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AP Environmental Science
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Subjects / Keywords: ENERGY, CYCLING OF MATTER, EARTH, ATMOSPHERE, BIOSPHERE, CARRYING CAPACITY, POPULATION GROWTH, WATER, MINERALS, SOILS, NON-RENEWABLE ENERGY SOURCES, RENEWABLE ENERGY SOURCES, SOLID WASTE, ENVIRONMENTAL ETHICS, ENVIRONMENTAL LAWS, ENVIRONMENTAL REGULATIONS, OGT+ ISBN: 9781616100124
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APEnvironmentalScience CollectionEditor: UniversityofCaliforniaCollegePrep

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APEnvironmentalScience CollectionEditor: UniversityofCaliforniaCollegePrep Authors: UniversityofCalifornia UniversityofCaliforniaCollegePrep Online: < http://cnx.org/content/col10548/1.1/ > CONNEXIONS RiceUniversity,Houston,Texas

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2008UniversityofCaliforniaCollegePrep ThisselectionandarrangementofcontentislicensedundertheCreativeCommonsAttributionLicense: http://creativecommons.org/licenses/by/2.0/

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TableofContents 1FLOWOFENERGY .............................................................................1 2CYCLINGOFMATTER ........................................................................5 3THESOLIDEARTH ............................................................................11 4THEATMOSPHERE ...........................................................................15 5THEBIOSPHERE ...............................................................................21 6HISTORYANDGLOBALDISTRIBUTION .................................................29 7CARRYINGCAPACITY .......................................................................35 8POPULATIONGROWTH ......................................................................39 9WATER ...........................................................................................41 10MINERALS .....................................................................................47 11SOILS ............................................................................................51 12BIOLOGICAL ..................................................................................55 13NON-RENEWABLEENERGYSOURCES ..................................................59 14RENEWABLEENERGYSOURCES .........................................................63 15LAND ............................................................................................67 16AIR,WATERANDSOIL .....................................................................71 17SOLIDWASTE .................................................................................77 18IMPACTONHUMANHEALTH .............................................................81 19FIRSTORDEREFFECTS ....................................................................85 20HIGHERORDERINTERACTIONS .........................................................91 21ECONOMICFORCES .........................................................................95 22CULTURALANDAESTHETICCONSIDERATIONS .....................................99 23ENVIRONMENTALETHICS ................................................................105 24ENVIRONMENTALLAWS®ULATIONS ...........................................109 25ISSUESANDOPTIONS .....................................................................113 Index ...............................................................................................119 Attributions ........................................................................................126

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iv

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Chapter1 FLOWOFENERGY 1 1.1THEFLOWOFENERGY 1.2INTRODUCTION Energy istheabilitytodo work .Workisdonewhenaforceisappliedtoanobjectoveradistance.Any movingobjecthas kineticenergy orenergyofmotion,anditthuscandowork.Similarly,workhasto bedoneonanobjecttochangeitskineticenergy.Thekineticenergyofanobjectofmass m andspeed v is givenbytherelation E =1 = 2 mv 2 Sometimesenergycanbestoredandusedatalatertime.Forexample,acompressedspringandwater heldbackbyadambothhavethepotentialtodowork.Theyaresaidtopossess potentialenergy Whenthespringorwaterisreleaseditspotentialenergyistransformedintokineticenergyandotherforms ofenergysuchasheat.Theenergyassociatedtothegravitationalforcenearthesurfaceoftheearthis potentialenergy.Otherformsofenergyarereallycombinationsofkineticandpotentialenergy.Chemical energy,forexample,istheelectricalpotentialenergystoredinatoms.Heatenergyisacombinationofthe potentialandkineticenergyoftheparticlesinasubstance. 1.3FORMSOFENERGY Mechanicalenergy putssomethinginmotion.Itmovescarsandliftselevators.Amachineusesmechanical energytodowork.Themechanicalenergyofasystemisthesumofitskineticandpotentialenergy.Levers, whichneedafulcrumtooperate,arethesimplesttypeofmachine.Wheels,pulleysandinclinedplanesare thebasicelementsofmostmachines. Chemicalenergy istheenergystoredinmoleculesandchemicalcompounds,andisfoundinfood, wood,coal,petroleumandotherfuels.Whenthechemicalbondsarebroken,eitherbycombustionorother chemicalreactions,thestoredchemicalenergyisreleasedintheformofheatorlight.Forexample,muscle cellscontainglycogen.Whenthemuscledoesworktheglycogenisbrokendownintoglucose.Whenthe chemicalenergyintheglucoseistransferredtothemuscleberssomeoftheenergygoesintothesurroundings asheat. Electricalenergy isproducedwhenunbalancedforcesbetweenelectronsandprotonsinatomscreate movingelectronscalledelectriccurrents.Forexample,whenwespinacopperwirethroughthepolesofa magnetweinducethemotionofelectronsinthewireandproduceelectricity.Electricitycanbeusedto performworksuchaslightingabulb,heatingacookingelementonastoveorpoweringamotor.Notethat electricityisa"secondary"sourceofenergy.Thatmeansothersourcesofenergyareneededtoproduce electricity. 1 Thiscontentisavailableonlineat. 1

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2 CHAPTER1.FLOWOFENERGY Radiantenergy iscarriedbywaves.Changesintheinternalenergyofparticlescausetheatomsto emitenergyintheformofelectromagneticradiationwhichincludesvisiblelight,ultravioletUVradiation, infraredIRradiation,microwaves,radiowaves,gammarays,andX-rays.Electromagneticradiationfrom thesun,particularlylight,isofutmostimportanceinenvironmentalsystemsbecausebiogeochemicalcycles andvirtuallyallotherprocessesoneartharedrivenbythem. Thermalenergy or Heatenergy isrelatedtothemotionorvibrationofmoleculesinasubstance. Whenathermalsystemchanges,heatowsinoroutofthesystem.Heatenergyowsfromhotbodiesto coldones.Heatow,likework,isanenergytransfer.Whenheatowsintoasubstanceitmayincreasethe kineticenergyoftheparticlesandthuselevateitstemperature.Heatowmayalsochangethearrangement oftheparticlesmakingupasubstancebyincreasingtheirpotentialenergy.Thisiswhathappenstowater whenitreachesatemperatureof100 C.Themoleculesofwatermovefurtherawayfromeachother,thereby changingthestateofthewaterfromaliquidtoagas.Duringthephasetransitionthetemperatureofthe waterdoesnotchange. NuclearEnergy isenergythatcomesfromthebindingoftheprotonsandneutronsthatmakeupthe nucleusoftheatoms.Itcanbereleasedfromatomsintwodierentways:nuclearfusionornuclearssion. In nuclearfusion ,energyisreleasedwhenatomsarecombinedorfusedtogether.Thisishowthesun producesenergy.In nuclearssion ,energyisreleasedwhenatomsaresplitapart.Nuclearssionisused innuclearpowerplantstoproduceelectricity.Uranium235isthefuelusedinmostnuclearpowerplants becauseitundergoesachainreactionextremelyrapidly,resultinginthessionoftrillionsofatomswithin afractionofasecond. 1.4SOURCESANDSINKS Thesourceofenergyformanyprocessesoccurringontheearth'ssurfacecomesfromthesun.Radiating solarenergyheatstheearthunevenly,creatingairmovementsintheatmosphere.Therefore,thesundrives thewinds,oceancurrentsandthewatercycle.Sunlightenergyisusedbyplantstocreatechemicalenergy throughaprocesscalledphotosynthesis,andthissupportsthelifeandgrowthofplants.Inaddition,dead plantmaterialdecays,andovermillionsofyearsisconvertedintofossilfuelsoil,coal,etc.. Today,wemakeuseofvarioussourcesofenergyfoundonearthtoproduceelectricity.Usingmachines,we converttheenergiesofwind,biomass,fossilfuels,water,heattrappedintheearthgeothermal,nuclearand solarenergyintousableelectricity.Theabovesourcesofenergydierinamount,availability,timerequired fortheirformationandusefulness.Forexample,theenergyreleasedbyonegramofuraniumduringnuclear ssionismuchlargerthanthatproducedduringthecombustionofanequalmassofcoal. USENERGYPRODUCTIONQuadrillionBTU

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3 Source:USDOE 1975 2000 Coal 14.989.4% 22.663.5% NaturalGasdry 19.640.0% 19.741.5% CrudeOil 17.729.9% 12.383.2% Nuclear 1.900.1% 8.009.2% Hydroelectric 3.155.1% 2.841.0% NaturalGasplantliquid 2.374.9% 2.607.6% Geothermal 0.070.1% 0.319.4% Other 1.499.5% 3.275.6% TOTAL 61.356 71.838 Table1.1 Source:USDepartmentofEnergy An energysink isanythingthatcollectsasignicantquantityofenergythatiseitherlostornot consideredtransferableinthesystemunderstudy.Sourcesandsinkshavetobeincludedinanenergy budgetwhenaccountingfortheenergyowingintoandoutofasystem. 1.5CONSERVATIONOFENERGY Thoughenergycanbeconvertedfromoneformtoanother,energycannotbecreatedordestroyed.This principleiscalledthe"lawofconservationofenergy."Forexample,inamotorcycle,thechemicalpotential energyofthefuelchangestokineticenergy.Inaradio,electricityisconvertedintokineticenergyandwave energysound. Machinescanbeusedtoconvertenergyfromoneformtoanother.Thoughidealmachinesconserve themechanicalenergyofasystem,someoftheenergyalwaysturnsintoheatwhenusingamachine.For example,heatgeneratedbyfrictionishardtocollectandtransformintoanotherformofenergy.Inthis situation,heatenergyisusuallyconsideredunusableorlost. 1.6ENERGYUNITS IntheInternationalSystemofUnitsSI,theunitofworkorenergyisthe Joule J.Forverysmallamounts ofenergy,theergergissometimesused.An erg isonetenmillionthofaJoule: 1 Joule = 10 ; 000 ; 000ergs .1 Power istherateatwhichenergyisused.Theunitofpoweristhe Watt W,namedafterJamesWatt, whoperfectedthesteamengine: 1 Watt = 1 Joule/second .2 Powerissometimesmeasuredin horsepower hp: 1 horsepower = 746Watts .3

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4 CHAPTER1.FLOWOFENERGY Electricalene rgyisgenerallyexpressedin kilowatt-hours kWh: 1 kilowatt )]TJ/F15 9.9626 Tf 9.963 0 Td [(hour = 3 ; 600 ; 000Joules .4 Itisimportanttorealizethatakilowatt-hourisaunitofenergynotpower.Forexample,an ironratedat 2000Watts wouldconsume 2 x 3 6 x 10 6 J ofenergyin 1 hour Heatenergyisoftenmeasuredincalories.Onecaloriecalisdenedastheheatrequired toraisethetemperatureof 1 gram ofwaterfrom 14.5 to 15.5 C: 1 calorie = 4 .189Joules .5 Anold,butstillusedunitofheatisthe BritishThermalUnit BTU.Itisdenedastheheatenergy requiredtoraisetheenergytemperatureof1poundofwaterfrom63to64 F PhysicalQuantity Name Symbol SIUnit Force Newton N kg m=s 2 Energy Joule J kg m 2 =s 2 Power Watt W kg m 2 =s 3 Table1.2 1 BTU = 1055Joules

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Chapter2 CYCLINGOFMATTER 1 2.1CYCLINGOFMATTER 2.1.1INTRODUCTION Theearth'sbiogeochemicalsystemsinvolvecomplex,dynamicprocessesthatdependuponmanyfactors. Thethreemainfactorsuponwhichlifeontheearthdependsare: 1.Theone-wayowofsolarenergyintotheearth'ssystems.As radiantenergy ,itisusedbyplants forfoodproduction.Asheat,itwarmstheplanetandpowerstheweathersystem.Eventually,the energyislostintospaceintheformof infraredradiation .Mostoftheenergyneededtocyclematter throughearth'ssystemscomesfromthesun. 2.Thecyclingofmatter.Becausethereareonlyniteamountsofnutrientsavailableontheearth,they mustberecycledinordertoensurethecontinuedexistenceoflivingorganisms. 3.Theforceofgravity.Thisallowstheearthtomaintaintheatmosphereencompassingitssurfaceand providesthedrivingforceforthedownwardmovementofmaterialsinprocessesinvolvingthecycling ofmatter. Thesefactorsarecriticalcomponentstothefunctioningoftheearth'ssystems,andtheirfunctionsare necessarilyinterconnected.Themainmatter-cyclingsystemsinvolveimportantnutrientssuchaswater, carbon,nitrogenandphosphorus. 2.1.2WATERCYCLE Theearthissometimesknownasthe"waterplanet"becauseover70percentofitssurfaceiscoveredby water .Thephysicalcharacteristicsofwaterinuencethewaylifeonearthexists.Thesecharacteristics include: Waterisaliquidatroomtemperature,andremainsassuchoverarelativelywidetemperaturerange -100 C.Thisrangeoverlapstheannualmeantemperatureofmostbiologicalenvironments. Ittakesarelativelylargeamountofenergytoraisethetemperatureofwateri.e.,ithasahighheat capacity.Forthisreason,thevastoceansactasabueragainstsuddenchangesintheaverageglobal temperature. Waterhasaveryhighheatofvaporization.Waterevaporationthusprovidesagoodmeansforan organismtodissipateunwantedheat. Waterisagoodsolventformanycompoundsandprovidesagoodmediumforchemicalreactions.This includesbiologicallyimportantcompoundsandreactions. 1 Thiscontentisavailableonlineat. 5

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6 CHAPTER2.CYCLINGOFMATTER Liquidwaterhasaveryhighsurfacetension,theforceholdingtheliquidsurfacetogether.Thisenables upwardtransportofwaterinplantsandsoilbycapillaryaction. Solidwatericehasalowerdensitythanliquidwateratthesurfaceoftheearth.Asaresultice oatsonthesurfaceofrivers,lakes,andoceansafteritforms,leavingliquidwaterbelowwheresh andotherorganismscancontinuetolive.Ificeweremoredensethanliquidwater,itwouldsink,and bodiesofwaterincoldclimatesmighteventuallyfreezesolid. Alllivingorganismsrequirewaterfortheircontinuedexistence.Thewatercycle hydrologiccycle is composedoftheinterconnectionsbetweenwaterreservoirsintheenvironmentandlivingorganismsandthe physicalprocessese.g.,evaporationandcondensationinvolvedinitstransportbetweenthosereservoirs. Theoceanscontainabout97percentofthetotalwaterontheplanet,whichleavesaboutthreepercentas freshwater.Mostofthefreshwaterislockedupinglacialandcapiceorburieddeepintheearthwhereit iseconomicallyunfeasibletoextractit.Oneestimategivestheamountoffreshwateravailableforhuman usetobeapproximately0.003percentofthetotalamountoffreshwater.However,thisisactuallyamore thanadequatesupply,aslongasthenaturalcycleofwaterisnotseverelydisturbedbyanoutsideforcesuch ashumanactivity. Thereareseveralimportantprocessesthataectthetransportofwaterinthewatercycle. Evaporation istheprocessbywhichliquidwaterisconvertedtowatervapor.Thesourceofenergyforthisprocessis usuallythesun.Forexample,thesun'sradiationheatsthesurfacewaterinalakecausingittoevaporate. Theresultingwatervaporisthusaddedtotheatmospherewhereitcanbetransportedtoanotherlocation. Twoimportanteectsoftheevaporationarecoolinganddrying. Transpiration isaprocessbywhichwaterevaporatesfromlivingplants.Waterfromthesoilisabsorbed byaplant'srootsandtransportedtotheleaves.There,someislostasvaportotheatmospherethrough smallsurfaceopenings. Whenwatervaporintheatmospherecools,itcantransformintotinydropletsofliquidwater.This processiscalled condensation ,anditcanoccuraswatervaporistransportedintothecoolerupper atmosphere.Dustandpollenintheatmospherehelptoinitiatetheprocessbyprovidingcondensation centers.Ifthedropletsremainsmallenoughtobesupportedbyairmotions,theycangrouptogetherto formacloud.Condensationcanalsooccurintheairnearthegroundasfogoronplantleavesasdew. Whencondensedwaterdropletsgrowsolargethattheaircannolongersupportthemagainstthepull ofgravity,theyfalltotheearth.Thisistheprocesscalled precipitation Ifthewaterdropletsfallasliquid,itiscalledrain.Ifthetemperatureofthesurroundingairmassiscold enoughtofreezethewaterdroplets,theresultantprecipitationcanbecalledsnow,sleetorhail,depending uponitsmorphology. Waterfallingonthegrounde.g.,asprecipitationorirrigation,canmovedownslopeoverthesurface e.g., surfaceruno orpenetratethesurfacee.g., inltration .Theamountofsurfacerunoand inltrationdependsuponseveralfactors:waterinfallrate,surfacemoisture,soilorrocktexture,typeand amountofsurfacecovere.g.,leavesandrootedplants,andsurfacetopography.Surfacerunoisthe predominateprocessthatoccursafterprecipitation,withmostofthewaterowingintostreamsandlakes. Onagroundslopeunprotectedbyvegetation,runocanoccurveryrapidlyandresultinsevereerosion. Waterthatinltratesthesurfacecanmoveslowlydownwardthroughthelayersofsoilorporousrock inaprocessknownas percolation .Duringthisprocess,thewatercandissolvemineralsfromtherockor soilasitpassesthrough.Thewatercollectsintheporesofrocksasgroundwaterwhenitisstoppedbyan impermeablelayerofrock.Theupperlimitofthis groundwater isknownasthe watertable andthe regionofwater-loggedrockisknownasan aquifer .Thegroundwatermayslowlyowdownhillthrough rockporesuntilitexitsthesurfaceasaspringorseepsintoastreamorlake. Wateristheessenceoflife.Therewouldbenolifeasweknowitwithoutwater.Thevastoceansof waterexertapowerfulinuenceontheweatherandclimate.Waterisalsotheagentbywhichthelandforms areconstantlyreshaped.Therefore,thewatercycleplaysanimportantroleinthebalanceofnature. Humanactivitycandisruptthenaturalbalanceofthewatercycle.Thebuildupofsaltsthatresultsfrom irrigatingwithgroundwatercancausesoilinfertilityandirrigationcanalsodepleteundergroundaquifers

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7 causinglandsubsidenceorsaltwaterintrusionfromtheocean.Theclearingoflandforfarming,construction,orminingcanincreasesurfacerunoanderosion,therebydecreasinginltration.Increasinghuman populationsandtheirconcentrationincertaingeographiclocalitieswillcontinuetostresswatersystems. Carefulthoughtisneededonlocal,regionalandglobalscalesregardingtheuseandmanagementofwater resourcesforwetlands,agriculture,industryandhome. 2.1.3CARBONCYCLE Carbonisthebasicbuildingblockofallorganicmaterials,andtherefore,oflivingorganisms.However,the vastmajorityofcarbonresidesasinorganicmineralsincrustalrocks.Otherreservoirsofcarbonincludethe oceansandatmosphere.Severalphysicalprocessesaectcarbonasitmovesfromonereservoirtoanother. Theinter-relationshipsofcarbonandthebiosphere,atmosphere,oceansandcrustalearthandtheprocesses aectingitaredescribedbythe carboncycle Thecarboncycleisactuallycomprisedofseveralinter-connectedcycles.Theoveralleectisthatcarbon isconstantlyrecycledinthedynamicprocessestakingplaceintheatmosphere,atthesurfaceandinthe crustoftheearth.Forexample,thecombustionofwoodtransfers carbondioxide totheatmosphere.The carbondioxideistakeninbyplantsandconvertedtonutrientsforgrowthandsustenance.Animalseatthe plantsforfoodandexhalecarbondioxideintotheatmospherewhentheybreathe. Atmosphericcarbondioxidedissolvesintheoceanwhereiteventuallyprecipitatesascarbonateinsediments.Theoceansedimentsaresubductedbytheactionsof platetectonics ,meltedandthenreturned tothesurfaceduringvolcanicactivity.Carbondioxidegasisreleasedintotheatmosphereduringvolcanic eruptions.Someofthecarbonatomsinyourbodytodaymaylongagohaveresidedinadinosaur'sbody, orperhapswereonceburieddeepintheearth'scrustascarbonaterockminerals. Themaincarboncyclingprocessesinvolvinglivingorganismsarephotosynthesisandrespiration.These processesareactuallyreciprocaltooneanotherwithregardtothecyclingofcarbon:photosynthesisremoves carbondioxidefromtheatmosphereandrespirationreturnsit.Asignicantdisruptionofoneprocesscan thereforeaecttheamountofcarbondioxideintheatmosphere. Duringaprocesscalled photosynthesis ,rawmaterialsareusedtomanufacturesugar.Photosynthesis occursinthepresenceof chlorophyll ,agreenplantpigmentthathelpstheplantutilizetheenergyfrom sunlighttodrivetheprocess.Althoughtheoverallprocessinvolvesaseriesofreactions,thenetreactioncan berepresentedbythefollowing: Figure2.1 Thesugarprovidesasourceofenergyforotherplantprocessesandisalsousedforsynthesizingmaterials necessaryforplantgrowthandmaintenance.Theneteectwithregardtocarbonisthatitisremovedfrom theatmosphereandincorporatedintotheplantasorganicmaterials. Thereciprocalprocessofphotosynthesisiscalledrespiration.Thenetresultofthisprocessisthatsugar isbrokendownbyoxygenintocarbondioxideandwater.Thenetreactionis:

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8 CHAPTER2.CYCLINGOFMATTER Figure2.2 Thisprocessoccursnotonlyinplants,butalsoinhumansandanimals.Unlikephotosynthesis,respiration canoccurduringboththedayandnight.Duringrespiration,carbonisremovedfromorganicmaterialsand expelledintotheatmosphereascarbondioxide. Anotherprocessbywhichorganicmaterialisrecycledisthedecompositionofdeadplantsandanimals. Duringthisprocess,bacteriabreakdownthecomplexorganiccompounds. Carbonisreleasedintothesoilorwaterasinorganicmaterialorintotheatmosphereasgases.Decomposedplantmaterialissometimesburiedandcompressedbetweenlayersofsediments.Aftermillionsof yearsfossilfuelssuchcoalandoilareformed.Whenfossilfuelsareburned,thecarbonisreturnedtothe atmosphereascarbondioxide. Thecarboncycleisveryimportanttotheexistenceoflifeonearth.Thedailymaintenanceofliving organismsdependsonthereadyavailabilityofdierentformsofcarbon.Fossilfuelsprovideanimportant sourceofenergyforhumans,aswellastherawmaterialsusedformanufacturingplasticsandotherindustriallyimportantorganiccompounds.Thecomponentprocessesofthecarboncyclehaveprovidedlivingthings withthenecessarysourcesofcarbonforhundredsofmillionsofyears.Ifnotfortherecyclingprocesses, carbonmightlongagohavebecomecompletelysequesteredincrustalrocksandsediments,andlifewould nolongerexist. Humanactivitythreatenstodisruptthenaturalcycleofcarbon.Twoimportantwaysbywhichhumans haveaectedthecarboncycle,especiallyinrecenthistory,are:1thereleaseofcarbondioxideintothe atmosphereduringtheburningoffossilfuels,and2theclearingoftreesandotherplantsdeforestation thatabsorbcarbondioxidefromtheatmosphereduringphotosynthesis.Theneteectoftheseactionsis toincreasetheconcentrationofcarbondioxideintheatmosphere.Itisestimatedthatglobalatmospheric carbondioxideisincreasingbyabout0.4%annually.Carbondioxideisa greenhousegas i.e.,itprevents infraredradiationfromtheearth'ssurfacefromescapingintospace.Theheatisinsteadabsorbedbythe atmosphere.Manyscientistsbelievethattheincreasedcarbondioxideconcentrationintheatmosphereis resultinginglobalwarming. Thisglobalwarmingmayinturncausesignicantchangesinglobalweather,whichcouldnegatively aectalllifeonearth.However,increasedphotosynthesisresultingfromtheincreaseintheconcentration ofcarbondioxidemaysomewhatcounteracttheeects.Unfortunately,theissuesoffossilfuelburning, deforestationandglobalwarmingareintertwinedwitheconomicandpoliticalconsiderations.Furthermore, thoughmuchstudied,theprocessesarestillnotwell-understoodandtheirramicationscannotbepredicted withcondence. 2.1.4NITROGENCYCLE TheelementNitrogenisimportanttolivingorganismsandisusedintheproductionof aminoacids proteins and nucleicacids DNA,RNA .MolecularnitrogenN2isthemostabundantgasinthe atmosphere.However,onlyafewsingle-cellorganismsareabletoutilizethisnitrogenformdirectly.These includethebacteriaspecies Rhizobium ,whichlivesontherootnodulesoflegumes,and cyanobacteria sometimescalledblue-greenalgae,whichareubiquitoustowaterandsoilenvironments.Inorderfor

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9 multi-cellularorganismstousenitrogen,itsmolecularformN2mustbeconvertedtoothercompounds, e.g.,nitratesorammonia.Thisprocessisknownas nitrogenxation .Microbialorganismssuchas cyanobacteriacarryoutmostoftheearth'snitrogenxation.Theindustrialmanufactureoffertilizers, emissionsfromcombustionenginesandnitrogenburninginlightningaccountforasmallerfraction. The nitrogencycle islargelydependentonmicrobialprocesses.Bacteriaxnitrogenfromtheatmosphereintheformof ammoniaNH3 andconverttheammoniato nitrateNO3. Ammoniaandnitrateareabsorbedbyplantsthroughtheirroots.Humansandanimalsgettheirnitrogen suppliesbyeatingplantsorplant-eatinganimals.Thenitrogenisreturnedtothecyclewhenbacteriadecomposethewasteordeadbodiesofthesehigherorganisms,andintheprocess,convertorganicnitrogeninto ammonia.Inaprocesscalled denitrication ,otherbacteriaconvertammoniaandnitrateintomolecular nitrogenandnitrousoxideN2O.Molecularnitrogenisthusreturnedtotheatmospheretostartthecycle overagain. Humanshavedisturbedthenitrogencycleinrecenthistorybyactivitiesinvolvingincreasedxationof nitrogen.Mostofthisincreasednitrogenxationresultsfromthecommercialproductionoffertilizersand theincreasedburningoffuelswhichconvertsmolecularnitrogentonitricoxide,NO.Theuseofcommercial fertilizersonagriculturallandsincreasestherunoofnitratesintoaquaticenvironments. Thisincreasednitrogenrunostimulatestherapidgrowthofalgae.Whenthealgaedie,thewater becomesdepletedinoxygenandotherorganismsdie.Thisprocessisknownas eutrophication .Theexcessiveuseoffertilizersalsostimulatesthemicrobial denitrication ofnitrateto nitrousoxide .Increased atmosphericlevelsofnitrousoxidearethoughttocontributetoglobalwarming.Nitricoxideaddedto theatmospherecombineswithwatertoform nitricacidHNO3 ,andwhennitricaciddissolvesinwater droplets,itformsacidrain.Acidraindamageshealthytrees,destroysaquaticsystemsanderodesbuilding materialssuchasmarbleandlimestone. 2.1.5PHOSPHOROUSCYCLE Phosphorus inearthsystemsisusuallyintheformof phosphatePO43.Inlivingorganismsitisan essentialconstituentofcellmembranes,nucleicacidsand ATP thecarrierofenergyforalllifeforms.It isalsoacomponentofboneandteethinhumansandanimals.The phosphoruscycle isrelativelysimple comparedtotheothercyclesofmatterasfewerreservoirsandprocessesareinvolved.Phosphorusisnota nominalconstituentoftheatmosphere,existingthereonlyindustparticles. Mostphosphorusoccursincrustalrocksorinoceansediments.Whenphosphate-bearingrockisweathered,thephosphateisdissolvedandendsupinrivers,lakesandsoils.Plantstakeupphosphatefromthe soil,whileanimalsingestphosphorusbyeatingplantsorplant-eatinganimals.Phosphateisreturnedtothe soilviathedecompositionofanimalwasteorplantandanimalmaterials.Thiscyclerepeatsitselfagain andagain.Somephosphorusiswashedtotheoceanswhereiteventuallyndsitswayintotheocean-oor sediments. Thesedimentsbecomeburiedandformphosphate-bearingsedimentaryrocks.Whenthisrockisuplifted, exposedandweathered,thephosphateisagainreleasedforusebylivingorganisms. Themovementofphosphorusfromrocktolivingorganismsisnormallyaveryslowprocess,butsome humanactivitiesspeeduptheprocess.Phosphate-bearingrockisoftenminedforuseinthemanufacture offertilizersanddetergents.Thiscommercialproductiongreatlyacceleratesthephosphorouscycle.In addition,runofromagriculturallandandthereleaseofsewageintowatersystemscancausealocal overloadofphosphate.Theincreasedavailabilityofphosphatecancauseovergrowthofalgae.Thisreduces theoxygenlevel,causingeutrophicationandthedestructionofotheraquaticspecies.Marinebirdsplaya uniqueroleinthephosphorouscycle.Thesebirdstakeupphosphorousfromoceansh.Theirdroppingson land guano containhighlevelsofphosphorousandaresometimesminedforcommercialuse.

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Chapter3 THESOLIDEARTH 1 3.1THESOLIDEARTH 3.1.1EARTH'SFORMATIONANDSTRUCTURE Theearthformedapproximately4.6billionyearsagofromanebularcloudofdustandgasthatsurrounded thesun.Asthegascooled,moresolidsformed.Thedustymaterialaccretedtothenebularmidplanewhere itformedprogressivelylargerclumps.Eventually,bodiesofseveralkilometersindiameterformed;theseare knownas planetesimals .Thelargestplanetesimalsgrewfastest,attheexpenseofthesmallerones.This processcontinueduntilanearth-sizedplanethadformed. Earlyinitsformation,theearthmusthavebeencompletelymolten.Themainsourceofheatatthattime wasprobablythedecayofnaturally-occurringradioactiveelements.Astheearthcooled,densitydierences betweentheformingmineralscausedtheinteriortobecomedierentiatedintothreeconcentriczones:the crust,mantleandcore.Thecrustextendsdownwardfromthesurfacetoanaveragedepthof35kmwhere themantlebegins.Themantleextendsdowntoadepthof2900kmwherethecorebegins.Thecoreextends downtothecenteroftheearth,adepthofabout6400kmfromthesurface. The core makesup16percentofthevolumeoftheearthandabout31percentofthemass.Itcan bedividedintotworegions:asolidinnercoreandaliquidoutercore.Theinnercoreisprobablymostly metallicironalloyedwithasmallamountofnickel,asitsdensityissomewhatgreaterthanthatofpure metalliciron.Theoutercoreissimilarincomposition,butprobablyalsocontainssmallamountsoflighter elements,suchassulfurandoxygen,becauseitsdensityisslightlylessthanthatofpuremetalliciron.The presenceofthelighterelementsdepressesthefreezingpointandisprobablyresponsiblefortheoutercore's liquidstate. The mantle isthelargestlayerintheearth,makingupabout82percentofthevolumeand68percentof themassoftheearth.Themantleisdominatedbymagnesiumandiron-richmacminerals.Heatfromthe coreoftheearthistransportedtothecrustalregionbylarge-scaleconvectioninthemantle.Nearthetopof themantleisaregionofpartiallymeltedrockcalledthe asthenosphere .Numeroussmall-scaleconvection currentsoccurhereashot magma i.e.,moltenrockrisesandcoolermagmasinksduetodierencesin density. The crust isthethinnestlayerintheearth,makinguponly1percentofthemassand2percentofthe volume.Relativetotherestoftheearth,thecrustisrichinelementssuchassilicon,aluminum,calcium, sodiumandpotassium.Crustalmaterialsareverydiverse,consistingofmorethan2000minerals.The lessdensecrustoatsuponthemantleintwoforms:the continentalcrust andthe oceaniccrust .The oceaniccrust,whichcontainsmore macminerals isthinneranddenserthanthecontinentalcrustwhich containsmineralsricherinsiliconandaluminum.Thethickcontinentalcrusthasdeepbuoyantrootsthat helptosupportthehigherelevationsabove.Thecrustcontainsthemineralresourcesandthefossilfuels 1 Thiscontentisavailableonlineat. 11

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12 CHAPTER3.THESOLIDEARTH usedbyhumans. 3.1.2GEOLOGICTIMESCALE Inordertodescribethetimerelationshipsbetweenrockformationsandfossils,scientistsdevelopedarelative geologictimescale inwhichtheearth'shistoryisdividedandsubdividedintotimedivisions.Thethree eons Phanerozoic Proterozoic ,and Archean representthelargesttimedivisionsmeasuredinbillions ofyears.Theyinturnaresubdividedinto Eras Periods and Epochs .Majordiscontinuitiesinthegeologic recordandinthecorrespondingbiologicalfossilrecordarechosenasboundarylinesbetweenthedierent timesegments.Forexample,theCretaceous-Tertiaryboundarymillionyearsagomarksasudden massextinctionofspecies,includingthedinosaurs.Throughtheuseofmodernquantitativetechniques, somerocksandorganicmattercanbeaccuratelydatedusingthedecayofnaturally-occurringradioactive isotopes.Therefore,absoluteagescanbeassignedtosomepartsofthegeologictimescale. 3.1.3THELITHOSPHEREANDPLATETECTONICS Thelayerofthemantleabovetheasthenosphereplustheentirecrustmakeuparegioncalledthe lithosphere .Thelithosphere,andtherefore,theearth'scrust,isnotacontinuousshell,butisbrokenintoa seriesofplatesthatindependently"oat"upontheasthenosphere,muchlikearaftontheocean.These platesareinconstantmotion,typicallymovingafewcentimetersayear,andaredrivenbyconvectioninthe mantle.Thescientictheorythatdescribesthisphenomenoniscalled platetectonics .Accordingtothe theoryofplatetectonics,thelithosphereiscomprisedofsomesevenmajorplatesandseveralsmallerones. Becausetheseplatesareinconstantmotion,interactionsoccurwhereplateboundariesmeet. Aconvergentcollidingplateboundaryoccurswhentwoplatescollide.Iftheconvergentboundary involvestwocontinentalplates,thecrustiscompressedintohighmountainrangessuchastheHimalayas. Ifanoceanicplateandacontinentalplatecollide,theoceaniccrustbecauseitismoredenseissubducted underthecontinentalcrust.Theregionwheresubductiontakesplaceiscalleda subductionzone and usuallyresultsinadeepoceantrenchsuchasthe "MarianaTrench" inthewesternPacicocean.The subductedcrustmeltsandtheresultantmagmacanrisetothesurfaceandformavolcano.A divergent plate boundaryoccurswhentwoplatesmoveawayfromeachother.Magmaupwellingfromthemantle regionisforcedthroughtheresultingcracks,formingnewcrust.Themid-oceanridgeintheAtlanticoceanis aregionwherenewcrustalmaterialcontinuallyformsasplatesdiverge.Volcanoescanalsooccuratdivergent boundaries.TheislandofIcelandisanexampleofsuchanoccurrence.Athirdtypeofplateboundaryisthe transformboundary .Thisoccurswhentwoplatesslidepastoneanother.Thisinteractioncanbuildup strainintheadjacentcrustalregions,resultinginearthquakeswhenthestrainisreleased.TheSanAndreas FaultinCaliforniaisanexampleofatransformplateboundary. 3.2GEOLOGICALDISTURBANCES 3.2.1VOLCANOES Anactive volcano occurswhen magma moltenrock reachestheearth'ssurfacethroughacrackorvent inthecrust.Volcanicactivitycaninvolvetheextrusionoflavaonthesurface,theejectionofsolidrockand ash,andthereleaseofwatervapororgascarbondioxideorsulfurdioxide.Volcanoescommonlyoccur nearplateboundarieswherethemotionoftheplateshascreatedcracksinthelithospherethroughwhichthe magmacanow.Abouteightypercentofvolcanoesoccuratconvergentplateboundarieswheresubducted materialmeltsandrisesthroughcracksinthecrust.TheCascadeRangewasformedinthisway. Volcanoescanbeclassiedaccordingtothetypeandformoftheirejecta.Thebasictypesare:compositevolcanoes,shieldvolcanoes,cindercones,andlavadomes. Compositevolcanoes aresteep-sided, symmetricalconesbuiltofmultiplelayersofviscouslavaandash.Mostcompositevolcanoeshaveacrater atthesummitwhichcontainsthecentralvent.Lavasowfrombreaksinthecraterwallorfromcrackson theanksofthecone.MtFujiinJapanandMtRanierinWashingtonareexamplesofcompositevolcanoes.

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13 Shieldvolcanoes arebuiltalmostentirelyofhighlyuidlowviscositylavaows.Theyformslowly fromnumerousowsthatspreadoutoverawideareafromacentralvent.Theresultantstructureisa broad,gentlyslopingconewithaprolelikeawarrior'sshield.MtKilaueainHawaiiisanexampleofa shieldvolcano. Cindercones arethesimplesttypeofvolcano.Theyformwhenlavablownviolentlyintothearea breaksintosmallfragmentsthatsolidifyandfallascinders.Asteep-sidedconeshapeisformedaround thevent,withacrateratthesummit.SunsetCraterinArizonaisacinderconethatformedlessthana thousandyearsago,disruptingthelivesofthenativeinhabitantsoftheregion. Lavadomes areformedwhenhighlyviscouslavaisextrudedfromaventandformsarounded,steepsideddome.Thelavapilesuparoundandontheventinsteadofowingaway,mostlygrowingbyexpansion fromwithin.Lavadomescommonlyoccurwithinthecratersorontheanksofcompositevolcanoes. 3.2.2EARTHQUAKES An earthquake occurswhenbuiltupstraininarockmasscausesittorupturesuddenly.Theregionwhere theruptureoccursiscalledthe focus .Thisisoftendeepbelowthesurfaceofthecrust.Thepointon thesurfacedirectlyabovethefocusiscalledthe epicenter .Destructivewavespropagateoutwardfromthe regionofthequake,travelingthroughouttheearth.Themagnitudeofanearthquakeisameasureofthe totalamountofenergyreleased.Therststepindeterminingthemagnitudeistomeasurethepropagated wavesusingadevicecalleda seismograph .Basedonthisinformation,theearthquakeisgivenanumber classicationonamodied Richterscale .Thescaleislogarithmic,soadierenceofoneunitmeansa dierenceoften-foldinwaveintensity,whichcorrespondstoanenergydierenceof32-fold.Theintensity ofanearthquakeisanindicatoroftheeectofanearthquakeataparticularlocale.Theeectdependsnot onlyonthemagnitudeoftheearthquake,butalsothetypesofsubsurfacematerialsandthestructureand designofsurfacestructures. Earthquakesgenerallyoccuralongbreaksintherockmassknownas faults ,andmostoccurinregions nearplateboundaries.Some80percentofallearthquakesoccurnearconvergentplateboundaries,triggered bytheinteractionoftheplates.Earthquakesarealsooftenassociatedwithvolcanicactivityduetothe movementofsub-surfacemagma.Whenanearthquakeoccursundertheocean,itcantriggeradestructive tidalwaveknownasa tsunami 3.2.3ROCKSANDTHEROCKCYCLE Theearth'scrustiscomposedofmanykindsofrocks,eachofwhichismadeupofoneormoreminerals. Rockscanbeclassiedintothreebasicgroups:igneous,sedimentary,andmetamorphic. Igneousrocks arethemostcommonrocktypefoundintheearth'scrust.Theyformwhenmagmacoolsandcrystallizes subsurfaceintrusiveigneousrocksorlavacoolsandcrystallizesonthesurfaceextrusiveigneousrocks. Graniteisanexampleofanintrusiveigneousrock,whereasbasaltisanextrusiveigneousrock. Sedimentaryrocks areformedbytheconsolidationoftheweatheredfragmentsofpre-existingrocks, bytheprecipitationofmineralsfromsolution,orbycompactionoftheremainsoflivingorganisms.The processesinvolvingweatheredrockfragmentsincludeerosionandtransportbywind,waterorice,followed bydepositionassediments.Asthesedimentsaccumulateovertime,thoseatthebottomarecompacted. Theyarecementedbymineralsprecipitatedfromsolutionandbecomerocks. Theprocessofcompactionandcementationisknownas lithication .Somecommontypesofsedimentaryrocksarelimestone,shale,andsandstone.Gypsumrepresentsasedimentaryrockprecipitatedfrom solution.Fossilfuelssuchascoalandoilshalearesedimentaryrocksformedfromorganicmatter. Metamorphicrocks areformedwhensolidigneous,sedimentaryormetamorphicrockschangein responsetoelevatedtemperatureandpressureand/orchemicallyactiveuids.Thisalterationusually occurssubsurface.Itmayinvolveachangeintexturerecrystallization,achangeinmineralogyorboth. Marbleisametamorphosedformoflimestone,whileslateistransformedshale.Anthraciteisametamorphic formofcoal.

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14 CHAPTER3.THESOLIDEARTH The rockcycle illustratesconnectionsbetweentheearth'sinternalandexternalprocessesandhowthe threebasicrockgroupsarerelatedtooneanother.Internalprocessesincludemeltingandmetamorphism duetoelevatedtemperatureandpressure.Convectivecurrentsinthemantlekeepthecrustinconstant motionplatetectonics.Buriedrocksarebroughttothesurfaceuplift,andsurfacerocksandsediments aretransportedtotheuppermantleregionsubduction. Twoimportantexternalprocessesintherockcycleareweatheringanderosion.Weatheringistheprocess bywhichrockmaterialsarebrokendownintosmallerpiecesand/orchemicallychanged.Oncerockmaterials arebrokendownintosmallerpieces,theycanbetransportedelsewhereinaprocesscallederosion.Themain vehicleoferosionismovingwater,butwindandglacierscanalsoeroderock. 3.2.4SOILFORMATION Soilisoneoftheearth'smostpreciousanddelicateresources.Itsformationinvolvestheweatheringofparent materialse.g.,rocksandbiologicalactivity.Soilhasfourprincipalcomponents:water,erodedinorganic parentmaterial,air,andorganicmattere.g.,livinganddecayingorganisms. Soilformation beginswithunconsolidatedmaterialsthataretheproductsof weathering .These materialsmaybetransportedtothelocationofsoilformationbyprocessessuchaswindorwater,ormay resultfromtheweatheringofunderlyingbedrock.Theweatheringprocessinvolvesthedisintegrationand decompositionoftherock.Itcanbephysicale.g.,waterseepingintorockcracksandthenfreezingor chemicale.g.,dissolutionofmineralsbyacidrain.Physicalprocessesaremoreprevalentincoldanddry climates,whilechemicalprocessesaremoreprevalentinwarmormoistclimates. Soilmaterialstendtomoveverticallyintheformationenvironment.Organicmaterialse.g.,leaflitter andsedimentscanbeadded,whileothermaterialse.g.,mineralscanbelostduetoerosionandleaching. Livingorganismse.g.,bacteria,fungi,worms,andinsectsalsobecomeincorporatedintothedeveloping soil. Thelivingcomponentofthesoilbreaksdownotherorganicmaterialstoreleasetheirnutrientse.g., nitrogen,potassiumandphosphorous.Thenutrientsarethenusedandrecycledbygrowingplantsand otherorganisms.Thisrecyclingofnutrientshelpscreateandmaintainaviablesoil. Severalfactorsinuencesoilformationincluding:climate,parentmaterial,biologicorganisms,topographyandtime.Theclimateofanareaprecipitationandtemperaturemaybethemostimportantfactorin soilformation.TemperatureaectstheratesofchemicalreactionsandrainfallaectssoilpHandleaching. ParentmaterialorbedrockvariesfromregiontoregionandcanaectthetextureandpHofsoils.Vegetation typeaectstherateatwhichnutrientsinthesoilarerecycled,thetypeandamountoforganicmatterin thesoil,soilerosion,andthetypesandnumbersofmicro-organismslivinginthesoil. Humanscanalsohaveaprofoundeectonsoilsthroughsuchactivitiesasplowing,irrigatingandmining. Thetopographyofaregionaectsrainfallruno,erosionandsolarenergyintake.Soilformationisa continuousprocess.Soilschangewithtimeasfactorssuchasorganicmatterinputandmineralcontent change.Theprocessofmakingasoilsuitableforusebyhumanscantaketensofthousandsofyears. Unfortunately,thedestructionofthatsoilcanoccurinafewshortgenerations.

