水文地球化學(xué)過程Hydrochemicalprocess培訓(xùn)課件

OutlineoftopicsWaterreactswithSoilsandrocksGroundwaterRegime&WaterQualityFlow&ReactionTimeOverviewofgroundwaterreactionsMostimportantindicatorparametersingroundwater(pH,EC,alkalinity,OrganicIndicators)Mostimportanttypesofreaction(acid/base,reduction/oxidation,solution/precipitation)Needtoconsiderreactionstoclassify,predictmigration,identifypersistenceandremediationOutlineoftopicsWaterreacts1WaterSoilsandRocksHydrogeochemistryHydrochemistryGeochemistryHydrogeologicalProcessWaterGroundwaterreactswithSoilsandrocksReactionWaterSoilsandRocksHydrogeoch2GroundwaterRegime&WaterQualityGroundwaterRegime&WaterQua3Flow&ReactionTimeFlow&ReactionTime4OverviewofgroundwaterreactionsSolidphaseinteractionsSolution-precipitationandvolatilizationAdsorptionincludingionexchange

EnrichmentNeutralisation-acidbasereactionOxidationReductionreactions(redox)

AdsorptionincludingIonexchange

ComplexationHydrolysisreactionsIsotopicreactionsDecarbonationDesulfationDiogenicagencyOverviewofgroundwaterreact5WhyshouldwestudyHydrochemicalReactions?Whyshouldwestudy6GroundwaterQualityDependentonrocktypesandlengthofreactiontimesUsuallylongenoughtoallowsignificantreactionHigherdissolvedsubstancesthansurfacewatersChemistryusuallyreflectscompositionofrocksinaquiferDolomites-Ca,Mg,HCO3Granites-Na,K,F,SandAquifer-lowTDS-relativelyinertrocks-rainfalldeterminingfactorGroundwaterQualityDependento7ComparisonofreactionratesComparisonofreactionrates8Oxidationofsulphideminerals,inthepresenceofoxygen,waterandbacteriaGenerallyinSouthAfricathemineralpyrite(FeS2)istheprimarycause.Pyriteoccursasanassociatedorganguemineralwithgold,thebasemetalsandalsocoalPyrite(Fool’sGold)3218BA1731:745mMalmesburyDissolveofPyriteOxidationofsulphideminerals9Detailedreactions(1)FeS2+7/2O2+H2O=>Fe2++2SO42-+2H+

(2)Fe2++1/4O2+H+=>Fe3++1/2H2O(ratelimitingstep)(3)Fe3++3H2O=>Fe(OH)3(yellowboy)+3H+

