化學(xué)污染與防治5課件

Chapterfour:AirPollutionTheatmosphereisdividedintotwolayers.ThelayernearestEarth,thetroposphere,harborsnearlyalllivingthingsandnearlyallhumanactivity.Theneatregion,thestratosphere,iswherewefindtheozonelayerthatshieldslivingcreaturesfromdeadlyultravioletradiation.AtmosphereVariationsofatmosphericpressureandaveragetemperaturewithaltitude.AirPollutionWhatisapollutant?Itismerelyachemicalinthewrongplaceinthewrongconcentration.Humanactivitiescanreleasesubstancesintotheair,someofwhichcancauseproblemsforhumans,plants,andanimals.Theexhaustfromburningfuelsinautomobiles,homes,andindustriesisamajorsourceofpollutionintheair.1.Suspendedparticulatematter(referredtoas"blackcarbon"pollution):releasedintotheairfromburningfuelforenergy.Theparticlesareverysmallpiecesofmattermeasuringabout2.5micronsorabout.0001inches.ThetypesofpollutionBlackcarbonpollutionisthereleaseoftinyparticlesintotheairfromburningfuelforenergy.Theexhaustfromburningfuelsinautomobiles,homes,andindustriesFossilfuels(petroleumproducts,coal,andnaturalgas)2.Anothertypeofpollutionisthereleaseofnoxiousgases,suchassulfurdioxide,carbonmonoxide,nitrogenoxides,andchemicalvapors.

Thesecantakepartinfurtherchemicalreactionsoncetheyareintheatmosphere,formingSmog,Acidrain,GreenhouseEffectandOzonedepletion

Carbondioxide(CO2)istheprinciplegreenhousegasemittedasaresultofhumanactivitiessuchastheburningofcoal,oil,andnaturalgases.Ozoneoccurnaturallyintheupperlayersoftheatmosphere.Atthegroundlevel,itisapollutantwithhighlytoxiceffects.Vehiclesandindustriesarethemajorsourceofground-levelozoneemissions.Ozonemakesoureyesitch,burn,andwater.Itlowersourresistancetocoldsandpneumonia.Sulphurdioxide(SO2)isagasproducedfromburningcoal,mainlyinthermalpowerplants.Someindustrialprocesses,suchasproductionofpaperandsmeltingofmetals,producesulphurdioxide.Itisamajorcontributortosmogandacidrain.SulfurdioxidecanleadtolungdiseasesSmogSmogisatypeoflarge-scaleoutdoorpollution.Itreferstohazyairthatcausesdifficultbreathingconditions.Smogisacombinationofvariousgaseswithwatervapouranddust.Itiscausedbychemicalreactionsbetweenpollutantsderivedfromdifferentsources,primarilyautomobileexhaustandindustrialemissions.SmogThemostharmfulcomponentsofsmogareground-levelozoneandfineairborneparticles.Ground-levelozoneformswhenpollutantsreleasedfromgasolineanddiesel-poweredvehiclesandoil-basedsolventsreactwithheatandsunlight.Theeffectsofsmogonhumanhealthwereevident,particularlywhensmogpersistedforseveraldays.Manypeoplesufferedrespiratorydiseasesandincreaseddeathswererecorded,notablythoserelatingtobronchialcauses.Londonsmog

Therearetwobasictypesofsmog.Onetype–---consistingmainlyofsmoke,fogsulfurdioxide,sulfuricacid,ash,andsoot?---iscalledLondonsmog.ThewordsmogisthoughttohaveoriginatedinEnglandin1905asacontractionofthewordssmoke