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Chapter4 THEATMOSPHERE 1 4.1THEATMOSPHERE 4.1.1INTRODUCTION The atmosphere ,thegaseouslayerthatsurroundstheearth,formedoverfourbillionyearsago.During theevolutionofthesolidearth,volcaniceruptionsreleasedgasesintothedevelopingatmosphere.Assuming theoutgasingwassimilartothatofmodernvolcanoes,thegasesreleasedincluded:watervaporH2O, carbonmonoxideCO,carbondioxideCO2,hydrochloricacidHCl,methaneCH4,ammoniaNH3, nitrogenN2andsulfurgases.Theatmospherewasreducingbecausetherewasnofreeoxygen.Mostof thehydrogenandheliumthatoutgassedwouldhaveeventuallyescapedintoouterspaceduetotheinability oftheearth'sgravitytoholdontotheirsmallmasses.Theremayhavealsobeensignicantcontributions ofvolatilesfromthemassivemeteoriticbombardmentsknowntohaveoccurredearlyintheearth'shistory. Watervaporintheatmospherecondensedandraineddown,eventuallyforminglakesandoceans.The oceansprovidedhomesfortheearliestorganismswhichwereprobablysimilartocyanobacteria.Oxygen wasreleasedintotheatmospherebytheseearlyorganisms,andcarbonbecamesequesteredinsedimentary rocks.Thisledtoourcurrentoxidizingatmosphere,whichismostlycomprisedofnitrogenroughly71 percentandoxygenroughly28percent.Watervapor,argonandcarbondioxidetogethercomprisea muchsmallerfractionroughly1percent.Theatmospherealsocontainsseveralgasesintraceamounts, suchashelium,neon,methaneandnitrousoxide.Oneveryimportanttracegasisozone,whichabsorbs harmfulUVradiationfromthesun. 4.1.2ATMOSPHERICSTRUCTURE Theearth'satmosphereextendsoutwardtoabout1,000kilometerswhereittransitionstointerplanetary space.However,mostofthemassoftheatmospheregreaterthan99percentislocatedwithintherst 40kilometers.Thesunandtheeartharethemainsourcesofradiantenergyintheatmosphere.The sun'sradiationspanstheinfrared,visibleandultravioletlightregions,whiletheearth'sradiationismostly infrared. Theverticaltemperatureproleoftheatmosphereisvariableanddependsuponthetypesofradiation thataecteachatmosphericlayer.This,inturn,dependsuponthechemicalcompositionofthatlayer mostlyinvolvingtracegases.Basedonthesefactors,theatmospherecanbedividedintofourdistinct layers:thetroposphere,stratosphere,mesosphere,andthermosphere. The troposphere istheatmosphericlayerclosesttotheearth'ssurface.Itextendsabout8-16kilometers fromtheearth'ssurface.Thethicknessofthelayervariesafewkmaccordingtolatitudeandtheseasonof theyear.Itisthickerneartheequatorandduringthesummer,andthinnernearthepolesandduringthe 1 Thiscontentisavailableonlineat. 15

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16 CHAPTER4.THEATMOSPHERE winter.Thetropospherecontainsthelargestpercentageofthemassoftheatmosphererelativetotheother layers.Italsocontainssome99percentofthetotalwatervaporoftheatmosphere. Thetemperatureofthetroposphereiswarmroughly17 Cnearthesurfaceoftheearth.Thisisdueto theabsorptionofinfraredradiationfromthesurfacebywatervaporandothergreenhousegasese.g.carbon dioxide,nitrousoxideandmethaneinthetroposphere.Theconcentrationofthesegasesdecreaseswith altitude,andtherefore,theheatingeectisgreatestnearthesurface.Thetemperatureinthetroposphere decreasesatarateofroughly6.5 Cperkilometerofaltitude.Thetemperatureatitsupperboundaryis verycoldroughly-60 C. Becausehotairrisesandcoldairfalls,thereisaconstantconvectiveoverturnofmaterialinthetroposphere.Indeed,thenametropospheremeansregionofmixing.Forthisreason,allweatherphenomena occurinthetroposphere.Watervaporevaporatedfromtheearth'ssurfacecondensesinthecoolerupper regionsofthetroposphereandfallsbacktothesurfaceasrain.Dustandpollutantsinjectedintothetropospherebecomewellmixedinthelayer,butareeventuallywashedoutbyrainfall.Thetroposphereis thereforeselfcleaning. Anarrowzoneatthetopofthetroposphereiscalledthe tropopause .Iteectivelyseparatesthe underlyingtroposphereandtheoverlyingstratosphere.Thetemperatureinthetropopauseisrelatively constant.Strongeastwardwinds,knownasthe jetstream ,alsooccurhere. The stratosphere isthenextmajoratmosphericlayer.Thislayerextendsfromthetropopauseroughly 12kilometerstoroughly50kilometersabovetheearth'ssurface.Thetemperatureproleofthestratosphere isquitedierentfromthatofthetroposphere.Thetemperatureremainsrelativelyconstantuptoroughly 25kilometersandthengraduallyincreasesuptotheupperboundaryofthelayer.Theamountofwater vaporinthestratosphereisverylow,soitisnotanimportantfactorinthetemperatureregulationofthe layer.Instead,itisozoneO3thatcausestheobservedtemperatureinversion. Mostoftheozoneintheatmosphereiscontainedinalayerofthestratospherefromroughly20to30 kilometers.ThisozonelayerabsorbssolarenergyintheformofultravioletradiationUV,andtheenergyis ultimatelydissipatedasheatinthestratosphere.Thisheatleadstotheriseintemperature.Stratospheric ozoneisalsoveryimportantforlivingorganismsonthesurfaceoftheearthasitprotectsthembyabsorbing mostoftheharmfulUVradiationfromthesun.Ozoneisconstantlybeingproducedanddestroyedin thestratosphereinanaturalcycle.Thebasicreactionsinvolvingonlyoxygenknownasthe" Chapman Reactions "areasfollows: Figure4.1 The productionofozone frommolecularoxygeninvolvestheabsorptionofhighenergyUVradiation UVAintheupperatmosphere.The destructionofozone byabsorptionofUVradiationinvolves moderateandlowenergyradiationUVBandUVC.Mostoftheproductionanddestructionofozone

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17 occursinthestratosphereatlowerlatitudeswheretheultravioletradiationismostintense. Ozoneisveryunstableandisreadilydestroyedbyreactionswithotheratmosphericspeciessuchnitrogen, hydrogen,bromine,andchlorine.Infact,mostozoneisdestroyedinthisway.Theuseof chlorouorocarbonsCFCs byhumansinrecentdecadeshasgreatlyaectedthenaturalozonecyclebyincreasingthe rateofitsdestructionduetoreactionswithchlorine.Becausethetemperatureofthestratosphereriseswith altitude,thereislittleconvectivemixingofthegases.Thestratosphereisthereforeverystable.Particles thatareinjectedsuchasvolcanicashcanstayaloftformanyyearswithoutreturningtotheground.The sameistrueforpollutantsproducedbyhumans.Theupperboundaryofthestratosphereisknownasthe stratopause ,whichismarkedbyasuddendecreaseintemperature. Thethirdlayerintheearth'satmosphereiscalledthe mesosphere .Itextendsfromthestratopause about50kilometerstoroughly85kilometersabovetheearth'ssurface.Becausethemesospherehas negligibleamountsofwatervaporandozoneforgeneratingheat,thetemperaturedropsacrossthislayer. Itiswarmedfromthebottombythestratosphere.Theairisverythininthisregionwithadensityabout 1/1000thatofthesurface.Withincreasingaltitudethislayerbecomesincreasinglydominatedbylighter gases,andintheouterreaches,theremaininggasesbecomestratiedbymolecularweight. Thefourthlayer,the thermosphere ,extendsoutwardfromabout85kilometerstoabout600kilometers. Itsupperboundaryisilldened.Thetemperatureinthethermosphereincreaseswithaltitude,upto1500 Cormore.Thehightemperaturesaretheresultofabsorptionofintensesolarradiationbythelastremaining oxygenmolecules.Thetemperaturecanvarysubstantiallydependinguponthelevelofsolaractivity. Thelowerregionofthethermosphereuptoabout550kilometersisalsoknownasthe ionosphere Becauseofthehightemperaturesinthisregion,gasparticlesbecomeionized.Theionosphereisimportant becauseitreectsradiowavesfromtheearth'ssurface,allowinglong-distanceradiocommunication.The visualatmosphericphenomenonknownasthenorthernlightsalsooccursinthisregion.Theouterregion oftheatmosphereisknownasthe exosphere .Theexosphererepresentsthenaltransitionbetweenthe atmosphereandinterplanetaryspace.Itextendsabout1000kilometersandcontainsmainlyheliumand hydrogen.Mostsatellitesoperateinthisregion. Solarradiation isthemainenergysourceforatmosphericheating.Theatmosphereheatsupwhen watervaporandothergreenhousegasesinthetroposphereabsorbinfraredradiationeitherdirectlyfromthe sunorre-radiatedfromtheearth'ssurface.Heatfromthesunalsoevaporatesoceanwaterandtransfersheat totheatmosphere.Theearth'ssurfacetemperaturevarieswithlatitude.Thisisduetounevenheatingof theearth'ssurface.Theregionneartheequatorreceivesdirectsunlight,whereassunlightstrikesthehigher latitudesatanangleandisscatteredandspreadoutoveralargerarea.Theangleatwhichsunlightstrikes thehigherlatitudesvariesduringtheyearduetothefactthattheearth'sequatorialplaneistilted23.5 relativetoitsorbitalplanearoundthesun.Thisvariationisresponsibleforthedierentseasonsexperienced bythenon-equatoriallatitudes. 4.1.3WIND Convectingairmassesinthetropospherecreateaircurrentsknownas winds ,duetohorizontaldierences inairpressure.Windsowfromaregionofhigherpressuretooneofalowerpressure.Globalairmovement beginsintheequatorialregionbecauseitreceivesmoresolarradiation.Thegeneralowofairfromthe equatortothepolesandbackisdisrupted,though,bytherotationoftheearth.Theearth'ssurfacetravels fasterbeneaththeatmosphereattheequatorandsloweratthepoles.Thiscausesairmassesmovingtothe northtobedeectedtotheright,andairmassesmovingsouthtobedeectedtotheleft.Thisisknownas the" CoriolisEect ."Theresultisthecreationofsixhuge convectioncells situatedatdierentlatitudes. Beltsofprevailingsurfacewindsformanddistributeairandmoistureovertheearth. Jetstreams areextremelystrongbandsofwindsthatforminornearthetropopauseduetolargeair pressuredierentials.Windspeedscanreachashighas200kilometersperhour.InNorthAmerica,there aretwomainjetstreams:thepolarjetstream,whichoccursbetweenthewesterliesandthepolareasterlies, andthesubtropicaljetstream,whichoccursbetweenthetradewindsandthewesterlies.

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18 CHAPTER4.THEATMOSPHERE 4.1.4WEATHER Theterm weather referstotheshorttermchangesinthephysicalcharacteristicsofthetroposphere.These physicalcharacteristicsinclude:temperature,airpressure,humidity,precipitation,cloudcover,windspeed anddirection.Radiantenergyfromthesunisthepowersourceforweather.Itdrivestheconvectivemixing inthetropospherewhichdeterminestheatmosphericandsurfaceweatherconditions. Certainatmosphericconditionscanleadtoextremeweatherphenomenasuchasthunderstorms,oods, tornadoesandhurricanes.A thunderstorm formsinaregionofatmosphericinstability,oftenoccurring attheboundarybetweencoldandwarmfronts.Warm,moistairrisesrapidlyupdraftwhilecoolerair owsdowntothesurfacedowndraft.Thunderstormsproduceintenserainfall,lightningandthunder.If theatmosphericinstabilityisverylargeandthereisalargeincreaseinwindstrengthwithaltitudevertical windshear,thethunderstormmaybecomesevere.Aseverethunderstormcanproduceashoods,hail, violentsurfacewindsandtornadoes. Floods canoccurwhenatmosphericconditionsallowastormtoremaininagivenareaforalengthof time,orwhenaseverethunderstormdumpsverylargeamountsofrainfallinashorttimeperiod.When thegroundbecomessaturatedwithwater,heexcessrunoowsintolow-lyingareasorriversandcauses ooding. A tornado beginsinaseverethunderstorm.Verticalwindshearcausestheupdraftinthestormto rotateandformafunnel.Therotationalwindspeedsincreaseandverticalstretchingoccursduetoangular momentum.Asairisdrawnintothefunnelcore,itcoolsrapidlyandcondensestoformavisiblefunnel cloud.Thefunnelclouddescendstothesurfaceasmoreairisdrawnin.Windspeedsintornadoescan reachseveralhundredmilesperhour.TornadoesaremostprevelantintheGreatPlainsregionoftheUnited States,formingwhencolddrypolarairfromCanadacollideswithwarmmoisttropicalairfromtheGulfof Mexico. A cyclone isanareaoflowpressurewithwindsblowingcounter-clockwiseNorthernHemisphereor clockwiseSouthernHemispherearoundit.Tropicalcyclonesaregivendierentnamesdependingontheir windspeed.ThestrongesttropicalcyclonesintheAtlanticOceanwindspeedexceeds74milesperhour arecalled hurricanes .Thesestormsarecalled typhoons PacicOceanorcyclonesIndianOceanin otherpartsoftheworld.Hurricanesarethemostpowerfulofallweathersystems,characterizedbystrong windsandheavyrainoverwideareas.Theyformoverthewarmtropicaloceanandquicklyloseintensity whentheymoveoverland.HurricanesaectingthecontinentalUnitedStatesgenerallyoccurfromJune throughNovember. 4.1.5OCEANCURRENTS Thesurfaceoftheearthisover71percentwater,soitisnotsurprisingthatoceanshaveasignicanteect ontheweatherandclimate.Becauseofthehighheatcapacityofwater,theoceanactsasatemperature buer.Thatiswhycoastalclimatesarelessextremethaninlandclimates.Mostoftheradiantheatfrom thesunisabsorbedbyoceansurfacewatersandoceancurrentshelpdistributethisheat. Currentsarethemovementofwaterinapredictablepattern.Surfaceoceancurrentsaredrivenmostly byprevailingwinds.The"CoriolisEect"causesthecurrentstoowincircularpatterns.Thesecurrents helptransportheatfromthetropicstothehigherlatitudes.TwolargesurfacecurrentsneartheUnited StatesaretheCaliforniacurrentalongthewestcoastandtheGulfStreamalongtheeastcoast.Deepocean currentsaredrivenbydierencesinwatertemperatureanddensity.Theymoveinaconvectivepattern. Thelessdenselowersalinitywarmwaterintheequatorialregionsrisesandmovestowardsthepolar regions,whilemoredensehighersalinitycoldwaterinthepolarregionssinksandmovestowardsthe equatorialregions.Sometimesthiscolddeepwatermovesbacktothesurfacealongacoastlineinaprocess knownas upwelling .Thiscolddeepwaterisrichinnutrientsthatsupportproductiveshinggrounds. Abouteverythreetosevenyears,warmwaterfromthewesternequatorialPacicmovestotheeastern equatorialPacicduetoweakenedtradewinds.TheeasternPacicOceanthusbecomeswarmerthanusual foraperiodofaboutayear.Thisisknownas ElNio .ElNiopreventsthenutrient-rich,cold-water upwellingsalongthewesterncoastofSouthAmerica.Italsoimpactstheglobalweatherconditions.Some

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19 regionsreceiveheavierthanusualrainfall,whileotherregionssuerdroughtconditionswithlowerthan usualrainfall. Probablythemostimportantpartofweatheris precipitation asrainfallorsnowfall.Waterfromthe vastsaltyoceansevaporatesandfallsoverlandasfreshwater.Itisrainfallthatprovidesfreshwaterfor landplants,andlandanimals.Wintersnowfallinmountainousregionsprovidesastoredsupplyoffresh waterwhichmeltsandowsintostreamsduringthespringandsummer. Atmosphericclouds arethegeneratorsofprecipitation.Cloudsformwhenarisingairmasscools andthetemperatureandhumidityarerightforcondensationtooccur.Condensationdoesnotoccurspontaneously,butinsteadrequiresa condensationnuclei .Thesearetinylessthan1 mdustorsmoke particles.Thecondensationdropletissmallenoughabout20 mthatitissupportedbytheatmosphere againstthepullofgravity.Thevisibleresultofthesecondensationdropletsisacloud. Undertherightconditions,dropletsmaycontinuetogrowbycontinuedcondensationontothedroplet and/orcoalescencewithotherdropletsthroughcollisions.Whenthedropletsbecomesucientlylarge theybegintofallasprecipitation.Typicalraindropsareabout2mmindiameter.Dependinguponthe temperatureofthecloudandthetemperatureproleoftheatmospherefromthecloudtotheearth'ssurface, varioustypesofprecipitationcanoccur:rain,freezingrain,sleetorsnow.Verystrongstormscanproduce relativelylargechunksoficecalled hailstones 4.1.6CLIMATE Climate canbethoughtofasameasureofaregion'saverageweatheroveraperiodoftime.Indeninga climate,thegeographyandsizeoftheregionmustbetakenintoaccount.Amicro-climatemightinvolvea backyardinthecity.Amacroclimatemightcoveragroupofstates.Whentheentireearthisinvolved,it isaglobalclimate.Severalfactorscontrollargescaleclimatessuchaslatitudesolarradiationintensity, distributionoflandandwater,patternofprevailingwinds,heatexchangebyoceancurrents,locationof globalhighandlowpressureregions,altitudeandlocationofmountainbarriers. Themostwidelyusedschemeforclassifyingclimateisthe K o ppenSystem .Thisschemeusesaverage annualandmonthlytemperatureandprecipitationtodeneveclimatetypes: 1. tropicalmoistclimates:averagemonthlytemperatureisalwaysgreaterthan18 C 2. dryclimates:decientprecipitationmostoftheyear 3. moistmid-latitudeclimateswithmildwinters 4. moistmid-latitudeclimateswithseverewinters 5. polarclimates:extremelycoldwintersandsummers. Table4.1 UsingtheK o ppensystemandtheseasonaldominanceoflargescaleairmassese.g.,maritimeorcontinental,theearth'sclimatezonescanbegroupedasfollows: 1. tropicalwet 2. tropicalwetanddry 3. tropicaldesert 4. mid-latitudewet 5. mid-latitudedrysummer 6. mid-latitudedrywinter 7. polarwet 8. dryandpolardesert

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20 CHAPTER4.THEATMOSPHERE Table4.2 LosAngeleshasamid-latitudedrysummerclimate,whereasNewOrleanshasamid-latitudewetclimate. Datafromnaturalclimaterecordse.g.oceansediments,treerings,Antarcticicecoresshowthatthe earth'sclimateconstantlychangedinthepast,withalternatingperiodsofcolderandwarmerclimates. Themostrecenticeageendedonlyabout10,000yearsago.Thenaturalsystemcontrollingclimateisvery complex.Itconsistsofalargenumberoffeedbackmechanismsthatinvolveprocessesandinteractionswithin andbetweentheatmosphere,biosphereandthesolidearth. Someofthenaturalcausesofglobalclimatechangeincludeplatetectonicslandmassandoceancurrent changes,volcanicactivityatmosphericdustandgreenhousegases,andlong-termvariationsintheearth's orbitandtheangleofitsrotationaxisabsoluteandspatialvariationsinsolarradiation. Morerecently,anthropogenichumanfactorsmaybeaectingtheglobalclimate.Sincethelate19th century,theaveragetemperatureoftheearthhasincreasedabout0.3to0.6 C.Manyscientistsbelieve thisglobalwarmingtrendistheresultoftheincreasedreleaseofgreenhousegasese.g.,CO2intothe atmospherefromthecombustionoffossilfuels.

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Chapter5 THEBIOSPHERE 1 5.1THEBIOSPHERE 5.1.1INTRODUCTION The biosphere istheregionoftheearththatencompassesalllivingorganisms:plants,animalsandbacteria.Itisafeaturethatdistinguishestheearthfromtheotherplanetsinthesolarsystem."Bio"meanslife, andthetermbiospherewasrstcoinedbyaRussianscientistVladimirVernadskyinthe1920s.Another termsometimesusedis ecosphere "eco"meaninghome.Thebiosphereincludestheouterregionofthe earththe lithosphere andthelowerregionoftheatmospherethe troposphere .Italsoincludesthe hydrosphere ,theregionoflakes,oceans,streams,iceandcloudscomprisingtheearth'swaterresources. Traditionally,thebiosphereisconsideredtoextendfromthebottomoftheoceanstothehighestmountaintops,alayerwithanaveragethicknessofabout20kilometers.Scientistsnowknowthatsomeformsof microbesliveatgreatdepths,sometimesseveralthousandmetersintotheearth'scrust. Nonetheless,thebiosphereisaverytinyregiononthescaleofthewholeearth,analogoustothethickness oftheskinonanapple.Thebulkoflivingorganismsactuallylivewithinasmallerfractionofthebiosphere, fromabout500metersbelowtheocean'ssurfacetoabout6kilometersabovesealevel. Dynamicinteractionsoccurbetweenthe bioticregion biosphereandthe abioticregions atmosphere, lithosphereandhydrosphereoftheearth.Energy,water,gasesandnutrientsareexchangedbetweenthe regionsonvariousspatialandtimescales.Suchexchangesdependupon,andcanbealteredby,theenvironmentsoftheregions.Forexample,thechemicalprocessesofearlylifeonearthe.g.photosynthesis, respiration,carbonateformationtransformedthereducingancientatmosphereintotheoxidizingfreeoxygenenvironmentoftoday.Theinteractiveprocessesbetweenthebiosphereandtheabioticregionswork tomaintainakindofplanetaryequilibrium.Theseprocesses,aswellasthosethatmightdisruptthis equilibrium,involvearangeofscienticandsocioeconomicissues. Thestudyoftherelationshipsoflivingorganismswithoneanotherandwiththeirenvironmentisthe scienceknownas ecology .ThewordecologycomesfromtheGreekwordsoikosandlogos,andliterallymeans "studyofthehome."Theecologyoftheearthcanbestudiedatvariouslevels:anindividualorganism, a population ,a community ,an ecosystem ,a biome ortheentire biosphere .Thevarietyofliving organismsthatinhabitanenvironmentisameasureofits biodiversity 5.1.2ORGANISMS Lifeevolvedafteroceansformed,astheoceanenvironmentprovidedthenecessarynutrientsandsupport mediumfortheinitialsimpleorganisms.ItalsoprotectedthemfromtheharshatmosphericUVradiation. Asorganismsbecamemorecomplextheyeventuallybecamecapableoflivingonland.However,thiscould 1 Thiscontentisavailableonlineat. 21

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22 CHAPTER5.THEBIOSPHERE notoccuruntiltheatmospherebecameoxidizingandaprotectiveozonelayerformedwhichblockedthe harmfulUVradiation.Overroughlythelastfourbillionyears,organismshavediversiedandadaptedtoall kindsofenvironments,fromtheicyregionsnearthepolestothewarmtropicsneartheequator,andfrom deepintherockycrustoftheearthtotheupperreachesofthetroposphere. Despitetheirdiversity,alllivingorganismssharecertaincharacteristics:theyallreplicateandalluse DNAtoaccomplishthereplicationprocess.Basedonthestructureoftheircells,organismscanbeclassied intotwotypes:eukaryotesandprokaryotes. Themaindierencebetweenthemisthata eukaryote hasanucleus,whichcontainsitsDNA,whilea prokaryote doesnothaveanucleus,butinsteaditsDNAisfree-oatinginthecell.Bacteriaare prokaryotes ,andhumansareeukaryotes.Organismscanalsobeclassiedaccordingtohowtheyacquireenergy. Autotrophs are"selffeeders"thatuselightorchemicalenergytomakefood.Plantsareautotrophs. Heterotrophs i.e.otherfeedersobtainenergybyeatingotherorganisms,ortheirremains.Bacteria andanimalsareheterotrophs.Groupsoforganismsthatarephysicallyandgeneticallyrelatedcanbeclassiedinto species .Therearemillionsofspeciesontheearth,mostofthemunstudiedandmanyofthem unknown.Insectsandmicroorganismscomprisethemajorityofspecies,whilehumansandothermammals compriseonlyatinyfraction.Inanecologicalstudy,asinglememberofaspeciesororganismisknownas an individual 5.1.3POPULATIONSANDCOMMUNITIES Anumberofindividualsofthesamespeciesinagivenareaconstitutea population .Thenumbertypically rangesanywherefromafewindividualstoseveralthousandindividuals.Bacterialpopulationscannumber inthemillions.Populationsliveinaplaceorenvironmentcalleda habitat .Allofthepopulationsofspecies inagivenregiontogethermakeupa community .Inanareaoftropicalgrassland,acommunitymightbe madeupofgrasses,shrubs,insects,rodentsandvariousspeciesofhoofedmammals. Thepopulationsandcommunitiesfoundinaparticularenvironmentaredeterminedbyabioticandbiotic limitingfactors .Thesearethefactorsthatmostaectthesuccessofpopulations.Abioticlimitingfactors involvethephysicalandchemicalcharacteristicsoftheenvironment.Someofthesefactorsinclude:amounts ofsunlight,annualrainfall,availablenutrients,oxygenlevelsandtemperature.Forexample,theamountof annualrainfallmaydeterminewhetheraregionisagrasslandorforest,whichinturn,aectsthetypesof animalslivingthere. Eachpopulationinacommunityhasa rangeoftolerance foranabioticlimitingfactor.Thereare alsocertainmaximumandminimumrequirementsknownas tolerancelimits ,aboveandbelowwhich nomemberofapopulationisabletosurvive.Therangeofanabioticfactorthatresultsinthelargest populationofaspeciesisknownasthe optimumrange forthatfactor.Somepopulationsmayhavea narrowrangeoftoleranceforonefactor.Forexample,afreshwatershspeciesmayhaveanarrowtolerance rangefordissolvedoxygeninthewater.Ifthelakeinwhichthatshspecieslivesundergoeseutrophication, thespecieswilldie.Thisshspeciescanthereforeactasan indicatorspecies ,becauseitspresenceor absenceisastrictindicatoroftheconditionofthelakewithregardtodissolvedoxygencontent. Bioticlimitingfactorsinvolveinteractionsbetweendierentpopulations,suchascompetitionforfood andhabitat.Forexample,anincreaseinthepopulationofameat-eatingpredatormightresultinadecrease inthepopulationofitsplant-eatingprey,whichinturnmightresultinanincreaseintheplantpopulation thepreyfeedson.Sometimes,thepresenceofacertainspeciesmaysignicantlyaectthecommunitymake up.Suchaspeciesisknownasa keystonespecies .Forexample,abeaverbuildsadamonastreamand causesthemeadowbehindittoood.Astarshkeepsmusselsfromdominatingarockybeach,thereby allowingmanyotherspeciestoexistthere. 5.1.4ECOSYSTEMS An ecosystem isacommunityoflivingorganismsinteractingwitheachotherandtheirenvironment. Ecosystemsoccurinallsizes.Atidalpool,apond,ariver,analpinemeadowandanoakforestareall examplesofecosystems.Organismslivinginaparticularecosystemareadaptedtotheprevailingabiotic

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23 andbioticconditions.Abioticconditionsinvolvebothphysicalandchemicalfactorse.g.,sunlight,water, temperature,soil,prevailingwind,latitudeandelevation.Inordertounderstandtheowofenergyand matterwithinanecosystem,itisnecessarytostudythefeedingrelationshipsofthelivingorganismswithin it. Livingorganismsinanecosystemareusuallygroupedaccordingtohowtheyobtainfood.Autotrophs thatmaketheirownfoodareknownas producers ,whileheterotrophsthateatotherorganisms,living ordead,areknownas consumers .Theproducersincludelandandaquaticplants,algaeandmicroscopic phytoplanktonintheocean.Theyallmaketheirownfoodbyusingchemicalsandenergysourcesfromtheir environment. Forexample,plantsusephotosynthesistomanufacturesugarglucosefromcarbondioxideandwater. Usingthissugarandothernutrientse.g.,nitrogen,phosphorusassimilatedbytheirroots,plantsproduce avarietyoforganicmaterials.Thesematerialsinclude:starches,lipids,proteinsandnucleicacids.Energy fromsunlightisthusxedasfoodusedbythemselvesandbyconsumers. Theconsumersareclassedintodierentgroupsdependingonthesourceoftheirfood. Herbivores e.g. deer,squirrelsfeedonplantsandareknownasprimaryconsumers. Carnivores e.g.lions,hawks,killer whalesfeedonotherconsumersandcanbeclassiedas secondaryconsumers .Theyfeedonprimary consumers. Tertiaryconsumers feedonothercarnivores.Someorganismsknownas omnivores e.g., bears,ratsandhumansfeedonbothplantsandanimals.Organismsthatfeedondeadorganismsarecalled scavengers e.g.,vultures,antsandies. Detritivores detritusfeeders,e.g.earthworms,termites,crabs feedonorganicwastesorfragmentsofdeadorganisms. Decomposers e.g.bacteria,fungialsofeedonorganicwasteanddeadorganisms,buttheydigestthe materialsoutsidetheirbodies.Thedecomposersplayacrucialroleinrecyclingnutrients,astheyreduce complexorganicmatterintoinorganicnutrientsthatcanbeusedbyproducers.Ifanorganicsubstancecan bebrokendownbydecomposers,itiscalled biodegradable Ineveryecosystem,eachconsumerleveldependsuponlower-levelorganismse.g.aprimaryconsumer dependsuponaproducer,asecondaryconsumerdependsuponaprimaryconsumerandatertiaryconsumer dependsuponasecondaryconsumer.Alloftheselevels,fromproducertotertiaryconsumer,formwhat isknownasa foodchain .Acommunityhasmanyfoodchainsthatareinterwovenintoacomplex food web .Theamountoforganicmaterialinafoodwebisreferredtoasits biomass .Whenoneorganismeats another,chemicalenergystoredinbiomassistransferredfromonelevelofthefoodchaintothenext.Most oftheconsumedbiomassisnotconvertedintobiomassoftheconsumer.Onlyasmallportionoftheuseable energyisactuallytransferredtothenextlevel,typically10percent.Eachhigherlevelofthefoodchain representsacumulativelossofuseableenergy.Theresultisa pyramidofenergyow ,withproducers formingthebaselevel. Assuming10percenteciencyateachlevel,thetertiaryconsumerlevelwoulduseonly0.1percentof theenergyavailableattheinitialproducerlevel.Becausethereislessenergyavailablehighontheenergy pyramid,therearefewertop-levelconsumers.Adisruptionoftheproducerbaseofafoodchain,therefore, hasitsgreatesteectonthetop-levelconsumer. Ecosystempopulationsconstantlyuctuateinresponsetochangesintheenvironment,suchasrainfall, meantemperature,andavailablesunlight.Normally,suchchangesarenotdrasticenoughtosignicantly alterecosystems,butcatastrophiceventssuchasoods,resandvolcanoescandevastatecommunitiesand ecosystems.Itmaybelongaftersuchacatastrophiceventbeforeanew,matureecosystemcanbecome established.Afterseveredisturbancethemakeupofacommunityischanged.Theresultingcommunity ofspecieschanges,asearly,postdisturbance,fast-growingspeciesareout-competedbyotherspecies.This naturalprocessiscalled ecologicalsuccession .Itinvolvestwotypesofsuccession: primarysuccession and secondarysuccession Primarysuccessionisthedevelopmentoftherstbiotainagivenregionwherenolifeisfound.An exampleisofthisisthesurroundingareaswherevolcaniclavahascompletelycoveredaregionorhasbuilt upanewislandintheocean.Initially,only pioneerspecies cansurvivethere,typically lichens and mosses ,whichareabletowithstandpoorconditions.Theyareabletosurviveinhighlyexposedareas withlimitedwaterandnutrients.Lichen,whichismadeupofbothafungusandanalga,survivesby

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24 CHAPTER5.THEBIOSPHERE mutualism.Thefungusproducesanacid,whichactstofurtherdissolvethebarrenrock.Thealgauses thoseexposednutrients,alongwithphotosynthesis,toproducefoodforboth.Grassseedsmaylandinthe cracks,carriedbywindorbirds.Thegrassgrows,furthercrackingtherocks,anduponcompletingitsown lifecycle,contributesorganicmattertothecrumblingrocktomakesoil.Intime,largerplants,suchas shrubsandtreesmayinhabitthearea,oeringhabitatsandnichestoimmigratinganimallife.Whenthe maximumbiotathattheecosystemcansupportisreached,the climaxcommunity prevails.Thisoccurs afterhundredsifnotthousandsofyearsdependingontheclimateandlocation. Secondarysuccessionbeginsatadierentpoint,whenanexistingecosystem'scommunityofspeciesis removedbyre,deforestation,orabulldozer'sworkinavacantlot,leavingonlysoil.Therstfewcentimeters ofthissoilmayhavetaken1000yearstodevelopfromsolidrock.Itmayberichinhumus,organicwaste, andmaybestockedwithreadyseedsoffutureplants.Secondarysuccessionisalsoanewbeginning,but onewithamuchquickerregrowthoforganisms.Dependingontheenvironment,successiontoaclimax communitymayonlyrequire100to200yearswithnormalclimateconditions,withcommunitiesprogressing throughstagesof earlyplant and animalspecies mid-species and latesuccessionalspecies .Some ecosystems,however,canneverbyregained. 5.1.5BIOMES Thebiospherecanbedividedintorelativelylargeregionscalledbiomes.Abiomehasadistinctclimate andcertainlivingorganismsespeciallyvegetationcharacteristictotheregionandmaycontainmany ecosystems.Thekeyfactorsdeterminingclimateareaverageannualprecipitationandtemperature.These factors,inturn,dependonthegeographyoftheregion,suchasthelatitudeandelevationoftheregion, andmountainousbarriers.Themajortypesofbiomesinclude: aquatic desert forest grassland and tundra .Biomeshavenodistinctboundaries.Instead,thereisatransitionzonecalledanecotone,which containsavarietyofplantsandanimals.Forexample,anecotonemightbeatransitionregionbetweena grasslandandadesert,withspeciesfromboth. Watercoversamajorportionoftheearth'ssurface,soaquaticbiomescontainarichdiversityofplants andanimals. Aquaticbiomes canbesubdividedintotwobasictypes: freshwater and marine Freshwaterhasalowsaltconcentration,usuallylessthan1percent,andoccursinseveraltypesofregions: pondsandlakes,streamsandrivers,andwetlands. Pondsandlakes rangeinsize,andsmallpondsmay beseasonal.Theysometimeshavelimitedspeciesdiversityduetoisolationfromotherwaterenvironments. Theycangettheirwaterfromprecipitation,surfaceruno,rivers,andsprings. Streamsandrivers are bodiesofowingwatermovinginonegeneraldirectioni.e.,downstream.Streamsandriversstartattheir upstreamheadwaters,whichcouldbesprings,snowmeltorevenlakes.Theycontinuedownstreamtotheir mouths,whichmaybeanotherstream,river,lakeorocean.Theenvironmentofastreamorrivermay changealongitslength,rangingfromclear,coolwaternearthehead,towarm,sediment-richwaternear themouth.Thegreatestdiversityoflivingorganismsusuallyoccursinthemiddleregion.Wetlandsare placesofstillwaterthatsupportaquaticplants,suchascattails,pondliliesandcypresstrees.Typesof wetlandsincludemarshes,swampsandbogs. Wetlands havethehighestdiversityofspecieswithmany speciesofbirds,fur-bearingmammals,amphibiansandreptiles.Somewetlands,suchassaltmarshes,are notfreshwaterregions. Marineregions covernearlythree-fourthsoftheearth'ssurface.Marinebodiesaresalty,having approximately35gramsofdissolvedsaltperliterofwater.5percent. Oceans areverylargemarine bodiesthatdominatetheearth'ssurfaceandholdthelargestecosystems.Theycontainarichdiversityof livingorganisms.Oceanregionscanbeseparatedintofourmajorzones: intertidal pelagic benthic and abyssal .Theintertidalzoneiswheretheoceanmeetstheland.Sometimes,itissubmergedandatother timesexposed,dependinguponwavesandtides.Thepelagiczoneincludestheopenoceanfurtheraway fromland.Thebenthiczoneistheregionbelowthepelagiczone,butnotincludingtheverydeepestparts oftheocean.Thebottomofthiszoneconsistsofsediments.Thedeepestpartsoftheoceanareknownas theabyssalzone.Thiszoneisverycoldnearfreezingtemperatures,andundergreatpressurefromthe overlyingmassofwater.Mid-oceanridgesoccurontheoceanoorinabyssalzones. Coralreefs arefound inthewarm,clear,shallowwatersoftropicaloceansaroundislandsoralongcontinentalcoastlines.

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25 Theyaremostlyformedfromcalciumcarbonateproducedbylivingcoral.Reefsprovidefoodandshelter forotherorganismsandprotectshorelinesfromerosion.Estuariesarepartiallyenclosedareaswherefresh waterandsiltfromstreamsorriversmixwithsaltyoceanwater.Theyrepresentatransitionfromlandto seaandfromfreshwatertosaltwater.Estuariesarebiologicallyveryproductiveareasandprovidehomesfor awidevarietyofplants,birdsandanimals. Deserts aredryareaswhereevaporationusuallyexceedsprecipitation.Rainfallislowlessthan25 centimetersperyearandcanbehighlyvariableandseasonal.Thelowhumidityresultsintemperature extremesbetweendayandnight.Desertscanbehotorcold. Hotdeserts e.g.theSonovanareveryhot inthesummerandhaverelativelyhightemperaturesthroughouttheyearandhaveseasonalrainfall. Cold deserts e.g.theGobiarecharacterizedbycoldwintersandlowbutyear-roundprecipitation.Deserts haverelativelylittlevegetationandthesubstrateconsistsmostlyofsand,gravelorrocks.Thetransition regionsbetweendesertsandgrasslandsaresometimescalled semiariddeserts e.g.theGreatBasinofthe westernUnitedStates. Grasslands coverregionswheremoderaterainfallissucientforthegrowthofgrasses,butnotenough forstandsoftrees.Therearetwomaintypesofgrasslands: tropicalgrasslands savannasand temperate grasslands .TropicalgrasslandsoccurinwarmclimatessuchasAfricaandverylimitedregionsofAustralia. Theyhaveafewscatteredtreesandshrubs,buttheirdistinctrainyanddryseasonspreventtheformationof tropicalforests.Lowerrainfall,morevariablewinter-through-summertemperaturesandanearlackoftrees characterizetemperategrasslands.Prairiesaretemperategrasslandsatfairlyhighelevation.Theymaybe dominatedbylongorshortgrassspecies.ThevastprairiesoriginallycoveringcentralNorthAmerica,orthe GreatPlains,weretheresultoffavorableclimateconditionscreatedbytheirhighelevationandproximity totheRockyMountains.Becausetemperategrasslandsaretreeless,relativelyatandhaverichsoil,most havebeenreplacedbyfarmland. Forestsaredominatedbytreesandcanbedividedintothreetypes: tropicalforests temperate forests and borealforests .Tropicalforestsarealwayswarmandwetandarefoundatlowerlatitudes. Theirannualprecipitationisveryhigh,althoughsomeregionsmayhavedistinctwetanddryseasons. Tropicalforestshavethehighestbiodiversityofthisbiome.Temperateforestsoccuratmid-latitudesi.e., NorthAmerica,andthereforehavedistinctseasons.Summersarewarmandwintersarecold.Thetemperate forestshavesueredconsiderablealterationbyhumans,whohaveclearedmuchoftheforestlandforfuel, buildingmaterialsandagriculturaluse.Borealforestsarelocatedinhigherlatitudes,likeSiberia,where theyareknownas" taiga ."Theyhaveverylong,coldwintersandashortsummerseasonwhenmostofthe precipitationoccurs.Borealforestsrepresentthelargestbiomeonthecontinents. Verylowtemperatures,littleprecipitationandlowbiodiversitycharacterizetundra.Itsvegetationis verysimple,withvirtuallynotrees.Thetundracanbedividedintotwodierenttypes: arctictundra and alpinetundra .Thearcticalpineoccursinpolarregions.Ithasaveryshortsummergrowingseason. Watercollectsinpondsandbogs,andthegroundhasasubsurfacelayerofpermanentlyfrozensoilknown aspermafrost.Alpinetundraisfoundathighelevationsintallmountains.Thetemperaturesarenotaslow asinthearctictundra,andithasalongersummergrowingseason. 5.1.6EVOLUTIONOFLIFE Wherevertheyarefoundinthebiosphere,livingorganismsarenecessarilylinkedtotheirenvironment. Ecosystems aredynamicandcommunitieschangeovertimeinresponsetoabioticorbioticchangesinthe environment.Forexample,theclimatemaybebecomewarmerorcolder,wetterordrier,orthefoodchain maybedisruptedbythelossofaparticularpopulationortheintroductionofanewone.Speciesmust beabletoadapttothesechangesinordertosurvive.Astheyadapt,theorganismsthemselvesundergo change. Evolution isthegradualchangeinthegeneticmakeupofapopulationofaspeciesovertime.It isimportanttonotethatitisthepopulationthatevolves,ratherthanindividuals. Aspeciesevolvestoaparticularnicheeitherbyadaptingtouseaniche'senvironmentoradaptingto avoidcompetitionwithanotherspecies.Recallthatnotwospeciescanoccupytheexactsamenicheinan ecosystem.Theavailabilityofresourcesispivotal.

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26 CHAPTER5.THEBIOSPHERE Inthecaseofvewarblerspecieswhichallconsumeinsectsofthesametree,tosurviveeachspecies needstogatheritsfoodinsectsindierentpartsofthattree.Thisavoidscompetitionandthepossible extinctionofoneormorespecies.Therefore,oneofthebirdspecieswilladapttohuntingatthetreetops; anotherthelowestbranches;anotherthemid-section.Inthisway,thesespecieshaveevolvedintodierent, yetsimilar,niches.Allvespeciesinthiswaycansurvivebyadaptingtoanarrowniche.Organismswith anarrownichearecalled specializedspecies .Anotherexampleisaspeciesthatmayevolvetoanarrow nichebyconsumingonlyonetypeofleaf,suchastheGiantPanda,whichconsumesbambooleaves. Thisstrategyallowsittoco-existwithanotherconsumerbynotcompetingwithit.Inbothcases,species withanarrownicheareoftenvulnerabletoextinctionbecausetheytypicallycannotrespondtochangesin theenvironment.Evolvingtoanewnichewouldtaketoomuchtimeforthespecializedspeciesunderthe duressofadrought,forexample. Ontheotherhand,aspeciesthatcanusemanyfoodsandlocationsinwhichtohuntorgatherareknown as generalizedspecies .Intheeventofadrought,ageneralizedspeciessuchasacockroachmaybemore successfulinndingalternativeformsoffood,andwillsurviveandreproduce. Yetanotherformofevolutionis co-evolution ,wherespeciesadapttooneanotherbyinteractingclosely. Thisrelationshipcanbeapredator-preytypeofinteraction.Preyisatrisk,butasaspeciesithasevolved chemicaldefensesorbehaviors.Ontheotherhand,co-evolutioncanbeamutualisticrelationship,often characterizedbytheantsandanacaciatreeofSouthAmerica.Theacaciaprovidesantswithfoodanda habitat,anditslargeprojectingthornsprovidesprotectionfrompredators.Theants,inturn,protectthe treebyattackinganyanimallandingonitandbyclearingvegetationatitsbase.Socloselyevolvedarethe speciesthatneithercanexistwithouttheother. Similarecosystemsmayoersimilarnichestoorganisms,thatareadaptedorevolvedtothatniche. Convergentevolution isthedevelopmentofsimilaradaptationsintwospeciesoccupyingdierentyet similarecosystems.Twospeciesevolveindependentlytorespondtothedemandsoftheirecosystem,and theydevelopthesamemechanismtodoso.Whatemergesareadaptationsthatresemblelook-alikes:Wings ofbirdsandbatsaresimilar,butevolvedseparatelytomeetthedemandsofyingthroughair.Thedolphin, amammal,sharesadaptationsthatallowformovementthroughwaterwiththeextinctreptileichthyosaur. Theyhavesimilarstreamlinedshapesofns,head,andnose,whichmakethebodiesbettersuitedfor swimming. Naturalselection isanotherprocessthatdependsonanorganism'sabilitytosurviveinachanging environment.Whileevolutionisthegradualchangeofthegeneticmakeupovertime,naturalselectionis theforcethatfavorsabenecialsetofgenes. Forexample,birdsmigratingtoanislandfacecompetitionfortheinsectsonatropicaltree.Onegenetic poolofanewgenerationmayincludealongerbeak,whichallowsthebirdtoreachintoatropicalower foritsnectar.Whenhighpopulationsofbirdscompeteforinsects,thisabilitytousethenicheofcollecting nectarfavorsthatbird'ssurvival.Thelong-beakedgeneispassedtothenextgenerationandthenext, becausebirdscancoexistwiththeinsect-gatheringbirdsbyusingadierentniche.Throughreproduction ofthesurvivinglonger-beakedbirds,naturalselectionfavorsitsadaptability. Aspecies,familyorlargergroupoforganismsmayeventuallycometotheendofitsevolutionaryline. Thisisknownas extinction .Whilebadnewsforthosethatbecomeextinct,it'sanaturaloccurrencethat hasbeentakingplacesincethebeginningoflifeonearth.Extinctionsofspeciesareconstantlyoccurring atsomebackgroundrate,whichisnormallymatchedbyspeciation.Thus,inthenaturalworld,thereisa constantturnoverofspecies. Occasionallylargenumbersofspecieshavebecomeextinctoverarelativelyshortgeologictimeperiod. Thelargest massextinction eventintheearth'shistoryoccurredattheendofthePermianperiod,245 millionyearsago.Asmanyas96percentofallmarinespecieswerelost,whileonlandmorethan75 percentofallvertebratefamiliesbecameextinct.Although,theactualcauseofthatextinctionisunclear, theconsensusisthatclimatechange,resultingfromsealevelchangeandincreasedvolcanicactivity,was animportantfactor.ThemostfamousofallmassextinctionsoccurredattheboundaryoftheCretaceous andTertiaryperiods,65millionyearsago.About85percentofspeciesbecameextinct,includingallofthe dinosaurs.MostscientistsbelievethattheimpactofasmallasteroidneartheYucatanPeninsulainMexico

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27 triggeredthatextinctionevent.Theimpactprobablyinducedadramaticchangeintheworldclimate. Themostseriousextinctionofmammalsoccurredabout11,000yearsago,asthelastIceAgewas ending.Overaperiodofjustafewcenturies,mostofthelargemammalsaroundtheworld,suchasthe mammoth,becameextinct.Whileclimatechangemayhavebeenafactorintheirextinction,anewforcehad alsoemergedontheearth-modernhumans.Humans,aidedbynew,sharp-pointedweaponsandhunting techniques,mayhavehurriedthedemiseofthelargelandmammals.Overtheyears,humanactivityhas continuedtosendmanyspeciestoanearlyextinction.Thebestknownexamplesarethepassengerpigeon andthedodobird,butnumerousotherspecies,manyofthemunknown,arekilledobyoverharvesting andotherhuman-causedhabitatdestruction,degradationandfragmentation.

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28 CHAPTER5.THEBIOSPHERE

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Chapter6 HISTORYANDGLOBAL DISTRIBUTION 1 6.1HISTORYANDGLOBALDISTRIBUTION 6.1.1INTRODUCTION Apopulationisagroupofindividualslivingtogetherinagivenareaatagiventime.Changesinpopulations aretermed populationdynamics .Thecurrenthumanpopulationismadeupofallofthepeoplewho currentlysharetheearth.Thersthumanswalkedtheplanetmillionsofyearsago.Sincethattime,the numberofhumanslivingontheplanetandwheretheylivehasconstantlychangedovertime.Everybirth anddeathisapartofhumanpopulationdynamics.Eachtimeapersonmovesfromonelocationtoanother, thespatialarrangementofthepopulationischanged,andthis,too,isanelementofpopulationdynamics. Whilehumansareuniqueinmanywaysasaspecies,theyaresubjecttomanyofthesamelimitingforces andunexpectedeventsofallpopulationsoforganisms. In1999,thehumanpopulationcrossedthesixbillionmark.Atcurrentgrowthrates,thepopulationwill doublewithin50years.Longago,whenthehumanpopulationwassmall,thedoublingofthepopulation hadlittleimpactonthehumanpopulationoritsenvironment.However,withthesizeoftoday'spopulation, theeectofdoublingthepopulationisquitesignicant.Already,mostofthepeopleoftheworlddonot haveadequatecleanwater,food,housingandmedicalcare,andthesedecienciesareatleastpartiallythe resultofoverpopulation.Asthepopulationcontinuestogrow,competitionforresourceswillincrease. Naturaldisastersandpoliticalconictswillexacerbatetheproblems,especiallyinthemorestressedregions ofdevelopingnations.Thesurvivorsofthiscompetitionwilllikelybedeterminedbyfactorssuchasplace ofbirthandeducationalopportunities. 6.1.2POPULATIONGROWTH Humanpopulationsarenotstagnant.Theynaturallychangeinsize,densityandpredominanceofage groupsinresponsetoenvironmentalfactorssuchasresourcesavailabilityanddisease,aswellassocialand culturalfactors.Theincreasesanddecreasesinhumanpopulationsizemakeupwhatisknownas human populationdynamics .Ifresourcesarenotlimited,thenpopulationsexperienceexponentialgrowth.A plotof exponentialgrowth overtimeresemblesa"J"curve.Absolutenumbersarerelativelysmallatrst alongthebaseofthe Jcurve ,butthepopulationrapidlyskyrocketswhenthecriticaltimenearthestem oftheJcurveisreached. FormostofthehistoryofmodernhumansHomosapiens,peoplewerehunter-gatherers.Food,especially meatfromlargemammals,wasusuallyplentiful.However,populationsweresmallbecausethenomadiclife 1 Thiscontentisavailableonlineat. 29

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30 CHAPTER6.HISTORYANDGLOBALDISTRIBUTION didnotfavorlargefamilysizes.Duringthosetimes,thehumanpopulationwasprobablynotmorethana fewmillionworldwide.ItwasstillinthebaseoftheJgrowthcurve. WiththeendofthelastIceAge,roughly10,000yearsago,theclimatesworldwidechangedandmany largemammalsthathadbeenthemainstayofhumandietbecameextinct.Thisforcedachangeindietand lifestyle,fromoneofthenomadichunter-gatherertothatofamorestationaryagriculturalsociety. Humansbegancultivatingfoodandstartedeatingmoreplantsandlessmeat.Havinglargerfamilieswas possiblewiththemorestationarylifestyle.Infact,havingalargefamilyincreasinglybecameanasset,as extrahandswereneededformaintainingcropsandhomes.Asagriculturebecamethemainstayofhuman life,thepopulationincreased. Asthepopulationincreased,peoplebeganlivinginvillages,thenintownsandnallyincities.This ledtoproblemsassociatedwithovercrowdedconditions,suchasthebuildupofwastes,povertyanddisease. Largefamilieswerenolongeradvantageous.InfanticidewascommonduringmedievaltimesinEurope,and communicablediseasesalsolimitedthehumanpopulationnumbers.Easilyspreadincrowded,rat-infested urbanareas,BlackDeath,therstmajoroutbreakoftheBubonicPlague-1351drasticallyreduced thepopulationsinEuropeandAsia,possiblybyasmuchas50percent. Startinginthe17thCentury,advancesinscience,medicine,agricultureandindustryallowedrapidgrowth ofhumanpopulationandinfanticideagainbecameacommonpractice. ThenextbiginuenceonthehumanpopulationoccurredwiththestartoftheIndustrialRevolution inthelate18thcentury.Withtheadventoffactories,childrenbecamevaluablelaborresources,thereby contributingtosurvival,andfamilysizesincreased.Theresultingpopulationboomwasfurtheraided byimprovementsinagriculturaltechnologythatledtoincreasedfoodproduction.Medicaladvancements increasedcontroloverdiseaseandlengthenedtheaveragelifespan.Bytheearly19thcentury,thehuman populationworldwidereachedonebillion.ItwasnowinthestemoftheJcurvegraph.Astheworld approachedthe20thcentury,thehumanpopulationwasgrowingatanexponentialrate. Duringthe20thcentury,anotherimportanteventinhumanpopulationdynamicsoccurred.Thebirth ratesinthehighlydevelopedcountriesdecreaseddramatically.Factorscontributingtothisdecreaseincluded: ariseinthestandardofliving,theavailabilityofpracticalbirthcontrolmethodsandtheestablishmentof childeducationandlaborlaws.Thesefactorsmadelargefamilieseconomicallyimpractical.InJapan,the birthratehasbeensolowinrecentyearsthatthegovernmentandcorporationsareworriedaboutfuture laborshortages.Therefore,theyareactivelyencouragingpopulationgrowth.Incontrast,thepopulations inlesswell-developedcountriescontinuetosoar.Worldwide,thehumanpopulationcurrentlyexceedssix billionandcontinuestogrowexponentially.Howmuchmoretheworldpopulationwillgrowisatopicof intensespeculation.Onethingiscertain:exponentialgrowthcannotcontinueforever,asearth'sresources arelimited. 6.1.3POPULATIONDEMOGRAPHICS Human demography populationchangeisusuallydescribedintermsofthebirthsanddeathsper1000 people.Whenbirthsofanareaexceeddeaths,populationincreases.Whenthebirthsofanareaarefewer thandeaths,thepopulationdecreases.Theannualrateatwhichthesizeofapopulationchangesis: Figure6.1

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31 Duringtheyear2000,thebirthratefortheworldwas22andthedeathratewas9.Thus,theworld's populationgrewatarateof1.3percent.Theannualrateofpopulationchangeforaparticularcityorregion isalsoaectedby immigration movementofpeopleintoaregionand emigration movementoutofa region. Figure6.2 Highlyindustrializednations,liketheUnitedStates,Canada,JapanandGermany,generallyhavelow birthanddeathrates.Annualratesofnaturalpopulationchangevaryfrom-0.1%to0.5%.Insomeindustrial nationse.g.GermanyandRussiadeathratesexceedbirthratessothenetpopulationdecreasesovertime. Newlyindustrializedcountriese.g.SouthKorea,MexicoandChinahavemoderatebirthratesandlow deathrates.Thelowdeathratesresultfrombettersanitation,betterheathcareandstablefoodproduction thataccompanyindustrialization.Theannualratesofnaturalpopulationchangeareabout1percentto2 percentinthesecountries.Countrieswithlimitedindustrialdevelopmente.g.PakistanandEthiopiatend tohavehighbirthratesandmoderatetolowdeathrates.Thesenationsaregrowingrapidlywithannual ratesofnaturalpopulationchangeexceeding2percent. Severalfactorsinuence humanfertility .Importantfactorsinuencingbirthandfertilityratesin humanpopulationsare:auence,averagemarriageage,availabilityofbirthcontrol,familylaborneeds, culturalbeliefs,religiousbeliefsandthecostofraisingandeducatingchildren. Therapidgrowthoftheworld'spopulationoverthepast100yearsismainlyresultsfromadeclinein deathrates.Reasonsforthedropindeathratesinclude:betternutrition,fewerinfantdeaths,increased averagelifespanandimprovementsinmedicaltechnology. Ascountriesbecomedevelopedandindustrialized,theyexperienceamovementfromhighpopulation growthtolowpopulationgrowth.Bothdeathandbirthratesdecline. Thesecountriesusuallymovefromrapidpopulationgrowth,toslowgrowth,tozerogrowthandnally toareductioninpopulation.Thisshiftingrowthratewithdevelopmentiscalledthe" demographic transition ."Fourdistinctstagesoccurduringthetransition:pre-industrial,transitional,industrialand post-industrial. Duringthe pre-industrialstage ,harshlivingconditionsresultinahighbirthrateandahighdeathrate. Thepopulationgrowsveryslowly,ifatall.The transitionalstage beginsshortlyafterindustrialization. Duringthisphase,thedeathratedropsbecauseofincreasedfoodproductionandbettersanitationand healthconditions,but,thebirthrateremainshigh.Therefore,thepopulationgrowsrapidly. Duringthe industrialstage ,industrializationiswellestablishedinthecountry.Thebirthratedrops andeventuallyapproachesthedeathrate.Couplesincitiesrealizethatchildrenareexpensivetoraiseand thathavinglargefamiliesrestricttheirjobopportunities.The post-industrial stageoccurswhenthebirth ratedeclinesevenfurthertoequalthedeathrate,thuspopulationgrowthreacheszero.Thebirthratemay eventuallyfallbelowthedeathrate,resultinginnegativepopulationgrowth. TheUnitedStatesandmostEuropeancountrieshaveexperiencedthisgradualtransitionoverthepast 150years.Thetransitionmovesmuchfasterfortoday'sdevelopingcountries.Thisisbecauseimprovements inpreventivehealthandmedicalcareinrecentdecadeshavedramaticallyreducedmortalityespecially infantmortalityandincreasedlifeexpectancy.Inagrowingnumberofcountries,couplesarehaving fewerchildrenthanthetwotheyneedto"replace"themselves.However,evenifthelevelof" replacement fertility "werereachedtoday,populationswouldcontinuetogrowforseveraldecadesbecauseofthelarge numbersofpeoplenowenteringtheirreproductiveyears.