(4)FeS2+14Fe3++8H2O=>15Fe2++2SO42-+16H+

BOTTOMLINE=Sulphides+water+oxygen(+bacteria)giveacidity(4H+)+sulphatesIfthisisnotneutralizeditcanresultinheavymetalmobilisationwhichcanhavedisastrousenvironmentalconsequencesDetailedreactions(1)FeS2+710ModelofpyriteoxidationModelofpyriteoxidation11aunreactedpyritebpyriteoxidation-oxygenconsumedcoxygendiffusestooxidationlayerdliquidphase-oxygenconcentrationinequilibriumwiththegasphaseeGasphasebetweenthewasterocks-oxygensupplybydiffussion andadvectionSulphideWaterfilmProductlayerMODELSOFPYRITEOXIDATION-microscaleaunreactedpyriteSulphideWa12InfluenceofbacteriaInfluenceofbacteria13四、加氣站人員培訓(xùn)考核制度電話測試也是一種檢測方式。對于電話服務(wù)人員，在應(yīng)征的時候就需要跟他講清楚工作的條款。公司要通過監(jiān)聽來掌控電話服務(wù)的品質(zhì)，可以錄音，或者隨時抽查監(jiān)聽，這樣的高級制度有助于維持服務(wù)品質(zhì)的一致化。此外，還可以進(jìn)行顧客滿意度調(diào)查和市場意見的反應(yīng)調(diào)查。四、加氣站人員培訓(xùn)考核制度第五條推薦方法和程序服務(wù)是企業(yè)和員工的天職。服務(wù)人員要樹立這樣的意識：服務(wù)并不是做給別人看的，而是自己的需要。因為高尚的生命情操要求自己時時刻刻把服務(wù)做好，提供良好的服務(wù)實際上就是肯定自己生命的價值。因此，服務(wù)人員應(yīng)該注意迎賓、引導(dǎo)和送客等各個環(huán)節(jié)的禮儀，給顧客最為溫馨的享受。2.9對容器的檢驗（查）人員、操作人員進(jìn)行安全技術(shù)教育和技術(shù)考核工作。第四條參加競爭上崗的人員，應(yīng)具備以下基本條件和資格:員工在整個服務(wù)過程中必須保持精神專注，時刻準(zhǔn)備著為顧客服務(wù)。舉例來說，有些營業(yè)場所會有老人光顧。在老人進(jìn)來的時候，因人而異的服務(wù)應(yīng)該怎樣體現(xiàn)呢？精神專注的員工就會注意觀察，有的老人行動不便，所以不能走太遠(yuǎn)。這時候可以在門口附近放置一把椅子供老人使用。這些都是因人而異的服務(wù)的技巧。每個顧客對服務(wù)的要求和標(biāo)準(zhǔn)是不一樣的，因此，在服務(wù)過程中要注意因人而異的服務(wù)技巧。例如，有的人口渴的時候喜歡喝白開水，有的人則喜歡或冷或熱的咖啡，這些都屬于個人愛好。又如，在餐廳吃飯的時候，有的顧客可能不吃辛辣、冰涼、油膩的食物，而選擇清淡的飲食。餐廳的服務(wù)人員了解到這些后，在點菜或者主動安排的時候就應(yīng)推薦相應(yīng)的食物。這些就是因人而異的服務(wù)。3．三分笑31.3符合性檢查是依據(jù)招標(biāo)文件的規(guī)定，從投標(biāo)文件的有效性、完整性和對招標(biāo)文件的響應(yīng)程度進(jìn)行審查，以確定是否對招標(biāo)文件的實質(zhì)性要求作出響應(yīng)。只要5S能徹底實施，任何活動的導(dǎo)入都能輕而易舉。因為5S強調(diào)的是全體員工必須遵守制定的標(biāo)準(zhǔn)，確實做好自主管理。如果連5S活動所制訂的規(guī)則都不能遵守的話，制定再多的規(guī)定都是多余的。(5) 按本合同規(guī)定，及時向承包方支付各種費用。InfluenceofpHonThiobacillusactivity四、加氣站人員培訓(xùn)考核制度InfluenceofpHo14OxygendependenceofbacteriaOxygendependenceofbacteria15ImportanceofbacterialcatalysisonoxidationrateImportanceofbacterialcataly16BufferlevelofsomecommonmineralsBufferlevelofsomecommonmi17BufferreactionsCaCO3+2H+

Ca2++H2O+CO2(g)H2O+CO2(g)H2CO3

H2CO3

H++HCO3-

H++CO32FeS2+2CaCO3+3,75O2+1,5H2OFe(OH)3+2SO42-+2Ca2++2CO2(opensystem)1moleofFeS2(64gsulphur)isneutralisedby2molesofCaCO3(200g)or1gsulphur:3.125gCaCO3

FeS2+2CaCO3+3,75O2+3,5H2OFe(OH)3+2SO42-+2Ca2++2H2CO3Closedsystem1moleofFeS2isneutralisedby4molesofCaCO3,whichresultsinamassratioof1gpyrite:6.25gcalcite

碳酸平衡BufferreactionsCaCO3+2H+18DistributionDiagramfortheCarbonateSystem

DistributionDiagramfortheC19OtherreactionsDolomiteCaMg(CO3)2+4H+=Ca2++Mg2++2H2O+2CO2AlbitedissolutionNaAlSi3O8(s)+H++9/2H2O=>Na++2H4SiO4+1/2Al2Si2O5(OH)4(s)AnorthitedissolutionCaAl2Si2O8(s)++H2O=>Ca2++Al2Si2O5(OH)4(s)K-feldspardissolutionKAlSi3O8(s)+H++9/2H2O=>K++2H4SiO04+1/2Al2Si2O5(OH)4(s)Ironoxy-hydroxidedissolutionFe(OH)3(s)+3H+=>Fe3++