andfog.TheChemistryofLondonSmogCoalismainlycarbon,butitcontainsasmuchas3%sulfur.Coalalsocontainsvaryingamountsofmineralmatter.Whenburned,thecarbonincoalisoxidizedtocarbondioxide. C+O2→CO2Notallthecarboniscompletelyoxidized.Someofitwindsupascarbonmonoxide. 2C+O2→2COTheChemistryofLondonSmogThesulfurincoalalsoburns,formingsulfurdioxide,achoking,acridgas. S+O2→SO2Sulfurdioxideisreadilyabsorbedintherespiratorysystem.Itisapowerfulirritantandisknowntoaggravatethesymptomsofpeoplewhosufferfromasthma,bronchitis,emphysema,andotherlungdiseases.Stillothercarbon,essentiallyunburned,endsupassoot.Londonsmogalsoischaracterizedbyhighlevelsofparticulatematter,solidandliquidparticlesofgreaterthanmolecularsize.Thelargeparticlesoftenarevisibleintheairasdustandsmoke.Smallerparticlesof1μmorlessindiameter?calledaerosols?areofteninvisible.Perhapsamoreinsidiousformofparticulatematteristhesulfates.Someofthesulfuricacidinsmogreactswithammoniatoformasolidmaterial,ammoniumsulfate.

2NH3+H2SO4→(NH4)2SO4solidammoniumsulfateareeasilytrappedinthelungs

TheothermaintypeofsmogisLosAngelessmog,or,moreproperly,photochemicalsmog.UnlikeLondonsmog,whichaccompaniescold,dampair,photochemicalsmogusuallyoccursduringdry,sunnyweather.

Theprincipalculpritsareunburnedhydrocarbonsandnitrogenoxidesfromautomobiles.LosAngelesSmogThechemistryofLosAngelessmogisexceedinglycomplex.Let’slookatthestuffthatcomesoutofanautomobile’sexhaustpipe

a.CarbonMonoxide:TheQuietKiller-Millionsofthisinvisiblebutdeadlygasarepouredintotheatmosphereeachyear,about75%ofitfromautomobileexhausts.-TheUnitedStatesgovernmenthassetdangerlevelsof9ppmcarbonmonoxide(average)over8hoursand35ppm(average)over1hour.Thechemistryof

LosAngelessmog

Thesymptomsofcarbonmonoxidepoisoningarethoseofoxygendeprivation,andthehearthastoworkhardertosupplyoxygentothetissues.Carbonmonoxideisalocalpollutionproblem.Itisaseverethreatinurbanareaswithheavytraffic,butitdoesnotappeartobeaglobalthreat.Oxygenintheatmosphereslowlyoxidizesthenitricoxidetonitrogendioxide(NO2).2NO+O2→2NO2Nitrogendioxideisanamber-coloredgas.SmartingeyesandabrownishhazeareexcellentindicatorsofLosAngelessmog.Testswithlaboratoryanimalsindicatethatchronicexposureintherangeof10to25ppmmightleadtoemphysema肺氣腫andotherdegenerativediseases變性疾病ofthelungs.Nitricoxideathighconcentrationsreactswithhemoglobin;aswithcarbonmonoxidepoisoning,thisleadstooxygendeprivation.Itisthisnitrogendioxidethatplaysavitalroleinphotochemicalsmog.Itabsorbsaphotonofsunlightandbreaksdownintonitricoxideandreactiveoxygenatoms.Theinitiator:NO2+sunlight→NO+OTheoxygenatomsreactwithothercomponentsofautomobileexhaustandtheatmospheretoproduceavarietyofirritatingandtoxicchemicalsSecondaryreactions: O+O2→O3 O+hydrocarbons→aldehydesTertiaryreactions:

O3+hydrocarbons→aldehydesHydrocarbons+oxygen+NO2→PANCH3COONO2OCOONO2OPANPBN過(guò)氧乙酰硝酸酯peroxyacetyl-nitrate過(guò)氧苯酰硝酸酯Thegasesalsocontributetothefadinganddiscolorationoffabrics.Byformingnitricacid,nitrogenoxidescontributetotheacidityofrainwater.c.Ozone:GoodNews,BadNewsOzone,anaturalcomponentofthestratosphere,shieldstheEarthfromlife-destroyingultravioletradiation.Ozoneisafamiliarconstituentofphotochemicalsmog.Inhaled,itisatoxic,dangerouschemical.Ozoneisapowerfuloxidizingagent.Atlowlevels,itcauseseyesirritation.Athighlevels,itcancausepulmonaryedema肺水腫,hemorrhage出血,andevendeath.Inhalationofozoneisparticularlydangerousduringvigorousphysicalactivity.Itcausesrubbertohardenandcrack,shorteningthelifeofautomobiletiresandotherrubberitems.Ozonealsocausesextensivedamagetocrops.Tobaccoandtomatoesareparticularlysusceptibled.Chlorofluorocarbons