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32 CHAPTER6.HISTORYANDGLOBALDISTRIBUTION Asaresultofreducedfertilityandmortality,therewillbeagradualdemographicshiftinallcountries overthenextfewdecadestowardsanolderpopulation.Indevelopedcountries,theproportionofpeople overage65hasincreasedfrom8to14percentsince1950,andisexpectedtoreach25percentby2050. Withinthenext35years,thoseoverage65willrepresent30percentormoreofthepopulationsinJapan andGermany.Insomecountries,thenumberofresidentsoverage85willmorethandouble. 6.1.4PATTERNSOFRESOURCEUSE Humanshavealwaysmadeanimpactontheenvironmentthroughtheiruseofresources.Earlyhumanswere primarilyhunter-gathererswhousedtoolstosurvive.Theyfashionedwoodandstonetoolsforhuntingand foodpreparation,andusedreforcooking.Earlyhumansdevelopedmethodsforchanginghabitattosuit theirneedsandherdingwildanimals.Astimepassed,humansdevelopedmoretoolsandtechniquesand cametorelyonthattechnologyintheirdailylives.Althoughthetoolsofearlyhumanswereprimitiveby today'sstandards,theysignicantlyaectedtheenvironmentandprobablyhastenedtheextinctionofsome largeIceAgemammals. AftertheendofthelastIceAge,someeightto10,000yearsago,humansbegandomesticatingwild animalsandplants.Therstknowninstanceoffarmingstartedinaregionextendingfromsoutheastern TurkeytowesternIran,knownasthe fertilecrescent Theseearlyfarmersdomesticatedcropssuchaschickpea,bittervetch,grapes,olives,barley,emmer wheat,lentils,andax.Theyhybridizedwheatformakingbreadfromwildgrassandemmerwheat.They alsodomesticatedanimalssuchassheep,goats,cattleandpigs.Thefertilecrescent'suniquediversityof wildcropsandanimalsoeredhumansamixofbasicagriculturalcommoditiesthatallowedarevolution inthedevelopmentofhumansociety.Withareliablefoodsupply,humanswereabletostayinoneplace andbeassuredofhavingaconstantsupplyofcarbohydrates,protein,milkandoil.Theyhadanimalsfor transportationandplantandanimalmaterialsforproducingclothingandrope.Agriculturaleconomiessoon displacedhunter-gatherereconomies.Within2,000years,farmingrangedfromPakistantosouthernItaly. Mostearlyagriculturewassubsistencefarminginwhichfarmersgrewonlyenoughfoodtofeedtheir families.Agricultureunderwentanotherimportantrevolutionabout5,000yearsagowiththeinventionof theplow.Theplowallowedhumanstoclearandfarmlargerplotsoflandthanwasotherwisepossible.This increasedthefoodsupplyandaconcomitantincreaseinhumanpopulationgrowth.Moreecientfarming methodsalsoresultedinurbanizationbecauseafewfarmerscouldproducealargesurplusoffoodtofeed thoseintheurbanareas. Overthelast10,000years,landclearingforagriculturehasdestroyedanddegradedthehabitatsofmany speciesofplantsandanimals.Today,growingpopulationsinlessdevelopedcountriesarerapidlyclearing tropicalforestsandsavannasforagriculturaluse.Thesetropicalrainforestsandsavannasprovidehabitat formostoftheearth'sspecies.Ithasbecomeclearthatmodernagriculturalpracticesarenotsustainable. Once-fertileareasarebecominginfertilebecauseofovergrazing,erosionandnutrientdepletion.Furthermore, modernagriculturerequireslargeinputsofenergyandfertilizers,usuallyproducedfromnonrenewablefossil fuels. Thenextmajorculturalchange,the IndustrialRevolution ,beganinEnglandinthemid-18thcentury. Itinvolvedashiftfromsmall-scaleproductionofgoodsbyhandtolarge-scaleproductionofgoodsbymachines.Industrialproductionofgoodsincreasedtheconsumptionofnaturalresourcessuchasmineralsfuel, timberandwaterbycities.AfterWorldWarI,moreecientmassproductiontechniquesweredeveloped, andindustrializationbecameprevalentintheeconomiesoftheUnitedStates,Canada,Japanandwestern Europe. Advancedindustrializationleadstomanychangesinhumansociety,andsomeofthosechangesnegatively aectthesupplyofnaturalresourcesandresultinenvironmentaldegradation.Thesechangesinclude: increasedproductionandconsumptionofgoodsbyhumans,dependenceonnon-renewableresourcessuchas oilandcoal,productionofsyntheticmaterialswhichmaybetoxicornon-biodegradableandconsumption oflargeamountsofenergyathomeandwork. Otherchangesmayhavepositivebenets.Theseinclude:creationandmassproductionofusefuland aordableproducts,signicantincreasesintheaverage GrossNationalProduct perperson,largeincreases

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33 inagriculturalproductivity,sharprisesinaveragelifeexpectancyandagradualdeclineinpopulationgrowth rates. Theinformationagewasbornwiththeinventionofminiaturizedelectronicssuchasintegratedcircuits andcomputercentralprocessingunits.Thisstageinhumandevelopmenthaschangedandcontinuesto changesocietyasweknowit.Informationandcommunicationhavebecomethemost-valuedresources. Thisshiftinturn,maylessenourinuenceontheearth'senvironmentthroughreducednaturalresource consumption.Forinstance,inrecentyearsenergyuseintheUnitedStateshasnotincreasedtotheextent expectedfromeconomicgrowth.Onlineshopping,telecommutingandotherInternetactivitiesmaybe lesseninghumanenergyconsumption. Bymakinggooduseofinformationtechnologies,lessdevelopedcountriesmaybeabletoreducepotential environmentalproblemsastheireconomiesexpandinthefuture.Withsomuchinformationeasilyavailable, developingcountriesmaynotrepeattheenvironmentalmistakesthatmoredevelopedcountriesmadeasthey becameindustrialized.

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Chapter7 CARRYINGCAPACITY 1 7.1CARRYINGCAPACITY 7.1.1INTRODUCTION Thehumancarryingcapacityisaconceptexploredbymanypeople,mostfamouslyThomasRobertMalthus -1834,forhundredsofyears. Carryingcapacity,"K," referstothenumberofindividualsofa populationthatcanbesustainedindenitelybyagivenarea.Atcarryingcapacity,thepopulationwillhave animpactontheresourcesofthegivenarea,butnottothepointwheretheareacannolongersustainthe population.Justasapopulationofwildebeestoralgaehasacarryingcapacity,sodoesahumanpopulation. Humans,whilesubjecttothesameecologicalconstraintsasanyotherspeciesaneedfornutrients, water,etc.,havesomefeaturesasindividualsandsomeasapopulationthatmakethemauniquespecies. Unlikemostotherorganisms,humanshavethecapacitytoaltertheirnumberofospring,levelofresource consumptionanddistribution.Whilemostwomenaroundtheworldcouldpotentiallyhavethesamenumber ofchildrenduringtheirlives,thenumbertheyactuallyhaveisaectedbymanyfactors.Dependingupon technological,cultural,economicandeducationalfactors,peoplearoundtheworldhavefamiliesofdierent sizes.Additionally,unlikeotherorganisms,humansinventandaltertechnology,whichallowsthemtochange theirenvironment.ThisabilitymakesitdiculttodeterminethehumanK. 7.1.2EFFECTSOFTECHNOLOGYANDTHEENVIRONMENT Whenscholarsinthe1700'sestimatedthetotalnumberofpeoplethattodayearthcouldsustain,theywere livinginaverydierentworldthanourworld.Todayairplanescantransportpeopleandfoodhalfway aroundtheworldinamatterofhours,notweeksormonths,aswasthecasewithshipsinthe1700s.Today wehavesophisticated,poweredfarmequipmentthatcanrapidlyplow,plant,fertilizeandharvestacresof cropsaday.Onefarmercancultivatehundredsofacresofland.Thisisafarcryfromthedraft-animal plowing,handplantingandhandharvestingperformedbyfarmersinthe1700s.Additionally,synthetic fertilizers,pesticidesandmodernirrigationmethodsallowustoproducecropsonformerlymarginallands andincreasetheproductivityofotheragriculturallands.Withtheincreaseintheamountoflandthat eachindividualcanfarm,thefoodproductionhasincreased.Thisincreasedfoodproduction,inturn,has increasedthepotentialhumanKrelativetoestimatesfromthe1700s. WhereastechnologicaladvanceshaveincreasedthehumanK,changesinenvironmentalconditionscould potentiallydecreaseit.Forexample,aglobalorevenalargeregionalchangeintheclimatecouldreduce Kbelowcurrentestimates.Coastaloodingduetorisingoceanlevelsassociatedwithglobalwarmingand deserticationofagriculturallandsresultingfrompoorfarmingpracticesornaturalclimatevariationcould causefoodproductiontobelessthanthatuponwhichthehumancarryingcapacitywasoriginallyestimated. 1 Thiscontentisavailableonlineat. 35

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36 CHAPTER7.CARRYINGCAPACITY Therearethosewhobelievethatadvancesintechnologyandotherknowledgewillcontinuetoprovide themeanstofeedvirtuallyanyhumanpopulationsize.Thosewhosubscribetothisphilosophybelievethat thiscontinuousinnovationwill"saveus"fromourselvesandchangesintheenvironment. Othersbelievethattechnologywillitselfreachalimittoitscapabilities.Thisgrouparguesthatresources onearthincludingphysicalspacearelimitedandthateventuallywemustlearntolivewithinourmeans. Asidefromthephysicallimitationsoftheearth'snaturalresourcesandfoodproductioncapabilities,we mustconsidertheconditionswearewillingtolivewith. 7.1.3EFFECTOFSTANDARDOFLIVING Giventhewherewithaltodoso,humanshaveaestheticexpectationsintheirdailylives.Thisisaconsiderationthatislessevidentinotherspecies.Whiletheearthmightbeabletoholdmanymorethanthecurrent humanpopulationofsixbillionestimatesofthehumanKwithcurrenttechnologygoashighas50billion atsomepointpeoplewillnditunacceptabletolivewiththecrowdingandpollutionissuesassociatedwith adramaticincreaseinpopulation.Thequalitativemeasureofaperson'sorpopulation'squalityoflifeis calledits standardofliving .Itisassociatednotonlywithaestheticsofsurroundingsandlevelsofnoise, airandwaterpollution,butalsowithlevelsofresourceconsumption. Americanshaveoneoftheworld'shigheststandardsofliving.Whiletherearemanywholiveinpoverty intheUnitedStates,onaveragewehaverelativelysmallfamilies,largehomes,manypossessions,plentiful foodsupplies,cleanwaterandgoodmedicalcare.Thisisnotthecaseinmostofthedevelopingworld. Whilemanynationshavelargeraveragefamilysizes,theyhavesmallerhomes,fewerpossessionsandless food.Suppliesofcleanwatermaybescarceandmedicalcaremaybeinadequate.Allpeopledesiretohave adequateresourcestoprovidegoodcarefortheirfamilies,andthuspopulationinmostdevelopingcountries arestrivingforstandardoflivingofdevelopednations. IsitpossibleforallsixbillionpeopleonearthtoliveatthesamelevelofresourceuseasintheUnited States,JapanandWesternEurope?Withcurrenttechnology,theansweris"no."However,thisdoesnot meanthatthepeopleofonenationaremoreorlessentitledtoagivenstandardoflivingthanthoseof another.WhatitdoesmeanforcitizensofnationsliketheUnitedStatesisthatwemustreduceourcurrent useofresources.OfallofthefoodpurchasedbytheaverageAmericanfamily,10percentiswasted.In addition,becausemostAmericansarenotvegetarians,wetendtoeathighonthefoodchain,whichrequires moreresourcesthanavegetariandiet. Calculationofecologicaleciencyindicatethatfromonetrophiclevelonthefoodchaintothenext, thereisonlya10percenteciencyinthetransferofenergy.Thuspeoplewhopredominatelyeatmore grains,fruitsandvegetablesaregettingmoreoutoftheenergyrequiredtoproducethefoodthanthosewho eatalotofmeat.Thecaloriesthatapersongetsfrombeefaremuchfewerthanthecaloriesinthegrain requiredtoraisethecattle.Thepersonisbetteroskippingthemiddlemanormiddlecowinthiscase andeatingthegrain.Thisiswhymanymorepeoplecanbesustainedonadietthatconsistsofalarger percentageofrice,milletorwheat,ratherthanofsh,beeforchicken. Inadditiontoresourcesusedtoprovidefood,Americansusedisproportionateamountsofnaturalresourcessuchastreesforpaper,furnitureandbuilding,amongotherthingsandfossilfuelsforautomobiles, homesandindustry.Wealsoproduceagreatamountof"quickwaste."Packagingthatcomesonfoodin thegrocerystoreisagoodexampleofquickwaste.Thehardplasticpackagingusedforsnackfoodsthatis immediatelyremovedandthrownawayandplasticgrocerybagsarebothexamplesofquickwaste.Thus, patronizingfastfoodrestaurantsincreasesresourceconsumptionandsolidwasteproductionatthesame time. Thegoodnewsfortheenvironmentfrombothasolidwasteandaresourceusestandpointisthatwe caneasilyreducetheamountofgoodsandresourcesthatweuseandwastewithoutdrasticallyaecting ourstandardofliving.Byproperlyinatingcartires,Americacouldsavemillionsofbarrelsofoilannually. Ifweweretousemorerenewableenergyresourceslikesolarandwindpowerasopposedtopetroleum andnuclearenergytherewouldbeareducedneedtoextractnon-renewableresourcesfromtheearth.The amountofpackagingusedforgoodscouldalsobereduced.Reusablecanvasbagscouldbeusedforshopping andplasticandpapergrocerybagscouldbereused.

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37 Athome,manywastematerialscouldberecycled,insteadofbeingthrownaway.Theserelativelyeasy stepscouldreducetheoverallecologicalimpactthateachpersonhasontheearth.Thisimpactissometimes termedaperson's ecologicalfootprint .Thesmallereachperson'secologicalfootprint,thegreaterthe standardoflivingpossibleforeachperson.

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38 CHAPTER7.CARRYINGCAPACITY

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Chapter8 POPULATIONGROWTH 1 8.1POPULATIONGROWTH 8.1.1INTRODUCTION Familiesindevelopingnationsareoftenlarger,butlessresourceintensivee.g.,theyusefewerresources perpersonthanthoseinmoredevelopednations.However,increasinglyhumanpopulationswishtohave a"western"standardofliving.Anincreaseintheworld'saveragestandardoflivingsignicantlylowers thepotentialhumancarryingcapacityoftheearth.Therefore,inordertoreducetheirimpactasaspecies, humansmustnotonlyreducetheresourcestheyuseperperson,theymustalsoreducetheiraveragefamily size. Determiningwaystoreducefamilysizerequiresanunderstandingofthemanyfactorsdeterminingfamily sizeandtheresultantpopulationdynamicsoftheregion. Manyeconomicandculturalinuencesaectfamilysize.Dependingupontheprevailingculturalvalues andeconomicforces,anation'speoplecanbeinducedtohavelargerorsmallerfamilies. Althoughhumanpopulationdynamicsareoftenconsideredonaglobalscale,factorsthataectpopulation growthvaryindierentpartsoftheworld.Therefore,itisessentialtounderstandthedierentforcesacting onpeoplethroughouttheworld. 8.1.2ECONOMICFACTORS Someofthefactorsinuencingfamilysizeandthereforepopulationgrowthareeconomicones.These factorsareprobablythemosteasilyunderstood.Forinstance,aruralagriculturalfamilyinadeveloping countrythatreliesuponaplowpulledbyawaterbualoneedsmanyfamilymemberstotakecareofthe planting,harvestingandmarketingofcrops.Afamilyofthreewouldnotprovideenoughlabortosustain thefamilybusiness. Incontrast,familiesindevelopedcountriestendtobesmallforeconomicreasons.Itisexpensivetoraise childrenattherelativelyhighstandardoflivingfoundinsuchcountries.Considerableresourcesmustbe devotedtofood,clothes,transportation,entertainmentandschooling.Alargeproportionofchildrenfrom developedcountriesattendcollege,thusaddingevenmoretotheexpense.Therefore,itiseconomically prudentinsuchcountriesforfamiliestohavefewchildren. Obviously,therearetechnologicalandeducationalwaystonegatetheneedformanychildren.Ifthefarm familyinadevelopingcountryisabletoobtainbetterfarmingtoolsandinformation,theycanimprovethe farm'sproductionbyirrigatingcropsandbyusingtechniquessuchascroprotatione.g.,plantingdierent cropsindierentyearstomaintainsoilfertility,preventerosionandmaximizeyields.Withtheacquisition 1 Thiscontentisavailableonlineat. 39

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40 CHAPTER8.POPULATIONGROWTH ofsuchnewtoolsandfarmingtechniques,fewerfamilymembersarerequiredtoworkthesameamountof land.Thelandmayevenbecomemoreproductive,evenwithlessmanuallabor. Additionaleconomicfactorssuchasthecostofmedicalcareandretirementcarealsoplayarolein familysize.Ifafamilyisunabletoaordadequatemedicalcare,thenfamilyplanningservicesandbirth controlmaterialsmaynotbeattainable.Also,whenmortalityratesforchildrenarehighandsignicant numbersofchildrendonotlivetoadulthood,thereisastrongmotivationtohaveasmanychildrenas possible. Doingsoensuresthatsomeofthechildrenwilllivetohelpinthefamilybusiness,andprovidealinkto posterity WithoutnationalsocialsecurityprogramslikethoseintheUnitedStatesandSweden,theelderlyin developingcountriesrelyonyounger,workingmembersoftheirfamiliestosupportthemintheirretirement. Alargerfamilymeansamoresecurefuture.Theexpenseofanationalsocialsecurityprogramalsoactsto reducefamilysizeinacountry,asthehightaxesimposedonworkerstosupportthesystemmakessupporting largefamiliesdicult. 8.1.3CULTURALFACTORS Aroundtheglobe, culturalfactors inuencefamilysizeandasaresult,aectpopulationgrowthrate. Fromaculturalstandpoint,religioncanhaveaprofoundeectonfamilyplanning.Manyreligionspromote largefamiliesasawaytofurtherthereligionortoglorifyahigherpower.Forexample,OrthodoxJudaism encourageslargefamiliesinordertoperpetuateJudaism.RomanCatholicismpromoteslargefamiliesfor thesamereason,andforbidstheuseofany"articial"meansofbirthcontrol.Devoutfollowersofareligion withsuchvaluesoftenhavelargefamilieseveninthefaceofotherfactors,suchaseconomicones.Thiscan beseenincountrieslikeIsraelJudaismandBrazilCatholicism,whichhavehighpercentagesofreligious followersintheirpopulations.Bothcountrieshavehighbirthratesandhighpopulationgrowthrates. Variousfactorsinvolvingwomencanalsoaectfamilysizes.Thesefactorsinclude:educationand employmentopportunitiesavailabletowomen,themarriageageofwomenandthesocietalacceptanceof birthcontrolmethods.Thesefactorsaresometimesstronglyinuencedbysociety'sculturalattitudestowards women. Aroundtheworld,statisticsindicatethatwithhigherlevelsofeducation,womenaremorelikelytobe employedoutsidethehome;inaddition,highermarriageageofwomenandthegreatertheacceptanceof birthcontrolmethods,thesmallerthefamilysize.Itisclearthatincreasingeducationalandprofessional opportunitiesforwomenwouldreduceoverallpopulationgrowthandimprovestandardsoflivingworldwide.

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Chapter9 WATER 1 9.1WATER 9.1.1INTRODUCTION Water isanabundantsubstanceonearthandcovers71percentoftheearth'ssurface.Earth'swaterconsists ofthreepercentfreshwaterand97percentsaltwater.Alllivingorganismsrequirewaterinordertolive.In fact,theyaremostlycomprisedofwater.Waterisalsoimportantforotherreasons:asanagentoferosion itchangesthemorphologyoftheland;itactsasabueragainstextremeclimatechangeswhenpresentas alargebodyofwater,andithelpsushawayanddilutepollutantsintheenvironment. Thephysicalcharacteristicsofwaterinuencethewaylifeonearthexists.Theuniquecharacteristicsof waterare: 1.Waterisaliquidatroomtemperatureandoverarelativelywidetemperaturerange-100 C.This widerangeencompassestheannualmeantemperatureofmostbiologicalenvironments. 2.Arelativelylargeamountofenergyisrequiredtoraisethetemperatureofwateri.e.,ithasahigh heatcapacity .Asaresultofthisproperty,largebodiesofwateractasbuersagainstextreme uctuationsintheclimate,watermakesasanexcellentindustrialcoolant,andithelpsprotectliving organismsagainstsuddentemperaturechangesintheenvironment. 3.Waterhasaveryhighheatofvaporization.Waterevaporationhelpsdistributeheatglobally;it providesanorganismwiththemeanstodissipateunwantedheat. 4.Waterisagoodsolventandprovidesagoodmediumforchemicalreactions,includingthosethatare biologicallyimportant.Watercarriesnutrientstoanorganism'scellsandushesawaywasteproducts, anditallowstheowofionsnecessaryformuscleandnervefunctionsinanimals. 5.Liquidwaterhasaveryhigh surfacetension ,theforceholdingtheliquidsurfacetogether.This, alongwithitsabilitytoadheretosurfaces,enablestheupwardtransportofwaterinplantsandsoil bycapillaryaction. 6.Solidwatericehasalowerdensitythanliquidwateratthesurfaceoftheearth.Ificeweredenser thanliquidwater,itwouldsinkratherthanoat,andbodiesofwaterincoldclimateswouldeventually freezesolid,killingtheorganismslivinginthem. Freshwatercomprisesonlyaboutthreepercentoftheearth'stotalwatersupplyandisfoundaseithersurface waterorgroundwater.Surfacewaterstartsasprecipitation.Thatportionofprecipitationwhichdoesnot inltratethegroundiscalled runo .Runoowsintostreamsandlakes. Thedrainagebasinfromwhichwaterdrainsiscalleda watershed .Precipitationthatinltratesthe groundandbecomestrappedincracksandporesofthesoilandrockiscalled groundwater .Ifgroundwater isstoppedbyanimpermeablebarrierofrock,itcanaccumulateuntiltheporousregionbecomessaturated. 1 Thiscontentisavailableonlineat. 41

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42 CHAPTER9.WATER Thetopofthisaccumulationisknownasthe watertable .Porouslayersofsandandrockthroughwhich groundwaterowsarecalled aquifers Mostfreshwaterislockedupinfrozenglaciersordeepgroundwaterwhereitisnotuseablebymost livingorganisms.Onlyatinyfractionoftheearth'stotalwatersupplyisthereforeusablefreshwater.Still, theamountavailableissucienttomaintainlifebecauseofthenaturalwatercycle.Inthewatercycle, waterconstantlyaccumulates,becomespuried,andisredistributed.Unfortunately,ashumanpopulations acrosstheglobeincrease,theiractivitiesthreatentooverwhelmthenaturalcycleanddegradethequalityof availablewater. 9.1.2AGRICULTURALWATERUSE Agriculture isthesinglelargestuserofwaterintheworld.Mostofthatwaterisusedforirrigatingcrops. Irrigation istheprocessoftransportingwaterfromoneareatoanotherforthepurposeofgrowingcrops. Thewaterusedforirrigationusuallycomesfromriversorfromgroundwaterpumpedfromwells.Themain reasonforirrigatingcropsisthatitincreasesyields.Italsoallowsthefarmingofmarginallandinarid regionsthatwouldnormallynotsupportcrops.Thereareseveralmethodsofirrigation:oodirrigation, furrowirrigation,dripirrigationandcenterpivotirrigation. Floodirrigation involvestheoodingofacroparealocatedongenerallyatland.Thisgravityow methodofwaterisrelativelyeasytoimplement,especiallyifthenaturaloodingofriverplainsisutilized,and thereforeiscost-eective.However,muchofthewaterusedinoodirrigationislost,eitherbyevaporation orbypercolationintosoiladjacenttotheintendedareaofirrigation.Becausefarmlandmustbeatfor oodirrigationtobeused,oodirrigationisonlypracticalincertainarease.g.riveroodplainsand bottomlands.Inaddition,becauselandiscompletelyooded,saltsfromtheirrigationwatercanbuildup inthesoil,eventuallyrenderingitinfertile. Furrowirrigation alsoinvolvesgravityowofwateronrelativelyatland.However,inthisformof irrigation,thewaterowisconnedtofurrowsorditchesbetweenrowsofcrops.Thisallowsbettercontrol ofthewaterand,therefore,lesswaterisneededandlessiswasted.Becausewatercanbedeliveredtothe furrowsfrompipes,thelanddoesnotneedtobecompletelyat.However,furrowirrigationinvolveshigher operatingcoststhanoodirrigationduetotheincreasedlaborandequipmentrequired.It,too,involves largeevaporativeloss. Dripirrigation involvesdeliveringsmallamountsofwaterdirectlytoindividualplants.Wateris releasedthroughperforatedtubingmountedaboveorbelowgroundneartherootsofindividualplants.This methodwasoriginallydevelopedinIsraelforuseinaridregionshavinglimitedwateravailableforirrigation. Itishighlyecient,withlittlewasteofwater.Somedisadvantagesofdripirrigationarethehighcostsof installationandmaintenanceofthesystem.Therefore,itisonlypracticalforuseonhigh-valuecashcrops. Center-pivotsprinklersystems deliverwatertocropsfromsprinklersmountedonalongboom,which rotatesaboutacenterpivot.Waterispumpedtothepivotfromanearbyirrigationwell.Thissystemhas theadvantagethatitisverymobileandcanbemovedfromoneeldtoanotherasneeded.Itcanalsobe usedonunevencropland,asthemovingboomcanfollowthecontoursoftheland.Center-pivotsystemsare widelyusedinthewesternplainsandsouthwestregionsoftheUnitedStates.Withpropermanagement, properlydesignedsystemscanbealmostasecientasdripirrigationsystems.Center-pivotsystemshave highinitialcostsandrequireanearbyirrigationwellcapableofprovidingasucientlyhighow.Constant irrigationwithwellwatercanalsoleadtosalinizationofthesoil. 9.1.3DOMESTICANDINDUSTRIALWATERUSE Waterisimportantforalltypesofindustriesi.e.,manufacturing,transportationandmining.Manufacturingsitesareoftenlocatednearsourcesofwater.Amongotherproperties,waterisanexcellentand inexpensivesolventandcoolant.Manymanufacturedliquidproductshavewaterastheirmainingredient. Chemicalsolutionsusedinindustrialandminingprocessesusuallyhaveanaqueousbase.Manufacturing equipmentiscooledbywaterandcleanedwithwater.Waterisevenusedasameansoftransportinggoods

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43 fromoneplacetoanotherinmanufacturing.Nuclearpowerplantsusewatertomoderateandcoolthe reactorcoreaswellastogenerateelectricity.Industrywouldliterallycometoastandstillwithoutwater. Peopleusewaterfordomesticpurposessuchaspersonalhygiene,foodpreparation,cleaning,andgardening.Developedcountries,especiallytheUnitedStates,tendtouseagreatdealofwaterfordomestic purposes. Waterusedforpersonalhygieneaccountsforthebulkofdomesticwateruse.Forexample,thewater usedinasingledayinsinks,showers,andtoiletsinLosAngeleswouldllalargefootballstadium.Humans requireareliablesupplyofpotablewater;otherwiseserioushealthproblemsinvolvingwater-bornediseases canoccur.Thisrequirestheestablishmentandmaintenanceofmunicipalwatertreatmentplantsinlarge populatedareas. Muchcleanwateriswastedinindustrialanddomesticuse.IntheUnitedStatesthisismainlydue tothegenerallylowcostofwater.Providingsucientquantitiesofcleanwaterinlargepopulationareas isbecomingagrowingproblem,though.Conservationmeasurescanminimizetheproblem:redesigning manufacturingprocessestouselesswater;usingvegetationforlandscapinginaridregionsthatrequiresless water;usingwater-conservingshowersandtoiletsandreusinggraywaterforirrigationpurposes. 9.1.4CONTROLOFWATERRESOURCES Householdsandindustrybothdependonreliablesuppliesofcleanwater.Therefore,themanagementand protectionofwaterresourcesisimportant.Constructingdamsacrossowingriversorstreamsandimpoundingthewaterinreservoirsisapopularwaytocontrolwaterresources.Damshaveseveraladvantages:they allowlong-termwaterstorageforagricultural,industrialanddomesticuse;theycanprovidehydroelectric powerproductionanddownstreamoodcontrol.However,damsdisruptecosystems,theyoftendisplace humanpopulationsanddestroygoodfarmland,andeventuallytheyllwithsilt. Humansoftentapintothenaturalwatercyclebycollectingwaterinman-madereservoirsorbydigging wellstoremovegroundwater.Waterfromthosesourcesischanneledintorivers,man-madecanalsorpipelines andtransportedtocitiesoragriculturallands.Suchdiversionofwaterresourcescanseriouslyaectthe regionsfromwhichwateristaken. Forexample,theOwensValleyregionofCaliforniabecameadesertafterwaterprojectsdivertedmost oftheSierraNevadarunototheLosAngelesmetropolitanarea.Thisbringsupthequestionofwhoowns orhastherightstowaterresources. Waterrightsareusuallyestablishedbylaw.IntheeasternUnitedStates,the" DoctrineofRiparian Rights "isthebasisofrightsofuse.Anyonewhoselandisnexttoaowingstreamcanusethewateraslong assomeisleftforpeopledownstream.ThingsarehandleddierentlyinthewesternUnitedStates,which usesa"rst-come,rst-served"approachknownasthe" PrincipleofPriorAppropriation "isused.By usingwaterfromastream,theoriginaluserestablishesalegalrightfortheongoinguseofthewatervolume originallytaken.Unfortunately,whenthereisinsucientwaterinastream,downstreamuserssuer. ThecaseoftheColoradoRiverhighlightstheproblemofwaterrights.Thefederalgovernmentbuilta seriesofdamsalongtheColoradoRiver,whichdrainsahugeareaofthesouthwesternUnitedStatesand northernMexico.Thepurposeoftheprojectwastoprovidewaterforcitiesandtownsinthisaridarea andforcropirrigation.However,asmoreandmorewaterwaswithdrawnfromthesedams,lesswaterwas availabledownstream.OnlyalimitedvolumeofwaterreachedtheMexicanborderandthiswassalineand unusable.TheMexicangovernmentcomplainedthattheircountrywasbeingdenieduseofwaterthatwas partlytheirs,andasaresultadesalinizationplantwasbuilttoprovideaowofusablewater. Commonlawgenerallygivespropertyownersrightstothegroundwaterbelowtheirland.However,a problemcanariseinasituationwhereseveralpropertyownerstapintothesamegroundwatersource.The OgallalaAquifer,whichstretchesfromWyomingtoTexas,isusedextensivelybyfarmersforirrigation. However,thisuseisleadingtogroundwaterdepletion,astheaquiferhasaveryslowrechargerate.Insuch casesasthis,ageneralplanofwateruseisneededtoconservewaterresourcesforfutureuse.

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44 CHAPTER9.WATER 9.2WaterDiversion Waterisnecessaryforalllife,aswellasforhumanagricultureandindustry.Greateortandexpensehas goneintodivertingwaterfromwhereitoccursnaturallytowherepeopleneedittobe.Thelarge-scale redistributionofsuchavitalresourcehasconsequencesforbothpeopleandtheenvironment.Thethree projectssummarizedbelowillustratethecostsandbenetsandcomplexissuesinvolvedinwaterdiversion. 9.3GarrisonDiversionProject ThepurposeoftheGarrisonDiversionProjectwastodivertwaterfromtheMissouriRivertotheRedRiver inNorthDakota,alongthewayirrigatingmorethanamillionacresofprairie,attractingnewresidentsand industries,andprovidingrecreationopportunities. Constructionbeganinthe1940s,andalthough$600millionhasbeenspent,only120milesofcanalsand afewpumpingstationshavebeenbuilt.Theprojecthasnotbeencompletedduetonancialproblemsand widespreadobjectionsfromenvironmentalists,neighboringstates,andCanada.Someobjecttooodingrare prairiehabitats.Manyareconcernedthatmovingwaterfromonewatershedtoanotherwillalsotransfernonnativeandinvasivespeciesthatcouldattacknativeorganisms,devastatehabitats,andcauseeconomicharm toshingandotherindustries.Asconstructionandmaintenancecostsskyrocketed,taxpayersexpressed concernthatexcessivepublicmoneywasbeingspentonaprojectwithlimitedpublicbenets. 9.4MelamchiWaterSupplyProject TheKathmanduValleyinNepalisanimportanturbancenterwithinsucientwatersupplies.Onemillion peoplereceivepipedwaterforjustafewhoursaday.Groundwaterreservoirsarebeingdrained,andwater qualityisquitelow.TheMelamchiWaterSupplyProjectwilldivertwatertoKathmanduthrougha28km tunnelfromtheMelamchiRiverinaneighboringvalley.Expectedtocostahalfabilliondollars,theproject willincludeimprovedwatertreatmentanddistributionfacilities. WhilethewaterproblemsintheKathmanduValleyaresevere,theprojectiscontroversial.Proponents sayitwillimprovepublichealthandhygieneandstimulatethelocaleconomywithoutharmingtheMelamchi Riverecosystem.Opponentssuggestthattheenvironmentalsafeguardsareinadequateandthatanumber ofpeoplewillbedisplaced.Perhapstheirbiggestobjectionisthattheprojectwillprivatizethewatersupply andraisecostsbeyondthereachofthepoor.Theyclaimthatcheaperandmoreecientalternativeshave beenignoredattheinsistenceofinternationalbanks,andthatdebtonprojectloanswillcrippletheeconomy. 9.5SouthtoNorthWaterDiversionProject ManyofthemajorcitiesinChinaaresueringfromseverewatershortages,especiallyinthenorthernpartof thecountry.Overuseandindustrialdischargehascausedseverewaterpollution.TheSouthtoNorthWater DiversionprojectisdesignedtoshiftenormousamountsofwaterfromriversinsouthernChinatothedry butpopulousnorthernhalfofthecountry.Newpollutioncontrolandtreatmentfacilitiestobeconstructed atthesametimeshouldimprovewaterqualitythroughoutthecountry. Thediversionwillbeaccomplishedbythecreationofthreeriversconstructedbyman,eachmorethan 1,000kmlong.Theywilltogetherchannelnearly50billioncubicmetersofwaterannually,creatingthe largestwaterdiversionprojectinhistory.Constructionisexpectedtotake10yearsandcost$60billion,but after2yearsofwork,thediversionisalreadyoverbudget. Suchamassiveshiftinwaterresourceswillhavelargeenvironmentalconsequencesthroughoutthesystem. Waterlevelsinriversandmarsheswilldropsharplyinthesouthandriseinthenorth.Peopleandwildlife willbedisplacedalongthecoursesofthenewrivers.

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45 Despiteitsstaggeringscale,theSouthtoNorthProjectalonewillnotbesucienttosolvewatershortages.Chinastillwillneedtoincreasewaterconservationprograms,makeindustriesandagriculturemore waterecient,andraisepublicawarenessofsustainablewaterpractices.

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Chapter10 MINERALS 1 10.1MINERALS 10.1.1INTRODUCTION Theearth'scrustiscomposedofmanykindsofrocks,eachofwhichisanaggregateofoneormoreminerals. Ingeology,thetermmineraldescribesanynaturally-occurringsolidsubstancewithaspeciccomposition andcrystalstructure.Amineral's composition referstothekindsandproportionsofelementsmakingup themineral.Thewaytheseelementsarepackedtogetherdeterminesthestructureofthemineral.More than3,500dierentmineralshavebeenidentied.Thereareonly12commonelementsoxygen,silicon, aluminum,iron,calcium,magnesium,sodium,potassium,titanium,hydrogen,manganese,phosphorusthat occurintheearth'scrust.Theyhaveabundancesof0.1percentormore.Allothernaturallyoccurring elementsarefoundinveryminorortraceamounts. Siliconandoxygenarethemostabundantcrustalelements,togethercomprisingmorethan70percentby weight.Itisthereforenotsurprisingthatthemostabundantcrustalmineralsarethesilicatese.g.olivine, Mg2SiO4,followedbytheoxidese.g.hematite,Fe2O3. Otherimportanttypesofmineralsinclude:the carbonates e.g.calcite,CaCO3the suldes e.g. galena,PbSandthe sulfates e.g.anhydrite,CaSO4.Mostoftheabundantmineralsintheearth'scrust arenotofcommercialvalue.Economicallyvaluablemineralsmetallicandnonmetallicthatprovidetheraw materialsforindustrytendtoberareandhardtond.Therefore,considerableeortandskillisnecessary forndingwheretheyoccurandextractingtheminsucientquantities. 10.1.2ECONOMICVALUEOFMINERALS Mineralsthatareofeconomicvaluecanbeclassiedas metallic or nonmetallic .Metallicmineralsare thosefromwhichvaluablemetalse.g.iron,coppercanbeextractedforcommercialuse.Metalsthat areconsideredgeochemicallyabundantoccuratcrustalabundancesof0.1percentormoree.g.iron, aluminum,manganese,magnesium,titanium.Metalsthatareconsideredgeochemicallyscarceoccurat crustalabundancesoflessthan0.1percente.g.nickel,copper,zinc,platinummetals.Someimportant metallicmineralsare:hematiteasourceofiron,bauxiteasourceofaluminum,sphaleriteasourceof zincandgalenaasourceoflead.Metallicmineralsoccasionallybutrarelyoccurasasingleelemente.g. nativegoldorcopper. Nonmetallicmineralsarevaluable,notforthemetalstheycontain,butfortheirpropertiesaschemical compounds.Becausetheyarecommonlyusedinindustry,theyarealsooftenreferredtoasindustrial minerals.Theyareclassiedaccordingtotheiruse.Someindustrialmineralsareusedassourcesofimportant chemicalse.g.haliteforsodiumchlorideandboraxforborates.Someareusedforbuildingmaterialse.g. 1 Thiscontentisavailableonlineat. 47

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48 CHAPTER10.MINERALS gypsumforplasterandkaolinforbricks.Othersareusedformakingfertilizerse.g.apatiteforphosphate andsylviteforpotassium.Stillothersareusedasabrasivese.g.diamondandcorrundum. 10.1.3MINERALDEPOSITS Mineralsareeverywherearoundus.Forexample,theoceanisestimatedtocontainmorethan70million tonsofgold.Yet,itwouldbemuchtooexpensivetorecoverthatgoldbecauseofitsverylowconcentration inthewater.Mineralsmustbeconcentratedintodepositstomaketheircollectioneconomicallyfeasible.A mineraldepositcontainingoneormoremineralsthatcanbeextractedprotablyiscalledan ore .Many mineralsarecommonlyfoundtogethere.g.quartzandgold;molybdenum,tinandtungsten;copper,lead andzinc;platinumandpalladium.Becausevariousgeologicprocessescancreatelocalenrichmentsof minerals,mineraldepositscanbeclassiedaccordingtotheconcentrationprocessthatformedthem.The vebasictypesofmineraldepositsare: hydrothermal magmatic sedimentary placer and residual Hydrothermalmineraldepositsareformedwhenmineralsaredepositedbyhot,aqueoussolutionsowing throughfracturesandporespacesofcrustalrock.Manyfamousorebodieshaveresultedfrom hydrothermal deposition,includingthetinminesinCornwall,EnglandandthecopperminesinArizonaandUtah. Magmatic mineraldepositsareformedwhenprocessessuchaspartialmeltingandfractionalcrystallization occurduringthemeltingandcoolingofrocks.Pegmatiterocksformedbyfractionalcrystallizationcan containhighconcentrationsoflithium,berylliumandcesium.Layersofchromitechromeorewerealso formedbyigneousprocessesinthefamousBushveldIgneousComplexinSouthAfrica. Severalmineralconcentrationprocessesinvolvesedimentationorweathering.Watersolublesaltscan form sedimentary mineraldepositswhentheyprecipitateduringevaporationoflakeorseawaterevaporate deposits.Importantdepositsofindustrialmineralswereformedinthismanner,includingtheboraxdeposits atDeathValleyandSearlesLake,andthemarinedepositsofgypsumfoundinmanystates. Mineralswithahighspecicgravitye.g.gold,platinum,diamondscanbeconcentratedbyowing waterinplacerdepositsfoundinstreambedsandalongshorelines.Themostfamousgold placer deposits occurintheWitwatersrandbasinofSouthAfrica. Residual mineraldepositscanformwhenweathering processesremovewatersolublemineralsfromanarea,leavingaconcentrationoflesssolubleminerals.The aluminumore,bauxite,wasoriginallyformedinthismannerundertropicalweatheringconditions.Thebest knownbauxitedepositintheUnitedStatesoccursinArkansas. 10.1.4MINERALUTILIZATION Mineralsarenotevenlydistributedintheearth'scrust.Mineral ores arefoundinjustarelativelyfew areas,becauseittakesaspecialsetofcircumstancestocreatethem.Therefore,thesignsofamineral depositareoftensmallanddiculttorecognize.Locatingdepositsrequiresexperienceandknowledge. Geologistscansearchforyearsbeforendinganeconomicmineraldeposit.Depositsize,itsmineralcontent, extractingeciency,processingcostsandmarketvalueoftheprocessedmineralsareallfactorsthatdetermine ifamineraldepositcanbeprotablydeveloped.Forexample,whenthemarketpriceofcopperincreased signicantlyinthe1970s,somemarginalorlow-gradecopperdepositssuddenlybecameprotableorebodies. Afterapotentiallyprotablemineraldepositislocated,itisminedbyoneofseveraltechniques.Which techniqueisuseddependsuponthetypeofdepositandwhetherthedepositisshallowandthussuitablefor surfaceminingordeepandthusrequiringsub-surfacemining. Surfaceminingtechniquesinclude:open-pitmining,areastripmining,contourstripminingandhydraulic mining. Open-pitmining involvesdiggingalarge,terracedholeinthegroundinordertoremoveanearsurfaceorebody.ThistechniqueisusedincopperoreminesinArizonaandUtahandironoreminesin Minnesota. Areastripmining isusedinrelativelyatareas.Theoverburdenofsoilandrockisremovedfroma largetrenchinordertoexposetheorebody.Afterthemineralsareremoved,theoldtrenchislledanda newtrenchisdug.Thisprocessisrepeateduntiltheavailableoreisexhausted. Contourstripmining is asimilartechniqueexceptthatitisusedonhillyormountainousterrains.Aseriesofterracesarecutinto thesideofaslope,withtheoverburdenfromeachnewterracebeingdumpedintotheoldonebelow.