OtherreactionsDolomite20ImportanceofreactionkineticsAlthoughallthesereactionscanconsumeH+andthusbufferthesystem,thereactionratesofmostoftheminerals(apartfromthecarbonates)areslowerthanthesulphideoxidationratesThusunlesstheacidproductionrateisverylow(lowSmaterial)onlythecarbonatespreventacidity(generally)Importanceofreactionkinetic21OPENPITAtfieldscaletheneutralisingmineralscanbufferthesystemfromacidityPRECIPITATIONPRECIPITATIONPRECIPITATIONPRECIPITATIONWASTEPILERIVERVALLEYUNDERGROUNDMINEWORKINGSTAILINGSBASINFILLMATERIALSWASTEPILELinesofdefenceagainstacidityincludeNaturalwatersalkalinity-pHashighas8+Carbonateminerals(Calcite/Dolomite)–pHabove6Silicates-reacttooslowlytoactasbuffer-pHfallstolevelswhereheavymetalsaremobilisedetcOPENPITAtfieldscaletheneu22GeneralresultsNotenoughneutralisingmineralsLowpHwaterHighsulphateHeavymetalsStaining(yellowboy)Neutralizedbyco-existingminerals(commonoccurrenceinSA)NeutralpHHighsulphateHighTDSStainingGeneralresultsNotenoughneut23OutflowataSAcoalmineWhatkindofhydrochemicalprocessoccurredinthispicture?OutflowataSAcoalmineWhat24.The10-90%concentrationrangeof23aciddrainagesfromcoalminesthroughouttheUnitedStatestakenfromtheEPAeffluentlimitationsdocument(U.S.EnvironmentalProtectionAgency,1982)..Medianof110drainagesfromcoalrefusedisposalsitesinSouthernIllinoisascompiledbyProudanetal.(1982)..RegionalestimatesfromCaruccio(1979)..AtypicalmetalminedrainagefromtheFrontRangeMineralBeltofColoradocollectedbyWildemanandLaudon(1989)..CompiledfromU.S.GovernmentPrintingOffice(1988).Forminedrainages,effluentlimitsinmilligrams/Literare:Fe,7.0dailymaximum,and3.5monthlyaverage;Mn,4.0dailymaximum,and2.0monthlyaverage;pHbetween6.0and9.0atalltimes.Fortheothersubstancesinthetable,therearenowrittenrestrictions(U.S.EnvironmentalProtectionAgency,1982)..AverageofU.S.coalcompiledbyValkovic(1983).ACIDMINEDRAINAGEinUS.The10-90%concentrationrang2520.投標(biāo)保證金（3）綜合評標(biāo)得分最高者。①劃分營銷區(qū)域，應(yīng)選擇一個較大的富裕的鄉(xiāng)鎮(zhèn)做為中心；26.1根據(jù)現(xiàn)行稅法規(guī)定向買方征收的與本合同有關(guān)的一切稅費均由買方負(fù)責(zé)。1.11站內(nèi)禁止使用手機、照相機、攝像機。1．人員服務(wù)禮儀1．主管級的教育訓(xùn)練35.4如果確定該投標(biāo)人無能力圓滿履行合同，招標(biāo)人將對下一個中標(biāo)候選人作類似的審查。服務(wù)人員一般都會認(rèn)真核實參觀的票據(jù)是否正確。在撕開參觀票以后，雙手奉還，并說聲“謝謝”。這個動作讓顧客覺得還沒有進(jìn)去看這個汽車博物館，就感覺到很受尊重，對服務(wù)人員訓(xùn)練得非常品質(zhì)化。中國移動通信公司非常注重挖掘企業(yè)資源，努力樹立起良好的社會形象。它以“愛心溝通，貼心服務(wù)”為口號，推出了“8858捐款短信”活動，形成了與社會的溝通。還利用通信網(wǎng)絡(luò)來對抗“非典”。因此，對于企業(yè)來說，贏利并不是惟一的目標(biāo)，還應(yīng)該追求一定的理念，承擔(dān)起社會責(zé)任。這些都是對社會的回饋，有助于提高企業(yè)形象，提升顧客滿意度。2.公布張貼在工作現(xiàn)場﹐與其放在桌子抽屜內(nèi)是不同的。不管你喜不喜歡﹐你每天都要看到它﹐因此會產(chǎn)生必須改善的心理。1.3定時檢查設(shè)備的運轉(zhuǎn)情況，注意有無異常聲響和跑、冒、滴、漏現(xiàn)象，發(fā)現(xiàn)問題及時檢查和整改，做到設(shè)備不帶故障運行，人員不帶思想情緒上崗。SummaryAMDiscausedbybacteriallymediatedoxidationofsulphidemineralsThe“essentialingredients”aresulphides,oxygen,waterandbacteriaSeveralmechanismsbufferthesystemThecarbonatesarethemostimportantoftheseduetoreactionrateconsiderations.20.投標(biāo)保證金SummaryAMDiscaused26Groundwaterquality&It’sinfluencefactorsVegetationalsoaffectscompositionbyselectiveuptakeofions.IonssuchasCl,Na,MgcanaccumulateinsoilsandbeflushedintoGWbyrechargeInareasofhigherevapotranspirationgreateraccumulationofsaltsHigherrechargeareas-moredilutionofsaltsandclosercorrelationtorainfallOtherreactions:ionexchange,dissolution,formationwater,contaminationPrecipitationofover-saturatedmineralsseldomasignificantfactor-reductioninconcentrationsusuallyduetomixing/rechargeetcRainwaterchemistryimportantinGWstudiesandinfluenceneedstobeconsideredGroundwaterquality&It’sinf27水文地球化學(xué)過程Hydrochemicalprocess培訓(xùn)課件28AcidsandBasesBronsted-LowrytheoryAcidisaprotondonor.BaseisaprotonacceptorAcidsandBasesBronsted-Lowry29水文地球化學(xué)過程Hydrochemicalprocess培訓(xùn)課件30StrongAcidsandBasesStrongacidswillcompletelydeionizeordissociatewhileweakacidswillonlypartlyionizeordissociateAtequilibrium,theweakeracidandtheweakerbasepredominateinconcentrationTheconjugatebaseofastrongacidisweakTheconjugateacidofastrongbaseisweakStrongAcidsandBasesStronga31ConjugatePairsConjugatePairs32pHConceptspHConcepts33pH&pOHpH&pOH34AnalysisChecksTotaldissolvedsolids-shouldbewithin20%ofsummationofdeterminedionsIonBalance(inmilliequivalents)Shouldbewithin5%(perhaps10%)DoesnotholdforveryhighandverylowpH-chelation,protonation,hydrolysisAtthesevaluesremembertobringH+orOH-intoaccountInverydilutewatersroundingoffcaninfluencebalanceAnalysisChecksTotaldissolved35EquilibriumVersusKineticDescriptionofReactionsInaclosedsystem,theequilibriumpointisapositionofmaximumthermodynamicstabilityAtequilibrium,thereisnochemicalenergytoaltertherelativedistributionofmassbetweenreactantsandproductsEquilibriumVersusKineticDes36Theoreticalapproachesusedtomodelchemicalcompositionatequilibrium.Givenoinformationabouthowlongitwouldtaketoreachequilibriumnorthereactionpathwaysthatareinvolved.KineticapproachisrequiredtoprovidethisinformationTheoreticalapproachesusedto37Groundwater=partialequilibriumsystem..Equilibriumreactionisfast/kineticreactionisslowinrelationtogroundwatermovement.ThesearerelativeconceptsEquilibriumrarelyreachedinrapidlyflowingandmixingsurfacewaters.Equilibriumtechniquesonlyprovideboundaryconditionsorbestorworstcasescenarios,showingthedirectionthatchangeswillmovetoward.Irreversiblereactionsproceedintheforwarddirectionuntilallthereactantsareusedup,suchreactionsarebestdescribedusingakineticapproach

