资源环境科学专业英语

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Unit1TheEnvironmentandEnvironmentalProblemsHumanshavealwaysinhabitedtwoworlds.Oneisthenaturalworldofplants,animals,soils,air,andwaterthatprecededusbybillionsofwhichweareapart.Theotheristheworldofsocialinstitutionsandartifactsthatwecreateforourselvesusingscience,technology,andpoliticalorganization.Bothworldsareessentialtoourlive,butintegratingthemsuccessfullycausesenduringtensions.Whereearlierpeoplelimitedabilitytoaltertheirsurroundings,wenowhavepowertoextractandconsumeresources,producewastes,andmodifyourworldinwaysthatthreatenbothourcontinuedexistenceandthatofmanyorganismswithwhichwesharetheplanet.Toensureasustainablefutureforourselvesandfuturegenerations,weneedtounderstandsomethingabouthowourworldworks,whatwearedoingtoit,andwhatwecandotoprotectandimproveit.EnvironmentandEnvironmentScienceEnvironment(fromtheFrenchenvironner:toencircleorsurround)canbedefinedas(1)thecircumstanceorconditionsthatsurroundanorganismorgroupoforganisms,or(2)thecomplexofsocialorculturalconditionsthataffectanindividualorcommunity.Sincehumansinhabitthenaturalaswellasthe“built”ortechnological,social,andculturalworld,allconstituteimportantpartsofourenvironment,Environmentalscience,then,isthesystematicstudyofourenvironmentandourproperplaceinit.Arelativelynewfield,environmentalscienceishighlyinterdisciplinary,integratingnaturaloftheworldaroundus.Incontrasttomoretheoreticaldisciplines,environmentalscienceismission-oriented.Thatis,itseeksnew,valid,generalizableknowledgeaboutthenaturalworldandourimpactsonit,butobtainingthisinformationcreatesaresponsibilitytogetinvolvedintryingtodosomethingabouttheproblemswehavecreated.AsdistinguishedeconomistBarbaraWardpointsout,foranincreasingnumberofenvironmentalissues,thedifficultyisnottoidentifyremedies.Remediesarenowwellunderstood.Theproblemistomakethemsocially,economically,andpoliticallyacceptable.Forestersknowhowtoplanttrees,butnottoestablishconditionsunderwhichvillagersindevelopingcountriescanmanageplantationsforthemselves.Engineersknowhowtocontrolpollution,butnothowtopersuadefactoriestoinstallthenecessaryequipment.Cityplannersknowhowtobuildhousinganddesignsafedrinkingwatersystems,butnothowtomakethemaffordableforthepoorestmembersofsociety.Thesolutionstotheseproblemsincreasinglyinvolvehumansocialsystemsaswellasnaturalsciences.EnvironmentalDilemmasImaginethatyouareanastronautreturningtoearthafteralongtriptothemoonorMars.Whatareliefitwouldbetocomebacktothisbeautiful,bountifulplanetafterexperiencingthehostile,desolateenvironmentofouterspace.Althoughtherearedangersanddifficultieshere,weliveinaremarkableprolificand hospitableworldthatis,asfarasweknow,uniqueintheuniverse.Comparedtotheconditionsonotherplanetsinoursolarsystem,temperaturesontheeartharemildandrelativelyconstant.Plentifulsuppliesofcleanair,freshwater,andfertilesoilareregeneratedendlesslyandspontaneouslybygeologicalandbiologicalcycles.Perhapsthemostamazingfeatureofourplanetistherichdiversityoflifethatexistshere.Millionsofbeautifulandintriguingspeciespopulatetheearthandhelpsustainahabitableenvironment.Thisvastmultitudeoflifecreatescomplex,interrelatedcommunitieswheretoweringtreesandhugeanimalslivetogetherwith,anddependupon,tinylife-formssuchasvirusesandfungi.Together,alltheseorganismsmakeupdelightfullydiverse,self-sustainingcommunities,includingdense,moistforests,vastsunnysavannas,andrichlycolorfulcoralreefs.Fromtimetotime,weshouldpausetorememberthat,inspiteofthechallengesandcomplicationsoflifeonearth,weareincrediblyluckytobehere.Weshouldaskourselves:whatisourproperplaceinnature?Whatoughtwetodoandwhatcanwedotoprotecttheirreplaceablehabitatthatproducedandsupportus?Thesearesomeofthecentralquestionsofenvironmentalscience.Whiletherearemanythingstoappreciateandcelebrateabouttheworldonwhichwelive,manypressingenvironmentalproblemscryoutforoutattention.Humanpopulationshavegrownatalarmingratesinthiscentury.Nearly6000millionpeoplenowoccupytheearthandweareadding100millionmoreeachyear.Inthenextdecade,ournumberswillincreasebynearlyasmanyasarenowaliveinChina.Mostofthegrowthwillbeinthepoorercountrieswhereresourcesandservicesarealreadystrainedbypresentpopulations.Somedemographersbelievethatthisunprecedentedgrowthratewillslowinthecenturyandthatthepopulationmighteventuallydropbackbelowitspresentsize.Otherswarnthatthenumberofhumansacenturyfromnowcouldbeforfivetimesmorethanthatofourpresentpopulationifwedon’tactquicklytobirthratesintobalancewithdeathrates.Whethertherearesufficientresourcestosupport6billionhumans-letalone25billion-onasustainablebasisisoneofthemostimportantquestionsweface.Howwemightstabilizepopulationandwhatlevelofresourceconsumptionfuturegenerationswecanaffordareequallydifficultpartsofthischallengingequation.Foodshortagesandfaminesalreadyaretoofamiliarinmanyplacesandmayincreaseinfrequencyandseverityifpopulationgrowth,soilerosion,andnutrientdepletioncontinueatthesamerateinthefutureastheyhaveinthepast.Wearecomingtorealize,however,thatfoodsecurityoftenhasmoretodowithpoverty,democracy,andequitabledistributionthatitdoeswiththeamountoffoodavailable.Waterdeficitsandcontaminationofexistingwatersuppliesthreatentobecriticalenvironmentalissuesinthefutureforagriculturalproductionaswellasfordomesticandindustrialuse.Manycountriesalreadyhaveseriouswatershortagesandmorethanonebillionpeoplelackaccesstocleanwateroradequatesanitation.Violentconflictsovercontrolofnaturalofnaturalresourcesmayflareupinmanyplacesifwedon’tlearntolivewithinnature’sbudget. Howweobtainanduseenergyislikelytoplayacrucialroleinourenvironmentalfuture.Fossilfuels(oil,coal,andnaturalgas)presentlysupplyabout80%oftheenergyusedinindustrializedcountries.Suppliesofthesefuelsarediminishingatanalarmingrateandproblemsassociatedwiththeiracquisitionanduse-airandwaterpollution,miningdamage,shippingaccidents,andpoliticalinsecurity-maylimitwhereandhowweuseremainingreserves.Cleanerrenewableenergyresources-solarpower,wind,andbiomass-togetherwithconservation,mayreplaceenvironmentallydestructiveenergysourcesifweinvestinappropriatetechnologyinthenextfewyears.Asweburnfossilfuels,wereleasecarbondioxideandotherheat-absorbinggasesthatcauseglobalwarmingandmaybringaboutsea-levelrisesandcatastrophicclimatechanges.Acidsformedintheextensivedamagetothebuildingmaterialsandsensitiveecosystems.inmanyplace.Continuedfossilfuelusewithoutpollutioncontrolmeasurescouldcauseevenmoreextensivedamage.Chlorinatedcompounds,suchasthechlorofluorocarbonsusedinrefrigerationandairconditioning,alsocontributetoglobalwarming.Aswellasdamagingthestratosphericozonewhichprotectsusfromcancer-causingultravioletradiationinsunlight.Destructionoftropicalforest,coralreefs,wetland,andotherbiologicallyvarietyandabundancethatcouldseverallylimitourfutureoptions.Manyrareandendangeredspeciesarethreateneddirectlyorindirectlybyhumanactivities.Inadditiontopracticalvalues,aestheticandethicalconsiderationssuggestthatweshouldprotectthesespeciesandthehabitatnecessaryfortheirsurvival.Toxicairandwaterpollutants,alongwithmountainsofsolidandhazardouswastes,arebecomingoverwhelmingproblemsinindustrializedcountries.Weproducehundredofmillionsoftonsofthesedangerousmaterialsannually,andmuchofitisdisposedofindangerousandirresponsibleways.noonewantsthisnoxiousstuffdumpedinhisorherownbackyard,buttoooftenthesolutionistoexportittosomeoneelse’s.wemaycometoapoliticalimpassewhereourfailuretodecidewheretoputourwastesorhowtodisposeofthemsafelywillclosedownindustriesandresultinwastesbeingspreadeverywhere.Thehealtheffectsofpollutiontoxicwastes.Stress,andtheotherenvironmentalillsofmodernsocietyhavebecomeagreaterthreatthaninfectiousdiseasesformanyofusinindustrializedcountries.Thisandothersimilarlyseriousproblemsillustratetheimportanceofenvironmentalscienceandenvironmentaleducationforeveryone.Whatwearedoingtoourworld,andwhatthatmanymeanforourfutureandthatofourchildrenisparamountconcernasweenterthetwenty-fistcentury. Unit2PopulationResourcesandEnvironmentPopulationExplosionAlltoooften,overpopulationisthoughtofsimplyascrowding:toomanypeopleinagivenarea,toohighapopulationdensity.Between1900andnow,theworld’spopulationhasroughlyquadrupledfromabout1.6billionin1900toabout6billiontodayandiscurrentlygrowingatanannualrateof1.2%,or77millionpeopleperyear.Sixcountriesaccountforhalfofthisannualgrowth:Indiafor21%,Chinafor12%,Pakistanfor5%,Nigeriafor4%,Bangladeshfor4%,andIndonesiafor3%.By2050,worldpopulationisexpectedtobebetween7.9billion(lowvariant)and10.9billion(highvariant),withthemediumvariantproducing9.3billion.Therewouldbearapidagingoftheworld’spopulation.Inthepast,themedianagefortheworld’spopulationhasbeenbetween20and25years.Itisnowabout26years.By2050,themedianageforadepopulatingglobewouldbeabout42years.Inthemoredevelopedregionsthemedianageofpopulationwouldbeover50.Thatistosay:foreverypersonundertheageof50,therewouldbesomeoneovertheageof50.Acompletetransformationoftheprofileoftheworldwouldthusoccur.Theexplosionofworldpopulationisanoutgrowthoftheindustrialage,andthreekeyfactorsaretoblame:increasedfoodproduction,diseasecontrol,andbettersanitation.Theseadvancesgreatlyincreasedthesurvivalrateofnewborns,butthisgreatchangeoccurredinmanycountrieswithoutanydecreaseinthenumberofbirth.Populationgrowthisattherootofvirtuallyallenvironmentproblems,includingpollutionandresourcesdepletion,andindirectsocialdisruptions.Suchashousingshortages,malnutritionandinadequatehealthcare,rapidgrowthinpopulationcreatesdifficultiesinmeetingthebasicneedsofpeople,crowdingmaycausementalillness,drugabuseandvariousformsofantisocialbehavior.Hunger,starvation,disease,poverty,illiteracy,pollution,unemployment,andbarrenlandscapesare,tomanyobservers,signsthatthehumanpopulationismuchtoobigfortheearth’sresources.Amongthenegativetrendstheybetwouldcontinuewere:Risingglobaltemperature;Shrinkingamountofcroplandperperson;Declineinamountofwheatandricegrownperperson;Shrinkingareaoftropicalmoistforests;Declininghumanspermcount;Growinggapbetweenrichandpoor.Populationgrownwouldhavetobestopped;familyplanningandlimitedeconomicaldevelopmentarewaystobringthehumanpopulationbackinliner.Familyplanningallowscouplestodeterminethenumberandspacingofoffspringprogramsmaybevoluntary,extendedvoluntary,orforced.Manyexpertsbelievedthatfamilyplanningthatpromoteseconomicdevelopment,jobsforwomen,healthandeducation.Tohaveaneffectivefamilyplanningprogram,wealsohaveaneffectiveeconomy-wherejobsareavailable,wherehealthfacilitiesareadequate.Small-scaleeconomicdevelopmentimprovededucation,betterhealthcare,andcontraceptioncanreducebirthrates.The criticalthingskillssuggestthatsolutionsrequiremanyapproaches.Familyplanningisacaseinpoint.Developednationscancontributetoasolutionbyreducingconsumptionandpopulationsize.Theycanassistthelessfortunatewithpopulationcontrol,agriculture,healthcare,andappropriatetechnologythroughfinancialaidand,especially,informationsharing.Manydevelopingnationshavepopulationcontrolprograms,althoughfundsareofteninadequate.Increasingexpendituresonsuchprogramscouldhavemanylong-rangbenefits.Tobeeffective,programsinsuchcountriesmusttakeintoaccounttheeffectsofreligiousbeliefs,psychologicalfactors,andeducationallevels. Unit3EnergySourceBasicsEnergyEnergymeansthepowerwhichdoesworkanddrivesmachines.Alllivingthing(includinghumans)relyonthesunasasourceofenergy.Coal,petroleum,andnaturalgasareenergysourcesavailabletodaybecauseorganismsinthepastcapturedsunlightenergyandstoreditincomplexorganicmoleculesthatmadeuptheirbodies,whichwerethencompressedandconcentrated.CoalThegeneraltermcoaldescribesalargerangeofsolidfossilfuelsderivedfrompartialdegradationofplants.Thecharacteristicsofthemajorclassesofcoaldifferentiatelargelybypercentageoffixedcarbon,percentageofvolatilematter,andheatingvalue(coalrank).Chemically,coalisaverycomplexmaterialandisbynomeanspurecarbon.Forexample,achemicalformulaforIllinoisNo.6coal,atypeofbituminouscoal,wouldbesomethinglikeC100H85S2.1N1.5O9.5.PetroleumPetroleummeansamineraloilobtainedfrombelowthesurfaceoftheearth,andusedtoproducevariouschemicalsubstances.Liquidpetroleumisfoundinrockformationsranginginporosityfrom10%to30%.Uptohalfoftheporespaceisoccupiedbywater.Theoilintheseformationsmustflowoverlongdistancestoanapproximately6-inchdiameterwellfromwhichitispumped.Therateofflowdependsonthepermeabilityoftherockformation,theviscosityoftheoil,thedrivingpressurebehindtheoil,andotherfactors.Petroleumasitcomesfromthegroundisnotinafromofsuitableforuse.Itmustberefined.Processingcrudeoiltoprovideusefulproductsgeneratesavarietyofproblems.Alloftheseprocessingactivitiesareopportunitiesforaccidentalorroutinereleasesthatcauseairorwaterpollution.Thepetrochemicalindustryisthemajorcontributortoairpollution.NaturalgasNaturalgas,thethirdmajorsourceoffossil-fuelenergy,consistingalmostentirelyofmethane,hasbecomemoreattractiveasanenergysource.Thisisbecauseofuncertaintiesregardingnaturalgasavailability,coupledwiththepotentialforthediscoveryanddevelopmentoftrulyenormousnewsourcesofthispremiumfuel.Inadditiontoitsuseasafuel,naturalgascanbeconvertedtomanyotherhydrocarbonmaterials.ItcanbeusedasarawmaterialfortheFischer-Tropschsynthesisofgasoline.Thediscoveryanddevelopmentoftrulymassivesourcesofnaturalgascouldprovideabundantenergyreservesforsomecountries,thoughat