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49 Hydraulicmining isusedinplacessuchastheAmazoninordertoextractgoldfromhillsides.Powerful, high-pressurestreamsofwaterareusedtoblastawaysoilandrockcontaininggold,whichisthenseparated fromtheruno.Thisprocessisverydamagingtotheenvironment,asentirehillsareerodedawayand streamsbecomecloggedwithsediment.Iflandsubjectedtoanyofthesesurfaceminingtechniquesisnot properlyrestoredafteritsuse,thenitleavesanunsightlyscaronthelandandishighlysusceptibletoerosion. Somemineraldepositsaretoodeeptobesurfaceminedandthereforerequirea sub-surfacemining method.Inthetraditionalsubsurfacemethodadeepverticalshaftisdugandtunnelsaredughorizontally outwardfromtheshaftintotheorebody.Theoreisremovedandtransportedtothesurface.Thedeepest suchsubsurfaceminesdeeperthan3500mintheworldarelocatedintheWitwatersrandbasinofSouth Africa,wheregoldismined.Thistypeofminingislessdisturbingtothelandsurfacethansurfacemining. Italsousuallyproducesfewerwastematerials.However,itismoreexpensiveandmoredangerousthan surfaceminingmethods. Anewerformofsubsurfaceminingknownas in-situmining isdesignedtoco-existwithotherland uses,suchasagriculture.Anin-situminetypicallyconsistsofaseriesofinjectionwellsandrecoverywells builtwithacid-resistantconcreteandpolyvinylchloridecasing.Aweakacidsolutionispumpedintothe orebodyinordertodissolvetheminerals.Then,themetal-richsolutionisdrawnupthroughtherecovery wellsforprocessingatareningfacility.Thismethodisusedforthein-situminingofcopperore. Onceanorehasbeenmined,itmustbeprocessedtoextractpuremetal.Processesforextractingmetal includesmelting,electrowinningandheapleaching.Inpreparationforthe smelting process,theoreis crushedandconcentratedbyaotationmethod.Theconcentratedoreismeltedinasmeltingfurnacewhere impuritiesareeitherburned-oasgasorseparatedasmoltenslag.Thisstepisusuallyrepeatedseveral timestoincreasethepurityofthemetal. Forthe electrowinning methodoreorminetailingsarerstleachedwithaweakacidsolutiontoremove thedesiredmetal.Anelectriccurrentispassedthroughthesolutionandpuremetaliselectroplatedontoa startercathodemadeofthesamemetal.Coppercanberenedfromoxideorebythismethod.Inaddition, coppermetalinitiallyproducedbythesmeltingmethodcanbepuriedfurtherbyusingasimilarelectrolytic procedure. Goldissometimesextractedfromorebythe heapleaching process.Alargepileofcrushedoreissprayed withacyanidesolution.Asthesolutionpercolatesthroughtheoreitdissolvesthegold.Thesolutionisthen collectedandthegoldextractedfromit.Allofthereningmethodscandamagetheenvironment.Smelters producelargeamountsofairpollutionintheformofsulfurdioxidewhichleadstoacidrain.Leaching methodscanpollutestreamswithtoxicchemicalsthatkillwildlife. 10.1.5MINERALSUFFICIENCYANDTHEFUTURE Mineralresourcesareessentialtolifeasweknowit.Anationcannotbeprosperouswithoutareliablesource ofminerals,andnocountryhasallthemineralresourcesitrequires.TheUnitedStateshasabout5percentof theworld'spopulationand7percentoftheworld'slandarea,butusesabout30percentoftheworld'smineral resources.Itimportsalargepercentageofitsminerals;insomecasessucientquantitiesareunavailablein theU.S.,andinotherstheyarecheapertobuyfromothercountries.Certainminerals,particularlythose thatareprimarilyimportedandconsideredofvitalimportance,arestockpiledbytheUnitedStatesinorder toprotectagainstembargoesorotherpoliticalcrises.Thesestrategicmineralsinclude:bauxite,chromium, cobalt,manganeseandplatinum. Becausemineralsareproducedslowlyovergeologictimescales,theyareconsiderednon-renewableresources.Theestimatedmineraldepositsthatareeconomicallyfeasibletomineareknownasmineralreserves. Thegrowinguseofmineralresourcesthroughouttheworldraisesthequestionofhowlongthesereserves willlast.Mostmineralsareinsucientsupplytolastformanyyears,butafewe.g.gold,silver,lead, tungstenandzincareexpectedtofallshortofdemandinthenearfuture.Currently,reservesforaparticular mineralusuallyincreaseasthepriceforthatmineralincreases.Thisisbecausethehigherpricemakesit economicallyfeasibletominesomepreviouslyunprotabledeposits,whichthenshiftsthesedepositstothe reserves.However,inthelongtermthiswillnotbethecasebecausemineraldepositsareultimatelynite.

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50 CHAPTER10.MINERALS Therearewaystohelpprolongthelifeofknownmineralreserves.Conservationisanobviousmethod forstretchingreserves.Ifyouuseless,youneedless.Recyclinghelpsincreasetheamountoftimea mineralormetalremainsinuse,whichdecreasesthedemandfornewproduction.Italsosavesconsiderable energy,becausemanufacturingproductsfromrecycledmetalse.g.aluminum,copperuseslessenergythan manufacturingthemfromrawmaterials.Governmentlegislationthatencouragesconservationandrecycling isalsohelpful.Thecurrent"GeneralMiningActof1872,"however,doesjusttheopposite.Itallowsmining companiestopurchasegovernmentlandveryinexpensivelyandnotpayanyroyaltiesformineralsextracted fromthatland.Asaresult,mineralpricesarekeptarticiallylowwhichdiscouragesconservationand recycling.

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Chapter11 SOILS 1 11.1SOILS 11.1.1INTRODUCTION Soilplaysanimportantroleinlandecosystems.Inorderforacommunityofproducersandconsumers tobecomeestablishedonland,soilmustbepresent.Furthermore,soilqualityisoftenalimitingfactor forpopulationgrowthinecosystems.Soilisacomplexmixtureofinorganicmaterials,organicmaterials, microorganisms,waterandair.Itsformationbeginswiththeweatheringofbedrockorthetransportof sedimentsfromanotherarea.Thesesmallgrainsofrockaccumulateonthesurfaceoftheearth.There theyaremixedwithorganicmattercalled humus ,whichresultsfromthedecompositionofthewasteand deadtissueoforganisms.Inltratingrainwaterandairalsocontributetothemixtureandbecometrapped inporespaces.Thisformationprocessisveryslowhundredstothousandsofyears,andthussoillossor degradationcanbeverydetrimentaltoacommunity. 11.1.2SOILPROFILE Maturesoilsarelayered.Theselayersareknownas soilhorizons ,andeachhasadistincttextureand composition.Atypicalsoilhasasoilproleconsistingoffourhorizons,whicharedesignated:O,A,Band C.The Ohorizon isthetoplayerattheearth'ssurface.Itconsistsofsurfacelitter,suchasfallenleaves du,sticksandotherplantmaterial,animalwasteanddeadorganisms.AdistinctOhorizonmaynotexist inallsoilenvironmentse.g.,desertsoil.BelowtheOhorizonisthe Ahorizon ,whichisalsoknownas topsoil .Thislayercontainsorganichumus,whichusuallygivesitadistinctivedarkcolor.The Bhorizon orsub-soilisthenextlayerdownfromthesurface.Itconsistsmostlyofinorganicrockmaterialssuchas sand,siltandclay.The Chorizon sitsatopbedrockandthereforeismadeupofweatheredrockfragments. Thebedrockisthesourceoftheparentinorganicmaterialsfoundinthesoil. TheOhorizonprotectstheunderlyingtopsoilfromerosionandmoisturelossbyevaporation.TheOand Ahorizonsintypicalmaturesoilshaveanabundanceofmicroorganismse.g.fungi,bacteria,earthworms andinsects.Theseorganismsdecomposetheorganicmaterialfromdeadorganismsandanimalwasteinto inorganicnutrientsuseablebyplants.TheorganichumusintheAhorizonaidsinholdingwaterandnutrients, makingitthemostfertilelayer.Therefore,plantswithshallowrootsareanchoredintheAhorizon.Water seepingthroughtheupperlayersmaydissolvewater-solublemineralsandtransportthemtolowerlayersin aprocesscalled leaching .Veryneclayparticlescanalsobetransportedbyseepingwaterandaccumulate inthesubsoillayer.Theaccumulationofclayparticlesandleachedmineralscanleadtocompactionofthe Bhorizon.Thiscompactioncanlimittheowofwaterthroughthelayerandcausethesoilabovetobecome waterlogged. 1 Thiscontentisavailableonlineat. 51

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52 CHAPTER11.SOILS TheBhorizonisnotasfertileastheAhorizon,butdeep-rootedplantscanutilizethewaterandminerals leachedintothislayer.TheChorizonrepresentsatransitionzonebetweenthebedrockandthesoil.Itlacks organicmaterial,butmaybesaturatedwithgroundwaterthatisunabletomovedeeperduetothesolid barrierofbedrockbelow. Dierenttypesofsoilmayhavedierentnumbersofhorizons,andthecompositionandthicknessofthose horizonsmayvaryfromsoiltosoil.Thetypeofsoildependsonanumberoffactorsincluding:thetype ofparentrockmaterial,thetypeofvegetation,theavailabilityoforganicmatter,waterandminerals,and theclimate.GrasslandanddesertsoilslackasignicantOhorizonastheygenerallyhavenoleaflitter. Grasslandsoil mayhaveaverythick,fertileAhorizon,whiledesertandtropicalrainforestsoilsmayhave verythin,nutrientpoorAhorizons.TheAhorizonsinconiferousforestsmaybeseverelyleached. 11.1.3SOILCHARACTERISTICS Mostsoilconsistsofweatheredinorganicrockmaterial.Therelativeamountsofdierentsizesandtypesof rockparticlesorgrainsdeterminesthetextureofthesoil.Thethreemaintypesofrockgrainsfoundinsoil are: sand silt and clay .Sandgrainshavethelargestgrainsizes.05-2.0mmofthethree.Siltparticles arene-grained.05-0.002mmandclayparticlesareveryne-grained < 0.002mm.Sandgrainsgivesoil itsgrittyfeel,andclayparticlesmakeitsticky.Soilsarenamedaccordingtowheretheirsandsiltandclay compositionplotsonasoilstructuretriangle.Variousregionsofthetrianglearegivendierentnames.A soilcontainingabout20:40:40mixtureofclay,siltandsandplotAtypicalloamsoilismadeupofabouta 20:40:40mixtureofclay,siltandsand.Ifthepercentageofsandisalittlehigher,thesoiliscalleda sandy loam ,andifthepercentageofsiltisalittlehigherthesoilisa siltyloam Thetextureofthesoildeterminesitsporosityandpermeability. Soilporosity isameasureofthe volumeofporespacesbetweensoilgrainspervolumeofsoilanddeterminesthewaterandairoxygen holdingcapacityofthesoil.Coarsegrainswithlargeporesprovidebetteraerationandnegrainswith smallporesprovidegoodwaterretention. Theaverageporesizedeterminesthesoilpermeabilityoreasewithwhichwatercaninltratethesoil. Sandysoilshavelowporositiesandhighpermeabilitiesi.e.waterisnotretainedwell,butowsthrough themeasily,andaerationisgood.Ontheotherhand,claysoilshavehighporositiesandlowpermeabilities i.e.waterisretainedverywell,butdoesnotowthroughiteasilyandaerationispoor.Soiltextureis thereforeimportantindeterminingwhattypeofvegetationthrivesonaparticularsoil. Thesoilstructureor"tilth"isrelatedtothesoiltexture. Soiltilth describeshowthevariouscomponents ofthesoilclingtogetherintoclumps.Itisdeterminedbytheamountofclayandhumusinthesoil.The physicalandchemicalpropertiesofclayandhumusenablethemtoadheretootherparticlesinthesoil, thusforminglargeaggregates.Thesesamepropertiesalsohelpprotectthesoilfromnutrientleaching.Soils lackingclayandhumusareverylooseandareeasilyblownorshiftedbythewindi.e.sanddunesinthe desert. 11.1.4SOILFERTILITYANDpH Thereare16elementsessentialforplantgrowth.Plantsobtainthreeofthemprimarilyfromairandwater: carbon,hydrogenandoxygen.Theother13elementsgenerallycomefromthesoil.Theseessentialelements forplantgrowthcanbegroupedintothreetypes: primarymacronutrients nitrogen,potassium,phosphorus, secondarymacronutrients calcium,magnesium,sulfurand micronutrients boron,chlorine, iron,manganese,copper,zinc,molybdenum.Theavailableprimarymacronutrientsinthesoilareusually thelimitingfactorinplantgrowth.Inundisturbedsoils,thesemacronutrientsarereplenishedbythenatural cyclesofmatter.Infarmedsoils,theyareremovedfromthenaturalcycleinsuchlargeamountswhen cropsareharvestedthattheyusuallymustbereplacedbysupplementarymeanse.g.fertilizer.Because micronutrientsarerequiredbyplantsinmuchlowerquantities,theyareoftennaturallymaintainedinthe soilinsucientquantitiestomakesupplementationwithfertilizersunnecessary. Animportantfactoraectingsoilfertilityissoil pH thenegativelogofthehydrogenionconcentration. SoilpHisameasureoftheacidityoralkalinityofthesoilsolution.OnthepHscaleto14avalueof

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53 sevenrepresentsaneutralsolution;avaluelessthansevenrepresentsan acidicsolution andavaluegreater thansevenrepresentsan alkalinesolution .SoilpHaectsthehealthofmicroorganismsinthesoiland controlstheavailabilityofnutrientsinthesoilsolution.Stronglyacidicsoilslessthan5.5hinderthe growthofbacteriathatdecomposeorganicmatterinthesoil.Thisresultsinabuildupofundecomposed organicmatter,whichleavesimportantnutrientssuchasnitrogeninformsthatareunusablebyplants. SoilpHalsoaectsthesolubilityofnutrient-bearingminerals.Thisisimportantbecausethenutrients mustbedissolvedinsolutionforplantstoassimilatethemthroughtheirroots.Mostmineralsaremore solubleinslightlyacidicsoilsthaninneutralorslightlyalkalinesoils. StronglyacidsoilspHfourtove,though,canresultinhighconcentrationsofaluminum,ironand manganeseinthesoilsolution,whichmayinhibitthegrowthofsomeplants.Otherplants,however,such asblueberries,thriveinstronglyacidicsoil.AthighpHgreaterthan8.5manymicronutrientssuchas copperandironbecomelimited.PhosphorusbecomeslimitedatbothlowandhighpH.AsoilpHrangeof approximatelysixtoeightisconducivetothegrowthofmostplants. 11.1.5SOILDEGRADATION Soilcantakehundredsorthousandsofyearstomature.Therefore,oncefertiletopsoilislost,itisnoteasily replaced. Soildegradation referstodeteriorationinthequalityofthesoilandtheconcomitantreduction initscapacitytoproduce.Soilsaredegradedprimarilybyerosion,organicmatterloss,nutrientlossand salinization.Suchprocessesoftenarisefrompoorsoilmanagementduringagriculturalactivities.Inextreme cases,soildegradationcanleadtodeserticationconversionoflandtodesert-likeconditionsofcroplands andrangelandsinsemi-aridregions. Erosion isthebiggestcauseofsoildegradation.Soilproductivityisreducedasaresultoflossesof nutrients,waterstoragecapacityandorganicmatter.Thetwoagentsoferosionarewindandwater,which acttoremovethenerparticlesfromthesoil.Thisleadstosoilcompactionandpoorsoiltilth.Human activitiessuchasconstruction,logging,ando-roadvehicleusepromoteerosionbyremovingthenatural vegetationcoverprotectingthesoil. Agriculturalpracticessuchasovergrazingandleavingplowedeldsbareforextendedperiodscontribute tofarmlanderosion.Eachyear,anestimatedtwobillionmetrictonsofsoilareerodedfromfarmlandsin theUnitedStatesalone.Thesoiltransportedbytheerosionprocessescanalsocreateproblemselsewhere e.g.bycloggingwaterwaysandllingditchesandlow-lyinglandareas. Winderosionoccursmostlyinat,dryareasandmoist,sandyareasalongbodiesofwater.Windnot onlyremovessoil,butalsodriesanddegradesthesoilstructure.Duringthe1930s,poorcultivationand grazingpracticescoupledwithseveredroughtconditionsledtoseverewinderosionofsoilinaregionof theGreatPlainsthatbecameknownasthe"DustBowl."Windstrippedlargeareasoffarmlandsoftopsoil, andformedcloudsofdustthattraveledasfarastheeasternUnitedStates. Watererosion isthemostprevalenttypeoferosion.Itoccursinseveralforms:rainsplasherosion, sheeterosion,rillerosionandgullyerosion. Rainsplash erosionoccurswhentheforceofindividual raindropshittinguncoveredgroundsplashessoilparticlesintotheair.Thesedetachedparticlesaremore easilytransportedandcanbefurthersplasheddownslope,causingdeteriorationofthesoilstructure. Sheet erosion occurswhenwatermovesdownslopeasathinlmandremovesauniformlayerofsoil. Rill erosion isthemostcommonformofwatererosionandoftendevelopsfromsheeterosion.Soilisremoved aswaterowsthroughlittlestreamletsacrosstheland. Gullyerosion occurswhenrillsenlargeandow together,formingadeepgully. Whenconsiderablequantitiesofsaltaccumulateinthesoilinaprocessknownas salinization ,many plantsareunabletogrowproperlyorevensurvive.Thisisespeciallyaprobleminirrigatedfarmland. Groundwaterusedforirrigationcontainssmallamountsofdissolvedsalts.Irrigationwaterthatisnot absorbedintothesoilevaporates,leavingthesaltsbehind.Thisprocessrepeatsitselfandeventuallysevere salinizationofthesoiloccurs.Arelatedproblemiswaterloggingofthesoil.Whencroplandisirrigated withexcessiveamountsofwaterinordertoleachsaltsthathaveaccumulatedinthesoil,theexcesswateris sometimesunabletodrainawayproperly.Inthiscaseitaccumulatesundergroundandcausesariseinthe subsurfacewatertable.Ifthesalinewaterrisestotheleveloftheplantroots,plantgrowthisinhibited.

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54 CHAPTER11.SOILS 11.1.6SOILCONSERVATION Becausesoildegradationisoftencausedbyhumanactivity,soilconservationusuallyrequireschangesin thoseactivities.Soilconservationisveryimportanttoagriculture,sovariousconservationmethodshave beendevisedtohaltorminimizesoildegradationduringfarming.Thesemethodsinclude:constructionof windbreaks,no-tillfarming,contourfarming,terracing,stripcroppingandagroforestry. Creatingwindbreaksbyplantingtalltreesalongtheperimeteroffarmeldscanhelpcontroltheeects ofwinderosion. Windbreaks reducewindspeedatgroundlevel,animportantfactorinwinderosion. Theyalsohelptrapsnowinthewintermonths,leavingsoillessexposed.Asasidebenet,windbreaksalso provideahabitatforbirdsandanimals.Onedrawbackisthatwindbreakscanbecostlytofarmersbecause theyreducetheamountofavailablecropland. Oneoftheeasiestwaystopreventwindandwatererosionofcroplandsistominimizetheamountof tillage ,orturningoverofthesoil.In no-tillagriculture alsocalledconservationtillage,thelandis disturbedaslittleaspossiblebyleavingcropresidueintheelds.Specialseeddrillsinjectnewseedsand fertilizerintotheunplowedsoil.Adrawbackofthismethodisthatthecropresiduecanserveasagood habitatforinsectpestsandplantdiseases. Contourfarming involvesplowingandplantingcroprowsalongthenaturalcontoursofgentlysloping land.Thelinesofcroprowsperpendiculartotheslopehelptoslowwaterrunoandthusinhibitthe formationofrillsandgullies. Terracing isacommontechniqueusedtocontrolwatererosiononmore steeplyslopedhillsandmountains.Broad,levelterracesareconstructedalongthecontoursoftheslopes, andtheseactasdamstrappingwaterforcropsandreducingruno. Stripcropping involvestheplantingofdierentcropsonalternatingstripsofland.Onecropisusually arowcropsuchascorn,whiletheotherisaground-coveringcropsuchasalfalfa.Thecovercrophelps reducewaterrunoandtrapssoilerodedfromtherowcrop.Ifthecovercropisanitrogen-xingplante.g. alfalfa,soybeans,thenalternatingthestripsfromoneplantingtothenextcanalsohelpmaintaintopsoil fertility. Agroforestry istheprocessofplantingrowsoftreesinterspersedwithacashcrop.Besideshelping topreventwindandwatererosionofthesoil,thetreesprovideshadewhichhelpspromotesoilmoisture retention.Decayingtreelitteralsoprovidessomenutrientsfortheinterplantedcrops.Thetreesthemselves mayprovideacashcrop.Forexample,fruitornuttreesmaybeplantedwithagraincrop.

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Chapter12 BIOLOGICAL 1 12.1BIOLOGICAL 12.1.1INTRODUCTION Theneedsofhumansandthelivingorganismsandprocessesthatcomprisethebiosphereareinextricably connected.Becauseofthisconnectionthepropermanagementofbiologicalresourcesrequiresthatgenetic diversityandsuitablehabitatsbemaintained.Thereisagrowingrealizationthatdiversityinbiological systemsisfundamentaltoagriculturalproductionandfoodsecurity.Unfortunately,thediversityofplants andanimalsandofthehabitatsinwhichtheyliveiscurrentlybeingdrasticallyreduced.Thepredominant methodsusedinagriculturalareseriouslyerodingthegeneticdiversityofplantsandlivestock.Thevariety ofspeciesandgenesoflivingorganismsandthehabitatsandecosystemsinwhichthoseorganismslive areimportantresourcesthatmustbeutilizedinasustainablefashionthroughconservation. Conservation isnotjustamatterofprotectingwildlifeinnaturereserves.Italsoinvolvessafeguardingthenaturalsystems thatpurifywater,recyclenutrients,maintainsoilfertility,yieldfood,andprotectgeneticdiversity. 12.1.2NATURALAREAS Naturalareas,or wildernessareas ,compriseecosystemsinwhichhumanactivityhasnotsignicantly aectedtheplantandanimalpopulationsortheirenvironment.Naturalprocessespredominate.According tothe"WildernessActof1964,"wildernessareasaredenedasbeingthoseareaswherethenearestroadisat leastvemilesawayandwherenopermanentbuildingsstand.Accordingtothe1898writingsofNaturalist JohnMuir,"InGod'swildernessliesthehopeoftheworldthegreatfresh,unblighted,unredeemed wilderness." Morethan100millionacresoflandarenowpreservedaswildernessunderthisact.Sparselypopulated Alaskacontainsthelargestchunkofwildernessareas,overhalfofit.Althoughwildernessareasarescattered amongmostofthelower48states,thelargestpercentageisfoundinthewesternstates.Fewundesignated areasinthecontiguousstatesremainthatwouldqualifyaswilderness. Californiacontainssignicantwildernessareas,withover4millionacresofNationalForestWilderness areas,and1.5millionacresofmostlydesertwildernessintheMojaveDesertNationalPreserve.Becauseof thelargepopulationofthestate,thedemandforrecreationaluseoftheseareasisveryhigh.Heavydemand fortheuseofarelativelyfewnaturalareasisaproblemthroughoutthecontiguousstates.Itisnotaneasy taskfornaturalresourcemanagerstomanagethesenaturalareasinawaythatconservesbiologicaldiversity andecosystemintegrity,whilesupportingasustainableandbalancedlevelofhumanuse. Itisimportanttopreservenaturalareasforseveralreasons.Somepeople,especiallyNativeAmericans, feelaculturalconnectiontothewildernessthroughtheirancestorsthatoncelivedthere.Wildernessareas 1 Thiscontentisavailableonlineat. 55

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56 CHAPTER12.BIOLOGICAL arealsoofeconomicimportance.Outdoorrecreationactivitiessuchashikingandcampingbenettourist industriesandmanufacturersofoutdoorclothesandequipment. Mostimportantly,theecologicalimportanceofnaturalareasisworthpreserving.Wildernessareashelp maintainecosystemdiversity.Theyprotectwatersheds,helptoimproveairqualityandprovideanatural undisturbedlaboratoryforscienticstudy. 12.1.3GENETICDIVERSITY Whereasecosystemdiversityisameasureofvariabilityamongpopulationsofspecies, geneticdiversity referstovariabilityamongindividualswithinasinglespeciespopulation.Agenerepresentsthefundamental physicalunitofheredity,andeachindividualinaspeciesadierentmixofgenes.Thisgeneticdiversity orvariationwithinspeciesallowspopulationstoadapttochangesinenvironmentalconditions.Millions ofyearsofadaptivechangemaybeencodedinthegenesofaspeciespopulation,anditisthosegenesthat providethebasisforfutureadaptations. Lossofgeneticdiversitymakesaspecieslessabletoreproducesuccessfullyandlessadaptabletoa changingenvironment.Smallpopulationsofspeciesareespeciallysusceptibletolossofgeneticdiversity. Whenaspecieslosestoomanyindividuals,itbecomesgeneticallyuniform.Someofthecausesforthelossin geneticdiversityinclude:inbreedingamongcloselyrelatedindividuals,andgeneticdriftinwhichthegenes ofafewindividuals,eventuallydominateinapopulation. Geneticdiversityisimportanttoagriculture.Muchoftheworld'sagricultureisbasedonintroduced orhybridcropstrains,asopposedtonativeor wildstrains .Themainpurposeofusinghybridstainsis toincreaseproductivity.Unfortunately,thisapprovedresultsinonlyafewhybridcropstrainsbeingused forcommercialagriculture.Thesehybridcropslackthegeneticdiversityofthemanywildstrains,andthe resistanceofhybridstopestsanddiseaseisgenerallymuchlower.Therefore,itisnecessarytoprotectand conservethewildstrainsasageneticlibrary,fromwhichonecandrawthegeneticinformationnecessary forproducingimprovedandmoreresistanthybridstrains.Asimilarsituationexistsinlivestockbreeding, exceptthatthelossofgeneticdiversityinlivestockhasevenmoresevereconsequences.Manylivestock breedsarenearextinctionbecauseofthepolicyoffavoringafewspecializedbreeds.Itisclearthathuman activityisprimarilyresponsibleforthegeneticerosionofplantandanimalpopulations. 12.1.4FOODRESOURCES Thethreemajorsourcesoffoodforhumansare:croplands,rangelandsandsheries. Croplands provide thebulkofhumanfood.Eventhoughtherearethousandsofedibleplantsintheworld,onlyfour staple crops wheat,rice,cornandpotatoesaccountformostofthecaloricintakeofhumans.Someanimals raisedformeat,milkandeggse.g.cattle,pigs,poultryarealsofedgrainfromcroplands. Rangelands provideanothersourceofmeatandmilkfromgrazinganimalse.g.cattle,sheep,goats. Fisheries provide sh,whichareamajorsourceofanimalproteinintheworld,especiallyinAsiaandcoastalareas.For mainlyeconomicreasons,thedietsofmostpeopleintheworldconsistofstaplegrains.Aspeoplebecome moreauent,theytendtoconsumemoremeat,eggs,milkandcheese. Therearetwotypesoffoodproduction: traditionalagriculture and industrializedagriculture Industrializedagricultureisknownashighinputagriculturebecauseitutilizeslargeamountscommercial fertilizers,pesticides,waterandfossilfuels.Largeeldsofsinglecrops monoculture areplanted,and theplantsareselectivelybredtoproducehighyields.Thelargeamountsofgrainproducedbythismethod alsofostertheproductionoflargenumbersoflivestockanimalsinfeedlots.Mostofthefoodproduced byindustrializedmethodsissoldbyfarmersforincome.Thistypeoffoodproductionismostcommonin developedcountriesbecauseofthetechnologyandhighexpensesinvolved.However,largeindustrialized plantationsspecializinginasinglecashcrope.g.acropspecicallyraisedforincomesuchasbananas, cocoa,coeearefoundinsomedevelopingcountries. Traditionalagricultureisthemostwidelypracticedformoffoodproduction,occurringmostlyindevelopingcountries.Itcanbeclassiedfurtheraseithertraditionalsubsistenceortraditionalintensiveagriculture.

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57 Thedierencesbetweenthetwoinvolvetherelativeamountsofresourcesinputandfoodproduced. Subsistenceagriculture usesonlyhumanandanimallaborandonlyproducesenoughfoodforthefarmer's family. Traditional, intensiveagriculture utilizesmorehumanandanimallabor,fertilizersandirrigatedwater. Itmayalsoinvolvegrowingmethodssuchas intercropping designedtomaintainsoilfertility.Intercropping involvesplantingtwocropssimultaneouslye.g.,anitrogen-xinglegumecropwithagraincrop.The increasedproductionresultingfromthemoreintensivemethodsprovidesenoughfoodforthefarmer'sfamily andforsellingtoothersinthelocalarea. Rangelandstendtobegrasslandsinsemiaridtoaridregionsthatarenotsuitedtogrowingcropswithout irrigation.Thegrassesprovidefoodforgrazinganimalssuchascattleandsheep.Theseanimalsnotonly providemeatforfood,butarealsoavaluablesourceofleatherandwool.Inregionswithregularrainfall, livestockcanberaisedinsetareasofopenrange.Inmorearidclimates,nomadicherdingoflivestockmay benecessaryinordertondsucientsuppliesofgrass. Overgrazingofrangelandbylivestockcanresultindeserticationofthearea.Indevelopedcountries, livestockraisedonrangelandareoftenfattenedwithgraininfeedlotsbeforeslaughter. Theoceanprovidesthebiggestlocationofsheries.Commercialmethodsusedtoharvestthesesheries dependuponthetypesofshe.g.surfacedwelling,bottomdwellingbeingproducedandtheirtendency toformschools.Trawlersdragnetsalongtheoceanbottomtocatchbottomdwellingdemersalshsuch ascodandshellshsuchasshrimp.Largeschoolsofsurfacedwellingpelagicsh,suchastuna,arecaught bypurse-seineshinginwhichanetsurroundsthemandthencloseslikeadrawstringpurse.Driftnetsup totensofkilometerslonghanglikecurtainsbelowthesurfaceandentanglealmostanythingthatcomesin contactwithit.Themajorproblemwithalloftheseshingmethodsisthattheytendtokilllargenumbers ofunwantedshandmarinemammalsthatareinadvertentlycaught. Analternativetooceanshingis aquaculture ,amethodinwhichshandshellsharedeliberately raisedforfood.Therearetwotypesofaquaculture:shfarmingandshranching.With shfarming ,the shorshellshe.g.carp,catsh,oystersareraisedinclosedpondsortankswithacontrolledenvironment. Whentheyreachmaturitytheyareharvested. Fishranching isusedwithspeciessuchassalmonthatlive onepartoftheirlivesinfreshwaterandtheotherpartinsaltwater anadromousspecies .Salmonare raisedincaptivityforafewyearsandthenreleased.Theyareharvestedwhentheyreturntospawn.Some ofthedisadvantagesofaquacultureincludetheneedforsupplyinglargeamountsoffoodandwater,and disposalofthelargeamountsofwastethatareproduced. 12.2AlgaeintoOil,BonesintoStones Scientistsandtextbookstendtoseparatebiologicalandgeologicalentitiesandprocesses,butthecomplex cyclingofmatteronEarthactuallyblursthosecategories.Indeed,someofourmostimportantenergyand mineralresourceshavebiologicalorigins.Asaconsequence,thelocationandsizeoftheseresourcesdepends uponthedistributionandproductivityofancienthabitats. 12.2.1Petroleum Petroleumisagenerictermforoilandnaturalgas,andtheirproducts.Petroleumdoesn'tlookorganic,but itisderivedfromtheremainsofcountlessmarineorganisms.Itbeginswithbloomsofmicroscopicalgaeand otherplanktoninoceansandlargelakes.Theseorganismssinkwhentheydie,andiftheseaoororlakebed theylandonhaslowoxygenandhighsedimentation,theycanbeburiedinmudbeforetheydecompose. Atdepthandovertime,heatandpressurebegintoconverttheorganicmoleculesintohydrocarbons.The hydrocarbonsbegintoliquefyintooilat50-60 C,andvaporizeintomethaneat100 C.Ifthetemperature exceeds200 C,theybreakdownanddisappear. Wherepetroleumisabundant,itcanbepumpedfrombelowgroundandrenedintofuelssuchasgasoline, propane,jetfuel,andheatingoil,andintotarandasphalt.Petroleumisalsoacomponentofplastics,dyes, syntheticbers,fertilizers,compactdiscs,cosmetics,andexplosives.

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58 CHAPTER12.BIOLOGICAL Petroleumisextremelyuseful,butitisunevenlydistributedaroundtheworld,andreservesarebeing depletedrapidly.Petroleumformationisacomplexprocessthatrequiresjusttherightbiologicalconditions toproducesucientplankton,andjusttherightgeologicconditionstopreserveandcooktheorganicmatter. Theentiresequencetakesamillionyearsormore.Becausemanycountries,liketheUnitedStates,havevery limiteddeposits,andbecauseallpetroleumreservesarebeingdrainedrapidly,conservationandalternatives aregainingimportance.Forinstance,wornhighwayasphaltisnowbeingreprocessedandreplacedrather thandiscarded.Plasticrecyclingisbecomingmorewidespread.Wind,solar,nuclear,geothermal,and hydroelectricpowerisincreasing. 12.2.2Limestone Limestoneisatypeofrockmadeofcalciumcarbonate.Althoughfewthingsseemlesslife-likethanrocks, mostlimestoneisactuallybiogenic,formedfromtheshellsandskeletonsandexcretionsofmarineinvertebrates.Intheshallowsaroundtropicalislandsandcontinents,warmclearwater,strongsunlight,and abundantnutrientsallowmollusks,crustaceans,andplanktontoourish.Whenthesecreaturesdieormolt, theirhardpartsfalltotheseaoor.Astheremainspileup,theweightoftheoverlyingdebriscompacts thedeepestlayers.Cementsprecipitateoutofgroundwater,fusingtheindividualfragmentsintosolidrock. Somelimestonegoesnofurther,sothatthecomponentshellsremaindistinctandclearlyvisible.Inother limestone,subjecttomoreintenseheatandpressure,theorganicmaterialisrecrystallizedintoafeatureless mass. Limestoneiswidelyusedinindustrialprocesses.Crushedlimestoneisacomponentofcement,paper, plastic,andpaint,andisusedtoadjustthepHofsoilandwater.Wholelimestonethatretainsvisibleshell materialisusedfordecorativestonework.Commonblackboardchalkisalimestonemadefrommicroscopic skeletons. Limestoneisextremelyabundant,makingupabout10-15%ofallsedimentaryrocksonEarth,sothat eventhoughitisheavilyused,itsreservearenotbeingsignicantlydepleted.

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Chapter13 NON-RENEWABLEENERGY SOURCES 1 13.1NON-RENEWABLEENERGYSOURCES 13.1.1INTRODUCTION Sucient,reliablesourcesofenergyareanecessityforindustrializednations.Energyisusedforheating, cooking,transportationandmanufacturing.Energycanbegenerallyclassiedasnon-renewableandrenewable.Over85%oftheenergyusedintheworldisfromnon-renewablesupplies.Mostdevelopednationsare dependenton non-renewable energysourcessuchasfossilfuelscoalandoilandnuclearpower.These sourcesarecallednon-renewablebecausetheycannotberenewedorregeneratedquicklyenoughtokeep pacewiththeiruse.Somesourcesofenergyarerenewableorpotentiallyrenewable.Examplesofrenewable energysourcesare:solar,geothermal,hydroelectric,biomass,andwind.Renewableenergysourcesaremore commonlybyusedindevelopingnations. Industrializedsocietiesdependonnon-renewableenergysources.Fossilfuelsarethemostcommonly usedtypesofnon-renewableenergy.Theywereformedwhenincompletelydecomposedplantandanimal matterwasburiedintheearth'scrustandconvertedintocarbon-richmaterialthatisuseableasfuel.This processoccurredovermillionsofyears.Thethreemaintypesoffossilfuelsarecoal,oil,andnaturalgas. Twootherless-usedsourcesoffossilfuelsareoilshalesandtarsands. 13.1.2COAL Coalisthemostabundantfossilfuelintheworldwithanestimatedreserveofonetrillionmetrictons.Most oftheworld'scoalreservesexistinEasternEuropeandAsia,buttheUnitedStatesalsohasconsiderable reserves.Coalformedslowlyovermillionsofyearsfromtheburiedremainsofancientswampplants.During theformationofcoal,carbonaceousmatterwasrstcompressedintoaspongymaterialcalled"peat,"which isabout90%water.Asthepeatbecamemoredeeplyburied,theincreasedpressureandtemperatureturned itintocoal. Dierenttypesofcoalresultedfromdierencesinthepressureandtemperaturethatprevailedduring formation.Thesoftestcoalabout50%carbon,whichalsohasthelowestenergyoutput,iscalled lignite Lignitehasthehighestwatercontentabout50%andrelativelylowamountsofsmog-causingsulfur.With increasingtemperatureandpressure,ligniteistransformedintobituminouscoalabout85%carbonand3% water.Anthracitealmost100%carbonisthehardestcoalandalsoproducesthegreatestenergywhen burned.Lessthan1%ofthecoalfoundintheUnitedStatesisanthracite.Mostofthecoalfoundinthe 1 Thiscontentisavailableonlineat. 59

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60 CHAPTER13.NON-RENEWABLEENERGYSOURCES UnitedStatesis bituminous .Unfortunately,bituminouscoalhasthehighestsulfurcontentofallthecoal types.Whenthecoalisburned,thepollutantsulfurdioxideisreleasedintotheatmosphere. Coalminingcreatesseveralenvironmentalproblems.Coalismostcheaplyminedfromnear-surfacedepositsusingstripminingtechniques. Strip-mining causesconsiderableenvironmentaldamageintheforms oferosionandhabitatdestruction. Sub-surfacemining ofcoalislessdamagingtothesurfaceenvironment,butismuchmorehazardousfortheminersduetotunnelcollapsesandgasexplosions.Currently,the worldisconsumingcoalatarateofabout5billionmetrictonsperyear.Themainuseofcoalisforpower generation,becauseitisarelativelyinexpensivewaytoproducepower. Coalisusedtoproduceover50%oftheelectricityintheUnitedStates.Inadditiontoelectricity production,coalissometimesusedforheatingandcookinginlessdevelopedcountriesandinruralareas ofdevelopedcountries.Ifconsumptioncontinuesatthesamerate,thecurrentreserveswilllastformore than200years.Theburningofcoalresultsinsignicantatmosphericpollution.Thesulfurcontainedin coalformssulfurdioxidewhenburned.Harmfulnitrogenoxides,heavymetals,andcarbondioxidearealso releasedintotheairduringcoalburning.Theharmfulemissionscanbereducedbyinstallingscrubbersand electrostaticprecipitatorsinthesmokestacksofpowerplants.Thetoxicashremainingaftercoalburningis alsoanenvironmentalconcernandisusuallydisposedintolandlls. 13.1.3OIL Crudeoil orliquidpetroleum,isafossilfuelthatisrenedintomanydierentenergyproductse.g., gasoline,dieselfuel,jetfuel,heatingoil.Oilformsundergroundinrocksuchas shale ,whichisrichin organicmaterials.Aftertheoilforms,itmigratesupwardintoporousreservoirrocksuchassandstoneor limestone,whereitcanbecometrappedbyanoverlyingimpermeablecaprock.Wellsaredrilledintothese oilreservoirstoremovethegasandoil.Over70percentofoileldsarefoundneartectonicplateboundaries, becausetheconditionsthereareconducivetooilformation. Oilrecovery caninvolvemorethanonestage.Theprimarystageinvolvespumpingoilfromreservoirs underthenormalreservoirpressure.About25percentoftheoilinareservoircanberemovedduringthis stage.Thesecondaryrecoverystageinvolvesinjectinghotwaterintothereservoiraroundthewell.This waterforcestheremainingoiltowardtheareaofthewellfromwhichitcanberecovered.Sometimesa tertiarymethodofrecoveryisusedinordertoremoveasmuchoilaspossible.Thisinvolvespumpingsteam, carbondioxidegasornitrogengasintothereservoirtoforcetheremainingoiltowardthewell.Tertiary recoveryisveryexpensiveandcancostuptohalfofthevalueofoilremoved.Carbondioxideusedin thismethodremainssequesteredinthedeepreservoir,thusmitigatingitspotentialgreenhouseeectonthe atmosphere.Thereningprocessrequiredtoconvertcrudeoilintouseablehydrocarboncompoundsinvolves boilingthecrudeandseparatingthegasesinaprocessknownasfractionaldistillation.Besidesitsuseas asourceofenergy,oilalsoprovidesbasematerialforplastics,providesasphaltforroadsandisasourceof industrialchemicals. Over50percentoftheworld'soilisfoundintheMiddleEast;sizeableadditionalreservesoccurinNorth America.Mostknownoilreservesarealreadybeingexploited,andoilisbeingusedataratethatexceeds therateofdiscoveryofnewsources.Iftheconsumptionratecontinuestoincreaseandnosignicantnew sourcesarefound,oilsuppliesmaybeexhaustedinanother30yearsorso. Despiteitslimitedsupply,oilisarelativelyinexpensivefuelsource.Itisapreferredfuelsourceovercoal. Anequivalentamountofoilproducesmorekilowattsofenergythancoal.Italsoburnscleaner,producing about50percentlesssulfurdioxide. Oil,however,doescauseenvironmentalproblems.Theburningofoilreleasesatmosphericpollutantssuch assulfurdioxide,nitrogenoxides,carbondioxideandcarbonmonoxide.Thesegasesaresmog-precursors thatpollutetheairandgreenhousegasesthatcontributetoglobalwarming.Anotherenvironmentalissue associatedwiththeuseofoilistheimpactofoildrilling.Substantialoilreserveslieundertheocean.Oil spillaccidentsinvolvingdrillingplatformskillmarineorganismsandbirds.Somereservessuchasthosein northernAlaskaoccurinwildernessareas.Thebuildingofroads,structuresandpipelinestosupportoil recoveryoperationscanseverelyimpactthewildlifeinthosenaturalareas.

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61 13.1.4NATURALGAS Naturalgas productionisoftenaby-productofoilrecovery,asthetwocommonlyshareunderground reservoirs.Naturalgasisamixtureofgases,themostcommonbeing methane CH4.Italsocontains some ethane C2H5, propane C3H8,and butane C4H10.Naturalgasisusuallynotcontaminated withsulfurandisthereforethecleanestburningfossilfuel.Afterrecovery,propaneandbutaneareremoved fromthenaturalgasandmadeinto liqueedpetroleumgas LPG .LPGisshippedinspecialpressurized tanksasafuelsourceforareasnotdirectlyservedbynaturalgaspipelinese.g.,ruralcommunities.The remainingnaturalgasisfurtherrenedtoremoveimpuritiesandwatervapor,andthentransportedin pressurizedpipelines.TheUnitedStateshasover300,000milesofnaturalgaspipelines.Naturalgasis highlyammableandisodorless.Thecharacteristicsmellassociatedwithnaturalgasisactuallythatof minutequantitiesofasmellysulfurcompound ethylmercaptan whichisaddedduringreningtowarn consumersofgasleaks. Theuseofnaturalgasisgrowingrapidly.Besidesbeingacleanburningfuelsource,naturalgasiseasy andinexpensivetotransportoncepipelinesareinplace.Indevelopedcountries,naturalgasisusedprimarily forheating,cooking,andpoweringvehicles.Itisalsousedinaprocessformakingammoniafertilizer.The currentestimateofnaturalgasreservesisabout100millionmetrictons.Atcurrentusagelevels,thissupply willlastanestimated100years.Mostoftheworld'snaturalgasreservesarefoundinEasternEuropeand theMiddleEast. 13.1.5OILSHALEANDTARSANDS Oilshaleandtarsandsaretheleastutilizedfossilfuelsources. Oilshale issedimentaryrockwithvery neporesthatcontain kerogen ,acarbon-based,waxysubstance.Ifshaleisheatedto490 C,thekerogen vaporizesandcanthenbecondensedasshaleoil,athickviscousliquid.Thisshaleoilisgenerallyfurther renedintousableoilproducts.Productionofshaleoilrequireslargeamountsofenergyforminingand processingtheshale.Indeedaboutahalfbarrelofoilisrequiredtoextracteverybarrelofshaleoil.Oil shaleisplentiful,withestimatedreservestotaling3trillionbarrelsofrecoverableshaleoil.Thesereserves alonecouldsatisfytheworld'soilneedsforabout100years.Environmentalproblemsassociatedwithoil shalerecoveryinclude:largeamountsofwaterneededforprocessing,disposaloftoxicwastewater,and disruptionoflargeareasofsurfacelands. Tarsand isatypeofsedimentaryrockthatisimpregnatedwithaverythickcrudeoil.Thisthickcrude doesnotoweasilyandthusnormaloilrecoverymethodscannotbeusedtomineit.Iftarsandsarenearthe surface,theycanbemineddirectly.Inordertoextracttheoilfromdeep-seatedtarsands,however,steam mustbeinjectedintothereservoirtomaketheoilowbetterandpushittowardtherecoverywell.The energycostforproducingabarreloftarsandissimilartothatforoilshale.Thelargesttar-sanddepositin theworldisinCanadaandcontainsenoughmaterialabout500billionbarrelstosupplytheworldwithoil forabout15years.However,becauseofenvironmentalconcernsandhighproductioncoststhesetarsand eldsarenotbeingfullyutilized. 13.1.6NUCLEARPOWER Inmostelectricpowerplants,waterisheatedandconvertedintosteam,whichdrivesaturbine-generator toproduceelectricity.Fossil-fueledpowerplantsproduceheatbyburningcoal,oil,ornaturalgas.Ina nuclearpowerplant ,the ssionofuraniumatoms inthereactorprovidestheheattoproducesteam forgeneratingelectricity. SeveralcommercialreactordesignsarecurrentlyinuseintheUnitedStates.Themostwidelyused designconsistsofaheavysteelpressurevesselsurroundingareactorcore.The reactorcore containsthe uraniumfuel,whichisformedintocylindricalceramicpelletsandsealedinlongmetaltubescalled fuel rods .Thousandsoffuelrodsformthereactorcore.Heatisproducedinanuclearreactorwhenneutrons strikeuraniumatoms,causingthemtosplitinacontinuouschainreaction. Controlrods ,whicharemade ofamaterialsuchasboronthatabsorbsneutrons,areplacedamongthefuelassemblies.

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62 CHAPTER13.NON-RENEWABLEENERGYSOURCES Whentheneutron-absorbingcontrolrodsarepulledoutofthecore,moreneutronsbecomeavailablefor ssionandthechainreactionspeedsup,producingmoreheat.Whentheyareinsertedintothecore,fewer neutronsareavailableforssion,andthechainreactionslowsorstops,reducingtheheatgenerated.Heat isremovedfromthereactorcoreareabywaterowingthroughitinaclosedpressurizedloop.Theheat istransferredtoasecondwaterloopthroughaheatexchanger.Thewateralsoservestoslowdown,or "moderate"theneutronswhichisnecessaryforsustainingthessionreactions.Thesecondloopiskeptat alowerpressure,allowingthewatertoboilandcreatesteam,whichisusedtopowertheturbine-generator andproduceelectricity. Originally,nuclearenergywasexpectedtobeacleanandcheapsourceofenergy.Nuclearssiondoes notproduceatmosphericpollutionorgreenhousegasesanditproponentsexpectedthatnuclearenergy wouldbecheaperandlastlongerthanfossilfuels.Unfortunately,becauseofconstructioncostoverruns, poormanagement,andnumerousregulations,nuclearpowerendedupbeingmuchmoreexpensivethan predicted.ThenuclearaccidentsatThreeMileIslandinPennsylvaniaandtheChernobylNuclearPlantin theUkraineraisedconcernsaboutthesafetyofnuclearpower.Furthermore,theproblemofsafelydisposing spentnuclearfuelremainsunresolved.TheUnitedStateshasnotbuiltanewnuclearfacilityinovertwenty years,butwithcontinuedenergycrisesacrossthecountrythatsituationmaychange.