Groundwater=partialequilibr38除了行走的姿態(tài)和速度，服務(wù)人員在走動的時候要時刻注意服務(wù)的禮儀。比如說跟顧客在一起走，要注意引導(dǎo)在前，陪同貴賓的時候上、下樓梯要注意引導(dǎo)貴賓，進(jìn)、出電梯要為顧客開門關(guān)門。此外還要注意服務(wù)人員的鞋子大小要合適，否則走起路來會發(fā)出令人不悅的響聲。當(dāng)速拓系列軟件還在市場上熱銷時，速拓公司于2004年年初整合公司的軟件開發(fā)精英，成立了“經(jīng)典版”開發(fā)小組，利用近兩年的時間開發(fā)出速拓家族的新生代產(chǎn)品—“經(jīng)典版”系列軟件。該系統(tǒng)完全滿足了企業(yè)對物流、信息流、資金流等集成管理的迫切需要，可以對企業(yè)各種經(jīng)營活動和管理行為實施全方位的過程控制與細(xì)化管理，從而以更簡便、實用的方式幫助中小企業(yè)迅速解決管理難題，全面提升整體競爭力。第一條服務(wù)青年成長成才，是黨政所需、青年所望，是企業(yè)共青團工作的出發(fā)點和落腳點。共青團組織向企業(yè)黨政和各重要部門、崗位推薦優(yōu)秀青年人才，既符合黨政中心工作對青年人才的迫切要求，又符合青工崗位成才的強烈愿望。根據(jù)“黨建帶團建”工作的有關(guān)要求，為認(rèn)真做好推薦優(yōu)秀青年人才上崗的工作，特制定本辦法。（1）技術(shù)規(guī)格中特別要求的備品備件、易損件和專用工具的費用。6.3做好加氣過程控制，如遇緊急情況應(yīng)立即解決，并及時向技術(shù)負(fù)責(zé)人反映。（4）提供虛假材料的。培訓(xùn)結(jié)果，并對培訓(xùn)的不足之處進(jìn)行整改。交公司備案。5.2.4生產(chǎn)、質(zhì)量、統(tǒng)計主管部門按選定認(rèn)可的統(tǒng)計方法進(jìn)行控制和統(tǒng)計分析，并評審其有效性與適用性;（5）其他附加服務(wù)。6.1氣體充裝前應(yīng)確認(rèn)氣瓶無凹陷、裂紋等缺陷。5.1.1統(tǒng)計方法選定的目的17.3如果本標(biāo)書第二章“前附表”中不允許投標(biāo)人提交備選方案的，投標(biāo)人提交的備選方案在評標(biāo)時不予考慮。TypesofreactionsandtimesSolute-soluteandsolute-waterreactionsarefast&homogeneousreactions.Acidbaseandcomplexreactionsarehomogeneousandthereforefast.Dissolution-precipitation:heterogeneousandwidelyrangingtimes.Surfacereactions:relativelyfastRedoxveryslowbutcatalysedbymicroorganismOrganicreactionsaregenerallyveryslow.Biodegradationoforganiccompoundsisfaster.除了行走的姿態(tài)和速度，服務(wù)人員在走動的時候要時刻注意服務(wù)的禮39RelativetimestoreachequilibriumRelativetimestoreachequili40Dissolution-PrecipitationReactionsEquilibriumModelsofReactionApplicabletoCarbonatesFeredoxreactionsIonexchangeHalitesCertainsulphatesetcDissolution-PrecipitationRe41GeneralFormulationMostarereversiblereactionsExpressedusingthegeneralformA+BC+DleChateleirsprincipleappliesAnychangewillforcethereactioninthedirectionthatminimizesthechangeGeneralFormulationMostarere42MassactionlawsThelawofmassactionstatesthattherateofachemicalreactionisproportionaltotheconcentrationofthereactingsubstances.If A+2BC Rate[A][B]2or Rate=k[A][B]2Forreversiblereactions: aA+bBcC+dDForwardrate=k1[A]a[B]bBackwardrate=k2[C]c[D]dMassactionlawsThelawofmas43Atequilibriumtheforwardrate=backwardrateThus k1[A]a[B]b=