substantiallyincreasedprices.GeothermalEnergyUndergroundheatintheformofsteam,hotwater,orhotrockusedtoproducesteamisalreadybeingusedasenergyresource.Thisenergywasfirstharnessedforthegenerationofelectricityin1904.Undergrounddrysteamisrelativelyrarebutisthemostdesirablefromthestandpointofpowergeneration.Morecommonly,energyreachesthesurfaceassuperheatedwaterandsteam.Insomecases,thewaterissopurethatitcanbeusedforirrigationandlivestock;inothercases,itisloadedwithcorrosive,scale-formingsalts.Utilizationoftheheatfromcontaminatedgeothermalwatergenerallyrequiresthatthewaterbereinjectedintothehotformationafterheatremovaltopreventcontaminationofsurfacewater.Theutilizationofhotrocksforenergyrequiresfracturingofthehotformation,followedbyinjectionofwaterandwithdrawalofsteam.Thistechnologyisstillintheexperimentalstate,butitpromisestoproduceenergyapproximatelytentimesasmuchasthatproducedbySteamandhotwatersources.NuclearFissionPowerTheawesomepoweroftheatomrevealedattheendofwordⅡheldoutenormouspromisefortheproductionofabundant,cheapenergy.Thispromisehasneverreallycometofruition,althoughnuclearenergycurrentlyprovidesasignificantpercentageofelectricenergyinmanycountries.Nuclearpowerreactorscurrentlyinusedependuponthefissionofuranium-235nucleibyreactionssuchas:toproducetworadioactivefissionproducts,anaverageof2.5neutrons,andanaverageof200MeVofenergyperfission.Theneutrons,initiallyreleasedasfast-moving,highlyenergeticparticles,areslowedtothermalenergiesinamoderatormedium.Forareactoroperatingatasteadystate,exactlyoneoftheneutronproductsfromeachfissionisusedtoinduceanotherfissionreactioninachainreaction.Theenergyfromthesenuclearreactionsisusedtoheatwaterinthereactorcoreandproducesteamtodriveasteamturbine.NuclearFusionPowerThetwomainreactionsbywhichenergycanbeproducedfromthefusionoftwolightnucleiintoaheaviernucleusarethedeuterium-deuteriumreactionandthedeuterium-tritiumreactionThesecondreactionismorefeasiblebecauselessenergyisrequiredtofusethetwonucleithantofusetwodeuteriumnuclei.Thetotalenergyfromdeuterium-tritiumfusionislimitedbytheavailabilityoftritium,whichismadefromnuclearreactionsoflithium-6(naturalabundance,7.4%).Thesupplyofdeuterium,however,isessentiallyunlimited;oneoutofevery6,700atomsofhydrogenisthedeuteriumisotope.The3Heby-productofReaction(1)reactswithneutrons,whichareabundantinanuclearfusionreactor,toproducetritiumrequired forReaction(2).SolarEnergy:AnIdealEnergySourceTherecipeforanidealenergysourcecallsforonethatisunlimitedinsupply,widelyavailable,andinexpensive;itshouldnotaddtotheearth’stotalheatburdenorproducechemicalairandwaterpollutants.Solarenergyfulfillsallofthesecriteria.Solarenergydoesnotaddexcessheattothatwhichmustberadiatedfromtheearth.Onaglobalbasis,utilizationofonlyasmallfractionofsolarenergyreachingtheearthcouldprovideforallenergyneeds.IntheUnitedStates,forexample,withconversionefficienciesrangingfrom10%to30%,itwouldonlyrequirecollectorsranginginareafrom1/10downto1/30thatofthestateofArizonatosatisfypresentU.S.energyneeds.Amajordisadvantageofsolarenergyisitsintermittentnature.However,flexibilityinherentinanelectricpowergridwouldenableittoacceptupto15%ofitstotalpowerinputfromsolarenergyunitswithoutspecialprovisionforenergystorage.Existinghydroelectricfacilitiesmaybeusedforpumped-waterenergystorageinconjunctionwithsolarelectricitygeneration.Hearorcoldcanbestoredinwater,inalatentforminwater(ice)oreutecticsalts,orinbedsofrock.Enormousamountsofheatcanbestoredinwaterasasupercriticalfluidcontainedathightemperaturesandveryhighpressuresdeepunderground.Mechanicalenergycanbestoredwithcompressedairorflywheels.Hydrogengas,H2,isanidealchemicalfuelthatmayserveasastoragemediumforsolarenergy.Electricitygeneratedbysolarmeanscanbeusedtoelectrolyzeasaltsolutioncontainingananionthatisverydifficulttooxidize,sothatoxygenisreleasedattheanodeandhydrogenisproducedatthecathode.ThenetreactionisHydrogen,andevenoxygen,canbepipedsomedistanceandthehydrogenburnedwithoutpollutionorusedinafuelcell.Thismay,infact,makepossiblea“hydrogeneconomy”.Disadvantagesofhydrogenusesasafuelincludethefactthatithasaheatingvalueperunitvolumeofaboutone-thirdthatofnaturalgasandthatitisexplosiveoverawiderangeofmixtureswithair.Noreallyinsurmountablebarriersexisttoblockthedevelopmentofsolarenergy,suchasmightbethecasewithfusionpower.Infact,theinstallationofsolarspaceandwaterheatersbecamewidespreadinthelate1970sandresearchofsolarenergywaswellsupportedintheU.S.untilafter1980,whenitbecamefashionabletobelievethatfreemarketforceshadsolvedthe“energycrisis”.Withtheinstallationofmoreheatingdevicesandtheprobabledevelopmentofsomecheap,directsolarelectricalgeneratingcapacity,itislikelythatduringthecomingcenturysolarenergywillbeprovidinganappreciablepercentageofenergyneedsinareasreceivingabundantsunlight. Unit4ErosionErosionisanimportantnaturalprocess,resultingintheredistributionoftheproductsofgeologicweathering,andispartofbothsoilformationandsoilloss.Theworld’slandscapeshavesculptedbyerosion.Whentheresultsarespectacularenough,weenshrinetheminnationalparksaswedidwiththeGrandCanyon.Whereerosionhasworndownmountainsandspreadsoilovertheplains,ordepositedrichalluvialsiltinriverbottoms,wegladlyfarmit.Erosionisadisasteronlywhenitoccursinthewrongplaceatthewrongtime.Insomeplace,erosionoccurssorapidlythatanyonecanseeithappen.Deepgulliesarecreatedwherewaterscoursawaythesoil,leavingfencepostsandtreessittingontallpedestalsasthelanderodesawayaroundthem.Inmostplaces,however,erosionissubtler.Itisacreepingdisasterthatoccursinsmallincrements.Athinlayeroftopsoiliswashedofffieldsyearafteryearuntileventuallynothingisleftbutpoor-qualitysubsoilthatrequiresmoreandmorefertilizerandwatertoproduceranycropatall.Theneteffect,worldwide,ofthisgeneral,widespreadtopsoilerosionisareductionincropproductionequivalenttoremovingabout1%ofworldcroplandeachyear.Manyfarmersareabletocompensateforthislossbyapplyingmorefertilizerandbybringnewlandintocultivation.Continuationofcurrenterosionrates,however,couldreduceagriculturalproduction25%inCentralAmericaandAfricaand20%inSouthAmericabytheyear2000.Thetotalannualsoillossfromcroplandsisthoughttobe25billionmetrictons.Abouttwicethatmuchsoilislostfromrangelands.forest,andurbanconstructionsiteseachyear.Inadditiontoreducedlandfertility,thiserosionresultsinsediment-loadingofriversandlakes,ofreservoirs,somethingofwetlandsandcoralreefs,andcloggingofwaterintakesandwaterpowerturbines.Itmakesriversunnavigable,increasesthedestructivenessandfrequencyoffloods,andcausegulliesthatturnsgoodlandsintouselesswastelands.Windandwaterarethemainagentsthatmovesoilaround.Thin,uniformlayersofsoilarepeeledoffthelandsurfaceinaprocesscalledsheeterosion.Whenlittlerivuletsofrunningwatergathertogetherandcutsmallchannelsinthesoil,theprocessiscalledrillerosion.Whenrillenlargetoformbiggerchannelsorravinesthattoolargetoberemovedbynormaltillageoperations,wecalltheprocessgullyerosion.Streambankerosionreferstothewashingawayofsoilfromthebanksofestablishedstream,creeks,orriversoftenasaresultofre-movingtreesandbrushalongstreambanksandbycattledamagetothebanks.Mostsoilerosiononagriculturallandissheetandrillerosion.Largeamountsofsoilcanbetransportedbythesemechanismswithoutbeingverynoticeable.Afarmfiledcanlose20metrictonsofsoilperhectareduringwinterandspringforrunoffinrillssosmallthattheyareoverthewholesurfacetothefield,hardlyapparenttoanybutmostdiscerningeye.Butitdoesn’ttakemuchmathematicalskilltoseethatifyoulosesoiltwiceasfastasitisbeingre-placed,eventuallyitwill