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Chapter14 RENEWABLEENERGYSOURCES 1 14.1RENEWABLEENERGYSOURCES 14.1.1INTRODUCTION Renewableenergy sourcesareoftenconsideredalternativesourcesbecause,ingeneral,mostindustrialized countriesdonotrelyonthemastheirmainenergysource.Instead,theytendtorelyonnon-renewable sourcessuchasfossilfuelsornuclearpower.BecausetheenergycrisisintheUnitedStatesduringthe1970s, dwindlingsuppliesoffossilfuelsandhazardsassociatedwithnuclearpower,usageofrenewableenergy sourcessuchassolarenergy,hydroelectric,wind,biomass,andgeothermalhasgrown. Renewableenergycomesfromthesunconsideredan"unlimited"supplyorothersourcesthatcan theoreticallyberenewedatleastasquicklyastheyareconsumed.Ifusedatasustainablerate,thesesources willbeavailableforconsumptionforthousandsofyearsorlonger.Unfortunately,somepotentiallyrenewable energysources,suchasbiomassandgeothermal,areactuallybeingdepletedinsomeareasbecausetheusage rateexceedstherenewalrate. 14.1.2SOLARENERGY Solarenergy istheultimateenergysourcedrivingtheearth.Thoughonlyonebillionthoftheenergy thatleavesthesunactuallyreachestheearth'ssurface,thisismorethanenoughtomeettheworld'senergy requirements.Infact,allothersourcesofenergy,renewableandnon-renewable,areactuallystoredformsof solarenergy.Theprocessofdirectlyconvertingsolarenergytoheatorelectricityisconsideredarenewable energysource.Solarenergyrepresentsanessentiallyunlimitedsupplyofenergyasthesunwilllongoutlast humancivilizationonearth.Thedicultieslieinharnessingtheenergy.Solarenergyhasbeenusedfor centuriestoheathomesandwater,andmoderntechnologyphotovoltaiccellshasprovidedawaytoproduce electricityfromsunlight. Therearetwobasicformsofradiantsolarenergyuse:passiveandactive. Passivesolarenergy systems arestatic,anddonotrequiretheinputofenergyintheformofmovingpartsorpumpinguidstoutilize thesun'senergy.Buildingscanbedesignedtocaptureandcollectthesun'senergydirectly.Materialsare selectedfortheirspecialcharacteristics:glassallowsthesuntoenterthebuildingtoprovidelightandheat; waterandstonematerialshavehighheatcapacities.Theycanabsorblargeamountsofsolarenergyduring theday,whichcanthenbeusedduringthenight.Asouthernexposuregreenhousewithglasswindowsand aconcreteoorisanexampleofapassivesolarheatingsystem. Activesolarenergy systemsrequirethe inputofsomeenergytodrivemechanicaldevicese.g.,solarpanels,whichcollecttheenergyandpump uidsusedtostoreanddistributetheenergy.Solarpanelsaregenerallymountedonasouthorwest-facing 1 Thiscontentisavailableonlineat. 63

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64 CHAPTER14.RENEWABLEENERGYSOURCES roof.Asolarpanelusuallyconsistsofaglass-faced,sealed,insulatedboxwithablackmatteinteriornish. Insidearecoilsfullofaheat-collectingliquidmediumusuallywater,sometimesaugmentedbyantifreeze. Thesunheatsthewaterinthecoils,whichispumpedtocoilsinaheattransfertankcontainingwater. Thewaterinthetankisheatedandtheneitherstoredorpumpedthroughthebuildingtoheatroomsor supplyhotwatertotapsinthebuilding. Photovoltaic cellsgenerateelectricityfromsunlight.Hundredsofcellsarelinkedtogethertoprovide therequiredowofcurrent.Theelectricitycanbeuseddirectlyorstoredinstoragebatteries.Because photovoltaiccellshavenomovingparts,theyareclean,quiet,anddurable.Earlyphotovoltaiccellswere extremelyexpensive,makingthecostofsolarelectricpanelsprohibitive.Therecentdevelopmentofinexpensivesemiconductormaterialshashelpedgreatlylowerthecosttothepointwheresolarelectricpanels cancompetemuchbettercost-wisewithtraditionally-producedelectricity. Thoughsolarenergyitselfisfree,largecostscanbeassociatedwiththeequipment.Thebuildingcosts forahouseheatedbypassivesolarenergymayinitiallybemoreexpensive.Theglass,stonematerials,and excellentinsulationnecessaryforthesystemtoworkproperlytendtobemorecostlythanconventional buildingmaterials.Along-termcomparisonofutilitybills,though,generallyrevealsnoticeablesavings.The solarpanelsusedinactivesolarenergycanbeexpensivetopurchase,installandmaintain.Leakscanoccur intheextensivenetworkofpipesrequired,therebycausingadditionalexpense.Thebiggestdrawbackofany solarenergysystemisthatitrequiresaconsistentsupplyofsunlighttowork.Mostpartsoftheworldhave lessthanidealconditionsforasolar-onlyhomebecauseoftheirlatitudeorclimate.Therefore,itisusually necessaryforsolarhousestohaveconventionalbackupsystemse.g.agasfurnaceorhot-waterheater. Thisdouble-systemrequirementfurtheraddstoitscost. 14.1.3HYDROELECTRICENERGY Hydroelectricpower isgeneratedbyusingtheenergyofowingwatertopowergeneratingturbinesfor producingelectricity.Mosthydroelectricpowerisgeneratedbydamsacrosslarge-owrivers.Adambuilt acrossrivercreatesareservoirbehindit.Theheightofthewaterbehindthedamisgreaterthanthat belowthedam,representingstoredpotentialenergy.Whenwaterowsdownthroughthepenstockofthe dam,drivingtheturbines,someofthispotentialenergyisconvertedintoelectricity.Hydroelectricpower, likeotheralternativesources,iscleanandrelativelycheapoverthelongtermevenwithinitialconstruction costsandupkeep.Butbecausetheriver'snormalowrateisreducedbythedam,sedimentsnormally carrieddownstreambythewaterareinsteaddepositedinthereservoir.Eventually,thesedimentcanclog thepenstocksandrenderthedamuselessforpowergeneration. Large-scaledamscanhaveasignicantimpactontheregionalenvironment.Whentheriverisinitially dammed,farmlandsaresometimesoodedandentirepopulationsofpeopleandwildlifearedisplacedby therisingwatersbehindthedam.Insomecases,thereservoircanoodhundredsorthousandsofsquare kilometers.Thedecreasedowdownstreamfromthedamcanalsonegativelyimpacthumanandwildlife populationslivingdownstream.Inaddition,thedamcanactasabarriertoshthatmusttravelupstreamto spawn.Aquaticorganismsarefrequentlycaughtandkilledinthepenstockandtheout-takepipes.Because ofthelargesurfaceareaofthereservoir,thelocalclimatecanchangeduetothelargeamountofevaporation occurring. 14.1.4WINDPOWER Windistheresultofthesun'sunevenheatingoftheatmosphere.Warmairexpandsandrises,andcool aircontractsandsinks.Thismovementoftheairiscalledwind.Windhasbeenusedasanenergysource formillennia.Ithasbeenusedtopumpwater,topowerships,andtomillgrains.Areaswithconstant andstrongwindscanbeusedbywindturbinestogenerateelectricity.IntheUnitedStates,thestateof Californiahasabout20,000 windturbines ,andproducesthemostwind-generatedelectricity.Windenergy doesnotproduceairpollution,canbevirtuallylimitless,andisrelativelyinexpensivetoproduce.Thereis aninitialcostofmanufacturingthewindturbineandthecostsassociatedwithupkeepandrepairs,butthe winditselfisfree.

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65 Themajordrawbacksofwind-poweredgeneratorsaretheyrequirelotsofopenlandandafairlyconstant windsupply.Lessthan15%oftheUnitedStatesissuitableforgeneratingwindenergy. Windmillsarealsonoisy,andsomepeopleconsiderthemaestheticallyunappealingandlabelthem asvisualpollution.Migratingbirdsandinsectscanbecomeentangledandkilledbytheturningblades. However,thelandusedforwindmillfarmscanbesimultaneouslyusedforotherpurposessuchasranching, farmingandrecreation. 14.1.5BIOMASSENERGY Biomassenergy istheoldestenergysourceusedbyhumans.Biomassistheorganicmatterthatcomposes thetissuesofplantsandanimals.UntiltheIndustrialRevolutionpromptedashifttofossilfuelsinthemid 18thcentury,itwastheworld'sdominantfuelsource.Biomasscanbeburnedforheatingandcooking,and evengeneratingelectricity.Themostcommonsourceofbiomassenergyisfromtheburningofwood,but energycanalsobegeneratedbyburninganimalmanuredung,herbaceousplantmaterialnon-wood,peat partiallydecomposedplantandanimaltissues,orconvertedbiomasssuchascharcoalwoodthathasbeen partiallyburnedtoproduceacoal-likesubstance.Biomasscanalsobeconvertedintoaliquidbiofuelsuch asethanolormethanol.Currently,about15percentoftheworld'senergycomesfrombiomass. Biomassisapotentiallyrenewableenergysource.Unfortunately,treesthatarecutforrewoodare frequentlynotreplanted.Inordertobeusedsustainably,onetreemustbeplantedforeveryonecutdown. Biomassismostfrequentlyusedasafuelsourceindevelopingnations,butwiththedeclineoffossil fuelavailabilityandtheincreaseinfossilfuelprices,biomassisincreasinglybeingusedasafuelsourcein developednations.Oneexampleofbiomassenergyindevelopednationsistheburningofmunicipalsolid waste.IntheUnitedStates,severalplantshavebeenconstructedtoburnurbanbiomasswasteandusethe energytogenerateelectricity. Theuseofbiomassasafuelsourcehasseriousenvironmentaleects.Whenharvestedtreesarenot replanted,soilerosioncanoccur.Thelossofphotosyntheticactivityresultsinincreasedamountsofcarbon dioxideintheatmosphereandcancontributetoglobalwarming.Theburningofbiomassalsoproduces carbondioxideanddeprivesthesoilofnutrientsitnormallywouldhavereceivedfromthedecompositionof theorganicmatter.Burningreleasesparticulatemattersuchasashintotheairwhichcancauserespiratory healthproblems. 14.1.6GEOTHERMALENERGY Geothermalenergy usesheatfromtheearth'sinternalgeologicprocessesinordertoproduceelectricity orprovideheating.Onesourceofgeothermalenergyissteam.Groundwaterpercolatesdownthoughcracks inthesubsurfacerocksuntilitreachesrocksheatedbyunderlyingmagma,andtheheatconvertsthewater tosteam.Sometimesthissteammakesitswaybacktothesurfaceintheformofageyserorhotspring. Wellscanbedugtotapthesteamreservoirandbringittothesurface,todrivegeneratingturbinesand produceelectricity.Hotwatercanbecirculatedtoheatbuildings.Regionsneartectonicplateboundaries havethebestpotentialforgeothermalactivity. ThewesternportionoftheUnitedStatesismostconduciveforgeothermalenergysources,andover halfoftheelectricityusedbythecityofSanFranciscocomesfromtheGeysers,anaturalgeothermaleld inNorthernCalifornia.Californiaproducesabout50percentoftheworld'selectricitythatcomesfrom geothermalsources. EntirecitiesinIceland,whichislocatedinavolcanicallyactiveregionnearamid-oceanridge,areheated bygeothermalenergy.TheRiftValleyregionofEastAfricaalsohasgeothermalpowerplants.Geothermal energymaynotalwaysberenewableinaparticularregionifthesteamiswithdrawnataratefasterthan itcanbereplenished,oriftheheatingsourcecoolso.TheenergyproducedbytheGeysersregionof Californiaisalreadyindeclinebecausetheheavyuseiscausingtheundergroundheatsourcetocool. Geothermalenergyrecoverycanbelessenvironmentallyinvasivethanengaginginrecoverymethodsfor non-renewableenergysources.Althoughitisrelativelyenvironmentallyfriendly,itisnotpracticalforall situations.Onlylimitedgeographicregionsarecapableofproducinggeothermalenergythatiseconomically

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66 CHAPTER14.RENEWABLEENERGYSOURCES viable.Therefore,itwillprobablyneverbecomeamajorsourceofenergy.Thecostandenergyrequirements fortappingandtransportingsteamandhotwaterarehigh.Hydrogensulde,antoxicairpollutantthat smellslikerotteneggs,isalsooftenassociatedwithgeothermalactivity.

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Chapter15 LAND 1 15.1LAND 15.1.1INTRODUCTION Theconceptoflandusei.e.,thewayaparticularpieceoflandisutilizedbyhumansandotherliving organisms,seemsatrstglanceasimpleandstraightforwardsubjectonthesurface.Humansuseland tobuildcitieswheretheyliveresidentiallandandworkcommercialland.Theyuselandforgrowing cropsandraisinglivestockagriculturallandforfood.Forestlandprovidesfuelforenergyandlumberfor building.Humansuselandforplayrecreationallandandsetsomeofitasideasexclusivewildlifehabitat wildernessland.Butnomatterhowlandisusedbyhumansandotherlivingspecies,humansultimately decidehowlandisused.Giventhenatureofhumans,landuseinvolvesacomplexinterplayofenvironmental parameters,economicneedsandoftenpolitics. 15.1.2RESIDENTIALANDCOMMERCIALLANDS Abouthalfoftheearth'shumaninhabitantsliveinurbanareas.Theseurbanareasincluderesidentialland forhomesandcommerciallandforbusinesses.Thenumberofpeoplelivinginurbanareascontinuestogrow eachyear,andasaresult,theamountoflandusedforresidentialandcommercialuseisalsoincreasing. CitiesintheUnitedStatesusuallyrequirethatresidentiallandbeseparatedfromcommercialland.This hasbeenafactorinthedevelopmentofurbansprawl,thelow-densityhousingdevelopmentssurrounding manycitiesandtowns. Acitygrowsinthreebasicways:concentric,sectorandmultiplenuclei.Inthe concentriccitymodel thecitydevelopsoutwardfromacentralbusinessdistrictinasetofconcentricringsi.e.,NewYorkCity. Commercialareasareconcentratedinthecentraldistrict,whiletheouterringsaretypicallyresidentialareas. A sectorcity developsoutwardinpie-shapedwedgesorstripsi.e.,theSiliconValleyregionsouthofSan Francisco. Thistypeofgrowthresultswhencommercialandresidentialareasarebuiltupalongmajortransportation routes.A multiple-nuclei cityevolveswithseveralcommercialcentersorsatellitecommunitiesscattered overtheurbanregioninsteadofasinglecentralbusinessdistrict.TheLosAngelesmetropolitanareaisa goodexampleofamultiple-nucleicity. Muchofthelandconvertedtoresidentialandcommercialuseincitieswasformerlyusedforagricultural purposesorconsistedofecologicallyimportantareassuchaswetlands.Citiesarebuiltonsuchlandasa resultofconventionallanduseplanning,whichencouragessubstantialurbangrowthforpurelyeconomic reasonsi.e.,asameansofincreasingthetaxbase.Unfortunately,wheneconomicfactorsaretheonlyone 1 Thiscontentisavailableonlineat. 67

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68 CHAPTER15.LAND considered,degradingeectstotheenvironmentaregenerallydisregarded.Somecitiesnowuseasmartgrowthmodelinwhichdevelopmentofurbanareasisdesignedtostrikeabalancebetweeneconomicneeds andsafeguardingtheenvironment. Onecitydesignapproachusedtocontrolurbangrowthisestablishing greenbelts aroundthecity peripheries.Greenbeltsprovidehabitatsuchasforestareasforanimalsandopenspaceforhumanrecreation, whileblockingtheoutwardgrowthofthecity.Anothermethodusedtolessentheeectsofurbansprawl isthe clusterdevelopmentmodel fornewresidentialareas.Inthisdesignhousingisconcentratedina restrictedportionofatract,leavingtherestofthelandinarelativelynaturalstatewithtrees,openspace andwaterways. 15.1.3AGRICULTURALANDFORESTLANDS LessthanhalfofthelandareaintheworldandintheUnitedStatesisusedforagriculture.Themajority ofagriculturallandsare rangeland or pasture .Rangelandsareunsuitableforgrowinggraincropsfor avarietyofreasons:thelandmaybetoorockyortoosteep,ortheclimatemaybetoocoolortoodry. Livestockgrazingisthemajoragriculturaluseofrangelandandpasture.Together,rangelandandpasture compriseabout35percentofnon-federallandmillionacresintheUnitedStates.Mostofthenation's rangelandsareinvastareasofthewesternstateswitharidtosemi-aridclimates.Pastures,whicharesmaller managedgrassyareas,arefoundonfarmsthroughouttheUnitedStates. Croplandsareimportantbecausetheyaccountforthebulkoffoodproduction.About20percentof thelandintheUnitedStatesabout400millionacresiscroplands,withthehighestconcentrationsinthe centralUnitedStates.About70percentofallcroplandintheUnitedStatesisclassiedasprimefarmland. Primefarmland islandthathasagrowingseason,awatersupplyfromprecipitationorirrigation,and sucientlyrichsoiltosustainhighyieldswhenmanagedaccordingtomodernfarmingmethods.Cropland maybecomeprimefarmlandwiththeadditionoftheirrigationoroodingprotectionneededtosustainhigh yields.FarmlandsintheeasternandsouthernUnitedStatesaregenerallysmallerandproduceagreater varietyofcropsthanthoseintheCornBeltandGreatPlains,whereafewmajorgraincropspredominate. Incountriesthroughouttheworld,agriculturallandisbeinglostforvariousreasons.Somelandis beinglosttootherusessuchashousingdevelopments,commercialdevelopmentsandroads.Unfortunately, thischangeinuseistakingfromusmuchprimeagriculturalland.IntheUnitedStates,federalprograms existthatencouragefarmerstostopfarmingagriculturallandsdenedassensitive,whichposeariskof environmentaldegradation.InanattempttohelppreserveprimefarmlandintheUnitedStates,somelocal andstategovernmentsandprivateorganizationshaveprogramstopurchaseeasementsoncroplandthat restrictsnonagriculturaluse. Suchcroplandsaretemporarilyorpermanentlyretiredfromactiveproductionandareplantedwith perennialgrassesortrees.Millionsofacresofagriculturallandinsemiaridregionsarelosteachyeardue toaphenomenoncalled desertication .Thisoccurswhenonce-productivelandbecomestooaridfor agriculturalusebecauseofclimatechangeorpoorlandmanagementi.e.,overgrazingofrangeland,erosion ofcroplands. Yearsago,thestandardpracticeforreplacinglostagriculturallandsorincreasingoverallproductionin manycountrieswastodevelopnewfarmlandfromformerlyuncultivatedland.Butnow,areasofpotentially arablelandareshrinkinginmostcountries.Mostoftheuncultivatedlandthatdoesremainismarginal, withpoorsoilsandeithertoolittlerainfallortoomuch. Tropicalrainforestsarebeingloggedatafastratetoprovidefarmland.However,soilsinrainforestsare nutrientpoorandpronetoerosionbyfrequenttropicalrains.Destructionofrainforestregionsmayalso contributetoglobalenvironmentalproblemssuchasglobalwarming.Forestsofallkindsareveryimportant ecologically.Asmajorbiomes,theyprovideahabitatforlivingspeciesandsupportthefoodwebsforthose species.Forestsplayanenvironmentalrolebyrecyclingnutrientsi.e.,carbon,nitrogenandgenerating oxygenthroughphotosynthesis.Theyeveninuencelocalclimaticconditionsbyaectingairhumidity throughevaporationandtranspirationprocesses.Economically,forestsarealsoveryimportant. Humanshaveutilizedforestsforthousandsofyearsasasourceofenergyi.e.,fuel,buildingmaterials lumberandpulpwoodforpaper,andtheseusesremainimportant.Whenforestlandsholdvaluablemineral

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69 resourcesbeneaththem,theymaybeclearedtoprovideaccesstotheminerals. TheUnitedStatesForestServicedenesforestlandsaslandsthatconsistofatleast10percenttreesof anysize.Theyinclude:transitionzonessuchasareasbetweenheavilyforestedandnonforestedlandsand forestareasadjacenttourbanareas.Inthewesternstatestheyincludepinyon-juniperandchaparralareas. Forestscoveraboutone-thirdoftheUnitedStates,whichisabout70percentoftheirextentwhenEuropean settlementbeganinthe17thcentury.About42percentofU.S.forestlandsarepubliclyowned.Ofthese, about15percentareinnationalparksorwildernessareasandarethusprotectedfromtimberharvest. Otherpublicforestlandsaremanagedforvarioususes:recreation,grazing,watershedprotection,timber production,wildlifehabitat,andmining.Forestsinthewesternstatesarepredominantlypubliclyowned, whilethoseineasternstatesarepredominantlyprivatelyowned. Forestscanbeclassiedbytheirrelativematurity. Old-growthforests havebeenundisturbedfor hundredsofyears.Theycontainnumerousdeadtreesandfallenlogswhichprovidespecieshabitatsandare eventuallyrecycledthroughdecay. Second-growthforests arelessmatureandoccurwhentheoriginal ecologicalcommunityinaregionisdestroyed,eitherbyhumanland-clearingactivitiesorbynaturaldisasters i.e.,res,storms,volcaniceruptions.Humanssometimescreatearticialforestsintheformoftreefarms. Usuallyonlyonetreespeciesisplantedinatreefarm.Aftermaturingenoughtobeofeconomicvalue,the treesareharvestedandnewtreesplantedintheirplace. Foresttreescanbeharvestedbydierentmethods:selectivecutting,seed-treecutting,stripcuttingand clearcutting.Mostofthesemethodshavedistincteectsontheecologyoftheharvestedarea.Selective cuttingisusuallyleastdamagingtothelocalecosystem.Inthismethodofharvesting,treesthataremoderate tofullymaturearecutsinglyorinsmallgroups.Thisapproachallowsmostofthetreestoremain,which helpsmaintainhabitatsandpreventsoilerosionandallowsuninterruptedrecreationaluse.However,in tropicalforestswhenonlythebiggestandbesttreesareremoved,selectivecuttingcanleadtosignicant ecosystemdamage.Becausethecanopyofatropicalforestisthickandintertwined,theremovalofonelarge treedamagesaconsiderableareaaroundit. Otherharvestingmethodsinvolveremovalofmostorallofthetreesinagivenarea. Seed-treecutting removesmostofthetreesinanarea,leavingonlyafewscatteredtreestoprovideseedsforregrowth.The remainingtreesprovidesomehabitatforanimalsandhelpreducesoilerosion.However,whenseedtreesare cut,theforestlosesitsdiversityandisoftenconvertedtoatreefarm. Clearcutting and stripcutting bothremovealltreesinanarea.Clear-cuttingusuallyinvolveslarge areasoflandresultingintheconcomitantdestructionofalargeareaofwildlifehabitat.Theloggedareas aresusceptibletosevereerosion,especiallywhentheclearcuttingoccursonslopes.Withstripcutting,trees areremovedfromconsecutivenarrowstripsofland.Thestripsareremovedoveraperiodofyearsandas aresultsometreesuncutorregrowtharealwaysavailableforanimalhabitat.Thecutareaispartially protectedfromerosionbytheuncutorregrowthtreesintheadjacentareas. 15.1.4RECREATIONALANDWILDERNESSLANDS Animportanthuman-centeredbenetofundevelopedlandistheirrecreationalvalue.Everyyear,millions ofpeoplevisitrecreationallandssuchasparksandwildernessareastoexperienceattractionsofthegreat outdoors:hikingamongthegiantsequoiasinCalifornia,travelingonaphotosafariinKenyaorjustpicnicking atalocalcountypark.Besidesprovidingpeoplewithobvioushealthbenetsandaestheticpleasures, recreationallandsalsogenerateconsiderabletouristmoneyforgovernmentandlocaleconomies. TheUnitedStateshassetasidemorelandforpublicrecreationalusethananyothercountry.Several dierentfederalorganizationsprovidelandsforrecreationaluse:theNationalForestSystem,theU.S.Fish andWildlifeService,theNationalParkSystemandtheNationalWildernessPreservationSystem.The NationalForestSystemmanagesmorethan170forestlandsandgrasslands,whichareavailableforactivities suchascamping,shing,hikingandhunting. TheU.S.FishandWildlifeServicemanagemorethan500NationalWildlifeRefuges,whichnotonly protectanimalhabitatsandbreedingareasbutalsoproviderecreationalfacilities.TheNationalParkSystem managesmorethan380parks,recreationareas,seashores,trails,monuments,memorials,battleeldsand

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70 CHAPTER15.LAND otherhistoricsites.TheNationalWildernessPreservationSystemmanagesmorethan630roadlessareas throughtheaforementionedgovernmentservicesaswellasthroughtheBureauofLandManagement. The NationalParkSystem consistsofmorethan80millionacresnationwide.Thelargestnational parkisWrangell-St.EliasNationalParkandPreserveinAlaskawithover13millionacres.Californiahas eightnationalparks:ChannelIslands,DeathValley,JoshuaTree,Lassen,Redwood,Sequoia,KingsCanyon andYosemite.ManynationalparkssuchasYosemite,YellowstoneandtheGrandCanyonaresuchpopular recreationdestinationsthattheecosystemsofthoseparksarebeingseverelytestedbyhumanactivities. Everystatehasalsosetasidesignicantamountsoflandforrecreationaluse.TheCaliforniaStatePark Systemmanagesmorethanonemillionacresofparklandsincluding:coastalwetlands,estuaries,scenic coastlines,lakes,mountainsanddesertareas.California'slargeststateparkisAnza-BorregoDesertState Park,whichisthelargeststateparkintheUnitedStateswith600,000acres.Thestatedmissionofthe CaliforniaStateParkSystemis:"Toprovideforthehealth,inspirationandeducationofthepeopleof Californiabyhelpingtopreservethestate'sextraordinarybiologicaldiversity,protectingitsmostvalued naturalandculturalresourcesandcreatingopportunitiesforhigh-qualityoutdoorrecreation." Thisisthebasicgoalofallrecreationallands:tomanageandconservenaturalecosystems,whilesupportingasustainableandbalancedlevelofhumanuseofthoseareas.Unfortunately,itisagoalwhichis sometimesdiculttoachieveduetotheincreasingpopularityanduseofrecreationallands. The" WildernessActof1964 "createdtheworld'srstwildernesssystemintheUnitedStates. Presently,the NationalWildernessPreservationSystem containsmorethan100millionacresofland thatwillforeverremainwild.Awiderangeofrecreation,scienticandoutdooractivitiesareavailablein wildernesslands.Miningoperationsandlivestockgrazingarepermittedtocontinueincertainwilderness areaswheresuchoperationsexistedpriortoanarea'sdesignation.Huntingandshingarealsoallowedin wildernessareasexceptinnationalparks. Formostpeople,wildernesslandsprovideameansforvariousformsofrecreation:hiking,horseback riding,birdwatching,shing,andhunting.Peoplecanescapethestressofmodern-daylifeandenjoyan undisturbedlookatnature.Wildernesslandsprovideanessentialhabitatforawidearrayofsh,wildlife, andplants,andareparticularlyimportantinprotectingendangeredspecies.Forscientists,wildernesslands serveasnaturallaboratories,wherestudiescanbeperformedthatwouldnotbepossibleindevelopedareas. Severalothertypesofpubliclandscomplementthedesignatedwildernesslandsystem.Theseinclude: nationalforestroadlessareas,nationaltrailssystem,naturalresearchareasandstateandprivatewilderness lands.Thenationalforestroadlessareasconsistofmillionsofacresofwild,undevelopedlandwithoutroads thatexistonNationalForestlandoutsideofdesignatedwildernesslands. The" NationalTrailSystem ,"establishedbyCongressin1968,includestrailsinwildernessareasand otherpubliclands. ResearchNaturalAreas locatedthroughoutthecountryonpubliclandsserveas outdoorlaboratoriestostudynaturalsystems.Theyareintendedinparttoserveasgenepoolsforrareand endangeredspeciesandasexamplesofsignicantnaturalecosystems.Somewildernesslandsaremaintained bystatesorprivateorganizations.Forexample,thestateofNewYorkhaslongpreservedaregionofthe Adirondacksaswilderness. Onaninternationallevel,importantwildernesslandshavebeendesignatedbytheUnitedNationsthrough its" ManandtheBiosphereProgram ."Thisprogramwasestablishedin1973toprotectexamplesof majornaturalregionsthroughouttheworld,andprovideopportunitiesforecologicalresearchandeducation. Biospherereserves areorganizedintothreeinterrelatedzones:the corearea ,the buerzone and the transitionarea .Thecoreareacontainsthelandscapeandecosystemstobepreserved.Thebuer zoneisanareawhereactivitiesarecontrolledtoprotectthecorearea.Theoutertransitionareacontains avarietyofagriculturalactivities,humansettlementsandotheruses.Localcommunities,conservation agencies,scientistsandprivateenterprisesthathaveastakeinthemanagementoftheregionworktogether tomakethereserveswork.MtKenyainAfricaandtheGalapagosIslandsareexamplesofwildernessareas protectedunderthisprovision.

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Chapter16 AIR,WATERANDSOIL 1 16.1AIR,WATERANDSOIL 16.1.1INTRODUCTION Humanactivitiesreleaseavarietyofsubstancesintothebiosphere,manyofwhichnegativelyaectthe environment.Pollutantsdischargedintotheenvironmentcanaccumulateintheair,water,orsoil.Chemicals dischargedintotheairthathaveadirectimpactontheenvironmentarecalled primarypollutants .These primarypollutantssometimesreactwithotherchemicalsintheairtoproducesecondarypollutants. Awidevarietyofchemicalsandorganismsaredischargedintolakes,riversandoceansdaily.Left untreated,thissewageandindustrialwastehasaseriousimpactonthewaterquality,notonlyinthe immediatearea,butalsodownstream. 16.1.2AIRPOLLUTANTS Theeightclassesofairpollutantsare:oxidesofcarbon,sulfurandnitrogen,volatileorganiccompounds, suspendedparticulatematter,photochemicaloxidants,radioactivesubstancesandhazardousairpollutants. Oxidesofcarbon include carbonmonoxide COand carbondioxide CO2.Carbonmonoxide, aprimarypollutant,ismainlyproducedbytheincompletecombustionoffossilfuels.Itisalsopresentin cigarettesmoke.Thecolorless,odorlessgasispoisonoustoair-breathinganimals.Carbonmonoxidebindsto hemoglobin,impedingdeliveryofoxygentocells.Thiscausesdizziness,nausea,drowsiness,andheadaches; athighconcentrationsitcancausedeath.Carbonmonoxidepollutionfromautomobilescanbereduced throughtheuseofcatalyticconvertersandoxygenatedfuels. Carbondioxideisproducedbythecompletecombustionoffossilfuels.Itisconsideredagreenhouse gasbecauseitheatsuptheatmospherebyabsorbinginfraredradiation.Asaresultofthischaracteristic, excessamountsofcarbondioxideintheatmospheremaycontributetoglobalwarming.Carbondioxidecan alsoreactwithwaterintheatmosphereandproduceslightlyacidicrain.Carbondioxideemissionscanbe reducedbylimitingtheamountoffossilfuelsburned. Oxidesofsulfur include sulfurdioxide SO2and sulfurtrioxide SO3.Sulfuroxidesareprimarily producedbythecombustionofcoalandoil.Oxidesofsulfurhaveacharacteristicrotteneggodor,and inhalationofthemcanleadtorespiratorysystemdamage.Theyreactwithatmosphericwatertoproduce sulfuricacid,whichprecipitatesasacidrainoracidfog.Acidrainisasecondarypollutantthatacidies lakesandstreams,renderingthewateruntforaquaticlife.Italsocorrodesmetals,anddissolveslimestone andmarblestructures.Oxidesofsulfurcanberemovedfromindustrialsmokestackgasesby"scrubbing" theemissions,byelectrostaticallyprecipitatingthesulfur,byltration,orbycombiningthemwithwater, therebyproducingsulfuricacidwhichcanbeusedcommercially. 1 Thiscontentisavailableonlineat. 71

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72 CHAPTER16.AIR,WATERANDSOIL Oxidesofnitrogen include: nitricoxide NO, nitrogendioxide NO2,and nitrousoxide N2O. Nitricoxideisaclear,colorlessgasformedduringthecombustionoffossilfuels.Nitrogendioxideformswhen nitricoxidereactswithatmosphericoxygen;thereddish-brownpungentgasisconsideredtobeasecondary pollutant.Exposuretooxidesofnitrogencancauselungdamage,aggravateasthmaandbronchitis,and increasesusceptibilitytotheuandcolds.Nitrogendioxidecancombinewithatmosphericwatertoform nitricacid,whichisprecipitatedasacidrain.Nitrogendioxideisalsoakeyingredientintheformationof photochemicalsmog,andnitrousoxideisagreenhousegas.Automobileemissionsofthesepollutantscan bereducedbycatalyticconverterswhichconvertthemtomolecularnitrogenandoxygen. VolatileorganiccompoundsVOCs include hydrocarbons suchasmethaneCH4,propane C3H8,andoctaneC8H18,and chlorouorocarbonsCFCs suchasdichlorodiuoromethane CCl2F2. Hydrocarbonsarereleasedintotheatmosphereinautomobileexhaustandfromtheevaporationof gasoline.Theycontributetotheformationof photochemicalsmog .Chlorouorocarbonswereusedas propellantsforaerosolsandasrefrigerantsuntilitwasdiscoveredtheycancausedepletionoftheprotective ozonelayer.Volatileorganiccompoundemissionscanbereducedbyusingvapor-recoverygasolinenozzles atservicestationsandbyburningoxygenatedgasolineinautomobileengines. Suspendedparticulatematter consistsoftinyparticlesofdust,soot,asbestos,andsalts,andof microscopicdropletsofliquidssuchassulfuricacidandpesticides.Sourcesofthesepollutantsincludethe combustionoffossilfuele.g.dieselenginesandroadandbuildingconstructionactivity.Exposuretothese particlescanleadtorespiratoryirritation,reductionoflungcapacity,lungcancer,andemphysema. Photochemicaloxidants areprimarilyproducedduringtheformationofphotochemicalsmog. Ozone O3isahighlyreactive,irritatinggasthatcausesbreathingproblems,aswellaseye,nose,andthroat irritation.Italsoaggravatesasthma,bronchitis,andheartdisease.Ozoneandotherphotochemicaloxidants candamageorkillplants,reducevisibility,anddegraderubber,paint,andclothes.Photochemicaloxidants aresecondarypollutants,andcanbecontrolledbyreducingtheamountofnitrogendioxideintheatmosphere. Radioactivesubstancesincluderadon-222,iodine-131,andstrontium-90. Radon isgasproducedduring thedecayofuraniumthatisnaturallypresentinrocksandbuildingmaterialsmadewiththeserocks.It isknowntocauselungcancerinhumans.Theotherradioisotopesareproducedbynuclearpowerplants iodine-131orarecontainedinthefalloutfromatmosphericnucleartestingstrontium-90.Theycanbe introducedintothefoodchainthroughplantsandbecomeincorporatedinthetissuesofhumansandother animals.Theirionizingradiationcanproducecancers,especiallythoserelatedtothethyroidandbone. Hazardousairpollutantsinclude benzene C6H6and carbontetrachloride CCl4.Benzeneisa commonorganicsolventwithnumerousindustrialuses.Carbontetrachloridewasformerlyusedasasolvent inthedrycleaningbusiness.Itisstillusedinindustrialprocesses.Exposuretothesecompoundscancause cancer,birthdefectsandcentralnervoussystemproblems. 16.1.3WATERPOLLUTANTS Theeightclassesofwaterpollutantsare:infectiousagents,oxygen-depletingwastes,inorganicchemicals, organicchemicals,plantnutrientpollutants,sediments,radioactivematerialsandthermalpollution.Infectiousagentssuchasbacteria,viruses,andparasiticwormsenterwaterfromhumanandanimalwaste,and causediseasessuchastyphoidfever,cholera,hepatitis,amoebicdysentery,andschistosomiasis,acondition markedbybloodlossandtissuedamage. Oxygen-depletingwastes includeanimalmanureinfeedlotandfarmruno,plantdebris,industrial discharge,andurbansewage.Theyareconsumedbyaerobicbacteria.Excessivegrowthoftheseorganisms candepletewaterofdissolvedoxygenwhichleadstoeutrophicationandtheeventualdeathofoxygenconsumingaquaticlife. Inorganicchemicalpollutants includemineralacids,toxicmetalssuchaslead,cadmium,mercury, andhexavalentchromium,andmineralsalts.Theyarefoundinindustrialdischarge,chemicalsinhousehold wastewater,andseepagefrommunicipaldumpsandlandlls.Thepresenceofinorganicchemicalpollutants inwatercanrenderitundrinkable,aswellascausecancerandbirthdefects.Inaddition,sucientconcen-

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73 trationsofthesechemicalsinwatercankillshandotheraquaticlife,causelowercropyieldsduetoplant damage,andcorrodemetals. Organicchemicalpollutants encompassawidevarietyofcompoundsincludingoil,gasoline,pesticides, andorganicsolvents.Theyalldegradethequalityofthewaterintowhichtheyaredischarged.Sources ofthesepollutantsincludeindustrialdischargeandrunofromfarmsandurbanareas.Sometimesthese chemicalsenteraquaticecosystemsdirectlywhensprayedonlakesandpondse.g.formosquitocontrol. Thesetypesofchemicalscancausecancer,damagethecentralnervoussystemandcausebirthdefectsin humans. Plantnutrientpollutants arefoundmainlyinurbansewage,runofromfarmsandgardens,andhouseholdwastewater.ThesechemicalsincludenitratesNO3-,phosphatesPO43-andammoniumNH4+salts commonlyfoundinfertilizersanddetergents.Toomuchplantnutrientsinthewatercancauseexcessive algaegrowthinlakesorponds.This,inturn,resultsintheproductionoflargeamountsofoxygen-depleting wastes.Thesubsequentlossofdissolvedoxygencauseseutrophicationofthelakesorponds. Erosionofsoilsisthemainprocesscontributing sediments ,or silts ,towaterbodies.Sedimentscancloud thewaterofstreamsandrivers,reducingtheamountofavailablesunlighttoaquaticplants.Theconcurrent reductioninphotosynthesiscandisruptthelocalecosystem.Soilfromcroplandsdepositedinlakesand streamscancarrypesticides,bacteria,andothersubstancesthatareharmfultoaquaticlife.Sedimentscan alsolluporcloglakes,reservoirs,andwaterwayslimitinghumanuseanddisruptinghabitats. Radioactivematerialssuchasiodine-131andstrontium-90arefoundinnuclearpowerplanteuentsand falloutfromatmosphericnucleartesting.Theycanbeintroducedintothefoodchainthroughplantsand becomeincorporatedinbodytissuesofhumansandanimals.Theirionizingradiationcanproducecancers, especiallyinthethyroidandbonewheretheytendtoconcentrate. Apowergeneratingplantcommonlydischargeswaterusedforcoolingintoanearbyriver,lake,orocean. Becausethedischargedwatercanbesignicantlywarmerthantheambientenvironment,itrepresentsa sourceof thermalpollution .Industrialdischargesarealsosourcesofthermalpollution.Theincreased temperatureofthewatermaylocallydepletedissolvedoxygenandexceedtherangeoftoleranceofsome aquaticspecies,thusdisruptingthelocalecosystem. Processingwaterintreatmentplantscanreducetheamountsofinfectiousagents,oxygen-depleting wastes,inorganicchemicals,organicchemicalsandplantnutrients.Bansandrestrictionsontheuseofcertain chemicals,suchasthoseonDDTandhexavalentchromiumcompounds,arealsoveryhelpfulinreducing theamountsofthesechemicalsintheenvironment.Bylimitingexposuretotheseharmfulsubstances,their negativeeectsonhumansandlocalecosystemscanbegreatlyreduced. 16.1.4SOILPOLLUTANTS Thepersistenceofpesticidesinthesoilisrelatedtohowquicklythesechemicalsdegradeintheenvironment. Therearethreewayspesticidesaredegradedinthesoil: biodegradation chemicaldegradation ,and photochemicaldegradation .Microorganismactivityplaysthepredominantroleinthebiodegradationof pesticides.Waterplaysanimportantroleinthechemicaldegradationofpesticidese.g.somepesticidesare hydrolyzedonthesurfacesofmineralsbywater.Exposuretosunlightcanalsodegradesomepesticides. Avarietyofpesticidesareusedtocontrolinsects,weeds,fungi,andmildewinagricultural,garden,and householdenvironments.Therearethreeclassesofpesticides: insecticides ,whichkillinsects; herbicides whichkillplants;and fungicides ,whichkillfungi.Eachoftheseclassesincludesdierenttypesofchemicals. Thesechemicalsdierinchemicalcomposition,chemicalaction,toxicity,andpersistenceresidencetime intheenvironment.Someofthesepesticidescanbioaccumulatee.g.theyconcentrateinspecicplantand animaltissuesandorgans.Pesticidescanaccumulateinthesoiliftheirstructuresarenoteasilybroken downintheenvironment.Besidesrenderingthesoiltoxictootherlivingorganisms,thesepesticidesmay leachoutintothegroundwater,pollutingwatersupplies. Theveclassesofinsecticidesare:chlorinatedhydrocarbons,organophosphates,carbamates,botanicals andsyntheticbotanicals. Chlorinatedhydrocarbons suchasDDT,arehighlytoxicinbirdsandshes, buthaverelativelylowtoxicityinmammals.Theypersistintheenvironment,lastingformanymonths oryears.Becauseoftheirtoxicityandpersistence,theiruseasinsecticideshasbeensomewhatrestricted.

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74 CHAPTER16.AIR,WATERANDSOIL Organophosphates ,suchas Malathion ,aremorepoisonousthanothertypesofinsecticides,buthave muchshorterresidencetimesintheenvironment.Thus,theydonotpersistintheenvironmentandcannot bioaccumulate. Carbamates ,suchas Sevin ,aregenerallylesstoxictomammalsthanareorganophosphates.Theyalsohavearelativelylowpersistenceintheenvironmentandusuallydonotbioaccumulate. Botanicals ,suchas camphor ,arederivedfromplantsources.Manyofthesecompoundsaretoxicto mammals,birds,andaquaticlife.Theirpersistenceintheenvironmentisrelativelylow,andasaresult bioaccumulationisnotaproblem. Syntheticbotanicals ,suchas Allethrin ,generallyhavealowtoxicity formammals,birds,andaquaticlife,butitisunclearhowpersistenttheyareandwhetherornotthey bioaccumulate. Thethreeclassesofherbicidesare:contactchemicals,systemicchemicalsandsoilsterilants.Most herbicidesdonotpersistinthesoilforverylong. Contactchemicals areapplieddirectlytoplants,and causerapidcellmembranedeterioration.Onesuchherbicide,Paraquat,receivednotorietywhenitwasused asadefoliantonmarijuanaelds.Paraquatistoxictohumans,butdoesnotbioaccumulate. Systemic chemicals ,suchasAlar,aretakenupbytherootsandfoliageofplants,andareoflowtomoderatetoxicity tomammalsandbirds;somesystemicherbicidesarehighlytoxictoshes.Thesecompoundsdonothavea tendencytobioaccumulate. Soilsterilants suchas Diphenamid ,renderthesoilinwhichtheplantslives toxic.Thesechemicalshavealowtoxicityinanimals,anddonotbioaccumulate. Fungicidesareusedtokillorinhibitthegrowthoffungi.Theycanbeseparatedintotwocategories: protectantsandsystemics.Protectantfungicides,suchasCaptan,protecttheplantagainstinfectionatthe siteofapplication,butdonotpenetrateintotheplant.Systemfungicides,suchasSovran,areabsorbed throughtheplant'srootsandleavesandpreventdiseasefromdevelopingonpartsoftheplantawayfrom thesiteofapplication.Fungicidesarenotverytoxicandaremoderatelypersistentintheenvironment. Soilcanabsorbvastamountofpollutantsbesidespesticideseveryyear.Sulfuricacidrainisconvertedin soiltosulfatesandnitricacidrainproducesnitratesinthesoil.Bothofthesecanfunctionasplantnutrient pollutants.Suspendedparticulatematterfromtheatmospherecanaccumulateinthesoil,bringingwithit otherpollutantssuchastoxicmetalsandradioactivematerials. 16.1.5PointandNon-pointPollutionSources Environmentalregulationsaredesignedtocontroltheamountsandeectsofpollutantsreleasedbyagricultural,industrial,anddomesticactivities.Theselawsrecognizetwocategoriesofpollutionandpolluters pointsourceandnon-pointsource. PointSourcePollution Pointsourcesaresingle,discretelocationsorfacilitiesthatemitpollution,likeafactory,smokestack, pipe,tunnel,ditch,container,automobileengine,orwell. Becausepointsourcescanbepreciselylocated,thedischargeofpollutantsfromthemisrelativelyeasyto monitorandcontrol.TheUnitedStatesEnvironmentalProtectionAgency,orEPA,setsemissionstandards forparticularchemicalsandcompounds.Then,outowfromthepointsourceissampled,andthepollutants initaremeasuredpreciselytoensurethatdischargelevelsareincompliancewithregulations. Newtechniquestoreduceemissionsfrompointsourcesaremorelikelytobedevelopedbecausetheir eectivenesscanbeevaluatedquicklyanddirectlyandbecausepointsourcepollutershaveanobvious nancialincentivetoreducewasteandavoidregulatorynes. Non-pointSourcePollution Non-pointsourcesarediuseandwidespread.Contaminantsaresweptintowaterwaysbyrainfalland snowmeltorblownintotheairbythewind.Theycomefrommultiplesources,suchasvehiclesdripping oilontoroadsandparkinglots,pesticidesusedonlawnsandparksandelds,wastesdepositedbylivestock andpets,orsoildisturbedbyconstructionorplowing. Non-pointsourcepollutionismorediculttoregulatethanpointsourceemissions.Contaminationis measurednotatthesource,butatthedestination.Samplesarecollectedfromtheair,soil,andwater,or fromthebloodandtissuesoforganismsinpollutedareas.Thecontributionofvariousnon-pointsources tothesepollutionlevelscanonlybeestimated.EPAregulationscannotbedirectedatspecicindividuals orbusinessesandareinsteadgenerallydirectedatmunicipalities.Forexample,federalstandardsareset

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75 forallowablelevelsofchemicalsindrinkingwater,andcommunitiesareresponsiblefortreatingtheirwater untilitmeetsthosestandards. Itcanbediculttoreducemanytypesofnon-pointsourcepollutionbecausemostofthepeoplewho contributetoitarenotdirectlyfacedwithlegalornancialconsequences.Individualsmustbepersuaded thattheiractivitiesarecausingecologicalharmandthattheyshouldaltertheirbehaviororspendtheir moneytoremedythesituation.Oncetheydo,theymayhavetowaitalongtimefornoticeableenvironmental results. 16.1.6PartspermillionppmandMicrogramspermilliliterug/mL Verysmallquantitiesofsomechemicalscanhavealargeimpactonorganisms.Becauseofthis,substances thatarepresentintraceamounts,suchasnutrientsandcontaminants,areusuallymeasuredandrecorded usingverysmallunits.Twoofthemostcommonmeasuresarepartspermillionandmicrogramspermilliliter. Microgramspermilliliterug/mL Microgramspermilliliter,orug/mL,measuresmasspervolume.Itisgenerallyusedtomeasurethe concentrationofasubstancedissolvedorsuspendedinaliquid.Onemicrogramisonemillionthofagram ug=0.0000001g,andonemilliliterisonethousandthofaliter. Partspermillionppm Partspermillion,abbreviatedasppm,isaunitlessmeasureofproportion.Itisobtainedbydividing theamountofasubstanceinasamplebytheamountoftheentiresample,andthenmultiplyingby106.In otherwords,ifsomequantityofgas,liquid,orsolidisdividedintoonemillionparts,thenumberofthose partsmadeupofanyspecicsubstanceistheppmofthatsubstance.Forexample,if1mLofgasolineis mixedwith999,999mLofwater,thewatercontains1ppmofgas. ConcentrationEquivalents Sinceamicrogramisonemillionthofagram,andamilliliterofwaterequalsonegramofwater,ug/mLis equivalenttopartspermillion.Ppmisalsoequivalenttomanyotherproportionalmeasurements,including milligramsperlitermg/L,milligramsperkilogrammg/Kg,andpoundsperacrelb/acre.Butpartsper millionisoftenmoreusefulindescribingandcomparingtraceamountsofchemicalsbecauseiteliminates specicunitsandisapplicabletoliquids,solids,andgases. Examples Bothppmandug/mLcanbeusedtodescribetheamountofparticulatedustinasampleofair: Ifthetotalparticulatedustinaonelitervolumeofairis5mg,thereis5ppmofparticulatedustinthe airthatwassampled,sincemg/Lmilligramsperliter=ppm. Howmuchdyeshouldyouaddtoonegallonofwatertoachieveanal500ppmmixture? ConcentrationMeasurementsandEnvironmentalRegulations Becausemanytoxinsbegintohavenegativeenvironmentaleectsatverylowlevels,theirabundancein ppmorug/mLareusedtosetthelimitsofpollutantsthatarelegallypermittedinstacksmoke,discharge water,soilcontamination,andsoon.Forexample,coalredpowerplantsmaybelimitedtoadischarge of0.5ppmofSO2inthestacksmoke.Ifaplant'semissionsexceedthatamount,itmaybeinviolationof localorfederalairqualitystandardsandcouldbesubjecttoane. 16.1.7PollutionEectsonWildlife Notunreasonably,wetendtobemostconcernedbytheimpactofpollutiononhumanhealthandinterests. However,thereisgrowingdocumentationoftheharmpollutionisinictingonwildlife.Thefollowingare justasmallsample. Pesticides ThepesticideDDTwasbannedintheU.S.in1972becauseitcausedraptoreggstothinandbreak.But residualDDTandotherpersistentorganochlorinepesticidescontinuetoimpactwildlifetoday.Additionally, DDTisstillusedinmanyothercountriesasthemosteectivecontrolofmalaria-bearingmosquitoes. PrescriptionDrugs

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76 CHAPTER16.AIR,WATERANDSOIL Prescriptiondrugs,caeine,andothermedicationscanpassthroughboththehumanbodyandsewage treatmentfacilities,andarenowpresentinmanywaterways.Someofthesemaybetoxictoaquaticlife. Others,especiallysteroids,estrogen,testosteroneandsimilarregulatoryhormones,arelikelytointerfere withthedevelopmentoforganisms. HeavyMetals Whenhuntersshootanimalswithleadshot,butdonotrecoverthedeadorinjuredanimals,theshotis eventuallyingestedbyotherwildlife.Theleadisconcentratedasitpassesupthefoodchain,andthetop predators,especiallyraptors,getleadpoisoning.Manystatesnowrequiretheuseofsteelshot. Miningwastesalsoreleasetoxiclevelsofsubstanceslikeleadandmercuryintowaterways. WaterAcidication Acidrainandsnowisproducedfromtheburningofhigh-sulfurcoalsinelectricalpowerplants.Acid minerun-oiscausedbythereactionofrainwaterwithminetailings.Acidicationcansterilizewater bodies,killingoallaquaticoraandfauna.Whenwildfowlandotherwildlifeingestthiswater,theycan bepoisonedbyheavymetals. Dioxin Dioxinisgeneratedbyburningwastesandintheproductionofsomepapersandplastics.Itaccumulates inanimalfatsandconcentratesupthefoodchain,andhasbeenlinkedtocancersandreproductiveissues inanumberofspecies. OilSpills Oilspillshaveimmediatedevastatingeectsmarinemammalsandwaterfowlcoatedwithoildrown,are poisoned,ordieofhypothermia.Ballsofoilthatsinktotheseaoorcansmotherorganisms.Lessobvious eectsincludetumorsandreproductivedamageinshesandcrustaceanscausedbyoilbyproducts. NoisePollution Chronicnoisepollutionfromlow-yingaircraft,snowmobiles,motorcycles,andtraccancausewildlife toabandonhabitats,losereproductivefunction,andbecomemorevulnerabletopredationduetolossof hearing. LightPollution Lightpollutionatnightdisorientsbats,insects,andmigratorybirds. Eutrophication Eutrophicationresultsfromtheadditionofenrichingagentsdetergents,fertilizers,andorganicwastes towaterbodies.Explosivegrowthandsubsequentdecayofalgaeuseupavailableoxygen,whichinturn suocatesaquaticanimalsandplants.Thechangeinwaterchemistrycanalsodriveoutnativespecies. Sedimentation Sedimentserodedduringconstructionoragriculturalpracticesarewashedintowaterways,damagingsh spawninggroundsandsmotheringbottomdwellingorganisms. 16.1.8Summary Studiesoftheeectsofpollutiononwildlifeareofmorethanacademicinterest.Liketheproverbialcanary inthecoalmine,diseaseanddamageinthenaturalworldisoftenaharbingerofsimilardangertoourselves.