k2[C]c[D]dandthusAtequilibriumtheforwardrat44TheKvalueConcentrationsofthereactantsatequilibriumexpressedintermsoftheequilibriumconstantK.ThevalueofKdependsontheunitsused(usuallymolarity)andontemperature.Formostsolidspeciesk2=1.Thusforasolidthatdissolvesinwatertheequilibriumconstantisequaltotheconcentrationoftheproducts:[C]c[D]d.TheKvalueConcentrationsoft45SolubilityProductpartlysolublesolids-assumeequilibriumThusKspisdefined(Solubilityproduct)KspisaconstantatequilibriumValuesaregivenintablesinliteratureSolubilityProductpartlysolub46TheSolubilityofcalciteanddolomiteareverysimilarinspiteoftheirKspvaluesbeingverydifferent10-8calciteand10-17dolomiteThisisduetothewaytheirmassactionlawsareexpressedKsp<10-4,compoundconsideredpartiallysolubleinnormalwater.SolubilitydependsonpH,temperature,ionicstrength,ductoftheconcentrationcalledionproductUsuallyuseIAP(activityratherthanconcentration)TheSolubilityofcalciteand47SolubilityIndexIftheionproductis=Ksp,thesolutionissaturated.Iftheionproductis<Ksp,ionsareinsolution.Iftheionproductis>Ksp,precipitationoccurs.SolubiltyIndexSolubilityIndexIftheionpro48SolubilityproductConstantsforSomeCommonMineralsHalite 101.54