Theyescapeintotheatmospherefromrefrigeratorsandairconditioners.chlorofluorocarbonsmightbemakingtheirwayupthroughtheatmospheretothestratosphere.e.Hydrocarbons:AnotherCulprit

Inurbanareas,theprocessinganduseofgasolineisthemajorsourceofhydrocarbonsintheenvironment.Theautomobile’sinternalcombustionenginealsocontributesbyexhaustingunburnedandpartiallyburnedhydrocarbons.Certainhydrocarbons,particularlythosethatcontainadoublebond,combinewithoxygenatomsorozonemoleculestoformaldehydes.Anothercomplicatedseriesofreactionsinvolvinghydrocarbons,oxygen,andnitrogendioxideleadstotheformationofperoxyacetyl-nitrate(PAN).Ozone,thealdehydes,andPANareresponsibleformuchofthedestructionbysmog.Theymakebreathingdifficultandmaketheeyessmartanditch.Homework:1.WhattoDoAboutLondonSmog?

2.WhattoDoAboutPhotochemicalSmog?Acidrain.AcidrainisdefinedasrainhavingapHlessthan5.6.(5.6isthepHofnormalrainwater,whichisslightlyacidicduetodissolvedcarbondioxide)Wehaveseenhowsulfuroxidesareconvertedtosulfuricacid.Similarly,nitrogenoxidesbecomenitricacid,TheseacidsfalluponEarthasacidrainoracidsnow.Whenapollutant,suchassulfuricacidcombineswithdropletsofwaterintheair,thewater(orsnow)canbecomeacidified.Theeffectsofacidrainontheenvironmentcanbeveryserious.Itdamagesplantsbydestroyingtheirleaves,itpoisonsthesoil,anditchangesthechemistryoflakesandstreams.Damageduetoacidrainkillstreesandharmsanimals,fish,andotherwildlife.

Acidscorrodemetalsandcanevendecomposestonebuildingsandstatues.Sulfuricacideatsawaymetaltoformasolublesaltandhydrogengas.Fe+H2SO4→FeSO4+H2IronIron(Ⅱ)sulfate

(orsteel)(soluble)

Marblebuildingsandstatuesaredisintegratedbysulfuricacidinasimilarreactionthatformscalciumsulfate,aslightlysoluble,crumblycompound.CaCO3+H2SO4→CaSO4+H2O+CO2MarbleCalciumorlimestonesulfateThegreenhouseeffectistheriseintemperaturethattheEarthexperiences.WithoutthegreenhouseeffecttheEarth'saverageglobaltemperaturewouldbe-18°Celsius,ratherthanthepresent15°Celsius.GreenhouseeffectMostgreenhouseslooklikeasmallglasshouse.Greenhousesareusedtogrowplants,especiallyinthewinter.Greenhousesworkbytrappingheatfromthesun.Theglasspanelsofthegreenhouseletinlightbutkeepheatfromescaping.ThiscausesthegreenhousetoheatupHaveyoueverseenagreenhouse?Theheatistrappedbygases,knownasgreenhousegasesthatbehavemuchliketheglassinagreenhouse.AssunlightreachestheEarth'ssurface,land,water,andbiosphereabsorbthesunlight’senergy.Onceabsorbed,thisenergyissentbackintotheatmosphere.Someoftheenergypassesbackintospace,butmuchofitremainstrappedbythegreenhousegases,causingourworldtoheatup.GreenhouseGases

Greenhousegasesincludewatervapor,carbondioxide(CO2),methane(CH4),nitrousoxide(N2O),halogenatedfluorocarbons(HCFCs),ozone(O3),hydrofluorocarbons(HFCs)andafewothergases.Theyallaremoleculescomposedofmorethantwocomponentatoms,boundlooselyenoughtogethertobeabletovibratewiththeabsorptionofheat.GreenhouseGases