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Chapter17 SOLIDWASTE 1 17.1SOLIDWASTE 17.1.1INTRODUCTION Innaturalsystems,thereisnosuchthingaswaste.Everythingowsinanaturalcycleofuseandreuse. Livingorganismsconsumematerialsandeventuallyreturnthemtotheenvironment,usuallyinadierent form,forreuse. Solidwaste ortrashisahumanconcept.Itreferstoavarietyofdiscardedmaterials, notliquidorgas,thataredeemeduselessorworthless.However,whatisworthlesstoonepersonmaybe ofvaluetosomeoneelse,andsolidwastescanbeconsideredtobemisplacedresources.Learningeective waystoreducetheamountofwastesproducedandtorecyclevaluableresourcescontainedinthewastesis importantifhumanswishtomaintainalivableandsustainableenvironment. Solidwastedisposalhasbeenanissuefacinghumanssincetheybeganlivingtogetherinlarge,permanent settlements.Withthemigrationofpeopletourbansettings,thevolumeofsolidwasteinconcentratedareas greatlyincreased. Ancientculturesdealtwithwastedisposalinvariousways:theydumpeditoutsidetheirsettlements, incorporatedsomeofitintoooringandbuildingmaterials,andrecycledsomeofit.Dumpingand/or burningsolidwastehasbeenastandardpracticeoverthecenturies.MostcommunitiesintheUnitedStates dumpedorburnedtheirtrashuntilthe1960s,whentheSolidWasteDisposalActof1965partoftheClean AirActrequiredenvironmentallysounddisposalofwastematerials. 17.1.2SOURCESANDTYPESOFSOLIDWASTE Therearetwobasicsourcesofsolidwastes:non-municipalandmunicipal. Non-municipalsolidwaste isthediscardedsolidmaterialfromindustry,agriculture,mining,andoilandgasproduction.Itmakesup almost99percentofallthewasteintheUnitedStates.Somecommonitemsthatareclassiedasnonmunicipalwasteare:constructionmaterialsroongshingles,electricalxtures,bricks;waste-watersludge; incineratorresidues;ash;scrubbersludge;oil/gas/miningwaste;railroadties,andpesticidecontainers. Municipalsolidwaste ismadeupofdiscardedsolidmaterialsfromresidences,businesses,andcity buildings.ItmakesupasmallpercentageofwasteintheUnitedStates,onlyalittlemorethanonepercent ofthetotal.Municipalsolidwasteconsistsofmaterialsfromplasticstofoodscraps.Themostcommon wasteproductispaperabout40percentofthetotal. Othercommoncomponentsare:yardwastegreenwaste,plastics,metals,wood,glassandfoodwaste. Thecompositionofthemunicipalwastescanvaryfromregiontoregionandfromseasontoseason.Food waste,whichincludesanimalandvegetablewastesresultingfromthepreparationandconsumptionoffood, iscommonlyknownasgarbage. 1 Thiscontentisavailableonlineat. 77

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78 CHAPTER17.SOLIDWASTE Somesolidwastesaredetrimentaltothehealthandwell-beingofhumans.Thesematerialsareclassied ashazardouswastes.Hazardouswastesaredenedasmaterialswhicharetoxic, carcinogenic cause cancer, mutagenic causeDNAmutations, teratogenic causebirthdefects,highlyammable,corrosive orexplosive.AlthoughhazardouswastesintheUnitedStatesaresupposedlyregulated,someobviously hazardoussolidwastesareexcludedfromstrictregulation;theseinclude:mining,hazardoushouseholdand smallbusinesswastes. 17.1.3WASTEDISPOSALMETHODS Mostsolidwasteiseithersentto landlls dumpedorto incinerators burned.Oceandumpinghasalso beenapopularwayforcoastalcommunitiestodisposeoftheirsolidwastes.Inthismethod,largebarges carrywasteouttoseaanddumpitintotheocean.ThatpracticeisnowbannedintheUnitedStatesdue topollutionproblemsitcreated.Mostmunicipalandnon-municipalwasteabout60%issenttolandlls. Landllsarepopularbecausetheyarerelativelyeasytooperateandcanhandleoflotofwastematerial. Therearetwotypesoflandlls:sanitarylandllsandsecurelandlls. Ina sanitarylandll solidwastesarespreadoutandcompactedinahole,canyonareaoragiant mound.Modernsanitarylandllsarelinedwithlayersofclay,sandandplastic.Eachdayaftergarbageis dumpedinthelandll,itiscoveredwithclayorplastictopreventredistributionbyanimalsorthewind. Rainwaterthatpercolatesthroughasanitarylandlliscollectedinthebottomliner.Thisliquidleachate maycontaintoxicchemicalssuchasdioxin,mercury,andpesticides.Therefore,itisremovedtopreventcontaminationoflocalaquifers.Thegroundwaternearthelandlliscloselymonitoredforsignsofcontamination fromtheleachate. Astheburiedwastesaredecomposedbybacteria,gasessuchasmethaneandcarbondioxideareproduced.Becausemethanegasisveryammable,itisusuallycollectedwithothergasesbyasystemofpipes, separatedandtheneitherburnedoorusedasasourceofenergye.g.,homeheatingandcooking,generatingelectricity.Othergasessuchasammoniaandhydrogensuldemayalsobereleasedbythelandll, contributingtoairpollution.Thesegasesarealsomonitoredand,ifnecessary,collectedfordisposal.Finally,whenthelandllreachesitscapacity,itissealedwithmorelayersofclayandsand.Gasandwater monitoringactivities,though,mustcontinuepasttheusefullifeofthelandll. Securelandlls aredesignedtohandlehazardouswastes.Theyarebasicallythesamedesignassanitary landlls,buttheyhavethickerplasticandclayliners.Also,wastesaresegregatedandstoredaccordingto type,typicallyinbarrels,whichpreventsthemixingofincompatiblewastes.Somehazardouswasteinthe UnitedStatesissenttoforeigncountriesfordisposal.Developingcountriesarewillingtoacceptthiswasteto raiseneededmonies.RecenttreatiesbytheU.N.EnvironmentProgrammehaveaddressedtheinternational transportofsuchhazardouswastes. Federalregulationmandatesthatlandllscannotbelocatednearfaults,oodplains,wetlandsorother bodiesofwater.Inmanyareas,ndinglandllspaceisnotaproblem,butinsomeheavilypopulatedareasit isdiculttondsuitablesites.Thereare,ofcourse,otherproblemsassociatedwithlandlls.Thelinersmay eventuallyleakandcontaminategroundwaterwithtoxicleachate.Landllsalsoproducepollutinggases, andlandllvehicletraccanbeasourceofnoiseandparticulatepollutantsforanynearbycommunity. About15percentofthemunicipalsolidwasteintheUnitedStatesisincinerated. Incineration isthe burningofsolidwastesathightemperatures > 1000 C.Thoughparticulatematter,suchasash,remains aftertheincineration,thesheervolumeofthewasteisreducedbyabout85percent.Ashismuchmore compactthanunburnedsolidwaste.Inadditiontothevolumereductionofthewaste,theheatfromthe trashthatisincineratedinlarge-scalefacilitiescanbeusedtoproduceelectricpower.Thisprocessiscalled waste-to-energy.Therearetwokindsofwaste-to-energysystems:massburnincineratorsandrefuse-derived incinerators. In massburnincinerators allofthesolidwasteisincinerated.Theheatfromtheincinerationprocess isusedtoproducesteam.Thissteamisusedtodriveelectricpowergenerators.Acidgasesfromtheburning areremovedbychemicalscrubbers. Anyparticulatesinthecombustiongasesareremovedbyelectrostaticprecipitators.Thecleanedgases arethenreleasedintotheatmospherethroughatallstack.Theashesfromthecombustionaresenttoa

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79 landllfordisposal. Itisbestifonlycombustibleitemspaper,woodproducts,andplasticsareburned.Ina refuse-derived incinerator ,non-combustiblematerialsareseparatedfromthewaste.Itemssuchasglassandmetalsmay berecycled.Thecombustiblewastesarethenformedintofuelpelletswhichcanbeburnedinstandard steamboilers.Thissystemhastheadvantageofremovingpotentiallyharmfulmaterialsfromwastebefore itisburned.Italsoprovidesforsomerecyclingofmaterials. Aswithanycombustionprocess,themainenvironmentalconcernisairquality.Incinerationreleases variousairpollutantsparticulates,sulfurdioxide,nitrogenoxides,andmethaneintotheatmosphere. Heavymetalse.g.,lead,mercuryandotherchemicaltoxinse.g.,dioxinscanalsobereleased.Many communitiesdonotwantincineratorswithintheircitylimits.Incineratorsarealsocostlytobuildandto maintainwhencomparedtolandlls.

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80 CHAPTER17.SOLIDWASTE

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Chapter18 IMPACTONHUMANHEALTH 1 18.1IMPACTONHUMANHEALTH 18.1.1INTRODUCTION Whenenvironmentalconditionsaredegradedsuchthattherangeoftoleranceisexceeded,therewillbea signicantimpactonhumanhealth.Ourindustrializedsocietydumpshugeamountsofpollutantsandtoxic wastesintotheearth'sbiospherewithoutfullyconsideringtheconsequences.Suchactionsseriouslydegrade thehealthoftheearth'secosystems,andthisdegradationultimatelyaectsthehealthandwell-beingof humanpopulations. 18.1.2AGENTS Formostofhumanhistory, biologicalagents werethemostsignicantfactorinhealth.Theseincluded pathogenicdiseasecausingorganismssuchasbacteria,viruses,protozoa,andinternalparasites.Inmodern times,cardiovasculardiseases,cancer,andaccidentsaretheleadingkillersinmostpartsoftheworld. However,infectiousdiseasesstillcauseabout22milliondeathsayear,mostlyinundevelopedcountries.These diseasesinclude:tuberculosis,malaria,pneumonia,inuenza,whoopingcough,dysenteryandAcquired ImmuneDeciencySyndromeAIDS.Mostofthoseaectedarechildren.Malnutrition,uncleanwater, poorsanitaryconditionsandlackofpropermedicalcareallplayrolesinthesedeaths. Compoundingtheproblemsofinfectiousdiseasesarefactorssuchasdrug-resistantpathogens,insecticideresistantcarriersandoverpopulation.Overuseofantibioticshaveallowedpathogenstodeveloparesistance todrugs.Forexample,tuberculosisTBwasnearlyeliminatedinmostpartsoftheworld,butdrug-resistant strainshavenowreversedthattrend.Anotherexampleismalaria.TheinsecticideDDTwaswidelyusedto controlmalaria-carryingmosquitopopulationsintropicalregions.However,aftermanyyearsthemosquitoes developedanaturalresistancetoDDTandagainspreadthediseasewidely.Anti-malarialmedicineswere alsooverprescribed,whichallowedthemalariapathogentobecomedrug-resistant. Inourindustrializedsociety, chemicalagents alsohavesignicanteectsonhumanhealth.Toxicheavy metals,dioxins,pesticides,andendocrinedisruptersareexamplesofthesechemicalagents.Heavymetals e.g.,mercury,lead,cadmium,bismuth,selenium,chromium,thalliumaretypicallyproducedasby-products ofminingandmanufacturingprocesses.Allofthembiomagnifyi.e.,theybecomemoreconcentratedin specieswithincreasingfoodchainlevel.Mercuryfrompollutedwatercanaccumulateinswordshto levelstoxictohumans.Whentoxic heavymetals getintothebody,theyaccumulateintissuesandmay eventuallycausesicknessordeath.Studiesshowthatpeoplewithabove-averageleadlevelsintheirbones haveanincreasedriskofdevelopingattentiondecitdisorderandaggressivebehavior.Leadcanalsodamage braincellsandaectmuscularcoordination. 1 Thiscontentisavailableonlineat. 81

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82 CHAPTER18.IMPACTONHUMANHEALTH Dioxins areorganiccompounds,usuallyproducedasabyproductofherbicideproduction.Theyare stablecompoundsandcanaccumulateintheenvironment.Dioxinsalsobiomagnifythroughthefoodchain andcancausebirthdefectsanddeathinwildlife.Althoughdioxinisknowntobeextremelytoxicto mammals,itslow-leveleectsonthehumanbodyarenotwellknown.TheinfamousAgentOrangeused asadefoliantduringtheVietnamwarcontainedadioxincomponent.Manyveteransfromthatwarsuer fromavarietyofmedicalproblemsattributedtoAgentOrangeexposure. Pesticides areusedthroughouttheworldtoincreasecropyieldsandasadeterrenttoinsect-borne diseases.ThepesticideDDTwaswidelyusedfordecades.Itwasseenasanidealpesticidebecauseitis inexpensiveandbreaksdownslowlyintheenvironment.Unfortunately,thelattercharacteristicallowsitto biomagnifythroughthefoodchain.Populationsofbirdspeciesatthetopofthefoodchain,e.g.,eaglesand pelicans,aregreatlyaectedbyDDTintheenvironment.WhenthesebirdshavesucientlevelsofDDT, theshellsoftheireggsaresothinthattheybreak,makingreproductionimpossible.AfterDDTwasbanned intheUnitedStatesin1972,aectedbirdpopulationsmadenoticeablerecoveries. AccordingtotheWorldHealthOrganization,morethanthreemillionpeoplearepoisonedbypesticides eachyear,mostlyinundevelopedcountries,andabout220,000ofthemdie.Long-termexposuretopesticides byfarmworkersandworkersinpesticidefactoriesseemstobepositivelycorrelatedwithanincreasedrisk ofdevelopingvariouscancers. Heavymetals,dioxinsandpesticidesmayallbe endocrinedisrupters .Endocrinedisruptersinterfere withthefunctionsofhormonesinthehumanbody,especiallythosecontrollinggrowthandreproduction. Theydothisbymimickingcertainhormonesandsendingfalsemessagestothebody.Becausetheyare activeeveninlowconcentrations,endocrinedisruptersmaycauseproblemsinrelativelylowdoses.Someof theeectsincludelowspermcountandsterilityinmales.Since1940,spermcountshavedropped50percent inhumanmales,possiblytheresultofexposuretoendocrinedisrupters. 18.1.3EFFECTS An acuteeect ofasubstanceisonethatoccursrapidlyafterexposuretoalargeamountofthatsubstance. A chroniceect ofasubstanceresultsfromexposuretosmallamountsofasubstanceoveralongperiodof time.Insuchacase,theeectmaynotbeimmediatelyobvious.Chroniceectsarediculttomeasure,as theeectsmaynotbeseenforyears.Long-termexposuretocigarettesmoking,lowlevelradiationexposure, andmoderatealcoholuseareallthoughttoproducechroniceects. Forcenturies,scientistshaveknownthatjustaboutanysubstanceistoxicinsucientquantities.For example,smallamountsofseleniumarerequiredbylivingorganismsforproperfunctioning,butlarge amountsmaycausecancer.Theeectofacertainchemicalonanindividualdependsonthedoseamount ofthechemical.Thisrelationshipisoftenillustratedbyadose-responsecurvewhichshowstherelationship betweendoseandtheresponseoftheindividual. Lethaldoses inhumanshavebeendeterminedformanysubstancesfrominformationgatheredfrom recordsofhomicidesandaccidentalpoisonings.Muchofthedose-responseinformationalsocomesfrom animaltesting.Mice,rats,monkeys,hamsters,pigeons,andguineapigsarecommonlyusedfordose-response testing.Apopulationoflaboratoryanimalsisexposedtomeasureddosesundercontrolledconditionsand theeectsnotedandanalyzed.Animaltestingposesnumerousproblems,however.Forinstance,thetests maybepainfultoanimals,andunrelatedspeciescanreactdierentlytothesametoxin.Inaddition,the manydierencesbetweentestanimalsandhumansmakesextrapolatingtestresultstohumansverydicult. Adosethatislethalto50percentofapopulationoftestanimalsiscalledthelethaldose-50percentor LD-50.DeterminationoftheLD-50isrequiredfornewsyntheticchemicalsinordertogiveameasureof theirtoxicity.Adosethatcauses50percentofapopulationtoexhibitanysignicantresponsee.g.,hair loss,stunteddevelopmentisreferredtoastheeectivedose-50percentorED-50. Sometoxinshaveathresholdamountbelowwhichthereisnoapparenteectontheexposedpopulation. Somescientistsbelievethatalltoxinsshouldbekeptatazero-levelthresholdbecausetheireectsatlow levelsarenotwellknown.Thatisbecauseofthesynergyeectinwhichonesubstanceexacerbatesthe eectsofanother.Forexample,ifcigarettesmokingincreaseslungcancerrates20timesandoccupational

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83 asbestosexposurealsoincreaseslungcancerrates20times,thensmokingandworkinginanasbestosplant mayincreaselungcancerratesupto400times. 18.1.4RELATIVERISKS Riskassessment helpsusestimatetheprobabilitythatanundesirableeventwilloccur.Thisenablesus tosetprioritiesandmanagerisksinaneectiveway.Thefourstepsofriskassessmentare: 1.Identicationofthehazard. 2.Dose-responseassessment.Findtherelationshipbetweenthedoseofasubstanceandtheseriousness ofitseectonapopulation. 3.Exposureassessment.Estimatetheamountofexposurehumanshavetoaparticularsubstance. 4.Riskcharacterization.Combinedatafromthedose-responseassessmentandtheexposureassessment. Riskmanagement ofasubstanceevaluatesitsriskassessmentinconjunctionwithrelevantpolitical, social,andeconomicconsiderationsinordertomakeregulatorydecisionsaboutthesubstance.Inoursociety political,social,andeconomicconsiderationstendtocountmorethantheriskassessmentinformation.Signs ofthisareevidenteverywhere.Peoplelistentoloudmusiceventhoughthelevelsareknowntodamage hearing.Theysmokecigarettesthattheyknowcancausecancerandheartdisease. Peopleareoftennotlogicalinmakingchoices.Anexampleofthisisasmokerwhodrinksbottledwater becausesheisafraidtapwaterisunhealthy.Riskassessmentshaveshownthatapersonis1.8milliontimes morelikelytogetcancerfromsmokingthanfromdrinkingtapwater.Onepossibleexplanationforthis behavioristhatpeoplefeeltheycancontroltheirsmokingiftheychooseto,butrisksoverwhichpeople havenocontrol,suchaspublicwatersuppliesandnuclearwastes,tendtoevokemorefearfulresponses. Becauseriskmanagementdealswiththeunknown,itoftenisonlylooselyrelatedtoscience.

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Chapter19 FIRSTORDEREFFECTS 1 19.1FIRSTORDEREFFECTS 19.1.1INTRODUCTION Thevariouscomponentsofearth'ssystemsinteractwithoneanotherthroughtheowofmatterandenergy. Forexample,masscarbondioxideandoxygengasesisexchangedbetweenthebiosphereandatmosphere duringplantphotosynthesis.Gasesmoveacrosstheocean-atmosphereinterface.Bacteriainthesoildecomposewastes,providingnutrientsforplantsandreturninggasestotheatmosphere.Furthermore,studiesof AntarcticandGreenlandicecoresshowacorrelationbetweenabruptclimatechangesandstormactivities intheAtlanticandPacicoceansduringhistoricaltimes.Alloftheseprocessesarelinkedbynaturalcycles establishedoverbillionsofyearsoftheearth'shistory. Humanshaveonlybeenpresentforatinyfractionofearth'shistory,andformuchofthattimetheir presencehadlittleimpactontheglobalenvironment.However,inrecenthistory,thehumanpopulation hasgrownanddevelopedtothepointwhereitisnolongerarelativelypassivepresenceinearth'ssystems. Peoplehavegreatlyincreasedtheiruseofair,water,landandothernaturalresourcesduringthelast200 years.Theirindustrialandagriculturalactivitieshaveaectedtheatmosphere,thewatercycle,andthe climate.Eachyearlargequantitiesofcarbondioxideandpollutantsareaddedtotheatmosphereandwater systemsduetofossilfuelburningandindustrialprocesses.Ecologicalsystemshavebeenalteredaswell. Thesizeofnaturalecosystemshasshrunkaspeopleincreasetheiruseoftheland.Plantsandanimalshave beenchangedbyhumanagriculturalpractices.Clearlyhumansarechangingtheglobalenvironmentand climate.Whatisuncleariswhetherearth'ssystemscanadjusttothesechanges. 19.1.2ATMOSPHERE Theearthismuchlikeabiggreenhouse.Energy,intheformofsunlight,passesthroughitsatmosphere, thoughtheclouds,waterandlandreectsomeofthatenergybackintospace,somesunlightisabsorbed, convertedtoheatandradiatedbackintotheatmosphereasinfraredradiation.Muchofthisinfraredradiation isabsorbedbyatmosphericcarbondioxideandothergasesratherthanradiatedintospace.Theprocessis similartothatofagreenhouse,withinfrared-absorbinggasessuchascarbondioxideandmethaneactingas panesofglasstotraptheinfraredheat.Forthisreason,thesegasesareknownas greenhousegases .The netresultofthisprocessisthattheatmosphereiswarmed. Formorethanacentury,scientistshaveponderedthepossibleeectsthatchangeintheamountsof greenhousegaseslikecarbondioxidewouldhaveontheearth'sclimate.Onenotabletheorythathasarisen fromthisisthatofthe greenhouseeect .Accordingtothistheory,iftheconcentrationofcarbondioxide intheatmospheresteadilyincreases,thentheatmospherewilltrapmoreandmoreheat.Thiscouldcause 1 Thiscontentisavailableonlineat. 85

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86 CHAPTER19.FIRSTORDEREFFECTS theearth'smeansurfacetemperaturetoriseovertime.Concernsoverpossibleclimateeectsledtoeorts tomonitorcarbondioxidelevels.Monitoringbeganinthelate1950's,withmonitoringstationsbeingsetup inAlaska,AntarcticaandHawaii. TheMaunaLoa,Hawaii,stationhasbeenoperatingsince1958.Thedatacompiledthereformorethan 40yearsshowsomeinterestingtrendsintheconcentrationofcarbondioxideintheatmosphere.Carbon dioxideconcentrationvariescyclicallybyseason,withhighsoccurringduringFallandlowsduringtheSpring. Thisfollowsthenormallifecycleofplantsduringtheyearandtheirassociatedphotosyntheticoutput. Superimposedovertheseseasonalvariationsisalong-termgradualincreaseincarbondioxideconcentration. Whatcausesthislong-termincrease?Willthetrendcontinue? Humansconsumelargeamountsoffossilfuelsinordertodrivetheirhighlyindustrializedsociety.The burningofcoal,oilandnaturalgasreleasesconsiderablequantitiesofcarbondioxideintotheatmosphere. Inarelativelyshorttime,humanshavereleasedorganiccarbonintotheatmospherethattookhundredsof millionsofyearstostoreinsedimentaryrocks.Deforestationbyhumansespeciallyintropicalareasis alsoasourceofnetcarbondioxideincreaseintheatmosphere.Theburningoftreesproducescarbondioxide directly,andtheremovalofthetreesalsoresultsinlesscarbondioxidebeingremovedfromtheatmosphere byphotosynthesis. However,itisnotclearastotheoverallroleoftheterrestrialbiospherewithregardtothecarbondioxide problem.Forestshaveregrowninsomeregionsoftheworlde.g.,thenortheasternUnitedStates.These addedforestsincreasecarbondioxideremovalfromtheatmosphere.Furthermore,someexperimentssuggest thatrisingcarbondioxideconcentrationsintheatmospheremaystimulateplantgrowthingeneral.Iftrue, thiswouldalsoleadtoanincreaseincarbonsequestrationbyplantlife.Modelsusedtopredictfuture levelsofcarbondioxideintheatmospheredependonanaccurateknowledgeofallrelevantcarbonsources andsinks.Questionsstillremainastothesize,locationandmagnitudeofthese.Therefore,considerable uncertaintyremainsastowhetherthecarbondioxideconcentrationintheatmospherewillcontinueto increase,willinsteaddecrease,orwillbecomeconstant. Carbondioxideisnottheonlygreenhousegasthatcouldsignicantlyaecttheglobalclimate.Methane gascouldalsobeamajorplayer.Itisreleasedasaby-productoforganicdecompositionbymicrobial activity,especiallyfromlandlls.Itisapollutantresultingfromtheuseoffossilfuels,andisevenproduced bycattle.Thelargestdepositsofmethanegas,however,maybetheoceansandvasttundrawastelands. Incoldwater,forexample,methanecanformcrystalstructuressomewhatsimilartowatericeknownas clathrates .Clathratesareknowntooccurontheedgesoftheoceans'continentalshelves.Theyalsooccur inthepermafrostoftundraregions.Whenwarmertemperaturesoccur,theclatharatesdestabilize,releasing thestoredmethane.Theincreaseinthegreenhouseeectthatwouldresultfromthereleaseofmethane fromclathratesonthecontinentalshelvesandinpermafrostworldwidecouldequalthatfromthecarbon dioxideproducedfromtheburningofalltheworld'scoalreserves. Thebuildupofgreenhousegasesisnottheonlyatmosphericconcern.Theconcentrationof chlorouorocarbons CFC'sintheatmospherehasincreasedsincetheywererstsynthesizedmorethan70years ago. Thesecompoundshavebeenusedasrefrigerantgases,aerosolpropellants,electroniccomponentcleaners andforblowingbubblesinstyrofoam.Mostoftheirusesinvolvetheireventualreleaseintotheatmosphere. Becausetheyarechemicallyveryinertandinsolubleinwater,theyarealsonoteasilyremovedfromthe atmospherebynormalprocessessuchasrainfall.Therefore,theconcentrationofCFCsintheatmosphere increasewithcontinuedrelease.WhenCFCseventuallyriseintothestratosphere,theycanbebrokendown byUVradiationfromthesunasfollows: CCl3F+UVenergy Cl+CCl2F Thefreechlorinethatisproducedcanreactwithozone,whichisalsopresentinthestratosphere.This hasimportantconsequencesforlivingorganismsonthesurfaceoftheearth. Ozone inthestratosphereprotectslivingorganismsbyabsorbingmostoftheharmfulUVradiationfrom thesun.Thisozoneisconstantlyproducedanddestroyedinanaturalcycle.Thebasicreactionsinvolving onlyoxygenknownasthe ChapmanReactions areasfollows:

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87 O2+UV 2O O+O2 O3ozoneproduction O3+UV O+O2ozonedestruction O+O2 O3ozoneproduction O3+O O2+O2ozonedestruction Table19.1 Duringthe1960s,measurementsofatmosphericozoneshowedthatitwasbeingdestroyedfasterthan couldbeaccountedforbythenaturalcyclealone.Itwasdeterminedthatother,fasterreactionswere controllingtheozoneconcentrationsinthestratosphere.Amongthemostimportantofthesewerethose involvingtheClatomsproducedfromthebreakdownofCFC's: Cl+O3 ClO+O2 ClO+O Cl+O2 Table19.2 BecausethenormalfateoftheOatomintheabovereactionwouldbetoformanotherozonemolecule, thenetresultofbothreactionsistheeliminationofoneozonemoleculeandonewould-beozonemolecule. Furthermore,attheendofthereactiontheClatomisfreetostartthedestructivecycleoveragain.By thiscatalyticchainreaction,oneClatomcandestroyabout100,000ozonemoleculesbeforeotherprocesses removeit. Ozonedestruction causedbyCFCshasresultedintheformationof"holes"inthestratosphericozone layeroverthepolarregions,wherethelayeristhinnest.In1987,the"MontrealProtocol"setfortha worldwideprocesstoreduceandeventuallytoeliminatetheuseofCFC's. Ithasapparentlybeensuccessful,ascurrentobservationsshowthattheincreaseinCFCsinthestratosphereislevelingo.Unfortunately,itwillbemanyyearsbeforeozonelevelswillreturntonormalbecause ofthelongatmosphericlifetimeto100yearsoftheCFCsalreadypresent. Curiously,althoughozoneinthestratosphereisbenecialtolifeonearth,ozoneintheloweratmosphere tropospherecanharmlifebyaggravatingrespiratoryailmentsinhumansanddamagingplants.Ozoneinthe troposphereisproducednaturallybylightning.Itisalsoasecondarypollutantproducedbyphotochemical reactionsinvolvingprimarypollutantssuchasnitrogenoxides.SmoggycitiessuchasLosAngelessuer fromconsiderable ozonepollution .Researchstudieshaveshownthatbiomassburningisalsoamajor sourceofozonepollution.Ozoneisproducedphotochemicallyfromprecursormoleculesreleasedduring theburningofforestsandgrasslands.Biomassburningismainlyconcentratedintropicalregions.Indeed, satelliteobservationsofSouthAmericaandNewGuineashowthattroposphericozoneisincreasinginthose areaswherebiomassburningisprevalent. 19.1.3OCEANS Inordertounderstandtheroletheoceansmayplayin globalclimatechange requiresanunderstanding ofthedynamicsofoceancirculationchanges.Globaloceancirculationiscontrolledby thermohaline circulation .Itisdrivenbydierencesinthedensityofseawater,whichisdeterminedbythetemperature thermoandsalinityhalineoftheseawater.IntheAtlantic,thermohalinecirculationtransportswarm andverysalinewatertotheNorth.There,thewatercoolsandsinksintothedeepocean.Thisnewly formeddeepwatersubsequentlymovessouthward.DensewateralsosinksnearAntarctica.Thecold,dense watersfromtheNorthAtlanticandAntarcticagraduallywarmandreturntothesurface,throughoutthe

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88 CHAPTER19.FIRSTORDEREFFECTS world'soceans.Theentiresystemmoveslikeagiantconveyorbelt.Themovementisveryslowroughly0.1 meters-per-second,buttheowisequivalenttothatof100Amazonrivers. ThiscirculationsystemprovideswesternEuropewithcomparativelywarmseasurfacetemperatures alongthecoastandcontributestoitsmildwinters.Oceancirculationmodelsshowthatthethermohaline circulationiscoupledtothecarbondioxidecontentoftheatmosphere,andthustothegreenhouseeect. Increasesincarbondioxideintheatmospherecanleadtoaslowingoracompletebreakdownofthecirculation system.OnemightexpecttemperaturesoverwesternEuropetodecreaseinsuchascenario.However,any suchchangewouldbesuperimposedonwarmingfromtheenhancedgreenhouseeect.Therefore,theremay belittlechangeintemperatureoverwesternEurope,andanycoolingcouldberestrictedtotheoceanarea awayfromland.Thepotentialeectsofsuchcirculationchangesonmarineecosystemsarelargelyunknown, butwouldprobablybesignicant.Furthermore,ifcirculationintheoceansisreduced,theirabilitytoabsorb carbondioxidewillalsobereduced.Thiswouldmaketheeectofhuman-producedcarbondioxideemissions evenmorepronounced. 19.1.4BIOTA Biodiversity isanimportantpartofanyecosystem.Theearth'sbiodiversityissignicantlyaectedby humanactivities.Theseactivitiesoftenleadtobiodiversityloss.Thislosscanresultfromanumberoffactors including:habitatdestruction,introductionofexotics,andover-harvesting.Ofthese,habitatdestruction isprobablythemostimportant.Humansdestroyhabitatsformanyreasons:agriculturalexpansion,urban expansion,roadconstructionandreservoirconstruction.Largerregionsthanthosedirectlydestroyedare generallyaectedbecauseoftheresultinghabitatfragmentation.Habitatfragmentationresultsinlarge populationsbeingbrokenintosmallerpopulations,whichmaybeisolatedfromoneanotherandmaynotbe largeenoughtosurvive. Forexample,theAswanHighDamofEgyptwasconstructedbecausethedesiretoincreasethesupply ofwaterforirrigationandpowerwasconsideredparamount.Theenvironmentalsideeects,however,have beenenormousandincludethespreadofthedisease schistosomiasis bysnailsthatliveintheirrigation channels;lossoflandinthedeltaoftheNileRiverfromerosiononcetheformersedimentloadoftheriver wasnolongeravailableforlandbuilding;andavarietyofotherconsequences.Theadvisabilityagencies concernedwithinternationaldevelopmenttoseekthebestenvironmentaladviceisnowgenerallyaccepted, butimplementationofthisunderstandinghasbeenslow. Whentherateofexploitationorutilizationofaspeciesexceedsitscapacitytomaintainaviablepopulation, over-harvesting results.Livingresourcessuchasforestsandwildlifeareusuallyconsideredrenewable resources.However,theycanbecomenon-renewableifover-harvested.Over-harvestingandhabitatlossoftenoccurtogether,becausetheremovalofanorganismfromitsenvironmentcanhaveadetrimentalimpact ontheenvironmentitself. Humanshavehistoricallyexploitedplantandanimalspeciestomaximizeshort-termbenets,usually attheexpenseofbeingabletosustainthespeciesinthelong-term.Aclassicexampleofover-harvesting involvesthepassengerpigeon.Itwasoncethoughttobethemostpopulousbirdonearth,withnumbers intothebillions.EarlysettlersinNorthAmericahuntedthebirdforfood.Thehuntingwassointense,that thebirddisappearedfromthewildby1900andwasextinctby1914.TheAmericanbualonearlysuered thesamefate.Originallynumberinginthetensofmillions,fewerthan1000wereleftby1890.Thespecies has,however,madeacomebackinreservesandprivateranchesandisnolongerconsideredthreatened. Theshingindustryhasalonghistoryofover-harvestingitsresources.TheCaliforniasardineindustry peakedinthe1930's.Bythelate1950s,thesardinesweregoneaswerethecanneriesinMonterey.The Peruviananchovysheryboomedinthe1960sandcollapsedinthe1970s.Over-harvestingofshhasonly increasedovertheyears,asshipshavebecomebiggerandmore"ecient"methodsofharvestingshe.g. thepurse-seinenet,havebeendeveloped.Bythemid-1990s,over40percentofthespeciesinAmerican sherieswereoverharvested. Over-harvestingoftropicalforestsiscurrentlyaworldwideproblem.Moreecientmethodsforharvesting andtransportinghavemadeitprotabletoremovetreesfrompreviouslyinaccessibleareas.Mahoganytrees areoverharvestedbyloggersinthetropicalforestsofBrazil,Bolivia,Peru,NicaraguaandGuatemala.

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89 Manyothertypesoftropicaltreesonceconsideredworthlessarenowvaluablesourcesofpulp,chipboard, berboardandcelluloseforplasticsproduction.Developingnationsareoftenwillingtosignovertimber rightstoforeigncompaniesforneededhardcurrency.Loggingoperationsalsoactasacatalystfortropical deforestation.Farmersuseroadsbuiltbyloggingcompaniestoreachremoteareas,whicharethencleared offorestsandusedforranchingandagriculture. Whenaspeciesistransplantedintoanenvironmenttowhichitisnotnative,itisknownasan introduced exotic .Whenevermanhassettledfarawayfromhome,hehastriedtointroducehisfamiliaranimalsand plants.Longago,Europeanexplorersreleasedgoatsandpigsintotheircoloniestoprovideasupplyof familiaranimalprotein.Manyexoticsareaccidentallyintroduced.Often,theintroductionofexoticshas disastrouseectsonthenativeoraandfauna.Theirnewhabitatmayhavefewerpredatorsordiseases thataectthem,andasaresultsotheirpopulationsgrowoutofcontrol.Organismstheypreyuponmay nothaveevolveddefensemechanismstothemandnativespeciesmaynotbesuccessfulincompetingwith themforspaceorfood. SomeofthemostabundantwildanimalsandplantsintheUnitedStatesareintroducedspecies.For example,starlings,eucalyptustreesandmanytypesofgrassesareintroducedexotics.Mostinsectandplant pestsareexoticspecies.Thekudzuvine,aJapanesespeciesintroducedin1876,toshadeporchesofsouthern mansionsandwidelyplantedinthe1940'stocontrolerosion,growssorapidlyuptoonefootperdaythat itkillsforestsbyentirelycoveringtreesandshrubs.ThegypsymothwasbroughtfromFrancein1869by anentomologistwhohopedtointerbreedthemwithsilkmoths.Theyescapedandestablishedacolony thatinvadedalloftheNewEnglandstates,defoliatingtreesofmanydierentkinds.Exoticsareafactor contributingtotheendangeredorthreatenedstatusofmanyanimalsandplantsintheU.S. 19.1.5DangersofBirdMigration Allcreaturesarethreatenedbyhabitatdegradationanddestruction.Formigratingbirds,theproblemis vastlycompounded.Birdstravelthousandsofmilesbetweensummerandwinterhomes,andenvironmental disruptionsanywherealongtherouteorateitherdestinationcanbedeadly.Indeed,massivedeclinesin manybirdpopulationshavebeendocumentedoverrecentdecades. ManyofthespeciescommonintheUnitedStatesare Neotropical theybreedinNorthAmericainthe summer,thenoverwinterinCentralorSouthAmerica.Thesesongbirds,waterfowl,raptors,andshorebirds, whofollowthesamemigrationroutestheirancestorsdid,facemanyhazardsalongtheway.Night-time lightinglightpollutioncandisorientthem.Collisionswithairplanes,wires,andbuildingscankilland injurethem. Oncethebirdsarriveattheirdestination,orwhentheystopin-route,theyneedfood,water,andaplace torest.Buturbansprawlisencroachingonbirdhabitat,andfoodandwatersuppliesarecontaminatedby pollution. Recently,anewproblemhasarisen.Formigratingbirds,timingiseverythingtheymustarriveattheir summerbreedinggroundswhenfoodsuppliesareattheirpeak,sothattheycanrebuildtheirbodyfatand reproducesuccessfully.Globalwarmingisbeginningtoupsetthedelicatebalancebetweenthelifecyclesof plantsandinsectsandbirds.Insomeareas,birdsareshowingupearly,beforeowersopenorinsectshatch, andndingverylittletoeat. Fortunately,manypeoplevaluebirdsandseveralconservationeortsareunderway,including: Creationofprotectiveshelterbeltsandhedgerowsaroundeldsandcommunityopenspace Easementstoprovidenativehabitatforbirdsinhumanactivityareas Timingofinsecticideapplicationstoavoidlossofthefoodbaseduringbirdmovementinthespring andfall Preservationofthequalityandquantityofcommunitywetlands Minimizationofpracticesthatnegativelyimpactbirds Inaddition,manyseektocoordinateactivitiesalongthemigratoryywaystoincreasethesuccessofthe migratingbirds.Althoughhumansareworkingtocreatenaturalreserves,theproblemofhumanimpacton migratorybirdsstillneedstobeaddressedtoasignicantdegree.

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Chapter20 HIGHERORDERINTERACTIONS 1 20.1HIGHERORDERINTERACTIONS 20.1.1INTRODUCTION Althoughhumanshavehadthecapabilitytomonitorearth'ssystemseectivelyonlyrelativelyrecently, previousglobalenvironmentaleventshavenotgoneunrecorded.Climateindicatorsexistinvariousforms e.g.,polleninlake-bottomsediments,patternsintree-rings,airbubblesfrozeninglacialiceandgrowthrings incoral.Theseindicatorsshowthatsignicantenvironmentalchangeshaveoccurredthroughoutearth's history.Thesechangesoccurredslowly,overrelativelylongperiodsoftime.However,humanactivitiesare alteringearth'ssystemsatanacceleratedpace.Large-scalepollution,increasednaturalresourceconsumption andthedestructionofplantandanimalspeciesandtheirhabitatsbyhumansarecausingsignicantchanges ofglobalproportions. Human-causedglobalchangesinclude:depletionofstratosphericozone,increasedcarbondioxideconcentrationintheatmosphereandhabitatdestruction.Theconsequencesofthesechangesinclude:global warming,increasedlevelsofsolarUVradiation,increasedsealevelsandlossofbiodiversity.Theramicationsofthesephenomenaarefar-reachingandpotentiallydevastatingtoalllifeonearth,includinghumans. Awarenessofthishaspromptedaninternationaleorttoincreasescienticunderstandingofglobalchanges andtheireects.Mostscientistsagreeoncertainpoints: Greenhousegasesabsorbandthenemitinfraredradiation. Atmosphericconcentrationsofcarbondioxide,methaneandchlorouorocarbonsCFCshaveincreased signicantlyabovepre-industriallevels,andtheincreaseisdirectlyattributabletohumanactivities. Increasedconcentrationsofgreenhousegasesproduceanetheatingeectontheearth. Globally,averagesurfaceairtemperaturesareabout0.5 Chigherthanthoseinthe19thcentury. Manycenturieswillpassbeforecarbondioxideconcentrationswillreturntonormallevels,evenifall human-causedemissionsarestoppedentirely. ThereturnofCFCconcentrationstotheirpre-industriallevelswilltakemorethanacentury,even withahaltinhuman-causedemissions. Whileageneralconsensushasbeenreachedontheabovepoints,nosuchconsensushasbeenreachedon theextenttowhichthesechangesareaectingtheglobalenvironmentandwhatcoursetheywillfollowin thefuture.Thescienticcommunitycanonlyinferwhatwillhappenfrompredictivemodelsbasedupon theirknowledgeofrelevantenvironmentalprocesses.Thisknowledgeisoftenlimitedbecausetheprocesses involvedandtheirrelationshipsareexceedinglycomplex.Moreover,thedistinctpossibilityexiststhatnot allprocessesareevenknown. 1 Thiscontentisavailableonlineat. 91

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92 CHAPTER20.HIGHERORDERINTERACTIONS 20.1.2ATMOSPHERE Theatmospheresurroundingtheearthisbothapartandaproductoflife.Humanshavesignicantlyaected theatmosphere.Forexample,hugeamountsofcarbondioxideandmethane,amongothercompounds,are addedannuallytotheatmosphereduetoanthropogenicusesoffossilfuels.Formanyyears,CFC'swere indiscriminatelyreleasedintotheatmosphere.Theadditionofthesechemicalpollutantstotheatmosphere raisesconcernsabouthowthechangesintheatmospheremayaectlifeonearth. Themostimmediateeectofincreasedamountsofgreenhousegasesintheatmosphereis globalwarming .Theglobalmeansurfacetemperatureisexpectedtorise1to3 Cbythemiddleofthe21stcentury. Theextentofthewarmingwilldependinpartuponatmosphericwatervaporlevelsandcloudcoverfeedback processes.Heatingoftheatmospherecanimpacttheglobalclimateinseveralways. Therateofwaterevaporationwillincreaseastheenvironmentwarms,andthiswillleadtoincreases intheglobalmeanprecipitation.Awarmer,wetteratmospheremaysubsequentlycauseanincreaseinthe frequencyoftropicalstorms,whichcancauseooding.Inadditiontodeathsfromfamineanddrowning, oodscanbringwiththemcholeraanddiseasesspreadbymosquitoes,suchasmalariaandyellowfever. Atmosphericheatingcouldalsocausesevereheatwaves,andprojectionsindicatethatheat-relateddeaths maydoubleby2020. High-altitudecooling,causedbythecombinationofreducedstratosphericozoneconcentrationsand increasedcarbondioxideconcentrations,maylowertheupper-stratospherictemperaturesbyasmuchas8to 20 C.Thiscoolingcouldchangetheatmosphere'scirculationpatterns.Inaddition,scientistsbelievethat stratospheric ozonedepletion couldhaveaseriousnegativeimpactonthehealthofhumans,plantsand animals.Thisisduetotheconcomitant increaseinUVradiation ,particularlyUV-B,thatreachesthe surfaceoftheearthwhenstratosphericozonelevelsdecrease. HumansDNAissusceptibletodamagebyUV-Bradiation,andexposurecancauseskincancer.Studies indicatethata10percentreductioninstratosphericozonecouldgiverisetoanadditional20,000skincancer caseseachyear.Otherconsequencestohumansincludesuppressionofthehumanimmunesystemand increasesintheoccurrenceofeyecataracts.PlantsrespondadverselytoexposuretoUV-Bradiation,with reducedleafarea,reducedshootlengthanddecreasesintherateofphotosynthesis.Suchresponsescould signicantlydecreasetheyieldsofagriculturalcrops.UV-Bradiationcankillplanktonintheocean,which inturncouldseverelyimpactmarinefoodchains.IncreasedexposuretoUV-Bradiationalsoappearstokill developingembryosintheeggsofsomereptilesandamphibians. 20.1.3OCEAN Evenamoderateincreaseinglobaltemperaturecanmeltsignicantamountsofsnowandice,shrinking glaciersandthepolaricecaps.Thisaectssealevels.Inasmuchas50percentoftheworld'shuman populationliveswithin50kilometersofthesea,theeectsofevenamoderateriseinsealevelsonthe orderofameterorlesswouldbesignicant.Researchsuggeststhat risingsealevels willoodsome coastalwetlandsandcommunities,andwillamplifytheimpactsofstormsurges,inwhichsealevelsrise becauseofseverestormwinds.Increasedprecipitationinhighnorthernlatitudesmayreducethesalinity anddensityoftheoceanwatersthere,whichinturnwillinuenceglobaloceanthermohalinecirculation. Coralreefsaredirectlyaectedbytheamountofcarbondioxideintheatmosphere,globaltemperature changeandincreasedUVradiation.Anincreaseinatmosphericcarbondioxideleadstoadecreaseof carbonateionintheseawater.Thisdecreasecancauseareductionintherateofcoralreefformation,or, inextremecases,couldcausecoralreefstodissolve.Aphenomenonknownas coralbleaching ,whichcan befataltoacoralcolony,iscausedbyunusuallyhighorlowtemperatures,highorlowsalinityorhigh amountsofUVradiation.Thersttwoofthesearelinkedtoglobalwarmingandthelastcouldresultfrom stratosphericozonedepletion. ScientistsattheNationalCenterforAtmosphericResearchhavereportedthatglobalwarmingmay accentuatetheeectsofElNioevents.Thename ElNio referstothewarmphaseofalargeoscillation,knownasthe ElNio/SouthernOscillationENSO ,inwhichthesurfacetemperatureofthe central/easternpartofthetropicalPacicwarms.Thisisaccompaniedbychangesinwindsandrainfall

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93 patterns.AbnormallydryconditionsoccurovernorthernAustralia,IndonesiaandthePhilippines.Drier thannormalconditionsarealsofoundinsoutheasternAfricaandnorthernBrazil. WetterthannormalconditionsareobservedalongthewestcoastoftropicalSouthAmerica,theNorth AmericanGulfCoastandsouthernBrazil.ThewarmElNiophasetypicallylastsforeightto10months. TheentireENSOcycleusuallylastsaboutthreetosevenyears.Overthepastcentury,ElNioeventshave becomemorefrequentandhavecausedgreaterclimatechangesparallelingtheriseinglobaltemperature. 20.1.4BIOTA Thevarietyoflifeonearthisits biodiversity .Thenumberofspeciesofplants,animals,microorganisms, theenormousdiversityofgenesinthesespecies,thedierentecosystemsontheplanetsuchasdeserts, rainforestsandcoralreefsareallpartofabiologicallydiverseearth.Thereisalinkbetweenbiodiversity andclimatechange.Rapidglobalwarmingcanaectanecosystem'schancestoadaptnaturallyinseveral ways.Aspeciesmaybeincapableofmigratingfarenoughtoreachahospitableclimatewhenfacedwith signicantglobalwarming.Existinghabitatmaybelostduringprogressiveshiftsofclimaticconditions. Speciesdiversitymaybereducedasaresultofreductionsinhabitatsize.Thefateofmanyspeciesina rapidlywarmingworldwilllikelydependontheirabilitytomigratefromincreasinglylessfavorableclimatic conditionstonewareasthatmeettheirphysical,biologicalandclimaticneeds. Humanactivityplaysamajorroleinthelossofbiodiversity.Forestsandwetlandsareconvertedto agriculturalandurbanlanduse.Logginghasclearedmostofthevirginforestsofthecontiguous48states. Thebiologicallydiversetropicalforestsarecurrentlybeingrapidlydestroyedasthelandisconvertedto farmingorclearedbyloggingandminingoperations.Onagriculturalland,largeeldsofmonoculturecrops replacethediverseplantlifethatoncewasthere.TheUnitedStateshaslostnearlyalloftheoriginaltallgrassprairiethatoncecoveredtheGreatPlains.Huntinghasdrivenspeciessuchaswolvesandgrizzlybears thatwereoncewidespreadoverthewesternUnitedStatestoafewisolatedreserves.Largelandmammals suchasrhinoceriandelephantshavehadtheirrangesgreatlydiminishedinAsiaandAfricabyhabitat destruction.Selectivebreedingbyfarmershasreducedthegeneticdiversityoflivestockanimals.Introduced exoticspecieshavedrivenoutnativeplantsandanimals. Oneofthebiggestsideeectsofthelossofbiodiversityistheprematureextinctionofspecies.Small changesinthecompetitiveabilityofaspeciesinonepartofafoodwebmayleadtoextinctionsinother parts,aschangesinpopulationdensityaremagniedbypredator-preyorhost-parasiteinteractions.Human activitiessuchashabitatdestruction,introductionofexoticsandover-harvestingarealsocausinglarge numbersofprematureextinctions.Itisestimatedthataboutone-thirdoftheplantspeciesintheUnited Statesarethreatenedbyextinction.Countlessunknownspeciesofplantsandanimalsarelosteveryyear becauseofthedestructionoftropicalforests.Plantsthatmightholdtheingredientsfornewmedicinesare insteadlostforever. Highbiodiversitycontributestothestabilityofanecosystem.Eachspecies,nomatterhowsmall,plays animportantrole.Diversityenablesecosystemstoavoidandrecoverfromavarietyofdisasters.Almost allcultureshaveinsomewayrecognizedtheimportancethatNatureanditsbiologicaldiversityhaveupon them.