Gypsum 10-4.58

Calcite 10-8.48

Dolomite 10-16.54

Fluorite 10-10.57

Quartz 10-3.98

Amorphoussilica 10-2.71

SolubilityproductConstantsf49

FeS2+2CaCO3+3,75O2+1,5H2OFe(OH)3+2SO42-+2Ca2++2CO2FeS2+2CaCO3+3,75O2+1,50GypsumvsSO4incoalmines

Over8000samplesConsideredSIofwatersPlotSIofgypsumvsSO4GypsumprecipitationformsanupperboundaryforSO4GypsumvsSO4incoalminesOve51ImportantweakacidbasereactionsinnaturalwatersystemsImportantweakacidbasereact52CarbonatesystemCarbonatemineralsoftenpresent(calcite,dolomite)CO2occursfromatmosphere-enrichedinthesoilDissolvestoformcarbonicacidCarbonatesystemCarbonatemine53CarbonatesystemcontinuedCarbonicacidisaweakacidthatdissociatestobicarbonateH2CO3

H++HCO3-

BicarbonatealsodissociatestofromcarbonateinsolutionHCO3-

H++CO32-

NeutralisationreactioncanbewrittenasfollowsCarbonatesystemcontinuedCarb54Carbonatesystem3equivalencepointswhichcanbedeterminebytitration(alkalinitytitration)ThreedistinctspecieswhicharedominantatdifferentpHvaluesCarbonatesystem3equivalence55pHdependenceofspeciesInacidconditionspH<6thepredominantspeciesisundissociatedcarbonicacidInthenormalgroundwaterpHrange6to8thepredominantcarbonatespeciesisbicarbonateInthealkalinerangepH>8carbonateionsaredominant.pHdependenceofspeciesInaci56ThereactionsgiveninthistableshowthatCO2dissolvedinwaterpartitionsbetweenH2CO3,HCO3-

andCO32IfthepHofthesolutionisfixedthenthemasslawequationsallowustocalculatetheconcentrationsoftheindividualspeciesThereactionsgiveninthista57NaturalwatershavepHintherange5to8.MinewatershavepH<3.Highlyalkalinewatersmaybeassociatedwithwastedisposalsites.Infieldmustdistinguishbetweenacid,neutralandalkalinewaters,todeterminewhatelementsshouldbeanalysedforNaturalwatershavepHinthe58SolubilityofcertainmetalswithpHSolubilityofcertainmetalsw59ExamplesMost

waterinsolublemetalhydroxidesthatarebasicoramphoteric

dissolveinstrongacidsFe(OH)3(s)+3H3O+

Fe3++6H2O(l)Al(OH)3(s)+3H3O+

Al3+

+6H2O(l).AllinsolubleMetalcarbonates

dissolveinacidsolutions:MCO3(s)+2H3O+

M2++CO2(g)

+3H2O(l).Metalsulphides(e.g.CuFeS2or(Fe,Ni)9S8)withrelativelylargesolubilityproductsaresolubleinacid.ExamplesMostwaterinsolublem60Fe3+

+3H2OFe(OH)3+3H+HydrolysisofmetalionstoformhydroxidesreleasesHpHCaCO3

Ca2++CO32-CO32-+H+

HCO3-HCO3-+H+

H2CO3Fe3++3H2OFe(OH)3+3H+61Manymetalhydroxidesareamphoteric

optimumpHfortheirremovalfromsolutioncanbefoundbyexperimentationMostmetalscanbeprecipitatedashydroxidesbyraisingthepHtobetween8and11Metalcarbonatescanbeprecipitatedbyaddingcalcite(expensiveoption)ordolomite

Manymetalhydroxidesareamph62CommonmetalsvspHCommonmetalsvspH63AmphotericsolubilityAmphotericsolubility64Oxidation-ReductionReactionsredoxreactionsoftenmediatedbyorganismsWithoutthiscatalysisthesereactionswouldbeverysloworganismsuseredoxreactionsasasourceofenergy,theyarethereforeusuallyautotrophicbacteriaOxidation-ReductionReactionsr65canbetreatedaselectrontransferreactionsfreeorsolvatedelectrons(e-)donotexistinaqueoussolutions.Oxidationisdefinedasane-

loss(increaseinoxidationstate).Reductionisdefinedasane-gain(decreaseinoxidationstate).(REG)Thesetwoalwayshappensimultaneouslybecausefreeelectrons(e-)donotexistinaqueoussolutionscanbetreatedaselectrontra66Redoxreactionsarewrittenastwohalfreactionsasifthee-existTablesgiveninliteratureForexample: Fe3++e-