runout.Windcanequalorexceedwaterinerosionforce,especiallyinadryclimateandonrelativelyflatland.Whenplantcoverandsurfacelitterareremovedfromthelandbyagricultureorgrazing,windliftsloosesoilparticlesandsweepsthemaway.Windbornedustissometimestransportedfromonecontinenttoanother.ScientistsinHawaiicantellwhenspringplowingbeginsinChinabecausedustfromChinesefarmlandiscarriedbywindsallthewayacrossthePacificOcean.Similarly,summerduststormsintheSaharaDesertofNorthAfricacreateahazyatmosphereoverislandintheCaribbeanSea,5,000kmaway.IthasbeenestimatedthatwindsblowingovertheMississippiRiverhaveonethousandtimesthesoil-carryingcapacityoftheriveritself.Althoughdataonsoilconditionandsoilerosionintheworldarenotcompleteanddifficulttoaccess,itisevidentthatmanyplaceshaveverysevereproblems.China,forexample,hasalargeareaofloess(windblownsilt)depositsdepositionontheNorthChinaPlainthatoncewascoveredbyforestandgrassland.Theforestswerecutdownandthegrasslandswereconvertedtocropland.Thisplateauisnowscarredbygullies30-40mdeep,andthesoillossisthoughttobeatleast480metrictonsperhectareperyear.Onewaytoestimatesoillossistomeasurethesedimentloadcarriedbyriversdraininganarea.ThehighestconcentrationofsedimentinanyriverisintheHuangHeRiverthatoriginatesintheloessplateauofChina.Althoughitsdrainagebasinisonlyone-fifthasbigasthatoftheMississippiRiver,theHuangHeRivercarriesmorethanfourtimesasmuchsoileachyear.ThissuggestthattheaveragesoillossperhectareinChinamaybetwentytimesthatintheUnitedStates.Initsmiddlereaches,theHuangHeRivercarriesabout700kgofsiltpercubicofwater,or50%byweight–justunderthelevelclassifiedasliquidmud.AstheriverwindsthroughnorthernChina,muchofthissedimentsettlesout,raisingtheriverbottomabovethelevelofthesurroundingcountryside.OnlybybuildingdikestocontaintheriverhavetheChinesebeenabletokeepitinitscourse.Insomeplaces,theriverbedisnow10mabovethefarmlandthoughwhichitflows.Ifthedikesgivewayduringthesummerriceseason,mil-lionsofpeoplewouldstarvetodeathasaresultoflostcrops.NextaftertheHuangHeRiverinannualsedimentloadistheGangerRiver,whichcarries1455millionmetrictonsofmudtobeBayofBengaleveryyear.MuchofthissedimentcomesfromthehillcountryofnorthernIndia,NepalandBangladesh.Populationpressuresandpreemptionofgoodbottomlandsforcashcropproductionhavefarmerstotrytogrowcropsonsteep,unstableslopes.Fuelwoodshortagesalsocauselocalpeopletocutdowntheforeststhatstabilizemountainsoils.Whenthemonsoonrainscome,theywashwholehill-sidesaway,destroyingvillagersandfarmlandbelow.Perhapstheworsterosionproblemintheworld,perhectareoffarmland,isinEthiopia.AlthoughEthiopiahasonly1/100asmuchcroplandincultivationastheUnitedStates,itisthoughtolose2billionmetrictonsofsoileachyeartoerosion.Thishighrateoferosionisbothacauseandconsequentoffamine,poverty, andcontinuedsocialunrestinthatcountry.Haitiisanothercountrywithseverelydegradedsoil.Oncecoveredwithlushtropicalforest,thelandhasbeendenudedforfirewoodandcropland.Erosionhasbeensobadthatsomeexpertsnowsaythecountryhasabsolutelynotopsoilleft,andpeasantfarmershavedifficultyraisinganycropsatall. Unit5BiodiversityAfterbillionsofyearsofevolution,earthishometoalargearrayoflifeformsandecosystems.Concernfornon-humanlifeformsgoesbackinhistoryandacrossmanycultures.However,thelevelandnatureofconcernfortheselifeformschangesovertime,reflectingourunderstandingofthenatureandimportanceofthislegacy,thevaluesweascribetoit,thethreatsitisunderandwhatmightbedonetoconserveit.DefiningbiodiversityTheevolutionarylegacyoflifeonearthisnowdescribedbytheterm“biodiversity”,butthistermhascomeintowideuseonlyrecently.Itreferstothevarietyoflifeofearth-plants,animalsandmicroorganisms,aswellasthevarietyofgeneticmaterialtheycontainandoftheecologicalsystemsinwhichtheyoccur.Itisasimpleconcept,butonewhichalsohasgreatcomplexityandsignificance.Biodiversitywasdefinedas:thevariabilityamonglivingorganismsfromallsourcesincluding,interalia,terrestrial,marineandotheraquaticecosystemsandtheecologicalcomplexesofwhichtheyareapart;thisincludesdiversitywithinspecies,betweenspeciesandofecosystems.Thisdefinitionwasexpandsonthethreelevelsatwhichbiodiversityoccurs.Theselevelsofbiodiversityare:·genetic:thevarietyofgeneticinformationcontainedinalloftheindividualplants,animalsandmicroorganismsthatinhabittheearth-geneticdiversityoccurswithinandbetweenthepopulationsoforganismsthatcompriseindividualspeciesaswellasamongspecies.·species:thevarietyofspeciesonearth.·ecosystems:thevarietyofhabitats,bioticcommunitiesandecologicalprocesses.Thesethreelevelsofdiversityareinterrelatedandinterdependent(e.g.apopulationofaspeciesisthoroughlydependentonitshabitatforsurvival,andafunctioningecosystemisdependentonthecomplexofspeciesthatcomprisesit.)ValuesassociatedwithbiodiversityThefollowingcategoriessummariesthedifferentvaluespeopleandsocietyplaceonbiodiversity:DirectutilitarianvalueBiodiversityisconsumedbyhumansasfoodandisusedtofeedstock.Itprovidesmaterialssuchastimberandfibre,medicines,chemicalsandgeneticmaterial.IndirectutilitarianvaluesIndirectutilitarianvaluesincludethemaintenanceof“ecosystemservices”orimportantecologicalprocesses.Examplesincludemaintainingwaterqualityincatchments,maintainingcoastalfunction,assimilatingorremovingwastesfromwaterorsoil,maintainingevolutionarypotentialinecosystems,sequesteringcarbonemissions,cyclingofnutrients,pestcontrol,andpollinationofcrops.Aestheticandrecreationalvalues