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Chapter21 ECONOMICFORCES 1 21.1ECONOMICFORCES 21.1.1INTRODUCTION Economics istheprocessbywhichhumansmanagetheirenvironmentanditsresources.Theprocessis madeupofasystemofproduction,distributionandconsumptionofgoodsandservices. Naturalresources providetherawmaterialsandenergyforproducingeconomicgoods,while humanresources providethe necessaryskillandlabortocarryouttheprocess.Dierentsocietiesmanagetheireconomiesindierent ways.Inatraditionaleconomy,peopleareself-sucienti.e.,theyproducetheirowngoods,butina pure commandeconomy thegovernmentcontrolsallstepsintheeconomicprocess. CapitalistcountriessuchastheUnitedStateshaveasystemthatislargelybasedona puremarket economy .Buyersandsellersmakeeconomicdecisionsbasedonthe PrincipleofSupplyandDemand Sellerssupplygoodsandbuyerscreatedemandforgoods.Thesetworolesareofteninconict:buyerswant tobuygoodsatlowpricesandsellerswanttosellgoodsathighprices.However,thetwosideseventually compromiseonapriceatwhichbuyerscanndsellerswillingtosellandsellerscanndbuyerswillingto buy.Thisisknownasthe marketequilibriumprice .Theequilibriumpricecanbeconsideredasthe intersectionofthesupplyanddemandcurves. Mostcountriesstrivetoincreasetheircapacitiestoproducegoodsandservicesandconsiderdoingso asapositivesignofdevelopment.Economicgrowthisstimulatedbypopulationgrowth,whichinturn increasestheconsumptionofnaturalresourcesandincreasesthepercapitaconsumptionofgoodsand services.Variousindicatorsareusedtomeasureeconomicgrowth.Oneofthemisthe GrossNational ProductGNP ,whichrepresentsthetotalmarketvalueofnalgoodsandservicesproducedbyacountry duringagivenperiodusuallyoneyear.Unfortunately,GNPdoesnottakeintoaccounttheglobalnature ofmanycompanies.Ifacompanyproducesgoodsinaforeigncountry,thenthe"home"countrydoesnot reallybenetfromthatproduction.Thus,ifPepsibottlesandsellssodainJapan,thoserevenuesshouldnot beincludedintheGNPoftheUnitedStates.The GDPGrossDomesticProduct providesabetter indicatorofthehealthofacountry'seconomy.Thismeasurereferstothevalueofthegoodsandservices producedwithintheboundariesofaneconomyduringagivenperiodoftime. BoththeGNPandGrossDomesticProductGDPareeconomicmeasuresandindicatenothingabout socialorenvironmentalconditionswithinacountry.Theyarenotmeasuresofthequalityoflife.Infact, severeenvironmentalproblemscanactuallyraisetheGNPandGDP,becausethefundsusedtocleanup environmentalmessessuchashazardouswastesiteshelptocreatenewjobsandincreasetheconsumption ofnaturalresources.The UnitedNationsHumanDevelopmentIndex isanestimateofthequalityof lifeinacountrybasedonthreeindicators:lifeexpectancy,literacyrateandpercapitaGNP. 1 Thiscontentisavailableonlineat. 95

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96 CHAPTER21.ECONOMICFORCES 21.1.2EXTERNALCOSTS Economicactivitygenerallyaectstheenvironment,usuallynegatively.Naturalresourcesareused,and largeamountsofwasteareproduced.Thesesideeectscanbeseenaswaysinwhichtheactionsofa producerimpactthewellbeingofabystander.Themarketfailstoallocateadequateresourcestoaddress suchexternalcostsbecauseitisonlyconcernedwithbuyersandsellers,notwiththewellbeingofthe environment.Onlydirectorinternalcostsareconsideredrelevant.Externalcostsareharmfulsocialor environmentaleectscausedbytheproductionorconsumptionofeconomicgoods.Governmentsmaytake actiontohelpalleviatetheeectsofeconomicactivity. Whenexternalcostsoccur,acompany'sprivateproductioncostandthesocialcostofproductionare atodds.Thermdoesnotconsiderthecostofpollutioncleanuptoberelevant,whilesocietydoes.The socialcostsofproductionincludethenegativeeectsofpollutionandthecostoftreatment.Asaresult, thesocialcostsendupexceedingtheprivateproductioncosts.Whenexternalpollutionandtreatmentcosts areincludedintheproductioncostoftheproduct,thesupplycurveintersectsthedemandcurveatahigher pricepoint.Asaresultofthehigherpricetherewillbelessdemandfortheproductandlesspollution produced. Forexample,exhaustpollutantsfromautomobilesadverselyaectthehealthandwelfareofthehuman population.However,oilcompaniesconsidertheircostofproducinggasolinetoincludeonlytheirexploration andproductioncosts.Therefore,anymeasurestoreduceexhaustpollutantsrepresentanexternalcost.The governmenttriestohelpreducetheproblemofexhaustpollutantsbysettingemissionsandfuel-eciency standardsforautomobiles.Italsocollectsagasolinetaxthatincreasesthenalpriceofgasoline,whichmay encouragepeopletodriveless. Sometimes,pollutionresultsfromtheproductionprocessbecausenopropertyrightsareinvolved.For example,ifapapermanufacturerdumpswasteinaprivatelyownedpond,thelandownergenerallytakes legalactionagainstthepaperrm,claimingcompensationforaspeciclossinpropertyvaluecausedbythe industrialpollution.Incontrast,theairandmostwaterwaysarenotownedbyindividualsorbusinesses, butinsteadareconsideredtobepublicgoods.Becausenopropertyrightsareinvolvedthegenerationof pollutiondoesnotaectsupplyanddemand. Firmshaveanincentivetousepublicgoodsintheproductionprocessbecausedoingsodoesnotcost anything.Ifthepapermanufacturercanminimizeproductioncostsbydumpingwastesforfreeintothelocal riverthenitwilldoso.Theconsequencesofthispollutionincludeadverseimpactsontheshandanimal populationsthatdependonthewater,degradationofthesurroundingenvironment,decreaseinthequality ofwaterusedinrecreationandbusiness,humanhealthproblemsandtheneedforextensivetreatmentof drinkingwaterbydownstreamcommunities.Animportantroleofthegovernmentistoprotectpublicgoods, especiallythosewithmultipleuses,frompollutionbycompaniesseekingtominimizecompanycostsandto maximizeprots.Peopledesirecleanwaterforrecreationanddrinking,andthegovernmentmustactto protectthebroadinterestsofsocietyfromthenarrowprot-drivenfocusofcompanies. Onewayto"internalize"someoftheexternalcostsofpollutionisforthegovernmenttotaxpollution. Apollutiontaxwouldrequirethatpollutingrmspayataxbasedontheair,waterandlandpollutionthat theygenerate.Thistaxwouldraisetheprivateproductioncostofacompanytoincludetothesocialcost ofproduction.Inaddition,thegeneratedtaxrevenuescouldbeusedbythegovernmenttohelpmitigate theeectsofpollution.Themaindrawbackofsuchataxisthatitwoulddiscourageeconomicactivityby increasingcoststothecompanies.Forexample,ataxoncoalandoilwouldincreasethecostofelectricity andgasoline.Taxedcompanieswouldbeforcedtoscalebackproductioninresponsetothesehighercosts, andinvestmentsandemploymentwouldsuer.Thetrickistosetthetaxatalevelatwhicheconomicloss doesnotexceedtheenvironmentalbenetsrealized. TradablePollutionPermitsTPPs areanalternativetopollutiontaxes.In1994,theUnitedStates governmentinauguratedaprogramtoreducesulfurdioxideemissionsbyrequiringthatcompanieshavea permitforeachtonofsulfurdioxidetheyemit.CompanieswereallocatedTPPsbasedontheirhistorical levelofsulfurdioxideemissions.TheprogramallowsTPPstobeboughtandsoldamongthecompanies. Therefore,acompanycaninvestinscrubbersorusemoreexpensivelowsulfurcoaltoreduceitssulfur dioxideemissionsandthensellitsexcesspermits,osettingpartofthecostofreducingthepollution.

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97 21.1.3COST-BENEFITANALYSES Ideally,onewouldliketoliveinaperfectworldwithzeropollution.Unfortunately,thisisnotpossible withcurrenttechnology.Peopledrivecarsandtrucks,andmostofthesevehicleshaveinternalcombustion engines,whichemitpollutants.Unlessgasolineordieselpoweredvehiclesarecompletelybanned,that pollutionwillpersist.However,afewelectricvehiclesarestartingtoappearontheroad,althoughthey areimpracticalforlongdistanceuseorheavyhauling.Obviously,mostpeoplearenotgoingtogiveup theirinternalcombustionenginevehiclesinthenearfuture.Peoplegenerallyacceptthatsomepollutionis aresultoflivinginamodernsociety.Thecriticalissue,then,ishowmuchpollutioncontroliseconomically practical.Acost-benetanalysisprovidesanestimateofthemosteconomicallyecientlevelofpollution reductionthatispractical. A cost-benetanalysis looksatthesocialbenetse.g.,healthandenvironmentalbenetsthatcan bederivedfrompollutionreductionversusthecostofachievingthatreduction.Asthepollutionreduction increases,sodoesthemoneyrequiredtoreducepollutionfurther.Itmaynotbeveryexpensivetoclean upthebulkofmostpollutants.However,asthereductioninpollutantsapproaches100percenti.e.,zero emissions,themarginalcostofeachadditionalunitofpollutionreductionrisesdramatically.Ifpublicfunds areusedforpollutioncontrol,thereisalimittohowmuchmoneycanbespentbeforethebudgetsofother importantpublicservicese.g.,police,reandparksdepartmentsarenegativelyimpacted.Abalancemust thereforebefoundbetweenthesocialbenetsofpollutionreductionandthecostofpollutionreduction.The properbalancebetweencostsandbenetsrepresentstheoptimumeconomiclevelofpollutionreduction. Theoptimumlevelisnotstatic,butcanchangeascircumstanceschange.Astechnologyimprovesover time,thecostofpollutionreductionmaydecrease.Likewise,asthehazardsofpollutionbecomebetter known,theperceivedbenetstobederivedfrompollutionreductionmayalsoincrease.Ineithercase, theoptimumlevelofpollutionreductionwillthenincreaseandagreaterlevelofpollutionreductionwillbe consideredeconomicallyfeasible.Theeco-eciencyprogramatthe3MCorporationisanexampleofhowthe optimumlevelofpollutionreductioncanberaisedthroughbettermanagementanddesignofmanufacturing processes.Overthetimeperiod1990to2000,thecompanyreduceditsairpollutionby88percent,water pollutionby82percentandwastegenerationby35percent. Oneproblemwithusingcost-benetanalysesfordeterminingtheoptimumlevelofpollutionreduction isthatitassumesallbenetscanbelabeledwithapricetag.However,aestheticbenetsfrompollution reductioncannotbepriced,andyettheyarejustasimportantasothers.Thebeautyofaclear-running streamandthequietsolitudeofawildernessareacannotbemeasuredindollarsandcents.

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Chapter22 CULTURALANDAESTHETIC CONSIDERATIONS 1 22.1CULTURALANDAESTHETICCONSIDERATIONS 22.1.1INTRODUCTION Theworld'sindustrializedcountriesareundergoingmanychangesastheymovetothelaterstagesofthe IndustrialRevolution.Economiesarebecomingmoreinformationbased,andcapitalisbeingmeasurednot onlyintermsoftangibleproductsandhumanworkers,butalsointermsofsocialandintellectualassets. Forexample,themakeupofthe GrossDomesticProductGDP fortheUnitedStateshasgradually changedfrombeingmainlymanufacturedgoodstoonewithservicespredominating.Computersoftware andmanyotherservices,whicharenoteasilycategorizedundertheoldeconomicsystem,nowrepresentthe largestsectoroftheUnitedStates'economy. Thischangeineconomicthinkinghasbroughtaboutadeeperawarenessofthenaturalprocessesand ecologicalassetsfoundinnature.Societyisslowlyshiftingtoanindustrialmodelthatincludesrecycling. Suchclosed-loopproductionencompassestheprinciplesofwaste-reduction,re-manufacturingandre-use. Conventionalindustrialeconomicsconsideredair,waterandtheearth'snaturalcyclestobe"free"goods. However,suchthoughtledtoconsiderableexternalenvironmentalandsocialcosts.Withtheriseofenvironmentallyresponsibleeconomics,thereisamovementtochangetofull-costpricingofgoods,whichincludes thesocialandenvironmentalcostsofproduction. AttemptshavebeenmadetooverhauleconomicindicatorssuchastheGDPtotakeintoaccountintangible assetsandintellectualproperty.In1994,theClintonAdministrationattemptedtointegrateenvironmental factorsintotheGDP.TheWorldBankin1995redeneditsWealthIndex.Anation'swealthnowconsistsof 60percenthumancapitalsocialandintellectualassets,20percentenvironmentalcapitalnaturalassets, and20percentbuiltcapitaltangibleassets.These greenGDP guresareintendedtoprovideabetter measureofthequalityoflifeinacountrythanthetraditionalGDP,whichlookedonlyattangibleeconomic factors.However,suchmethodsfailtotakeintoaccountotherareasthataectthequalityoflifeina country,suchashumanrights,healthandeducation. Inattemptstodevelopabettermeasureofthequalityoflifeofaregion,separatesetsofeconomic, environmentalandsocialindicatorshavebeendevised.Thereasoningofthisisthatitisbettertoconsider severalseparateindicators,ratherthantrytocreateasingle,catch-allindex.Thisapproachdoesnotrequire thedicult,ifnotimpossible,attempttoplacemonetaryvaluesonallfactors.TheCalvert-HendersonGroup chosetwelveseparatequalityoflifeindicators:education,employment,energy,environment,health,human rights,income,infrastructure,nationalsecurity,publicsafety,recreationandshelter.Althoughseparate, eachindicatorisrelatedtotheothers,andallarebasedonreadilyavailabledemographicdata. 1 Thiscontentisavailableonlineat. 99

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100 CHAPTER22.CULTURALANDAESTHETICCONSIDERATIONS 22.1.2CATEGORIZINGCOUNTRIES Countriesarecategorizedbyavarietyofmethods.DuringtheColdWarperiod,theUnitedStatesgovernment categorizedcountriesaccordingtoeachgovernment'sideologyandcapitalisticdevelopment.Inthissystem, the"FirstWorld"includedthecapitalistcountries;the"SecondWorld"includedthecommunistcountries andthepoorercountrieswerelabeledas"ThirdWorld."WiththeendoftheColdWar,thissystemhas beendiscarded. Currentclassicationmodelsutilizeeconomicandsometimesotherfactorsintheirdetermination. Onetwo-tieredclassicationsystemdevelopedbytheWorldBankclassiescountriesas developing and developed .AccordingtotheWorldBankclassication, developingcountries arethosewithlowor middlelevelsofGNPpercapita.Morethan80percentoftheworld'spopulationlivesinthemorethan100 developingcountries.Afewcountries,suchasIsrael,KuwaitandSingapore,arealsoclassiedasdeveloping countries,despitetheirhighpercapitaincome.Thisiseitherbecauseofthestructureoftheireconomies,or becausetheirgovernmentsociallyclassifythemselvesassuch. Developedcountries arethosethathave alargestockofphysicalcapitalandinwhichmostpeoplehaveahighstandardofliving.Someeconomists considermiddle-incomecountriesasdevelopedcountrieswhentheyhavetransitionaleconomiesthatare highlyindustrialized. Athree-tieredclassicationsystemwasdevelopedtocategorizecountriesmoreprecisely,especiallythose thatarenoteasilyclassiedaseitherdevelopingordeveloped.Thesethreecategoriesare: lessdeveloped countryLDC moderatelydevelopedcountryMDC and highlydevelopedcountryHDC Criteriausedtodetermineacountry'scategoryinclude:GNPpercapita,transportationandcommunication facilities,energyconsumption,literacyandunemployment. AcountrycategorizedasanLDChasamarginalphysicalenvironment.MostAfricancountriesandmany AsiancountriesarecategorizedasLDC.AnLDChasthefollowingcharacteristics:lowenergyproduction andconsumption,mostlysubsistencefarming,alargepercentageofthepopulationisunder15,ahighinfant mortalityrate,poorlydevelopedtradeandtransportationinadequatemedicalfacilities,alowliteracyrate, ahighunemploymentrateandaverylowpercapitaGNP. CountriessuchastheUnitedStates,Japan,andmostoftheWesternEuropeancountriesarecategorized asHDC.HDCsarecharacterizedby:extensivetrade,advancedinternalcommunicationsystems,highly developedtransportationnetworks,highenergyproductionandconsumption,advancedmedicalfacilities, lowpopulationgrowth,politicalstabilityandahighpercapitaGNP.TheMDCshavecharacteristicsthat tintoboththeLDCandHDCcategories,buthaveamoderatepercapitaGNP.SaudiArabia,Braziland MexicoareconsideredMDCs. Inaway,progressoflessdevelopedcountriesisdeterminedsomewhat,ifnotactivelyundermined,bythe developedcountries.Becausedevelopedcountriesarethemoretechnologicallyadvanced,theyareableto maintaintheiradvantagerelativetolessdevelopedcountries.Onewaytheyaccomplishthisisthrough"brain drain."Withbraindrain,thebesteducatedpeopleinlessdevelopedcountriesmovetodevelopedcountries wheretheyhavebetteropportunitiestoimprovetheirstandardofliving.Anotherwayisfordeveloped countriestoexploitthenaturalandhumanresourcesoflessdevelopedcountries.Developingcountries generallydesperatelyneedthecapitalthatdevelopedcountriescangivethem.Becauseenvironmentalissues oftentakeabackseattoeconomicissues,environmentaldisastercanfollow. AnexampleofexploitationbyaforeigncorporationoccurredinBhopal,India.Becauseoftheavailability ofcheaplaborandlaxenvironmentallaws,itwaseconomicallyadvantageoustolocateaUnionCarbide chemicalplantthere.Onedayin1984,acloudofpoisonousmethylisocyanatewasaccidentallyreleasedfrom theplant,killingmostoftheunprotectedpeopleintheadjacentareas.Housesneartheplantweremostly ofpoorfamiliesandstreetsneartheplantwerepopulatedwithmanyhomelessmen,womenandchildren. Severalthousandpeoplewerekilledinthisdisaster.Evenafterthesettlementoflawsuitsstemmingfrom theaccident,theinjuredandrelativesofthedeadreceivedlittlecompensation.Manyofthehomelesswere completelyignored. Initsrushtowarddevelopment,Bangladeshhasestablishedaprogramofintenseuseofland,forest, sheriesandwaterresources.Thishasledtosevereenvironmentaldegradation:lossofsoilfertility,excessive extractionofgroundwaterforirrigation,andincreasedairandwaterpollution.Theloweringofwatertables

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101 throughouttheland,inparticular,hasledtopollutionofgroundwaterbyarsenic.Asmanyas40million peopleinBangladeshmaybeexposedtotoxiclevelsofarsenicpresentinmanyofthenation'ssixmillion privateandpublicwells.Thecountrydoesnothavetheeconomicresourcesforadequatetestingofwellsto determinewhicharepoisonedandwhicharesafe.Becauseofthis,millionsmaydieofcancerorarsenicosis. Someidealisticpeoplebelievethatadenitionofadevelopedcountrymustincludefactorssuchas conservationandqualityoflifeandthatatrulydevelopedcountrywouldnotexploitalargefractionof theworld'sresources.Accordingly,characteristicsofsuchadevelopedcountrymightinclude:economic prosperityofallpeople,regardlessofgenderorage,sustainableuseofresourcesandmorecontrolleduse oftechnologytoensureahighqualityoflifeforallpeople.Aneconomicallyandtechnologicallydeveloped countrysuchastheUnitedStateswouldnotqualifyasbeingatrulydevelopedcountrybythesecriteria. 22.1.3ENVIRONMENTALJUSTICE Wheneveracommunityisfacedwiththepotentialofanenvironmentallyundesirablefacility,suchasthe placementofahazardouswastedumpinitsmidst,theusualresponsefromresidentsis:"Notinmyback yard!"SucharesponseisknownastheNIMBYprinciple.Suchreactionsareusuallyreactionstovisionsof previousenvironmentalirresponsibility:uncontrolleddumpingofnoxiousindustrialwastesandrustysteel drumsoozinghazardouschemicalsintotheenvironment.Suchoccurrenceswerealltoorealinthepastand somearestilltakingplace.Itisnowpossibleandmuchmorecommontobuildenvironmentallysound, state-of-the-artdisposalfacilities.However,theNIMBYprincipleusuallypreventstheconstructionofsuch newfacilities.Instead,hazardouswastefacilitiestendtobebuiltuponpre-existing,alreadycontaminated sites,eventhoughthegeologyofsuchlocationsmaybelessfavorableforcontainmentthanpotentialnew sites. Duringthe1980'sminoritygroupsprotestedthathazardouswastesiteswerepreferentiallysitedinminorityneighborhoods.In1987, BenjaminChavis oftheUnitedChurchofChristCommissionforRacism andJusticecoinedthetermenvironmentalracismtodescribesuchapractice.Thechargesgenerallyfailed toconsiderwhetherthefacilityorthedemographyoftheareacamerst.Mosthazardouswastesitesare locatedonpropertythatwasusedasdisposalsiteslongbeforemodernfacilitiesanddisposalmethodswere available.Areasaroundsuchsitesaretypicallydepressedeconomically,oftenasaresultofpastdisposal activities.Personswithlowincomesareoftenconstrainedtoliveinsuchundesirable,butaordable,areas. Theproblemmorelikelyresultedfromoneofinsensitivityratherthanracism.Indeed,theethnicmakeup ofpotentialdisposalfacilitieswasmostlikelynotconsideredwhenthesiteswerechosen. Decisionsincitinghazardouswastefacilitiesaregenerallymadeonthebasisofeconomics,geological suitabilityandthepoliticalclimate.Forexample,asitemusthaveasoiltypeandgeologicalprolethat preventshazardousmaterialsfrommovingintolocalaquifers.Thecostoflandisalsoanimportantconsideration.Thehighcostofbuyinglandwouldmakeiteconomicallyunfeasibletobuildahazardouswastesite inBeverlyHills.Somecommunitieshaveseenahazardouswastefacilityasawayofimprovingtheirlocal economyandqualityoflife.EmelleCounty,Alabamahadilliteracyandinfantmortalityratesthatwere amongthehighestinthenation.Alandllconstructedthereprovidedjobsandrevenuethatultimately helpedtoreducebothgures. Inanidealworld,therewouldbenohazardouswastefacilities,butwedonotliveinanidealworld. Unfortunately,weliveinaworldplaguedbyyearsoframpantpollutionandhazardouswastedumping. Ourindustrializedsocietyhasnecessarilyproducedwastesduringthemanufactureofproductsforourbasic needs.Untiltechnologycanndawaytomanageoreliminatehazardouswaste,disposalfacilitieswillbe necessarytoprotectbothhumansandtheenvironment.Bythesametoken,thisproblemmustbeaddressed. Industryandsocietymustbecomemoresociallysensitiveintheselectionoffuturehazardouswastesites. Allhumanswhohelpproducehazardouswastesmustsharetheburdenofdealingwiththosewastes,not justthepoorandminorities.

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102 CHAPTER22.CULTURALANDAESTHETICCONSIDERATIONS 22.1.4INDIGENOUSPEOPLE Sincetheendofthe15thcentury,mostoftheworld'sfrontiershavebeenclaimedandcolonizedbyestablished nations.Invariably,theseconqueredfrontierswerehometopeoplesindigenoustothoseregions.Somewere wipedoutorassimilatedbytheinvaders,whileotherssurvivedwhiletryingtomaintaintheiruniquecultures andwayoflife.TheUnitedNationsociallyclassiesindigenouspeopleasthose"havinganhistorical continuitywithpre-invasionandpre-colonialsocieties,"andconsiderthemselvesdistinctfromothersectors ofthesocietiesnowprevailinginthoseterritoriesorpartsofthem."Furthermore,indigenouspeopleare determinedtopreserve,developandtransmittofuturegenerations,theirancestralterritories,andtheir ethnicidentity,asthebasisoftheircontinuedexistenceaspeoplesinaccordancewiththeirowncultural patterns,socialinstitutionsandlegalsystems."Afewofthemanygroupsofindigenouspeoplearoundthe worldare:themanytribesofNativeAmericansi.e.,Navajo,Siouxinthecontiguous48states;theEskimos ofthearcticregionfromSiberiatoCanada;therainforesttribesinBrazilandtheAinuofnorthernJapan. Manyproblemsfaceindigenouspeople,including:lackofhumanrights,exploitationoftheirtraditional landsandthemselves,anddegradationoftheirculture.Inresponsetotheproblemsfacedbythesepeople, theUnitedNationsproclaimedan"InternationalDecadeoftheWorld'sIndigenousPeople"beginningin 1994.Themainobjectiveofthisproclamation,accordingtotheUnitedNations,is"thestrengtheningof internationalcooperationforthesolutionofproblemsfacedbyindigenouspeopleinsuchareasashuman rights,theenvironment,development,health,cultureandeducation."Itsmajorgoalistoprotecttherights ofindigenouspeople.Suchprotectionwouldenablethemtoretaintheirculturalidentity,suchastheir languageandsocialcustoms,whileparticipatinginthepolitical,economicandsocialactivitiesoftheregion inwhichtheyreside. DespitetheloftyU.N.goals,therightsandfeelingsofindigenouspeopleareoftenignoredorminimized, evenbysupposedlyculturallysensitivedevelopedcountries.IntheUnitedStatesmanyofthoseinthefederal governmentarepushingtoexploitoilresourcesintheArcticNationalWildlifeRefugeonthenortherncoast ofAlaska.TheGwich'in,anindigenouspeoplewhorelyculturallyandspirituallyontheherdsofcaribou thatliveintheregion,claimthatdrillingintheregionwoulddevastatetheirwayoflife.Thousandsof yearsofculturewouldbedestroyedforafewmonths'supplyofoil.Drillingeortshavebeenstymiedinthe past,butmostlyoutofconcernforenvironmentalfactorsandnotnecessarilytheneedsoftheindigenous people.Curiously,anothergroupofindigenouspeople,theInupiatEskimo,favoroildrillingintheArctic NationalWildlifeRefuge.Becausetheyownconsiderableamountsoflandadjacenttotherefuge,theywould potentiallyreapeconomicbenetsfromthedevelopmentoftheregion. IntheCanadianregionencompassingLabradorandnortheasternQuebec,theInnuNationhasbattled theCanadianDepartmentofNationalDefenseDNDtopreventsupersonictestightsovertheirhunting territory.TheInnuNationassertsthatsuchightsarepotentiallyharmfultoInnuhuntersandwildlifein thepathofsuchights.ThenatureofInnuhuntingincludestravellingoverlongdistancesandstayingout onthelandforlongperiodsoftime.TheInnuNationclaimsthatlow-levelsupersonicy-oversgenerate shockwaves,whichcanirreversiblydamagetheearsandlungsofanyoneinthedirectightpath.Theyalso claimthattheDNDhasmadenoseriouseortstowarntheInnupeopleofthepossibledangers. IntherainforestregionsofBrazil,indigenouspeoplesofseveraltribesareworkingtogethertostrengthen theircommonconcernovertheimpactoflargedevelopmentprojectsontheirtraditionallands.Suchprojects rangefromtheconstructionofdamsandhydroelectricpowerplantstothealterationofthenaturalcourses ofriverstoprovidecommercialwaterways.ThegovernmentofBraziltoutsdevelopmentoftheTocantinsAraguaiawaterwayasameanstofacilitaterivernavigationintheeasternAmazon.ItwillpromoteagriculturaldevelopmentinBrazil'sheartlandandintheeasternAmazonbyprovidingaccesstomarketsofgrains, fuelandfertilizers.However,thewaterwaywillnegativelyimpactfteenindigenouspeopleswhoobjectthat thechangesinthenaturalriverswillcausethedeathoftheshandanimalsuponwhichtheydependfor survival. Theheartofmostenvironmentalconictsfacedbygovernmentsusuallyinvolveswhatconstitutesproper andsustainablelevelsofdevelopment.Formanyindigenouspeoples,sustainabledevelopmentconstitutes anintegratedwholeness,wherenosingleactionisseparatefromothers.Theybelievethatsustainable developmentrequiresthemaintenanceandcontinuityoflife,fromgenerationtogenerationandthathumans

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103 arenotisolatedentities,butarepartoflargercommunities,whichincludetheseas,rivers,mountains,trees, sh,animalsandancestralspirits.These,alongwiththesun,moonandcosmos,constituteawhole.From thepointofviewofindigenouspeople,sustainabledevelopmentisaprocessthatmustintegratespiritual, cultural,economic,social,political,territorialandphilosophicalideals.

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Chapter23 ENVIRONMENTALETHICS 1 23.1ENVIRONMENTALETHICS 23.1.1INTRODUCTION Theconceptof ethics involvesstandardsofconduct.Thesestandardshelptodistinguishbetweenbehavior thatisconsideredrightandthatwhichisconsideredwrong.Asweallknow,itisnotalwayseasyto distinguishbetweenrightandwrong,asthereisnouniversalcodeofethics.Forexample,apoorfarmer clearsanareaofrainforestinordertogrowcrops.Somewouldnotopposethisaction,becausetheact allowsthefarmertoprovidealivelihoodforhisfamily.Otherswouldopposetheaction,claimingthatthe deforestationwillcontributetosoilerosionandglobalwarming.Rightandwrongareusuallydeterminedby anindividual's morals ,andtochangetheethicsofanentiresociety,itisnecessarytochangetheindividual ethicsofamajorityofthepeopleinthatsociety. Thewaysinwhichhumansinteractwiththelandanditsnaturalresourcesaredeterminedbyethical attitudesandbehaviors.EarlyEuropeansettlersinNorthAmericarapidlyconsumedthenaturalresources oftheland.Aftertheydepletedonearea,theymovedwestwardtonewfrontiers.Theirattitudetowards thelandwasthatofa frontierethic .Afrontierethicassumesthattheearthhasanunlimitedsupplyof resources.Ifresourcesrunoutinonearea,morecanbefoundelsewhereoralternativelyhumaningenuity willndsubstitutes.Thisattitudeseeshumansasmasterswhomanagetheplanet.Thefrontierethicis completely anthropocentric human-centered,foronlytheneedsofhumansareconsidered. Mostindustrializedsocietiesexperiencepopulationandeconomicgrowththatarebaseduponthisfrontier ethic,assumingthatinniteresourcesexisttosupportcontinuedgrowthindenitely.Infact,economic growthisconsideredameasureofhowwellasocietyisdoing.ThelateeconomistJulianSimonpointedout thatlifeonearthhasneverbeenbetter,andthatpopulationgrowthmeansmorecreativemindstosolve futureproblemsandgiveusanevenbetterstandardofliving.However,nowthatthehumanpopulationhas passedsixbillionandfewfrontiersareleft,manyarebeginningtoquestionthefrontierethic.Suchpeople aremovingtowardan environmentalethic ,whichincludeshumansaspartofthenaturalcommunity ratherthanmanagersofit.Suchanethicplaceslimitsonhumanactivitiese.g.,uncontrolledresourceuse, thatmayadverselyaectthenaturalcommunity. Someofthosestillsubscribingtothefrontierethicsuggestthatouterspacemaybethenewfrontier. Ifwerunoutofresourcesorspaceonearth,theyargue,wecansimplypopulateotherplanets.This seemsanunlikelysolution,aseventhemostaggressivecolonizationplanwouldbeincapableoftransferring peopletoextraterrestrialcoloniesatasignicantrate.Naturalpopulationgrowthonearthwouldoutpace thecolonizationeort.Amorelikelyscenariowouldbethatspacecouldprovidetheresourcese.g.from asteroidminingthatmighthelptosustainhumanexistenceonearth. 1 Thiscontentisavailableonlineat. 105

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106 CHAPTER23.ENVIRONMENTALETHICS 23.1.2SUSTAINABLEETHIC A sustainableethic isanenvironmentalethicbywhichpeopletreattheearthasifitsresourcesarelimited. Thisethicassumesthattheearth'sresourcesarenotunlimitedandthathumansmustuseandconserve resourcesinamannerthatallowstheircontinueduseinthefuture.Asustainableethicalsoassumesthat humansareapartofthenaturalenvironmentandthatwesuerwhenthehealthofanaturalecosystemis impaired.Asustainableethicincludesthefollowingtenets: Theearthhasalimitedsupplyofresources. Humansmustconserveresources. Humanssharetheearth'sresourceswithotherlivingthings. Growthisnotsustainable. Humansareapartofnature. Humansareaectedbynaturallaws. Humanssucceedbestwhentheymaintaintheintegrityofnaturalprocessessandcooperatewithnature. Forexample,ifafuelshortageoccurs,howcantheproblembesolvedinawaythatisconsistentwitha sustainableethic?Thesolutionsmightincludendingnewwaystoconserveoilordevelopingrenewable energyalternatives.Asustainableethicattitudeinthefaceofsuchaproblemwouldbethatifdrillingfor oildamagestheecosystem,thenthatdamagewillaectthehumanpopulationaswell.Asustainableethic canbeeitheranthropocentricor biocentric life-centered.Anadvocateforconservingoilresourcesmay consideralloilresourcesasthepropertyofhumans.Usingoilresourceswiselysothatfuturegenerations haveaccesstothemisanattitudeconsistentwithananthropocentricethic.Usingresourceswiselytoprevent ecologicaldamageisinaccordwithabiocentricethic. 23.1.3LANDETHIC AldoLeopold ,anAmericanwildlifenaturalhistorianandphilosopher,advocatedabiocentricethicinhis book,ASandCountyAlmanac.Hesuggestedthathumanshadalwaysconsideredlandasproperty,justas ancientGreeksconsideredslavesasproperty.Hebelievedthatmistreatmentoflandorofslavesmakes littleeconomicormoralsense,muchastodaytheconceptofslaveryisconsideredimmoral.Allhumans aremerelyonecomponentofanethicalframework.Leopoldsuggestedthatlandbeincludedinanethical framework,callingthisthe landethic Thelandethicsimplyenlargestheboundaryofthecommunitytoincludesoils,waters,plantsand animals;orcollectively,theland.Inshort,alandethicchangestheroleofHomosapiensfromconquerorof theland-communitytoplainmemberandcitizenofit.Itimpliesrespectforhisfellowmembers,andalso respectforthecommunityassuch.AldoLeopold,1949 Leopolddividedconservationistsintotwogroups:onegroupthatregardsthesoilasacommodityand theotherthatregardsthelandasbiota,withabroadinterpretationofitsfunction.Ifweapplythisideato theeldofforestry,therstgroupofconservationistswouldgrowtreeslikecabbages,whilethesecondgroup wouldstrivetomaintainanaturalecosystem.Leopoldmaintainedthattheconservationmovementmust bebaseduponmorethanjusteconomicnecessity.Specieswithnodiscernibleeconomicvaluetohumans

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107 maybeanintegralpartofafunctioningecosystem.Thelandethicrespectsallpartsofthenaturalworld regardlessoftheirutility,anddecisionsbaseduponthatethicresultinmorestablebiologicalcommunities. Anythingisrightwhenittendstopreservetheintegrity,stabilityandbeautyofthebioticcommunity. Itiswrongwhenittendstodootherwise.AldoLeopold,1949 Leopoldhadtwointerpretationsofanethic:ecologically,itlimitsfreedomofactioninthestruggle forexistence;whilephilosophically,itdierentiatessocialfromanti-socialconduct.Anethicresultsin cooperation,andLeopoldmaintainedthatcooperationshouldincludetheland. 23.1.4HETCHHETCHYVALLEY In1913,theHetchHetchyValleylocatedinYosemiteNationalParkinCaliforniawasthesiteofa conictbetweentwofactions,onewithananthropocentricethicandtheother,abiocentricethic.As thelastAmericanfrontiersweresettled,therateofforestdestructionstartedtoconcernthepublic.The conservationmovementgainedmomentum,butquicklybrokeintotwofactions.Onefaction,ledby Giord Pinchot ,ChiefForesterunderTeddyRoosevelt,advocatedutilitarianconservationi.e.,conservationof resourcesforthegoodofthepublic.Theotherfaction,ledbyJohnMuir,advocated preservation of forestsandotherwildernessfortheirinherentvalue.Bothgroupsrejectedthersttenetoffrontierethics, theassumptionthatresourcesarelimitless.However,theconservationistsagreedwiththerestofthetenets offrontierethics,whilethepreservationistsagreedwiththetenetsofthesustainableethic. TheHetchHetchyValleywaspartofaprotectedNationalPark,butafterthedevastatingresofthe 1906SanFranciscoearthquake,residentsofSanFranciscowantedtodamthevalleytoprovidetheircity withastablesupplyofwater.GiordPinchotfavoredthedam. AstomyattituderegardingtheproposeduseofHetchHetchybythecityofSanFrancisco ::: Iam fullypersuadedthat ::: theinjury ::: bysubstitutingalakeforthepresentswampyoorofthevalley ::: is altogetherunimportantcomparedwiththebenetstobederivedfromit'suseasareservoir. Thefundamentalprincipleofthewholeconservationpolicyisthatofuse,totakeeverypartoftheland anditsresourcesandputittothatuseinwhichitwillservethemostpeople.GiordPinchot,1913 JohnMuir,thefounderoftheSierraClubandagreatloverofwilderness,ledtheghtagainstthedam. Hesawwildernessashavingan intrinsicvalue ,separatefromits utilitarian valuetopeople.Headvocated preservationofwildplacesfortheirinherentbeautyandforthesakeofthecreaturesthatlivethere.The issuearousedtheAmericanpublic,whowerebecomingincreasinglyalarmedatthegrowthofcitiesand thedestructionofthelandscapeforthesakeofcommercialenterprises.Keysenatorsreceivedthousandsof lettersofprotest. Thesetempledestroyers,devoteesofravagingcommercialism,seemtohaveaperfectcontemptfor Nature,andinsteadofliftingtheireyestotheGodoftheMountains,liftthemtotheAlmightyDollar. JohnMuir,1912 Despitepublicprotest,Congressvotedtodamthevalley.Thepreservationistslosttheghtforthe HetchHetchyValley,buttheirquestioningoftraditionalAmericanvalueshadsomelastingeects.In 1916,Congresspassedthe NationalParkSystemOrganicAct ,whichdeclaredthatparksweretobe maintainedinamannerthatleftthemunimpairedforfuturegenerations.Asweuseourpubliclands,we continuetodebatewhetherweshouldbeguidedbypreservationismorconservationism. 23.1.5THETRAGEDYOFTHECOMMONS Inhisessay,TheTragedyoftheCommons, GarrettHardin lookedatwhathappenswhenhumans donotlimittheiractionsbyincludingthelandaspartoftheirethic.Thetragedyofthecommonsdevelops inthefollowingway:Pictureapastureopentoall.Itistobeexpectedthateachherdsmanwilltryto keepasmanycattleaspossibleonthecommons.Suchanarrangementmayworksatisfactorilyforcenturies, becausetribalwars,poachinganddiseasekeepthenumbersofbothmanandbeastwellbelowthecarrying capacityoftheland.Finally,however,comesthedayofreckoningi.e.,thedaywhenthelong-desiredgoalof socialstabilitybecomesareality.Atthispoint,theinherentlogicofthecommonsremorselesslygenerates tragedy.

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108 CHAPTER23.ENVIRONMENTALETHICS Asarationalbeing,eachherdsmanseekstomaximizehisgain.Explicitlyorimplicitly,moreorless consciously,heasks:"Whatistheutilitytomeofaddingonemoreanimaltomyherd?"Thisutilityhas bothnegativeandpositivecomponents.Thepositivecomponentisafunctionoftheincrementofoneanimal. Sincetheherdsmanreceivesalltheproceedsfromthesaleoftheadditionalanimal,thepositiveutilityis nearly+1.Thenegativecomponentisafunctionoftheadditionalovergrazingcreatedbyonemoreanimal. However,astheeectsofovergrazingaresharedbyalloftheherdsmen,thenegativeutilityforanyparticular decision-makingherdsmanisonlyafractionof-1. Thesumoftheutilitiesleadstherationalherdsmantoconcludethattheonlysensiblecourseforhimto pursueistoaddanotheranimaltohisherd,andthenanother,andsoforth.However,thissameconclusion isreachedbyeachandeveryrationalherdsmansharingthecommons.Thereinliesthetragedy:eachman islockedintoasystemthatcompelshimtoincreasehisherd,withoutlimit,inaworldthatislimited.Ruin isthedestinationtowardwhichallmenrush,eachpursuinghisownbestinterestinasocietythatbelieves inthefreedomofthecommons.Freedominthecommonsbringsruintoall. Hardinwentontoapplythesituationtomoderncommons.Thepublicmustdealwiththeovergrazing ofpubliclands,theoveruseofpublicforestsandparksandthedepletionofshpopulationsintheocean. Individualsandcompaniesarerestrictedfromusingariverasacommondumpinggroundforsewageand fromfoulingtheairwithpollution.Hardinalsostronglyrecommendedrestrainingpopulationgrowth. The"TragedyoftheCommons"isapplicabletotheenvironmentalproblemofglobalwarming.The atmosphereiscertainlyacommonsintowhichmanycountriesaredumpingexcesscarbondioxidefrom theburningoffossilfuels.Althoughweknowthatthegenerationofgreenhousegaseswillhavedamaging eectsupontheentireglobe,wecontinuetoburnfossilfuels.Asacountry,theimmediatebenetfromthe continueduseoffossilfuelsisseenasapositivecomponent.Allcountries,however,willsharethenegative long-termeects.

