses of ozone depletionEffects of ozone depletionSolutions in tackling ozone depletionAbout global warmingAbout greenhouse effectSources of greenhouse gasesEffects of global warmingDiscussion of controversial viewsSolutions in tackling global warmingAbout acid rainCauses of acid rainEffects of acid rainSolutions in tackling acid rainConclusion
2 IntroductionAir pollution is exerting increasing impact on the environment. Humans have been altering the chemistry of the atmosphere on a global scale. These changes may:Modify the global climateThreaten the health of human beingsCreate many environmental problems such asAcid rainDepletion of ozone layerGlobal warmingSeriously upset the global ecosystem
3 What is ozone depletion? Ozone is a highly reactive gas comprising triatomic oxygenOzone layer in the stratosphere protects the Earth’s surface from UV lightOzone depletion refers to a lowered concentration of ozone in the upper atmosphere“Holes” are formedMore UV radiation is reaching the Earth’s surface October ozone levels over Antarctica since the late 1950s.
4 What are the causes of ozone depletion? Presence of chlorofluorocarbons (CFCs)Presence of oxides of nitrogenPresence of halogensPresence of bromineThe radicals would speed up the loss of ozone because they constantly re-emerge to trigger another reaction
5 What are the effects of ozone depletion? UV radiation is absorbed by DNA and modifies them, affecting the expression of genetic informationA higher incidence of skin cancer,lung diseases and cataractReduce the yields of cropsDisruption of the ecological balance in the oceanA higher incidence of photochemical smog
6 What can we do to solve the problems of ozone depletion? Reduce emissions of ozone-depleting chemicalsReduce the uses of aerosol spraysUse the aerosol sprays that are free of CFC compounds instead
8 What is global warming?Global warming refers to the gradual increase in the average temperature in the atmosphereIncrease in concentration of greenhouse gases in the atmosphereThe heat loss from the Earth to the Space is slowed downAn enhancement of the greenhouse effect leads to global warmingGreenhouse gases include carbon dioxide, chlorofluorocarbons, methane, nitrous oxides, ozone, water vapour, etc
10 What is greenhouse effect? Most of the incoming solar radiation is in the visible part of the spectrumMost visible light passes through the atmosphere without being absorbedThe earth radiates heat back out towards space when warmed upMuch of the radiation does not escape into spaceMost is trapped by certain gases in the atmosphere, carbon dioxide and particular water vapour
11 What are the sources of greenhouse gases? Greenhouse gases are generated by varies human activities, because ofburning of fossil fuelsdeforestationextensive rearing of livestockextensive use of cooling agents, blowing agents, insulating and packaging materials, aerosol sprays and solvents
14 What are the effects of global warming? Thermal expansion of the oceans, melting of glacial iceFloodingLow-lying cities would be submergedGlobal climate would be affected due to the removal of rainforestsDistribution of the climatic regions and ocean currents would be changedIncrease in frequency and severity of weather extremesIncrease in temperature of marineBiodiversityAlter disease pattern, thus, increase the spread of epidemicsPests could become more active and grow faster
18 It is believed that an increase in atmospheric temperature would lead to faster growth of plants and phytoplankton on land and aquatic environments. This would increase the consumption of carbon dioxide in photosynthesis, bringing a re-balance of carbon dioxide in the atmosphere. Plants would transpire faster in the warmer air. The atmosphere would thus become more humid and more advantageous to plant growth.
19 What can we do to solve the problems of global warming? Use “cleaner energy”Smart transportation and land useForestationWatch less TVUse less air conditionerTurn off the light when leaving the roomTake public transportUse less microwave oven
21 What is acid rain?Acid rain refers to precipitation in the form of dilute acid solutionsNot a single phenomenonThe pollutants involved are sulphur dioxide, oxides of nitrogen, ammonia, ozone and various volatile organic vapoursAcid rain typically has a pH from 4.0 to 5.4
22 What are the causes of acid rain? Sulpur dioxide reacts with oxygen in air, forming sulphur trioxideSulphur trioxide dissolved in rain water to form a dilute solution of sulphuric acidSulphur dioxide can also dissolves in rain water directlyNitrogen dioxide is formed by combining nitrogen monoxide with oxygenNitrogen dioxide reacts with water and oxygen to form nitric acid
24 What are the effects of acid rain? Damage the buildings, statuesCorrode marble and metalsCauses human respiratory diseasesIncreases the acidity of soilInduce the release of aluminium ions from soil particlesAcidify lakes
25 What can we do to solve the problems brought by acid rain? For individuals:Individuals can contribute directly by conserving energy, since energy production causes the largest portion of the acid deposition problem.Turn off lights, computers, and other appliances when you're not using themUse energy efficient appliances: lighting, air conditioners, heaters, refrigerators, washing machines, etc.Only use electric appliances when you need them.Carpool, use public transportation, or better yet, walk or bicycle whenever possibleBuy vehicles with low NOx emissions, and maintain all vehicles well.
26 For society:Understand acid deposition's causes and effectsClean up smokestacks and exhaust pipesUse alternative energy sourcesRestore a damaged environmentLook to the future