Biodiversityhasaestheticandrecreationalusesforhumans,bothintheformofspecifictaxasuchasflowers,birds,treesorwhales,andascomponentsofnaturalorsemi-naturallandscapessuchastheGreatBarrierReefandthewetlandsofKakaduNationalPark.ScientificandeducationalvaluesScientificdiscoverycanleadtothedevelopmentofutilitarianvalues.Itwilloftenbethroughscientificresearch,otherformsofinvestigationandlearningaboutcommunityorindigenousknowledgethatsuchuseswillberecognized.Also,thevarietyoflifeisofeducationalvalueacrossawidevarietyofsubjectsanddisciplines(e.g.biology,biochemistry,ecology,geneticsandagronomy.)Intrinsic,spiritualandethicalvaluesVariousculturalandreligioussystems(e.g.AboriginalandTorresStraitIslanderpeople)placevalueoncomponentsofbiodiversity.Also,thereistheethicalpositionthatnon-humanformsoflifehaveintrinsicvalueandarighttoexistindependentofanyusetohumans.Futureor“option”valuesForalloftheabovevaluesthereistheaddeddimensionofkeepingoptionsopenforthefuture.Weareuncertainastothatspeciesandpopulationsarecrucialtoecosystemservices,ortheactualsignificanceofsomeoftheseservices.Similarly,theremaybeusesforspeciesorgeneticdiversityyettobediscovered,suchasforfoodormedicine.And,ifthevaluesheldinsocietychangeastheyhaveinthepast,thenwhatisviewedasunimportantnowmaybemorehighlyvaluedinthefuture.ProtectingbiodiversityTheuseofthetermbiodiversitygrewoutofaconcernthateffortswereneededtoconserve,notjustparticularlycharismaticanimals,butthediversityoflifearoundtheworld,includingmanyplantsandanimalsthatwillnevergrace-local,national,andinternational-tobalancetheneedsofhumanpopulationswiththeprotectionofendangeredandthreatenedspecies.Thebasicunitofbiodiversityisaspecies.Howmanyspeciesarethere?Nooneknows,noteven“tothenearestorderofmagnitude”.Oneofthefirstchallengesfacedbyconservationistsistoanswerthisquestion.Thisisanenormousundertaking,becausetherearevastareasoftheplanetthatareonlynowbeginningtobestudied.Areassuchasthebottomofthehaverevealedthemtobefulloflife.Newspeciesarebeingdiscoveredallthetome.Theblank-facedliontamarin,anewmonkeyinGabon,amuntjakdeerinVietnam,andapigmybeakedwhalehaveallbeendiscoveredinjustthelastdecade.TheWashingtonPostrecentlyreportedthediscoveryofatinynewmonkeyinBrazil,a“squirrel-sizedmarmoset”.Themajorthreattobiodiversitystemsformlanduse.About1%to2%percentoftheEarth’ssurfaceisdevotedtourbanuse,butmodificationsofsurfaceareaaremoreextensiveLandacquisitionforagricultureandforestproductshasintensifiedinmanydevelopingcountries,whichareexperiencingrapidpopulationgrowth.Introductionofspeciesintonewareas,eitherbyaccidentorintention,isasecondmajorcauseofthreatstospecies. Therearevaryingopinionsaboutthebestapproachtoprotectingbiodiversity.Inpastdecades,conservationefforts(andfunding)havebeenfocuseddisproportionatelyonindividualendangeredspecies,particularlymammals,butthisiscostlyandconcernshavebeenraisedabouttheadequacyofaspecies-by-speciesapproach.Toprovideprotection,wildlifepreservesandwildernessareashavebeensetasideinsomecountries.However,thisapproachhasbeencriticizedasinsufficientorineffective,particularlyindevelopingcountriesinwhichthepopulationisheavilydependentuponnaturalresourcesforsurvival.Ecotourismandbioprospecting(derivingmedicinesandotherproductsfromnaturalresources)arestrategiestohelpthesepopulationsextractproductsandvaluefromexistingforest,butquestionshavebeenraisedabouttheeffectivenessoftheseefforts. Unit6OzoneLayerDepletionOzoneisaformofoxygeninwhichthreeoxygenatomsjointogethertoformamoleculeofozone(O3).Itisformedbytheactionofsunlightonmoleculesofordinaryoxygeninthestratosphere.Ozoneisanirritating,corrosive,colorlessgaswithasmellsomethinglikeburningelectricalwiring.Itismainlyscatteredinalayerwhereover90%oftheearth’sozoneresidesataltitudesbetweenabout10and30kmabovetheearth’ssurface.Aswellasemittingvisiblelight,thesunalsoemitsshort-wavelengthultravioletradiation.theozonelayerabsorbstheshorter,morehazardous,ultravioletwavelengthsandhencekeeps95%--99%ofthesunsultravioletradiationfromstrikingtheearth.AnumberofconsequencescanresultfromincreasedlevelsofUV(ultravioletradiation)strikingtheearth,including:geneticdamage,eyedamageanddamagetomarinelife.Thisshort-wavelengthultravioletradiationcanaffecthumanhealthbycausingskincancerandaffectingtheimmunesystem.Italsocontributestovarioustypesofdamagetotheeyes(e.g.keratitisorsnowblindness,andvariousopacitiesonandwiththeeyes,includingpinguecula,andcataract).However,theozonelayerisbeingdamaged.Thedecreaseofstratosphericozonewasfirstreportedin1974andthedecreasewasquicklylinkedtotheincreasingpresenceofaclassofmanmadecompoundscalledCFCsorChlorofluorocarbons.CFCsareafamilyofnon-reactive,non-flammablegasesofandvolatileliquids.Becauseoftheirpropertiestheyareusedinamultitudeofapplications.Thenon-reactivityofCFCs,sodesirabletoindustry,allowsthemtodriftforyearsintheenvironmentuntiltheyeventuallyreachthestratosphere.HighinthestratosphereintenseUVsolarradiationseverschlorinesoffoftheCFCs,anditistheseunattachedchlorinesthatareabletocatalyticallyconvertozonemoleculesintooxygenmolecules:CL+O3---------CLO+O2CL+O3---------2O2+CLThetern“catalyst”isappliedtocompoundswhichcanbeusedrepeatedlyinareactionwithoutbeingconsumed.Thismeansthatasmallamountofcatalystcanbreakdownaverylargeamountofozoneintooxygenbeforethatchlorinebecomespartofalessreactivecompound,suchasHCL,andeventuallyisprecipitatedoutofthestratospherebywatervapor.In1985,theBritishAntarcticAtmosphericSurveyannouncedastartlinganddisturbingdiscovery：ozonelevelsinthestratosphereovertheSouthPoleweredroppingprecipitouslyduringSeptemberandOctobereveryyearasthereappearsattheendofthelongpolarwinter.Thisozonedepletionhasbeenoccurringatleastsincethe1960sbutwasnotrecognizedbecauseearlierresearchersprogrammedtheir instrumentstoignorechangesinozonelevelsthatwerepresumedtobeerroneous.Eachyeartheozone“hole”hasgrownlarger.In1993,asmuchas70%oftheAntarcticstratosphericozonewasdestroyedoveranareaaboutthesizeofNorthAmerica.Ominously,thisphenomenonisnowspreadingtootherpartsoftheworld.About10%ofallstratosphericozoneworldwidewasdestroyedduringthewinterof1993andlossesovernorthernCanadaandSiberiasometimesexceeded25%.Thismeansthatmuchmoreshort-wavelengthultravioletreachingtheground.Currently,littleevidenceshowsthatultravioletlevelshaveincreasedinEuropeandothernon-polarregions,althoughthesituationisbeingcarefullymonitoredtomakesurethisdoesnotoccur.Scientistssaidthatitisverydifficulttopredictexactlywhatwillhappenandaverycarefulworldwidewatchisbeingkeptonlevelsofbothozoneandultravioletsothatanyworseningoftheproblemcanrapidlybeidentified. Unit7AcidRainAcidChemicalcompoundcontaininghydrogen,whichdissolvesinwaterandfirmshydrogenorreactswithanalkalitoformasaltandwater,andturnslitmuspaperred.InorganicacidsAcidswhicharederivedformminerals,suchashydrochloricacidandsulphuricacid.OrganicacidsWeakacidswhichcontainscarbon,someofwhicharepesticides.AcidificationProcessofbecomingacidorofmakingasubstancemoreacid.AcidificationofthesoilleadstothedestructionofsomelivingorganismsAcidityLevelofacidinasolution.Acidificationofthesoilleadstothedestructionofsomelivingorganisms.AcidityLevelofacidinasolution.AcidityandalkalinityawemeasureaccordingtothePHscale.Thesolution7PHisneutral,above7PHalkalic,andbelow7phacid.Acid-proofAbletoresisttheeffectofacid.AcidicpropertiesPropertiesassociatedwithacids.AcidicwaterWaterwhichcontainsacid.AcidrainAcidrain(aciddeposition,acidprecipitation):rainorsnowwhichcontainsahigherlevelofacidthannormal.Acidrainismainlycausedbysulphurdioxide,nitrogenoxideandotherpollutantswhicharereleasedintotheatmospherewhenfossilfuels(suchasoilorcoal)containingsulphurareburnt.Acidrainrarelyfallsnearthesourceof