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Chapter24 ENVIRONMENTALLAWS& REGULATIONS 1 24.1ENVIRONMENTALLAWS®ULATIONS 24.1.1INTRODUCTION Althoughenvironmentallawsaregenerallyconsidereda20thcenturyphenomenon,attemptshavebeenmade tolegislateenvironmentalcontrolsthroughouthistory.In2,700B.C.,themiddle-easterncivilizationinUr passedlawsprotectingthefewremainingforestsintheregion.In80A.D.,theRomanSenatepassedalaw toprotectwaterstoredfordryperiodssoitcouldbeusedforstreetandsewercleaning.DuringAmerican colonialtimes, BenjaminFranklin arguedfor"publicrights"lawstoprotectthecitizensofPhiladelphia againstindustrialpollutionproducedbyanimalhidetanners. Signicantenvironmentalactionbeganatthebeginningofthe20thcentury.In1906,Congresspassedthe AntiquitiesAct,whichauthorizesthepresidenttoprotectareasoffederallandsasnationalmonuments.A fewyearslater, AliceHamilton pushedforgovernmentregulationsconcerningtoxicindustrialchemicals. Shefought,unsuccessfully,tobantheuseofleadingasoline.Shealsosupportedthelegalactionstakenby womenwhoweredyingofcancerfromtheirexposuretotheradiumthenusedinglow-in-the-darkwatch dials.Duringtheearly1960's,biologist RachelCarson pointedouttheneedtoregulatepesticidessuchas DDTtoprotectthehealthofwildlifeandhumans. Withtheestablishmentofthe EnvironmentalProtectionAgencyEPA in1970,environmental lawbecameaeldsubstantialenoughtooccupylawyersonafull-timebasis.Sincethen,federalandstate governmentshavepassednumerouslawsandcreatedavastnetworkofcomplicatedrulesandregulations regardingenvironmentalissues.Moreover,internationalorganizationsandagenciesincludingthe United Nations ,the WorldBank ,andthe WorldTradeOrganization havealsocontributedenvironmental rulesandregulations. Becauseofthelegalandtechnicalcomplexitiesofthesubjectscoveredbyenvironmentallaws,persons dealingwithsuchlawsmustbeknowledgeableintheareasoflaw,scienceandpublicpolicy.Environmental lawstodayencompassawiderangeofsubjectssuchasairandwaterquality,hazardouswastesandbiodiversity.Thepurposeoftheseenvironmentallawsistoprevent,minimize,remedyandpunishactionsthat threatenordamagetheenvironmentandthosethatliveinit.However,somepeoplebelievethattheselaws unreasonablylimitthefreedomofpeople,organizations,corporationsandgovernmentagenciesbyplacing controlsontheiractions. 1 Thiscontentisavailableonlineat. 109

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110 CHAPTER24.ENVIRONMENTALLAWS®ULATIONS 24.1.2FEDERALLAWS EarlyattemptsbyCongresstoenactlawsaectingtheenvironmentincludedthe AntiquitiesAct in1906, the NationalParkServiceAct in1916,the FederalInsecticide FungicideandRodenticideAct in 1947andthe WaterPollutionControlAct in1956.The WildernessAct of1964,protectedlargeareas ofpristinefederallandsfromdevelopmentandusheredinthenewageofenvironmentalactivismthatbegan inthe1960's.However,itwasthe NationalEnvironmentalPolicyActNEPA enactedin1969and theformationoftheEnvironmentalProtectionAgencyEPAin1970thatstartedenvironmentallegislation inearnest.Themainobjectiveofthesetwofederalenactmentswastoassurethattheenvironmentwouldbe protectedfrombothpublicandprivateactionsthatfailedtotakeintoaccountthecostsofdamageinicted ontheenvironment. ManyconsiderNEPAtobethemostfar-reachingenvironmentallegislationeverpassedbyCongress.The basicpurposeofNEPAistoforcegovernmentalagenciestocomprehensivelyconsidertheeectsoftheir decisionsontheenvironment.Thisiseectedbyrequiringagenciestopreparedetailed Environmental ImpactStatements EISforproposedprojects.TheEPAisthegovernment'senvironmentalwatchdog. Itischargedwithmonitoringandanalyzingthestateoftheenvironment,conductingresearch,andworking closelywithstateandlocalgovernmentstodevisepollutioncontrolpolicies.TheEPAisalsoempoweredto enforcethoseenvironmentalpolicies.Unfortunately,theagencyissometimescaughtupinconictsbetween thepublicwantingmoreregulationforenvironmentalreasonsandbusinesseswantinglessregulationfor economicreasons.Consequently,thedevelopmentofanewregulationcantakemanyyears. Since1970,Congresshasenactedseveralimportantenvironmentallaws,allofwhichincludeprovisions toprotecttheenvironmentandnaturalresources.Someofthemorenotablelawsinclude: The FederalCleanAirAct ,1977&1990establishednationalstandardsforregulatingthe emissionofpollutantsfromstationaryandmobilesources. The FederalWaterPollutionControlAct amendedbythe CleanWaterAct 1987,establishedwaterqualitystandards;providesfortheregulationofthedischargeofpollutants intonavigablewatersandfortheprotectionofwetlands. The FederalSafeDrinkingWaterAct ,1977&1986setdrinkingwaterstandardsforlevels ofpollutants;authorizingtheregulationofthedischargeofpollutantsintoundergrounddrinkingwater sources. The ToxicSubstancesControlAct providedfortheregulationofchemicalsubstancesby theEPAandthesafetytestingofnewchemicals. The ResourceConservationandRecoveryAct establishedcradle-to-graveregulationsfor thehandlingofhazardouswastes. The ComprehensiveEnvironmentalResponse CompensationandLiabilityAct ,also knownasthe Superfund program,providedforthecleanupoftheworsttoxicwastesites. The FoodSecurityAct ,1990lateramendedbythe FederalAgricultureImprovement andReformAct ,discouragedcultivationofenvironmentallysensitivelands,especiallywetlands,andauthorizedincentivesforfarmerstowithdrawhighlyerodiblelandsfromproduction. Theapplication,orenforcement,ofanenvironmentallawisnotalwaysstraightforward,andproblemscan arise.Often,thebiggestproblemisthatCongressfailstoallocatethefundsnecessaryforimplementing orenforcingthelaws.Administrativeredtapemaymakeitimpossibletoenforcearegulationinatimely manner.Italsomaybeunclearastowhichagencyorbranchofanagencyisresponsibleforenforcinga particularregulation.Furthermore,agencypersonneldeclinetoenforcearegulationforpoliticalreasons.

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111 24.1.3STATELAWS Moststates,likeCalifornia,haveenactedtheirownenvironmentallawsandestablishedagenciestoenforce them.Californiafacedsomeofitsrstenvironmentalchallengesinthemid-1800's,withregardtodebrisfrom thehydraulicminingofgold.Waterqualityconcerns,dangersofooding,negativeimpactonagriculture andhazardstonavigationpromptedthestatetoact. SomeofCalifornia'senvironmentalregulationsprecededsimilarfederallaws.Forexample,California establishedthenation'srstairqualityprograminthe1950s.MuchofthefederalCleanAirActamendments of1990werebaseduponthe CaliforniaCleanAirActof1988 .Californiaalsopioneeredadvancesin vehicleemissioncontrols,controloftoxicairpollutantsandcontrolofstationarypollutionsourcesbefore federaleortsinthoseareas.The Porter-CologneActof1970 ,uponwhichthestate'swaterquality programisbased,alsoservedasthemodelforthefederalCleanWaterAct. California'sstateenvironmentalregulationsaresometimesmorestringentthanthefederallawse.g., theCaliforniaCleanAirActandvehicleemissionsstandards.Inotherprogramareas,nocomparable federallegislationexists.Forexample,theCalifornia IntegratedWasteManagementAct established acomprehensive,statewidesystemofpermitting,inspections,enforcementandmaintenanceforsolidwaste facilitiesandsetsminimumstandardsforsolidwastehandlinganddisposaltoprotectair,waterandland frompollution.Also, Proposition65 SafeDrinkingWaterandToxicEnforcementAct requires theGovernortopublishalistofchemicalsthatareknowntotheStateofCaliforniatocausecancer,birth defectsorotherreproductiveharm. Despitethestate'sleadershipinenvironmentalprogramsandlaws,thecreationofacabinet-levelenvironmentalagencyinCalifornialaggedmorethantwodecadesbehindtheestablishmentofthefederalEPA. Originally,organizationofCalifornia'senvironmentalqualityprogramswashighlyfragmented.Eachseparateprogramhandledaspecicenvironmentalprobleme.g.,the AirResourcesBoard ,withenforcement responsibilityfallingtobothstateandlocalgovernments.Itwasnotuntil1991thataCaliforniaEPAwas nallyestablishedandunitedtheseparateprogramsunderoneagency. 24.1.4INTERNATIONALTREATIESANDCONVENTIONS Conventions,ortreaties,generallysetforthinternationalenvironmentalregulations.Theseconventionsand treatiesoftenresultfromeortsbyinternationalorganizationssuchasthe UnitedNationsUN orthe WorldBank .However,itisoftendicult,ifnotimpossible,toenforcetheseregulationsbecauseofthe sovereignrightsofcountries.Inadditionrulesandregulationssetforthinsuchagreementsmaybenomore thannon-bindingrecommendations,andoftencountriesareexemptedfromregulationsduetoeconomicor culturalreasons.Despitetheseshortcomings,theinternationalcommunityhasachievedsomesuccessviaits environmentalagreements.Theseincludeaninternationalconventionthatplacedamoratoriumonwhaling andatreatythatbannedtheoceandumpingofwastes. TheUNoftenfacilitatesinternationalenvironmentaleorts.In1991,theUNenactedan Antarctica Treaty ,whichprohibitsminingoftheregion,limitspollutionoftheenvironmentandprotectsitsanimal species.TheUnitedNationsEnvironmentProgramUNEPisabranchoftheUNthatspecicallydeals withworldwideenvironmentalproblems.Ithashelpedwithseveralkeyeortsatglobalenvironmental regulations: The1987MontrealProtocolonSubstancesthatDepletetheOzoneLayer .Asaresultof thisglobalagreement,industrializedcountrieshaveceasedorreducedtheproductionandconsumption ofozone-depletingsubstancessuchaschlorouorocarbons. ThePriorInformedConsentProcedureforCertainHazardousChemicalsandPesticides inInternationalTrade .Thisagreementenhancestheworld'stechnicalknowledgeandexpertiseon hazardouschemicalsmanagement.

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112 CHAPTER24.ENVIRONMENTALLAWS®ULATIONS TheConventiononInternationalTradeinEndangeredSpeciesofWildFaunaandFlora CITES .Thisagreementprotectsover30,000oftheworld'sendangeredspecies. In1995 UNEPandtheInternationalOlympicCommitteeIOC signedapartnershipagreementtodevelopenvironmentalguidelinesforsportsfederationsandcountriesbiddingtohostthe Olympicgames. TheRotterdamConvention addressedthegrowingtradeinhazardouspesticidesandchemicals.Importingcountriesmustnowgiveexplicitinformedconsentbeforehazardouschemicalscan crosstheirborders. TheInternationalDeclarationonCleanerProduction .Thesignatoriescommittheir countriestoimplementcleanerindustrialproductionandsubsequentmonitoringeorts. In1992,theUNmembernationscommittedtheirresourcestolimitinggreenhousegase.g.,carbondioxide emissionsatorbelow1990levels,asputforthbythe UNFrameworkConventiononClimateChange Unfortunately,theagreementwasnon-bindingandbythemid-1990's,ithadhadnoeectoncarbonemissions.The1997 KyotoProtocol wasabindingresolutiontoreducegreenhousegases.AlthoughtheUnited Statesinitiallysupportedtheresolution,theSenatefailedtoratifythetreaty,andby2001theresolution wasopposedbyPresidentBushasthreateningtheUnitedStateseconomy.

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Chapter25 ISSUESANDOPTIONS 1 25.1ISSUESANDOPTIONS 25.1.1INTRODUCTION Environmentalissuesareaconcernofmany,ifnotmost,Americans.However,thereisconsiderabledisagreementonhowsuchissuesshouldbehandled.Dierentpeoplecaninterpretevenaverygeneralissue suchasconservationverydierently.Somebelievethatconservationmeanslimitingtheuseofresourcesto allowaresourcetolastlonger.Othersseetheconservationofresourcesasawaytomaximizebenetsto humans.Thisutilitarianapproachtoconservationpolicy,wouldplacenovalueonsavingendangeredspecies thatprovidenodirectbenettohumans.Attheotherextreme,someenvisionconservationasmeaning theprotectionofresourceswithoutregardtoprotormaterialbenettohumans.Thisviewplacesthe preservationasbeingoftheutmostimportance,andissometimesviewedaselitist. Eventhesimpleststrategiesfordealingwithenvironmentalissuescannotbecarriedoutwithoutthe expenditureoftime,eortandmoney.Itfollowsthatenvironmentalpolicydecisionsthatareadoptedbya countryareusuallymadewithinthecontextofthelevelofauenceandeducationofthatcountry.Thisis especiallytruewhenitcomestoconservationissues.AdevelopedcountryliketheUnitedStatescanaord tosetasideandmanagewildernessareasorplacerestrictionsontimbercutting,miningandoildrillingon publiclands.However,adevelopingcountrymustcontendwithinsucientfundstomeetthebasicneedsof itspeople.Thisoftenleadstoshort-sighteddecisionsthatallowexploitationofitsforestsandothernatural resources.Theneedforhardcashoverridestheneedtoconserve. Thedevelopmentandpromotionofaplatformonenvironmentalissuesrequirescarefulplanningand well-conceivededucationprograms.Politicalbackingisanecessityforimplementingsuchaplatform,as wellasforgarneringthelegislativepowerstoenforcerulesandguidelines.Politicianswereforthemost partdisinterestedinenvironmentalissuesuntilthe1970's.Themainreasonforthiswasthatissuessuch asconservationwereperceivedaslong-termissues,andpoliticalconcernsaremostlyshortterm,changing astheadministrationschanged.However,politiciansrealizedthattheyhadtoformulatesomemedium orlong-termstrategies,whenariseininternationalenvironmentalactivismforcedthemtoconsiderthese issues. 25.1.2RESOURCEUSE BeforethearrivalofEuropeansettlers,theindigenouspeopleoftheNorthAmericancontinentlivedin relativeharmonywiththeirenvironment.Althoughtheyhuntedanimalsandsomeraisedcropsusingslash andburntechniques,theyhadlittleimpactontheenvironmentbecausetheirpopulationswererelatively small.ThissituationchangedafterEuropeancolonistssettledwhatisnowtheeasterncoastoftheUnited 1 Thiscontentisavailableonlineat. 113

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114 CHAPTER25.ISSUESANDOPTIONS States.Astheirnumbersgrew,theymovedwestward.Thesettlersclearcutforestsastheymovedthrough thefrontierregions,leavingdenudedlandscapes.Farmersgrewcropsuntilthesoilbecameinfertileand thenmovedontootherlocations.Peopleusedwaterresourcesfreelywithoutgivingmuchthoughtto conservation.Thecommonapproachwasthatofexploitationoftheseeminglyendlessnaturalresourcesthe countryoered. However,thistraditionofexploitationbegantochangeastheUnitedStatesbecameindustrializedand urbanized.Asearlyasthelate18thcentury,peoplesuchasGeorgeWashingtonandThomasJeersonbegan experimentingwithcroprotationandsoilconservationtechniques.Duringthe19thcentury,growingcities developedwaterworkstosupplycleanwater.Somepeoplebegantorealizetheimportanceofconserving naturalresourcessuchaswater.By1900,variousAmericanscientists,politiciansandbusinessleadersvoiced concernsaboutthedepletionoftheforests,soilandothernaturalresources. Thetermconservationwasrstappliedtowaterresources.MuchofthewesternUnitedStateswasarid, andgovernmentscientistsdevelopedtheideaofbuildingdamstoimpoundwaterfromspringoods.They reasonedthatthewatercouldthenbeusedyearroundforirrigationandotherpurposes.Useoftheterm quicklyspreadtoincludeallnaturalresources.Conservationemergedfromthe19thcenturyasaformof appliedscience.Itinvolvedthescienticplanningoftheuseofnaturalresources.Conservationleaders camefromeldslikeforestry,agronomy,geology,andhydrology.AnearlyproponentwasGiordPinchot, therstheadoftheUnitedStatesForestService.Theconservationprinciplesofthattimecontrastedwith thoseespousedbyproponentsofpreservation. Preservationistswantednaturalareaspreservedandprotectedfromanytypeofhumandevelopment.The leadingpreservationistofthetimewasJohnMuir.Becauseoftheirdierentviews,thepreservationmovementandtheconservationmovementweresometimesatoddswitheachother.Themostpublicizedcontroversyoftheearly20thcenturyconcernedtheplantobuildadamtooodthebeautifulHetch-Hetchyvalley tosupplythecityofSanFranciscowithfreshwater.Thedam,supportedbyconservationistsandopposed bypreservationists,waseventuallybuilt.PresidentTheodoreRooseveltsupportedbothconservationand preservation.Hevigorouslyexpandedthenation'sinfantsystemofnationalparksandmonumentsinorder toprotectpristinenaturalareasfromexploitation Themainissuesofresourceconservationtodaydierfromthoseattheturnofthe20thcentury.During the1960'sthegeneralpublicbecameconcernedwiththeproblemsofpollution.Theeectsofpesticides suchasDDTonwildlifeweredocumentedinabookSilentSpringbyRachelCarson.Therewerehighly publicizedenvironmentalincidentsinLakeErieseverewaterpollution,NewYorkCityairpollutionand SantaBarbaraoilspill.Eventssuchasthesefueledthestartofanewenvironmentalmovement.This movementgenerallysupportstheconceptthatresourceconservationincludesmaintainingthequalityof thoseresources.Thismovementcontinuestodayandsupportssuchissuesasgovernmentclean-upofold areasofpollution,reductionofcurrentemissionlevelsofpollutionandprotectionofremainingpristine environments. 25.1.3RESTORATIONECOLOGY Humanshavedeforestedtheland,strippeditssurfacetoremoveitsmineralresources,exploiteditsgrasslands anddraineditswetlands,alltosustainthegrowinghumanpopulation.Rivershavebeenstraightened, divertedanddammedtoprovidehumanswithwater,transportation,oodcontrol,electricpowerand recreationalfacilities.However,whenecosystemsareoverexploitedtheydegenerate.Healthyecosystemsare necessaryinordertosustaintheearth'ssoil,waterandairresources.Somepeoplefeelthatenvironmental degradationshouldbereversedthroughrestorationecologyi.e.,therestorationofdegradedenvironments tohealthyecosystems.However,theconceptsinvolvedarevaried. Themodernconceptofreclamationinvolvesanattempttoreturnadamagedecosystemtosomekind ofproductiveusethatissociallyacceptable.Forexample,aminedareamightbeconvertedtopastureland oranorchard.Inthisprocessrehabilitationoftheminedareaalsooccurs,makingthelandmorevisually pleasing.Historically,thetermreclamationwasusedtodescribethealterationofanativeecosystemto oneofvaluetohumans,suchasthellingofawetlandsareainordertoprovidelandforurbanhousing.

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115 Today,suchanactionmightbeconsideredenvironmentaldegradation.Becauseoftheconictingdenitions, theuseofthetermreclamationcanbeconfusing. Sometimes,actionscanbetakentoavoid,reduceorcompensatefortheeectsofenvironmentaldamage. SuchmitigationeortshavebeentakenbytheArmyCorpsofEngineersduringconstructionprojects.The nativeplantsareremovedfromasitebeforeconstructionbeginsandtransplantedataspecialholdingsite. Aftertheconstructionprojectiscompleted,thenativeplantsarerestoredusingthosefromtheholding site.Anotherexampleofmitigationmightinvolvethecreationorenhancementofwetlandsinonearea, inordertocompensateforpermittedwetlandlossesinanotherarea.Mitigationoftengoeshand-in-hand withrestoration.Texaco,inconjunctionwithenvironmentalgroupsandtheUnitedStatesFishandWildlife Service,restored500acresofagriculturallandsinthelowerMississippiDeltatobottomlandhardwoods. Texacoreceivedenvironmentalcreditsforthemitigatingeectsofthenewwoodlandsonairquality. Restorationinvolvesreturninganalteredordegradedsitetoitsapproximateconditionbeforealteration. Thisincludesrestoringrelatedphysical,chemicalandbiologicalcharacteristics.Fullrestorationinvolves thecompletereturnofasitetoitsoriginalstate.Restoringanecosystemtoitsfullproductivehealthis notaneasytask.Itrequiresabroadinterdisciplinaryapproachinvolvingmanydierentscienticeldsof studye.g.,biology,ecology,hydrologyandgeology.Inherentinrestorationprojectsareimportantthough questionableandoftenunrealisticassumptions:historicalenvironmentalconditionscanberecreated,existing ecosystemscanbereplaced,thephysicalenvironmentcanbealteredinordertosupportthedesiredplants andanimals,thedesiredplantsandanimalswillbecomeestablished,andtheecosystemwillbeableto sustainitself. Besidesphysicalprocesses,socio-economicfactorsmustalsobeconsideredinarestorationproject.Actionsofhumanshavehistoricallybeenimportantinshapingecosystems,andareimportantindetermining thesuccessofrestorationeorts.Becausethecosttorestoreanindividualsitecaninvolvemillionsofdollars,governmentsupportisanecessity.Evenwiththebesteorts,restorationprojectscansometimesbe hamperedbyunexpectedevents.Aneortbyoneenvironmentalgrouptorestoreasavannahecosystemin Illinoiswasblockedbyanotherenvironmentalgroupthatobjectedtotheremovalofthetreesfromthearea. 25.1.4ENVIRONMENTALINVOLVEMENT "Neverdoubtthatasmallgroupofthoughtful,committedcitizenscanchangetheworld:indeedit'sthe onlythingthateverhas."-MargaretMead Theenvironmentalmovementhaditsbeginningsintheearly1960's,whenbiologistRachelCarlsonpublishedherbook"TheSilentSpring."Thebookhighlightedtheharmfuleectsofpesticidesonwildlife.Soon therewasagrowinggrassrootscampaigndemandingthatthegovernmentacttoprotecttheenvironment. TherewasalsoanincreaseinthepopularityofestablishedconservationgroupssuchastheSierraClub andtheWildernessSociety.Theearlyyearsofthemovementledtosuchmilestonesasthepassageofthe WildernessActin1964andtheLandandWaterConservationActin1965,aswellastheestablishment oftheEnvironmentalProtectionAgencyin1970. EnvironmentalgroupsintheUnitedStatescarryoutavarietyofactivities:lobbyingfornewenvironmentallaws,lobbyingagainstharmfulprojects,actingaspollutionwatchdogs,activelyprotectinglandand wildlifeandeducatingthepubliconenvironmentalissues.SomemoreradicalgroupssuchasEarthFirst! addcivildisobedienceandsabotagetotheirenvironmentalactivities.Greenpeaceisoneofthelargestinternationalenvironmentalgroupsandisprobablybestknownforitseortstostopcontinuedcommercial whalingbyJapanandNorway. Ananti-environmentalistmovement,theWiseUseMovement,isacoalitionoftimberandmining companiesandcattleranchers.Themembersadvocatelogging,mining,grazinganddevelopingallpublic lands,regardlessoftheenvironmentalconsequences.Throughoutthe1990'sthegroupattemptedtorepeal orweakenmanyenvironmentallawsanddiscreditenvironmentalgroups.Theireortswerelargelythwarted; however,theywereabletoblocksomeproposedenvironmentallegislation. Althoughstrengthinnumbersisalwaysaneectivestrategywhentakingonenvironmentalissues,individualscanalsomakesignicantinroadsinenvironmentalactivism.In1978,alonewomanlivinginthe LoveCanalareaofNiagaraFalls,NewYork,awakenedthenationtothedangersofhazardouswastedumps.

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116 CHAPTER25.ISSUESANDOPTIONS Workingrstatthelocallevel,thenthestatelevelandnallythenationallevel,shelobbiedgovernments totakeactiontoprotectpeoplefromthetoxicchemicalscontainedinsuchdumps.Hereortsledtothe creationofanationalSuperfundin1980tocleanupandregulatehazardouswastesites. Peoplewhowanttomaketheirvoicesheardonenvironmentalissuescandosoinanumberofways. Locally,theycansendletterstotheeditorsofcommunitynewspaperstoreachawideaudience.Public hearingsandcommunitymeetingsalsoprovideopportunitiestomakeastrongvocalstatement.Onalarger politicalscale,atypedorhandwrittenlettertoagovernmentocialisparticularlyeective.Faxingthe lettertotheocialisanotheroption.Telephonecallstolegislatorsshowthatthecallerscareenoughto spendalittlemoney,andalsooersanunparalleledopportunityforimmediatefeedback.However,itisnot alwayseasytoactuallygetconnectedtotherecipient.E-mailsarelesspersonalthanregularletters,but theyareveryconvenientandthehavethepotentialtomobilizehundredsorthousandsofmessages,making itanindispensabletoolfortheenvironmentalactivist. 25.1.5Sustainability Sustainabilityreferstopracticesthatallowcurrentpopulationstomeettheirneedswithoutimpactingthe abilityoffuturegenerationstomeettheirownneeds.Theideawasdevelopedtodescribethelong-term useofnaturalresourcesbuthasbeenexpandedtoincludeadiversityofsituations,includingcommunity structures,economicpolicies,andsocialjustice.Sustainabilityisarelativelynewconceptthatisbecoming acommonidealbutisnotyetwidelypracticed. 25.1.6Non-renewableResources Theuseofnon-renewableresourcesisbydenition,unsustainable.Theuseoffossilfuelsisaprimeexample. Industrialsocietiesrelyonoilandnaturalgastopowermanufacturing,propelvehicles,heathomes,andcook meals.Inaddition,manygoods,likeplastics,arepartiallymadeofpetroleumproducts.Ongoinggeologic processesarecontinuingtoproducefossilfuels,astheyhaveformillennia,buttherateatwhichweare usingthemfaroutstripstherateatwhichnaturalcyclesregeneratethem.Somescientistsprojectthatoil andgasreserveswillbelargelydrainedin50200years.Futuregenerationswillhavetondothersources ofenergy. 25.1.7EnvironmentalDegradation Somepracticesarenotsustainablebecausetheycausesevereenvironmentaldamage.Forexample,some modernagriculturalmethodsactuallydestroythesoiltheyrelyon,sothatfarmsourishforatimebut thenmustbeabandoned.Desertlandscangrowcropsiftheyareintensivelyirrigated.Butwhenirrigation waterevaporatesinhotclimates,thesoilbecomesmoreandmoresalty,untilplantgrowthisstunted.In thetropics,whenrainforestsarechoppeddowntomakewayforcrops,soilslosethesteadynutrientsupply theforestprovidedandsoonbecomeinfertile. 25.1.8RenewableResources Renewableresourcescanbeusedfarintothefuture.Windpowerisatypeofrenewableenergy.Windmills, whichturninthewindtospinturbinesthatgenerateelectricity,don'tuseupordiminishtheair.Andthe supplyofwindisrenewedeveryday,whenunevensolarheatingoftheEarthcauseshotairtoriseandcold airtosink. 25.1.9BestManagementPractices Bestmanagementpracticesaretechniquesandmethodsdesignedtominimizeenvironmentalimpacts.In agriculture,thesepracticesincludegrowingnativecropsorthosesuitedtolocalconditions,rotatingcrops,

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117 minimizingsoiltilling,andreducingpesticideuse.Withpropercare,soilscanremainfertileandhealthyfor manyyears. 25.1.10EnvironmentalRemediation Formanythousandsofyears,eversincetheybuilttherstcampre,humanactivityhasgeneratedair, water,andsoilpollution.Formostofhumanhistory,however,thesecontaminantshadrelativelylittle environmentalimpact.Butoverthelastfewcenturies,pollutionlevelsskyrocketedasaresultofpopulation growthandtheIndustrialRevolution.Asaresult,regulationshavebeenenactedtocontrolemissions.Even wheretheseareeectiveincurbingcurrentpollutionsources,highlevelsofcontaminationmayexistfrom pastactivity.Andnewcontaminationcanoccurthroughindustrialaccidentsorotherinadvertentreleases oftoxicsubstances.Dangertohumanhealthfrombothhistoricandmoderncontaminationrequiresthat cleanupmeasuresbeimplemented.Thisisthepurposeofenvironmentalremediation. 25.1.11ContaminationSources Justunder300milliontonsofhazardouswastesareproducedeachyearintheUnitedStates.Althoughthe safedisposalofwastesismandated,accidentalreleasesdooccur,andsometimesregulationsareignored. Someofthemostwidespreadordangerouspollutantsthatrequireremediationcomefrommining,fuelspills andleaks,andradioactivematerials. Heavymetalscopper,lead,mercury,andzinccanleachintosoilandwaterfromminetunnels,tailings, andspoilpiles.Acidminedrainageiscausedbyreactionofminewastes,suchassuldes,withrainfallor groundwatertoproduceacids,likesulfuricacid.TheEnvironmentalProtectionAgencyestimatesthat40% ofthewatershedsinthewesternUnitedStatesarecontaminatedbyminerun-o. Organiccontaminationcanresultfromdischargeofsolventstogroundwatersystems,naturalgasorfuel spills,andabove-groundandundergroundstoragetankleakage. Radioactivecontaminationofsoils,water,andaircanresultfromminingactivity,processingofradioactiveores,andimproperdisposaloflaboratorywasteandspentfuelrodsusedatnuclearpowerplants.The best-knownexampleofradioactivecontaminationistheChernobyldisaster.In1986,workersataRussian nuclearpowerplantignoredsafetyproceduresduringareactortest,andthefuelrodssuperheatedthecooling watertocauseanexplosionthatkilled30peopleandreleasedahugecloudofradioactivesteam.Although morethan100,000peoplewereevacuatedfromaroundtheplant,adramaticincreaseincancerratesamong thepopulationhasoccurred.Asthesteamclouddispersedintotheatmosphere,increasesinradioactivity weremeasuredovermuchofthenorthernhemisphere. 25.1.12RemediationEorts Manycommunitiesarestrugglingtondthefundsandtechnologicalexpertiseneededtocleanuppolluted areas.Somesettings,suchasbrownelds,canbereclaimedfairlyeasily.Otherareas,becauseoftheirsize ortheextremetoxicityoftheircontaminants,requireveryexpensive,complex,andlong-termremediation. ManyofthesehavebeendesignatedasSuperfundsites. Brownelds areabandonedindustrialorcommercialfacilitiesorblightedurbanareasthatneedtobe cleansedofcontaminationbeforetheycanberedeveloped. Superfundsites areareaswiththemosttoxiccontaminationintheUnitedStates.Thecontamination maynotonlymakethesiteitselftoodangeroustoinhabit,butoftenleakstoxiclevelsofpollutantsintothe surroundingsoil,water,orair.AnexampleofaSuperfundsiteisLoveCanalinNiagaraFalls,NewYork. Thecanalwasachemicalwastedumpformanyyears,theninthe1950'swascoveredwithsoilandsold tothecity.Overtime,manyhomesandaschoolwerebuiltovertheformerdump.Inthe1970's,heavy rainsraisedthewatertableandcarriedcontaminantsbacktothesurface.Residentsnoticedfoulsmells, andgardensandtreesturnedblackanddied.Soonafter,ratesofbirthdefects,cancer,andotherillnesses begantorisesharply.In1977,theStateofNewYorkandthefederalgovernmentbeganremediationwork. Buildingswereremoved,andallresidentswereboughtoutandrelocated,contaminateddepositsandsoils

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118 CHAPTER25.ISSUESANDOPTIONS wereexcavated,andremainingsoilsandgroundwaterweretreatedandsealedotopreventfurtherspread ofthecontamination.Remediationactivitieshavenowbeencompletedatthissite. 25.1.13RemediationMethods Thetypeofpollutionandthemediumaectedair,water,orsoildetermineremediationmethods.Methods includeincineration,absorptionontocarbon,ionexchange,chemicalprecipitation,isolation,orbioremediation.Bioremediationistheuseofplants,bacteria,orfungustodigestthecontaminanttoanon-toxicor lesstoxicform.Allofthesemethodstendtobeexpensiveandtime-consuming. Remediationisaimedatneutralization,containment,and/orremovalofthecontaminant.Thegoalis topreventthespreadofthepollution,ortoreduceittolevelsthatwillnotappreciablyriskhumanhealth. Manytimes,itisphysicallyimpossibleornanciallyunfeasibletocompletelyclearallcontamination.Often, expertsandthepublicdisagreeonhowcleaniscleanenough.

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INDEX 119 IndexofKeywordsandTerms Keywords arelistedbythesectionwiththatkeywordpagenumbersareinparentheses.Keywords donotnecessarilyappearinthetextofthepage.Theyaremerelyassociatedwiththatsection. Ex. apples,1.1 Terms arereferencedbythepagetheyappearon. Ex. apples,1 "MarianaTrench",12 HNO3,9 A Ahorizon,51 abioticregions,21 abyssal,24 acidicsolution,53 Activesolarenergy,63 acuteeect,82 Agriculture,42 Agroforestry,54 AirResourcesBoard,111 AldoLeopold,106 AliceHamilton,109 alkalinesolution,53 Allethrin,74 alpinetundra,25 aminoacids,8 ammoniaNH3,9 anadromousspecies,57 animalspecies,24 AntarcticaTreaty,111 anthropocentric,105 AntiquitiesAct,110 AP,1,2,3,4,5, 6,7,8,9,10, 11,12,13,14,15, 16,17,18,19,20, 21,2299,23,24, 25 aquaculture,57 aquatic,24 Aquaticbiomes,24 aquifer,6 aquifers,42 Archean,12 arctictundra,25 Areastripmining,48 asthenosphere,11 atmosphere,15 Atmosphericclouds,19 ATP,9 Autotrophs,22 B Bhorizon,51 BenjaminChavis,101 BenjaminFranklin,109 benthic,24 benzene,72 biocentric,106 biodegradable,23 biodegradation,73 biodiversity,21,88,93 biologicalagents,81 biomass,23 Biomassenergy,65 biome,21 biosphere,21,21 Biospherereserves,70 bioticregion,21 bituminous,60 borealforests,25 Botanicals,74 BritishThermalUnit,4 Brownelds,117 buerzone,70 butane,61 C Chorizon,51 CaliforniaCleanAirActof1988,111 camphor,74 Carbamates,74 carboncycle,7 carbondioxide,7,71 carbonmonoxide,71 carbontetrachloride,72 carbonates,47 carcinogenic,78 Carnivores,23 Carryingcapacity,"K,",35 Center-pivotsprinklersystems,42 ChapmanReactions,16,86 chemicalagents,81

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120 INDEX chemicaldegradation,73 Chemicalenergy,1 Chlorinatedhydrocarbons,73 chlorouorocarbons,86 chlorouorocarbonsCFCs,17,72 chlorophyll,7 chroniceect,82 Cindercones,13 clathrates,86 clay,52 CleanWaterAct,110 Clearcutting,69 Climate,19 climaxcommunity,24 clusterdevelopmentmodel,68 co-evolution,26 Colddeserts,25 community,21,22 CompensationandLiabilityAct,110 Compositevolcanoes,12 composition,47 ComprehensiveEnvironmentalResponse,110 ConcentrationEquivalents,75 ConcentrationMeasurementsand EnvironmentalRegulations,75 concentriccitymodel,67 condensation,6 condensationnuclei,19 Conservation,55 consumers,23 Contactchemicals,74 continentalcrust,11 Contourfarming,54 Contourstripmining,48 Controlrods,61 convectioncells,17 Convergentevolution,26 coralbleaching,92 Coralreefs,24 core,11 corearea,70 CoriolisEect,17 cost-benetanalysis,97 Croplands,56 Crudeoil,60 crust,11 culturalfactors,40 cyanobacteria,8 cyclone,18 D Decomposers,23 demographictransition,31 demography,30 denitrication,9,9 desert,24 desertication,68 Deserts,25 destructionofozone,16 Detritivores,23 developed,100 Developedcountries,100 developing,100 developingcountries,100 Dioxin,76 Dioxins,81 Diphenamid,74 divergentplate,12 DNA,RNA,8 DoctrineofRiparianRights,43 Dripirrigation,42 E earlyplant,24 earthquake,13 ecologicalfootprint,37 ecologicalsuccession,23 ecology,21 Economics,95 ecosphere,21 ecosystem,21,22 Ecosystems,25 ElNio,18,92 ElNio/SouthernOscillationENSO,92 Electricalene,4 Electricalenergy,1 electrowinning,49 emigration,31 endocrinedisrupters,82 Energy,1 energysink,3 Environment,1,2,3,4, 5,6,7,8,9, 10,11,12,13,14, 15,16,17,18,19, 20,21,22,23, 24,25113 environmentalethic,105 EnvironmentalImpactStatements,110 EnvironmentalProtectionAgencyEPA,109 epicenter,13 Epochs,12 Eras,12 erg,3 Erosion,53 ethane,61

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INDEX 121 ethics,105 ethylmercaptan,61 eukaryote,22 eutrophication,9,76 Evaporation,6 Evolution,25 Examples,75 exosphere,17 exponentialgrowth,29 extinction,26 F faults,13 FederalAgricultureImprovementandReform Act,110 FederalCleanAirAct,110 FederalInsecticide,110 FederalSafeDrinkingWaterAct,110 FederalWaterPollutionControlAct,110 fertilecrescent,32 shfarming,57 Fishranching,57 Fisheries,56 ssionofuraniumatoms,61 Floodirrigation,42 Floods,18 focus,13 foodchain,23 FoodSecurityAct,110 foodweb,23 forest,24 freshwater,24 frontierethic,105 fuelrods,61 FungicideandRodenticideAct,110 fungicides,73 Furrowirrigation,42 G GarrettHardin,107 GDPGrossDomesticProduct,95 generalizedspecies,26 geneticdiversity,56 geologictimescale,12 Geothermalenergy,65 GiordPinchot,107 globalclimatechange,87 globalwarming,92 grassland,24 Grasslandsoil,52 Grasslands,25 greenGDP,99 greenbelts,68 greenhouseeect,85 greenhousegas,8 greenhousegases,85 GrossDomesticProductGDP,99 GrossNationalProduct,32 GrossNationalProductGNP,95 groundwater,6,41 guano,9 Gullyerosion,53 H habitat,22 hailstones,19 heapleaching,49 heatcapacity,41 Heatenergy,2 HeavyMetals,76,81 herbicides,73 Herbivores,23 Heterotrophs,22 highlydevelopedcountryHDC,100 horsepower,3 Hotdeserts,25 humanfertility,31 humanpopulationdynamics,29 humanresources,95 humus,51 hurricanes,18 Hydraulicmining,48 hydrocarbons,72 Hydroelectricpower,64 hydrologiccycle,6 hydrosphere,21 hydrothermal,48,48 I Igneousrocks,13 immigration,31 in-situmining,49 Incineration,78 incinerators,78 increaseinUVradiation,92 indicatorspecies,22 individual,22 IndustrialRevolution,32 industrialstage,31 industrializedagriculture,56 inltration,6 infraredradiation,5 Inorganicchemicalpollutants,72 insecticides,73 IntegratedWasteManagementAct,111 intensiveagriculture,57 intercropping,57 intertidal,24

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122 INDEX intrinsicvalue,107 introducedexotic,89 ionosphere,17 Irrigation,42 J Jcurve,29 jetstream,16 Jetstreams,17 Joule,3 K kerogen,61 keystonespecies,22 kilowatt-hours,4 kineticenergy,1 KyotoProtocol,112 K o ppenSystem,19 L landethic,106 landlls,78 latesuccessionalspecies,24 Lavadomes,13 leaching,51 lessdevelopedcountryLDC,100 Lethaldoses,82 lichens,23 LightPollution,76 lignite,59 limitingfactors,22 liqueedpetroleumgas,61 lithication,13 lithosphere,12,21 LPG,61 M macminerals,11 magma,11,12 magmatic,48,48 Malathion,74 ManandtheBiosphereProgram,70 mantle,11 marine,24 Marineregions,24 marketequilibriumprice,95 massburnincinerators,78 massextinction,26 Mechanicalenergy,1 mesosphere,17 metallic,47 Metamorphicrocks,13 methane,61 Microgramspermilliliterug/mL,75 micronutrients,52 mid-species,24 moderatelydevelopedcountryMDC,100 moltenrock,12 monoculture,56 morals,105 mosses,23 multiple-nuclei,67 Municipalsolidwaste,77 mutagenic,78 N NationalEnvironmentalPolicyActNEPA, 110 NationalParkServiceAct,110 NationalParkSystem,70 NationalParkSystemOrganicAct,107 NationalTrailSystem,70 NationalWildernessPreservationSystem,70 Naturalgas,61 Naturalresources,95 Naturalselection,26 Neotropical,89 nitrateNO3-,9 nitricacid,9 nitricoxide,72 nitrogencycle,9 nitrogendioxide,72 nitrogenxation,9 nitrousoxide,9,72 no-tillagriculture,54 NoisePollution,76 Non-municipalsolidwaste,77 Non-pointSourcePollution,74 non-renewable,59 nonmetallic,47 NuclearEnergy,2 nuclearssion,2 nuclearfusion,2 nuclearpowerplant,61 nucleicacids,8 O Ohorizon,51 oceaniccrust,11 Oceans,24 Oilrecovery,60 Oilshale,61 OilSpills,76 Old-growthforests,69 omnivores,23 Open-pitmining,48 optimumrange,22 ore,48 ores,48 Organicchemicalpollutants,73 Organophosphates,74

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INDEX 123 over-harvesting,88 Oxidesofcarbon,71 Oxidesofnitrogen,71 Oxidesofsulfur,71 Oxygen-depletingwastes,72 Ozone,72,86 ozonedepletion,92 Ozonedestruction,87 ozonepollution,87 P Partspermillionppm,75 Passivesolarenergy,63 pasture,68 pelagic,24 percolation,6 Periods,12 Pesticides,75,82 pH,52 Phanerozoic,12 phosphatePO43-,9 Phosphorus,9 phosphoruscycle,9 photochemicaldegradation,73 Photochemicaloxidants,72 photochemicalsmog,72 photosynthesis,7 Photovoltaic,64 pioneerspecies,23 placer,48,48 planetesimals,11 Plantnutrientpollutants,73 platetectonics,7,12 PointSourcePollution,74 Pondsandlakes,24 population,21,22 populationdynamics,29 Porter-CologneActof1970,111 post-industrial,31 potentialenergy,1 Power,3 pre-industrialstage,31 precipitation,6,19 PrescriptionDrugs,75 preservation,107 primarymacronutrients,52 primarypollutants,71 primarysuccession,23 Primefarmland,68 PrincipleofPriorAppropriation,43 PrincipleofSupplyandDemand,95 producers,23 productionofozone,16 prokaryote,22 prokaryotes,22 propane,61 Proposition65,111 proteins,8 Proterozoic,12 purecommandeconomy,95 puremarketeconomy,95 pyramidofenergyow,23 R RachelCarson,109 Radiantenergy,2,5 Radon,72 Rainsplash,53 rangeoftolerance,22 rangeland,68 Rangelands,56 reactorcore,61 refuse-derivedincinerator,79 Renewableenergy,63 replacementfertility,31 ResearchNaturalAreas,70 residual,48,48 ResourceConservationandRecoveryAct,110 Rhizobium,8 Richterscale,13 Rillerosion,53 risingsealevels,92 Riskassessment,83 Riskmanagement,83 rockcycle,14 runo,41 S SafeDrinkingWaterandToxicEnforcement Act,111 salinization,53 sand,52 sandyloam,52 sanitarylandll,78 scavengers,23 schistosomiasis,88 Science,1,2,3,4, 5,6,7,8,9, 10,11,12,13,14, 15,16,17,18,19, 20,21,22,23, 24,25113 Second-growthforests,69 secondaryconsumers,23 secondarymacronutrients,52 secondarysuccession,23 sectorcity,67

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124 INDEX Securelandlls,78 sedimentary,48,48 Sedimentaryrocks,13 Sedimentation,76 sediments,73 Seed-treecutting,69 seismograph,13 semiariddeserts,25 Sevin,74 shale,60 Sheeterosion,53 Shieldvolcanoes,12 silt,52 silts,73 siltyloam,52 smelting,49 Soildegradation,53 Soilformation,14 soilhorizons,51 Soilporosity,52 Soilsterilants,74 Soiltilth,52 Solarenergy,63 Solarradiation,17 Solidwaste,77 specializedspecies,26 species,22 standardofliving,36 staplecrops,56 stratopause,17 stratosphere,16 Streamsandrivers,24 Stripcropping,54 stripcutting,69 Strip-mining,60 sub-surfacemining,49,60 subductionzone,12 Subsistenceagriculture,57 sulfates,47 suldes,47 sulfurdioxide,71 sulfurtrioxide,71 Superfund,110 Superfundsites,117 surfaceruno,6 surfacetension,41 Suspendedparticulatematter,72 sustainableethic,106 Syntheticbotanicals,74 Systemicchemicals,74 T taiga,25 Tarsand,61 temperateforests,25 temperategrasslands,25 teratogenic,78 Terracing,54 Tertiaryconsumers,23 The1987MontrealProtocolonSubstances thatDepletetheOzoneLayer,111 TheConventiononInternationalTradein EndangeredSpeciesofWildFaunaandFlora CITES,112 TheInternationalDeclarationonCleaner Production,112 ThePriorInformedConsentProcedurefor CertainHazardousChemicalsandPesticides inInternationalTrade,111 TheRotterdamConvention,112 Thermalenergy,2 thermalpollution,73 thermohalinecirculation,87 thermosphere,17 thunderstorm,18 tillage,54 tolerancelimits,22 topsoil,51 tornado,18 ToxicSubstancesControlAct,110 TradablePollutionPermitsTPPs,96 traditionalagriculture,56 transformboundary,12 transitionarea,70 transitionalstage,31 Transpiration,6 tropicalforests,25 tropicalgrasslands,25 tropopause,16 troposphere,15,21 tsunami,13 tundra,24 typhoons,18 U UCCP,1,2,3,4,5, 6,7,8,9,10, 11,12,13,14,15, 16,17,18,19,20, 21,22,23,24, 25 UNFrameworkConventiononClimate Change,112 UNEPandtheInternationalOlympic CommitteeIOC,112 UnitedNations,109

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INDEX 125 UnitedNationsUN,111 UnitedNationsHumanDevelopmentIndex,95 upwelling,18 utilitarian,107 V VolatileorganiccompoundsVOCs,72 volcano,12 W water,5,41 WaterAcidication,76 Watererosion,53 WaterPollutionControlAct,110 watertable,6,42 watershed,41 Watt,3 weather,18 weathering,14 Wetlands,24 wildstrains,56 WildernessAct,110 WildernessActof1964,70 wildernessareas,55 windturbines,64 Windbreaks,54 winds,17 work,1 WorldBank,109,111 WorldTradeOrganization,109

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126 ATTRIBUTIONS Attributions Collection: APEnvironmentalScience Editedby:UniversityofCaliforniaCollegePrep URL:http://cnx.org/content/col10548/1.1/ License:http://creativecommons.org/licenses/by/2.0/ Module:"FLOWOFENERGY" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16468/1.2/ Pages:1-4 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"CYCLINGOFMATTER" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16470/1.2/ Pages:5-9 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"THESOLIDEARTH" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16682/1.1/ Pages:11-14 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"THEATMOSPHERE" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16687/1.1/ Pages:15-20 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"THEBIOSPHERE" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16693/1.1/ Pages:21-27 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"HISTORYANDGLOBALDISTRIBUTION" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16700/1.1/ Pages:29-33 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/

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ATTRIBUTIONS 127 Module:"CARRYINGCAPACITY" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16710/1.1/ Pages:35-37 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"POPULATIONGROWTH" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16720/1.1/ Pages:39-40 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"WATER" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16727/1.1/ Pages:41-45 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"MINERALS" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16728/1.1/ Pages:47-50 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"SOILS" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16466/1.2/ Pages:51-54 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"BIOLOGICAL" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16729/1.2/ Pages:55-58 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"NON-RENEWABLEENERGYSOURCES" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16730/1.1/ Pages:59-62 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"RENEWABLEENERGYSOURCES" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16731/1.1/ Pages:63-66 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/

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128 ATTRIBUTIONS Module:"LAND" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16732/1.1/ Pages:67-70 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"AIR,WATERANDSOIL" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16733/1.1/ Pages:71-76 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"SOLIDWASTE" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16734/1.1/ Pages:77-79 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"IMPACTONHUMANHEALTH" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16736/1.1/ Pages:81-83 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"FIRSTORDEREFFECTS" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16738/1.1/ Pages:85-89 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"HIGHERORDERINTERACTIONS" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16740/1.1/ Pages:91-93 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"ECONOMICFORCES" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16741/1.1/ Pages:95-97 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"CULTURALANDAESTHETICCONSIDERATIONS" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16742/1.1/ Pages:99-103 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/

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ATTRIBUTIONS 129 Module:"ENVIRONMENTALETHICS" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16743/1.1/ Pages:105-108 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"ENVIRONMENTALLAWS®ULATIONS" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16744/1.1/ Pages:109-112 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/ Module:"ISSUESANDOPTIONS" By:UniversityofCaliforniaCollegePrep,UniversityofCalifornia URL:http://cnx.org/content/m16773/1.1/ Pages:113-118 Copyright:UniversityofCaliforniaCollegePrep License:http://creativecommons.org/licenses/by/2.0/

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APEnvironmentalScience TextassociatedwithUniversityofCaliforniaCollegePrepUCCPAdvancedPlacementAPEnvironmental Scienceonlinecourse. AboutConnexions Since1999,Connexionshasbeenpioneeringaglobalsystemwhereanyonecancreatecoursematerialsand makethemfullyaccessibleandeasilyreusablefreeofcharge.WeareaWeb-basedauthoring,teachingand learningenvironmentopentoanyoneinterestedineducation,includingstudents,teachers,professorsand lifelonglearners.Weconnectideasandfacilitateeducationalcommunities. Connexions'smodular,interactivecoursesareinuseworldwidebyuniversities,communitycolleges,K-12 schools,distancelearners,andlifelonglearners.Connexionsmaterialsareinmanylanguages,including English,Spanish,Chinese,Japanese,Italian,Vietnamese,French,Portuguese,andThai.Connexionsispart ofanexcitingnewinformationdistributionsystemthatallowsfor PrintonDemandBooks .Connexions haspartneredwithinnovativeon-demandpublisherQOOPtoacceleratethedeliveryofprintedcourse materialsandtextbooksintoclassroomsworldwideatlowerpricesthantraditionalacademicpublishers.