Thesinglemostimportantgasiscarbondioxidewhichaccountsforabout55%ofthechangeintheintensityoftheEarth'sgreenhouseeffect.Thecontributionsoftheothergasesare25%forchlorofluorocarbons,15%formethane,and5%fornitrousoxide.Ozone'scontributiontotheenhancementofgreenhouseeffectisstillyettobequantified.GreenhouseGas:carbondioxideIncreaseincarbondioxideintheatmosphereisprimarilyduetotheactivitiesofhumans.Beginningin1700,societalchangesbroughtaboutbytheIndustrialRevolutionincreasedtheamountofcarbondioxideenteringtheatmosphere.Themajorsourcesofthisgasincludefossilfuelcombustionforindustry,transportation,andcooking;andvegetation植被changesinnaturalelectricitygenerationprairie,woodland,andforestedecosystems.1971年1991年2010年CO2排放量單位（億噸）AnnualconcentrationofatmosphericCO2since1850.GreenhouseGas:chlorofluorocarbonArtificiallycreatedchlorofluorocarbonsarethestrongestgreenhousegaspermolecule.However,lowconcentrationsintheatmospherereducetheiroverallimportanceintheenhancementofthegreenhouseeffect.GreenhouseGas:methaneTheprimarysourcesformethaneaddedtotheatmospherearericecultivation,domesticgrazinganimals,termites白蟻,landfills,coalmining,andoilandgasextraction.Since1750,methaneconcentrationsintheatmospherehaveincreasedbymorethan150%.GreenhouseGas:nitrousoxide

Theaverageconcentrationofnitrousoxideintheatmosphereisnowincreasingatarateof0.2to0.3%peryear.Sourcesforthisincreaseincludedeforestationandtheconversionofforest;fossilfuelcombustion;biomassburning;andsoilfertilization.WhenDoYouSendGreenhouseGasesintotheAir?Wheneveryou...

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PlayaVideoGameListentoaStereoWashorDryClothesUseaDishWasherMicrowaveaMealWithoutthegreenhouseeffect,theEarthwouldnotbewarmenoughforhumanstolive.Butifthegreenhouseeffectbecomesstronger,itcouldmaketheEarthwarmerthanusual.ScientistsestimatethattheEarth'saverageglobaltemperaturehasalreadyincreasedby0.3to0.6°Celsius,sincethebeginningofthiscentury.GlobalWarming:GlobalWarming:GlobalwarmingreferstoanaverageincreaseintheEarth'stemperature,whichinturncauseschangesinclimate.

Whenscientiststalkabouttheissueofclimatechange,theirconcernisaboutglobalwarmingcausedbyhumanactivities.AwarmerEarthmayleadtochangesinrainfallpatterns,ariseinsealevel,andawiderangeofimpactsonplants,wildlife,andhumans.Globalwarmingcouldmakelargeareasoftheworlduninhabitableandcausemassivefoodandwatershortages,sparkingwidespreadmigrationsandwar.

CertainconsequencesofGlobalWarmingMeltingglaciers,earlysnowmeltandseveredroughtswillcausemoredramaticwatershortagesintheAmericanWest.

RisingsealevelswillleadtocoastalfloodingontheEasternseaboard,inFlorida,andinotherareas,suchastheGulfofMexico.

WarmerseasurfacetemperatureswillfuelmoreintensehurricanesinthesoutheasternAtlanticandGulfcoasts.

Forests,farmsandcitieswillfacetroublesomenewpestsandmoremosquito-bornediseases.

Disruptionofhabitatscoulddrivemanyplantandanimalspeciestoextinction.

ClimatechangeTemperaturewillhaveincreasedby1–3.5°Cdependingonpopulationandeconomicgrowth.Sealevelwillbe15–90cmhigher,threateningabout92millionpeoplewithfloods.Rainfallwouldhavedecreasedandtherewouldbeareductionoffoodcrops.OzonedepletionOzonedepletionisanotherresultofpollution.Thetermozonedepletionisusedtodescribetwodistinctbutrelatedobservations:A:aslow,steadydeclineofabout3percentperdecadeinthetotalamountofozoneinEarth's

stratosphereduringthepasttwentyyears;B:alarger,butseasonal,decreaseinstratosphericozoneoverEarth'spolarregions(Antarctica),commonlyreferredtoastheozonehole.ozonelayer"Alayerinthestratospherecontainingarelativelyhighconcentrationofozone.Theozonelayerabsorbs97-99%ofthesun'shighfrequencyultravioletlight,