thepollution,becausethesmokefromchimneyscanbecarriedbyraincurrentsformanykilometersbeforeitfinallyfallsasrain.SoScandinaviareceivesacidrainwhichiscausedbypollutionfromBritishandGermanfactories;CanadareceivesacidrainfromfactoriesintheU.S.Acidsoot,ontheotherhand,canfallrelativelyclosetothesourceofpollution.Itiscausedwhencarboncombineswithsulphurtrioxidefromsulphur-richfueltofromparticlesofanacidsubstancewhichcandamagethesurfacesitfallson(suchasstonebuildings).Theeffectsofacidrainareprimarilyfeltbywildlife.Thewaterinlakesbecomesveryclearanfishandmicroscopicanimallifearekilled.Itisbelievedthatitisacidrainthatkillstrees,especiallyconifers,whichgraduallylosetheiranddie.PollutantsTransportationofAcidRainThetransportedairpollutantsconsideredinthisstudyresultfromtheemissionofthreeprimarypollutants:sulfurdioxide,nitrogenoxides,andhydrocarbons.Asthesepollutantsarecarriedawayfromtheirsources,theycanbetransformedthroughcomplexchemicalprocessesintosecondarypollutants:ozoneandairbornefineparticlessuchassulfate.AciddepositionresultswhensulfurandnitrogenoxidesandtheirtransformationproductsreturnfromtheatmospheretotheEarth’ssurface.Elevatedlevelsofozoneareproducedthroughthechemicalinteractionofnitrogenoxidesandhydrocarbons.Numerouschemicalreactionsandprevailingweatherpatternsaffecttheoveralldistributionofaciddepositionandozoneconcentrations.During1980some27milliontonsofsulfurdioxideand21milliontonsofnitrogenoxidewereemittedintheUniteStates.Since1940,sulfurdioxideemissionshaveincreasedbyabout50%andnitrogenoxidesemissionsabouttripled.Futureemissionswilldependonsuchasthedemandforenergy,thetypeofenergy,thetypeofenergyused,andtherateatwhichexistingsourcesofpollutionarereplacedbynewer,cleanerfacilities.By2030mostexistingfacilitieswillhavebeenretired.DespiterelativelystrictpollutioncontrolsmandatedfornewsourcesbytheCleanAirAct,emissionsofbothsulfurandnitrogenoxidesarelikelytoremainhighforatleastthenexthalfcentury.ThepollutantsresponsibleforaciddepositioncanreturntoEarthinrain,snow,fog,ordeworasdryparticlesandgases.AveragedovertheEasternUnitedStates,aboutequalamountsofsulfurcompoundsaredepositedinwetanddryforms.PollutantsemittedintotheatmospherecanreturntoEarthalmostimmediatelyorremainaloftforlongerthanaweek,dependingonweatherpatternsandthepollutants’chemicalinteractions.Duringthistimetheymovewithprevailingwinds,whichintheEasternUnitedStatestendtomovefromwesttoeastandfromsouthtonorth.Preliminaryanalysessuggestthataboutone-thirdofthetotalamountofsulfurcom-poundsdepositedovertheEasternUnitedStatesasawholeoriginatesfromsourcesover500kmawayfromtheregioninwhichtheyaredeposited.Anotherone-thirdcomesfromsourcesbetween200and500kmaway,andtheremainingone-thirdcomesfromsource Unit8EnvironmentalPollution“Webelieveallcitizenshaveaninherentrighttotheenjoymentofpureanduncontaminataminatedairandwaterandsoil;thatthisrightshouldberegardedasbelongingtothewholecommunity;andthatnaoneshouldbeallowedtotrespassuponitbyhiscarelessnessorhisavariceorevenhisignorance.”Thisresolution,adoptedin1869bytheMassachusettsBoardofHealth,istheidealofpollutioncontrol.Overahundredyearsago,therefore,pollutionwasalreadyrecognizedasevil,andthisresolutionwasanattempttodefinetheproblem.Unfortunately,thisdefinitionisonlyanideal,sincetotaleliminationofpollutionwouldeffectivelyrequiretheeliminationofmoderncivilization,Thedefinitionofpollutionmustthereforebemorerealisticifittobeofpracticalvalue.Itisimportanttounderstandthatpollutioncanbedefinedinmanyways,andthespecificdefinitionusedinaspecificcasecanbeimportant.Forexample,ifanindustryspewingforthcontaminantstowaterandaircanconvincethepublicandtheregulatoryagenciesthatbytheirdefinitiontheyarenotpolluting,pressuretoforcethemtocleanupmightnevermaterialize,eventhoughtheresuleoftheinadequatewastedisposalareobvious.Manyprofessionsaredirectlyinvolvedinenvironmentalpollution,andallhavedefinedpollutiontofitthespecificneed.Itmaybeinstructivetoreviewofthesedefinition,andcommentontherationaleemployed.Theecologist,trainedtoperceivelifethrougawide-anglelens,looksatpollutionassomethingwhichupsetstheequilibriumofasystem.Typically,waterpollutionisdefinedas“anythingwhichbringsaboutareductioninthediversityofaquaticlifeandeventuallydestroysthebalanceoflife,”or“anyinfluenceonthestreambroughtaboutbytheitroductionofmaterialstoitwhichadverselyaffectstheorganismslivingintheatream.”Thesedefinitionshavevaluetoecologiststoecologistssinceecologistsaremoreconcernedwiththeeffectofoutsideforce(people)onastreamorlakethatwiththedirectbenefitsthewatercoursemighthavetoman.Thisisnottoinanywaybelittlethisapproachsince,inthelongrun,ifwecannotadjustourcivilizationtobecompatiblewiththeecosystem,wewillundoubtedlylosetheconflict.Incontrasttotheecologistswhoconsideranymanmadeadditionswhicharenotecologicallycompatibletotheexistingenvironmenttobepollution,theengineersconsidertheseadditionstobepollutiononlyifandwhentheyprecipitateanimmediateadverseeffect.Engineerspridethemselvesonbeingrealists,abletoanalyzeproblemsandpresentcleanandneatsolutions.Engineershavethusproposeddefinitionsofpollutionwhichare,tothem,morerationalthanthe“cleanaspossible”approachsuggestedinthefirstparagraphorthe“onchange”thinkingofmanyecologists.Alloftheengineeringdefinitionshaveasacorethewell-being(economic,physical,social)ofhumans.Forexample,someengineerssuggestthatsincepollutioncontrolcostsmoney, thebenefitsderivedfromacleanstream(oratmosphere)mustbeweighedagainstthebenefitsderivedbyspendingthemoneyonhospitals,roads,etc.Theimplicationisthatpollutionisnotbadintheabsolute,butthataslongaswedon’tstartkillingmorepeoplebycholera,typhoid,emphysema,etc.thatwedoonthehighways,itislogicalandprudenttobuildbetterhighwaysandneglectpollutioncontrol.Otherengineersdefinepollutionas“animparirmentofthesuitabilityofwater(ofair)foranyofitsbeneficialuses,actualorpotential,byman-causedchangesinquality.”Againthebenefitstohumansareemphasized,andpollutialcontrolisdependentonafavorablebenefit/costraito.TheEngineersJointCouncil(composedofrepresentativesfromthevariousprofessionalengineeringassociations)hasdefinedairpollutionas“thepresenceintheoutdooratmosphereofoneormorecontaminants,suchasdust,fumes,gas,mist,odor,smokeorvapor,inquantitiesorcharacteristics,andordurationsuchastobeinjurioustohuman,plantoranimallifeortoproperty,orwhichunreasonablyinterfereswiththecomfortableenjoymentoflifeandproperty.”Althoughthislongwindeddefinitionseemstocoverallbases,itavoidsclassifyingemissionsfromremotelyhavingthepowertoruntheairconditionersandelectriccanopenersenhancesman’scomfort.Whatismissingisanadmissionthatairisnotawastebasket,andthatadefenseofsuchemissionisuntenable,regardless,oftheirunmeasurableacuteeffectonplantoranimalphysiology.Probablythemostwidelyacceptedoftheengineeringdefinitionsofpollutionis“unreasinableinterferencewithotherbeneficialuses.”Bythisdefinition,ifthegreatestbeneficialuseofawatercourseiswastedischarge,thentheuseofthestreamforawimmingandfishingmighebe“unreasonable.”Valuejudgmentsarethereforerequiredastowhatusesastream,lake,orairoveracitymighthave.Ifreasonablemendecidethatitisreasonabletousealakeasasepticethankandairaswastebasket,thenwearedoomedtosucha“reasonable”existence.Inallfairness,however,itmustbenotedthatthiatypeofthinkingischanging:Engineersarebecomingmoreawareoftheirsocialresponsibities,andveryfewwillstillespousetheuseofastreamasanopensewerevenifthismightbethemosteconomicallysoundbeneficialuse.TheWorldHealthOrganization(WHO)thinksofairpollutionasanything“harmfultohumans,animals,plantsorproperty.”TheWHOmosquitocontrolprogramsusingDDTsprayedfromairplaneswouldqualifyasairpollutionunderthisdefinition.Otherarhuethatpollutionoccurswhenanadditionaluserofascarceresource“willcauseotherstohavetoincuradditionalcostsorsufferdisutilityassociatedwithcongestion.”Althougheconomicallysoundintheclassicsense,thisconceptviewsairquality,forexample,allbeingacceptableuntilsomedetrimentaleffectisnoted,anargumentwhichpresupposethatalleffectsofpollutionareknown,ablatantlyfalsesupposition.Further,theblottingoutofasunsetwithsmokecannotbecalculatedindollarsandcents.Wecouldgoonquotingdefinitionsofenvironmentalpollution,butthepointhasbeenmade.Noteveryoneviewsenvironmentalpollutioninthesamelight,andnoteveryoneagreesontheshortaswellaslong-termeffects.Itshouldbeclear, therefore,whysomepeoplefeelthatthepollutionproblemisnottakenseriouslyenough,andwhyatthesametimeothersfeelthatgovernmentalagencieshavebecometoostrictwithregardtothecontrolofindustrialandmunicipaldischarges.Perhapswecannotdefinepollutiontoeveryone’ssatisfaction,andprobablythereisnoneedtodothataslongaswerememberthattherearemanydefinitions(andhenceopinions)ofenvironmentalpollution.Earlymanspenthisentireexistencesurviving.Theprocurementoffoodandshelterforthefamilytookallofhiatime.Whenfarmingsndhuntingadvancedtothepointwherenotalloftheavailable,orpotters,orpoliticians.Withincreasedspecialization,manbegantobetterhialifestyle.Thishadtwoeffects:thepopulationandthepercapitaconsumptionofgoodsbothincreased.Untilthe16thcentury,manwasstillnotveryproficientinproducingfoodorcontrollingdisease,sndfaminesandplaguesheldthepopulationwithinbounds.Butwiththeindustrialrevolutionandthebirthofmodemmedicine,theworldpopulationbegantoclimbwildly.Theearthisnowcrowdedwithpeople,andallofthemconsumeresoures,andcreatewaste.Thewastemustbereturnedtotheearthinsomefrom,andthisprocessdestroysoralterstheecology.Overpopulationisnot,however,theonlydanger.Ineconmicallydevelopedcountries,consumptionofbothmanufacturedandnaturalresourceshasincreasedtremendouslywithinthelastfewdecades.Infact,theproblemwithpollutioninmanycountriestodayismainlythatofover-consumption,whilepopulationgrowthisresponsibleforonlyaboutonetenthoftheincreaseintheuseofnaturalresources(andtherelstedpollution).Theconsumptionspiralseemstohavenoned,exceptwhenwefinallyrunoutofresources.Thisisclearlyunacceptable.Onesolutionistodrasticallyalterourhabitsasconsumers.Aslongasthereisnotaxontheuseofnaturalresources(thereisinfactarewardforusingsame,suchastheoildepletionallowance),theeducationofconsumersisareasonablealternative.Unfortunately,thisrunscountertohumannature,andtheprognosticationisnotgood.Itissafetostatethattheroofofourenvironmentalpollutionproblemsisthetremendousleapinhumanpopulation,accompaniedofrawmatweials.Althoughenvironmentalpollutionisdifficulttodefine,wedoknowthatwqperilouslyclosetopermanentlyspoilingourhome.Wemustimmediatelycontrolpopulationgrowthandstriveeithertolimitconsumptionordevelopbettermeansofrecyclingourresources.Wecanonlyhopethatpeopleoftheworldwillsoonembracetheecvironmentalethic,beforewepermanentlyfoulupourspaceship. Unit9TheworldasIseeitHowstrangeisthelotofusmortals!Eachofusishereforabriefsojourn;forwhatpurposeheknowsnot,thoughhesometimesthinkshesensesit.Butwithoutdeeperreflectiononeknowsfromdailylifethatoneexistsforotherpeople--firstofallforthoseuponwhosesmilesandwell-beingourownhappinessiswhollydependent,andthenforthemany,unknowntous,towhosedestiniesweareboundbythetiesofsympathy.AhundredtimeseverydayIremindmyselfthatmyinnerandouterlifearebasedonthelaborsofothermen,livinganddead,andthatImustexertmyselfinordertogiveinthesamemeasureasIhavereceivedandamstillreceiving.IamstronglydrawmtoafrugallifeandamoftenoppressivelyawarethatIamengrossinganundueamountoftheloborofmyfellow-man.Ialsobelievethatasimpleandunassuminglifeisgoodforeverybody,physicallyandmentally.Idonotatallbelieveinhumanfreedominthephilosophicalsense.Everybodyactsnotonlyunderexternalcompulsionbutalsoinaccordancewithinnernecessity.Schopenhauer’ssaying,“Amancandowhathewants,butnotwantwhathewants,”hasbeenaveryrealinspirationtomesincemyyouth;ithasbeenacontinualconsolationinthefaceoflife’shardships,myownandothers’,andanunfailingwell-springoftolerance.Thisrealizationmercifullymitigatestheeasilyparalyzingsenseofresponsibilityandpreventsusfromtakingourselvesandotherpeoplealltooseriously;itisconductivetoaviewoflifewhich,inparticular,giveshumoritsdue.Toinquireafterthemeaningorobjectofone’sownexistenceorthatofallcreatureshasalwaysseemedtomeabsurdfromanobjectivepointofview.Andyeteverybodyhascertainidealswhichdeterminethedirectionofhisendeavorsandhisjudgment.InthissenseIhaveneverlookeduponeaseandhappinessasendsinthemselves--thisethicalbasisIcalltheidealofapigsty.Theidealswhichhavelightedmyway,andtimeaftertimehavegivenmenewcouragetofacelifecheerfully,havebeenKindness,Beauty,andTruth.Withoutthesenseofkinshipwithmenoflikemind,withouttheoccupationwiththeobjectiveworld,theeternallyunattainableinthefieldofartandscientificendeavors,lifewouldhaveseemedtomeempty.Thetriteobjectsofhumanefforts--possessions,outwardsuccess,luxury--havealwaysseemedtomecontemptible. Mypassionatesenseofsocialjusticeandsocialresponsibilityhasalwayscontrastedoddlywithmypronouncedlackofneedfordirectcontactwithotherhumanbeingsandhumancommunities.Iamtrulya“lonetraveler”andhaveneverbelongedtomycountry,myhome,myfriends,orevenmyimmediatefamily,withmywholeheart;inthefaceofalltheseties,Ihaveneverlostasenseofdistanceandaneedforsolitude-feelingswhichincreasewiththeyears.Onebecomessharplyaware,butwithoutregret,ofthelimitsofmutualunderstandingandconsonancewithotherpeople.Nodoubt,suchapersonlosessomeofhisinnocenceandunconcern;ontheotherhand,heislargelyindependentoftheopinions,habits,andjudgmentsofhisfellowsandavoidsthetemptationtobuildhisinnerequilibriumuponsuchinsecurefoundations.Mypoliticalidealisdemocracy.Leteverymanberespectedasanindividualandnomanidolized.ItisanironyoffatethatImyselfhavebeentherecipientofexcessiveadmirationandreverencefrommyfellow-beings,throughnofault,andnomerit,ofmyown.Thecauseofthismaywellbethedesire,unattainableformany,tounderstandthefewideastowhichIhavewithmyfeeblepowersattainedthroughceaselessstruggle.Iamquiteawarethatitisnecessaryfortheachievementoftheobjectiveofanorganizationthatonemanshoulddothethinkinganddirectingandgenerallybeartheresponsibility.Buttheledmustnotbecoerced,theymustbeabletochoosetheirleader.Anautocraticsystemofcoercion,inmyopinion,soondegenerates.Forforcealwaysattractsmenoflowmorality,andIbeliveittobeaninvariablerulethattyrantsofgeniusaresucceededbyscoundrels.Thistopicbringsmetothatworstoutcropofherdlife,themilitarysystem,whichIabhor.Thatamancantakepleasureinmarchinginfourstothestrainsofabandisenoughtomakemedespisehim.Hehasonlybeengivenhisbigbrainbymistake;unprotectedspinalmarrowwasallheneeded.Thisplaguespotofcivilizationoughttobeabolishedwithallpossiblespeed.Heroismoncommand,senselessviolence,andalltheloathsomenonsensethatgoesbythenameofpatriotism--howpassionatelyIhatethem!Howvileanddespicableseemswartome!Iwouldratherbehackedinpiecesthantakepartinsuchanabominablebusiness.MyopinionofthehumanraceishighenoughthatIbelievethisbogeywouldhavedisappearedlongago,hadthesoundsenseofthepeoplesnotbeensystematicallycorruptedbycommercialandpoliticalinterestsactingthroughtheschoolsandthePress. Themostbeautifulexperiencewecanhaveisthemysterious.Itisthefundamentalemotionwhichstandsatthecradleoftrueartandtruescience.Whoeverdoesnotknowitandcannolongerwonder,nolongermarvel,isasgoodasdead,andhiseyesaredimmed.Itwastheexperienceofmystery--evenifmixedwithfear--thatengenderedreligion.Aknowledgeoftheexistenceofsomethingwecannotpenetrate,ourperceptionsoftheprofoundestreasonandthemostradiantbeauty,whichonlyintheirmostprimitiveformsareaccessibletoourminds--itisthisknowledgeandthisemotionthatconstitutetruereligiosity;inthissenseandinthisalone,Iamadeeplyreligiousman.IcannotconceiveofaGodwhorewardsandpunisheshiscreatures,orhasawillofthekindthatweexperienceinourselves.NeithercanInorwouldIwanttoconceiveofanindividualthatsurviveshisphysicaldeath;letfeeblesouls,fromfearorabsurdegoism,cherishsuchthoughts.Iamsatisfiedwiththemysteryoftheeternityoflifeandwiththeawarenessandaglimpseofthemarvelousstructureoftheexitingworld,togetherwiththedevotedstrivingtocomprehendaportion,beiteversotiny,ofthereasonthatmanifestsitselfinnature. Unit10HistoricalBasisofPollution1.Atonetime,ahumanwasjustanotherconsumersomewhereinthefoodchain.Humanfellpreytopredatorsanddiedasaresultofdiseaseandaccidentjustlikeothereanimals.Thetoolstheyusedwereprimitive,sothesepeopledidnothavealong-termeffectontheirsurroundings.Theyonlyminimallyexploitedmineralandenergyresources.Theyminedchert,obsidian,andrawcopperforthemanufactureoftools,andusedcertainothermineralmatertals,suchassalt,clay,andother,asnutrients,formakingpots,oraspigments.Asidefromoccasionaluseofsurfaceseamsofcoalorsurfaceoilseeps,earlyhumansmetmostoftheirenergyneedsbymusclepowerortheburningofbiomass.2.Ashumanpopulationsgrew,andastheirtoolsandmethodsofusingthembecamemoreadvanced,theimpactthatasinglehumancouldhaveonhisorhersurroundingsincreasedtremendously.Thepurposefuluseoffirewasoneofthefirsteventsthatmarkedthecapabilityofhumanstochangeecosystems.Althoughinmanyecosystemsfireswerenaturalevents,theuseoffirebyhumanstocapturegameandtoclearlandforgardenscoulddestroyclimaxcommunitiesandreturntnemtoearliersuccessionalstagesmorefrequentlythannormal.3.Astechnologyadvanced,woodwasneededforfuelandbuildingmaterials,landwasclearedforfarming,streamsweredammedtoprovidewaterpower,andvariousmineralresourceswereexploitedtoprovideenergyandbuildmachines.Thesemodificationsallowedlarderhumanpopulationstosurvive,butalwaysattheexpenseofpreviouslyexistingecosystems.4.Today,withabout6billionpeopleontheearth,nearlyicecapsshowtheeffectsofhumanactivity.Variouskindsoforganicpollutantsandleadresiduesfromtheburningofleadedgasolinecanbeidentifiedinthelayersoficethatbuildupfromthecontinuousaccumulationofsnowintheseareas.(Theamountofleadiscurrentlydecreasingbecausesomecountrieshavebeenmakingthetransitionfromburningleadedfueltounleadedfuelinautomobiles.)5.Pollutionisusuallydefinedassomethingthatpeopleproduceinlargeenoughquantitiesthatitinterfereswithourhealthofwell-being.Towprimaryfactorsthataffecttheamountofdamagedonebypollutionarethesizeofthepopulationandthedevelopmentoftechnologythat“invents”newformsofpollution.6.Whenthehumanpopulationwassmallandpeoplelivedinasimplemanner,thewaetesproducedwerebiologicalandsodilutethattheyusuallydidnotconstituteapollutionproblem.Peopleuesdwhatwasnaturallyavailableanddidnotmanufacturemanyproducts.Human,likeanyotheranimal,fitintotheirnaturalecosystems.Theirwasteproductswerebiodegradablematerials.Biodegradablematerials,areasourceoffoodfordecomposers,theorganismsthatbreakthematerialdownintosimplerchemicals,suchaswaterandcarbondioxide.7.Pollutionbeganwhenhumanpopulationbecamesocincentratedthattheirwastematerialscouldnotbebrokendownasfastastheywereproduced.Asthepopulationincreased,peoplebegantocongregateandestablishcities.Thereleaseoflargeamountsofsmokeandother formsofwasteintotheaircausedunhealthyconditionbecausethepollutantswerereleasedfasterthantheycouldbeabsorbedanddispersedbytheatmosphere.1.Throughouthistory,humanshavemadenumerousattemptstoeliminatethemiserycausedbyhungeranddisease.Ingeneral,werelyonscienceandtechnologytoimproveourqualityoflife.However,technologicalprogressoftenoffersshort-termsolutionsthatintheprocessofsolvingoneproblemcancreatenewfromsofpollution.2.Thedevelopmentofthesteamengineallowedmachinestoreplacehumanlaborbutincreasedtheamountofsmokeandotherpollutantsintheairandincreasedtheneedforfule.Themodernchemicalindustryhasproducedmanyextremelyvaluablesyntheticmaterials(plastics,pesticides,medicines)buthasalsoproducedtoxicpollutants.3.Evenidentifyingpollutionisnotalwayseasy.Tosomethesmellofalittlewoodsmokeintheairispleasant;otherdonotliketheodor.Abusinessmayconsideradvertisingsignsvaluableandnecessary;otherconsiderthemtobevisualpollution.Eventhepresenceofchemicalsindrinkingwatercanbedifficulttoclassifyasaclear-cutexampleofpollution.Toxicheavymetalssuchasarseniccertainlyshouldbeconsideredhazardous,butwedonotknowhowmucharseniccontaminationisallowablebeforeharmoccurs.Arethesmallquantitiesofarsenicingroundwatergreatenoughthat,overaperiodoftime,theywillaccumlateandcausedamagetoindividuals?Isthearsenicanormalpartofthegroundwater,ofisittheresultofpastheavysprayingofarsenic-containingpesticidesonappletrees?4.Certainly,ifthearsenicistheresultofhumanacticityandiscausinghealthproblems,itisapollutant.Ifitisanaturalpartofthegroundwater,itmaystillbeahealthhazardbutistechnicallynotapollutant