Fe2+and O2+4H++4e-

2H2ORedoxreactionsarewrittenas67EhisusuallyusedinplaceofE,becauseitismeasuredwithreferencetothehydrogenstandardelectrode,andisreferredtoastheredoxpotential

itisespeciallyusefulingeochemistry.uelectronactivity(pEorsometimespeisusedtoexpressitasnumbersEhisusuallyusedinplaceof68VariationofOxidisingConditionsWithDepthBelowSurfaceVariationofOxidisingConditi69NaturalgroundwatersituationGroundwatertendstoEh0(reducingconditions).Groundwaterisisolatedfromtheatmosphere,anyoxygenthatisconsumedbyhydrochemicalandbiochemicalreactionscannotbereplacedTheseoxygenconsumingreactionsusuallytakeplaceinthesoilwherethereisabundantorganicmatterfromdecayingplantdebrissothatO2isusedandCO2buildsupinthesoilNaturalgroundwatersituationG70OrganicOxidationinsoilAsimplecarbohydrate(CH2O)canbeusedtoillustrateatypicalreaction:CH2O+H2O+O2+4H++4e-=CO2(g)+4H++4e-+2H2O CH2O+O2=CO2+H2O CO2+H2O=H2CO3Mustbecombinedwithoxidation1/2reactionexamplecombinationwith: O2(g)+4H++4e-

=2H2Oyields: O2(g)+CH2O=CO2(g)+H2OOrganicOxidationinsoilAsim71CommonsubsurfaceredoxreactionsProcess Equation

Sulphideoxidation 2O2+HS-=SO42-+H+

Ironoxidation O2+4Fe2++4H+=4Fe3++2H2O Nitrification 2O2+NH4+=NO3-+2H++H2O Manganeseoxidation O2+2Mn2++2H2O=2MnO2(s)+4H+

Ironsulphideoxidation 15/4O2+FeS2(s)+7/2H2O=Fe(OH)3(s)+2SO42-+H+

ThesereactionsconsumedissolvedoxygenCommonsubsurfaceredoxreacti72NaturalRedoxZoningProcess Typicalreaction AerobicRespiration CH2O + O2(g)

= CO2

+ H2O

Denitrification CH2O + 4/5NO3

=

2/5N2(g) + HCO3- + 1/5H+ + 2/5H2O Manganese(IV)Reduction CH2O + 2MnO2(s)

+ 3H+

= 2Mn2+ + HCO3- + 2H2O Iron(III)Reduction CH2O + 4Fe(OH)3(s) + 7H+

= 4Fe2+ + HCO3- + 10H2O SulphateReduction CH2O + 1/2SO42-

=

1/2HS- + HCO3- + 1/2H+

MethaneFermentation CH2O + 1/2H2O

= 1/2CH4

+ 1/2HCO3- + 1/2H+

NitrogenFixation CH2O + H2O +

2/3N2(g) + 4/3H+

= 4/3NH4+

+ CO2

NaturalRedoxZoningProcess Ty73水文地球化學(xué)過程Hydrochemicalprocess培訓(xùn)課件74RedoxzoningUsuallyinnaturalenvironmentsredoxprocessesproceedfromthehighestenergyyielddownwards.ThusoxygenrichwaterthatentersanaquiferrichinorganicmatterwillfirstbefreedfromitsDO,thenfromitsnitratefollowedbysulphateafterwhichmethanemaybeproduced.ThuszonesofincreasingreductionareusuallyencounteredasonemovesdownwardthroughanaquiferRedoxzoningUsuallyinnatural75RedoxzoningThezonesareoftenreferredtoasOXIC(atthewatertable)antheregionbelowitcontainingDOinthisregionoxidemineralsarestable..ANOXICthedeeppartsoftheaquifercontainingnoDO,inthisregionsulphidemineralsarestable.Theanoxiczoneisfurtherdividedinto,post-oxic,sulphidicandmethanic,dependingonthedominantredoxprocesses.RedoxzoningThezonesareofte76水文地球化學(xué)過程Hydrochemicalprocess培訓(xùn)課件77UnnaturalzoningThereverseorderhappenswhenorganic-richlandfillleachateentersanoxicaquiferDecompositionoforganicrichmaterial,domesticwaste,sewageetcproducesanorganicrichwastewhichonenteringanoxicaquifer.DOisremovedfirstgivingrisetolargeamountsofCO2whichcanraisethealkalinity.MnandFeoxidesarereducedgivingrisetoferrousiron,thesequencecontinuesthroughsulphatereduction,ammonificationandmethaneproduction.UnnaturalzoningThereverseor78OxidationandReductioninContextOxidationandReductioninCon79水文地球化學(xué)過程Hydrochemicalprocess培訓(xùn)課件80水文地球化學(xué)過程Hydrochemicalprocess培訓(xùn)課件81FromShengetal.,1985MigrationDegreeofElementsFromShengetal.,1985Migrati82InfluenceofbacteriaInfluenceofbacteria83GeneralresultsNotenoughneutralisingmineralsLowpHwaterHighsulphateHeavymetalsStaining(yellowboy)Neutralizedbyco-existingminerals(commonoccurrenceinSA)NeutralpHHighsulphateHighTDSStainingGeneralresultsNotenoughneut84StrongAcidsandBasesStrongacidswillcompletelydeionizeordissociatewhileweakacidswillonlypartlyionizeordissociateAtequilibrium,theweakeracidandtheweakerbasepredominateinconcentrationTheconjugatebaseofastrongacidisweakTheconjugateacidofastrongbaseisweakStrongAcidsandBasesStronga85SolubilityproductConstantsforSomeCommonMineralsHalite 101.54

Gypsum 10-4.58

Calcite 10-8.48

Dolomite 10-16.54

Fluorite 10-10.57

Quartz 10-3.98

Amorphoussilica 10-2.71

SolubilityproductConstantsf86

FeS2+2CaCO3+3,75O2+1,5H2OFe(OH)3+2SO42-+2Ca2++2CO2FeS2+2CaCO3+3,75O2+1,87Fe3+

+3H2OFe(OH)3+3H+HydrolysisofmetalionstoformhydroxidesreleasesHpHCaCO3

Ca2++CO32-CO32-+H+

HCO3-HCO3-+H+

H2CO3Fe3++3H2OFe(OH)3+3H+88水文地球化學(xué)過程Hydrochemicalprocess培訓(xùn)課件89水文地球化學(xué)過程Hydrochemicalprocess培訓(xùn)課件90OutlineoftopicsWaterreactswithSoilsandrocksGroundwaterRegime&WaterQualityFlow&ReactionTimeOverviewofgroundwaterreactionsMostimportantindicatorparametersingroundwater(pH,EC,alkalinity,OrganicIndicators)Mostimportanttypesofreaction(acid/base,reduction/oxidation,solution/precipitation)Needtoconsiderreactionstoclassify,predictmigration,identifypersistenceandremediationOutlineoftopicsWaterreacts91WaterSoilsandRocksHydrogeochemistryHydrochemistryGeochemistryHydrogeologicalProcessWaterGroundwaterreactswithSoilsandrocksReactionWaterSoilsandRocksHydrogeoch92GroundwaterRegime&WaterQualityGroundwaterRegime&WaterQua93Flow&ReactionTimeFlow&ReactionTime94OverviewofgroundwaterreactionsSolidphaseinteractionsSolution-precipitationandvolatilizationAdsorptionincludingionexchange

EnrichmentNeutralisation-acidbasereactionOxidationReductionreactions(redox)

AdsorptionincludingIonexchange

ComplexationHydrolysisreactionsIsotopicreactionsDecarbonationDesulfationDiogenicagencyOverviewofgroundwaterreact95WhyshouldwestudyHydrochemicalReactions?Whyshouldwestudy96GroundwaterQualityDependentonrocktypesandlengthofreactiontimesUsuallylongenoughtoallowsignificantreactionHigherdissolvedsubstancesthansurfacewatersChemistryusuallyreflectscompositionofrocksinaquiferDolomites-Ca,Mg,HCO3Granites-Na,K,F,SandAquifer-lowTDS-relativelyinertrocks-rainfalldeterminingfactorGroundwaterQualityDependento97ComparisonofreactionratesComparisonofreactionrates98Oxidationofsulphideminerals,inthepresenceofoxygen,waterandbacteriaGenerallyinSouthAfricathemineralpyrite(FeS2)istheprimarycause.Pyriteoccursasanassociatedorganguemineralwithgold,thebasemetalsandalsocoalPyrite(Fool’sGold)3218BA1731:745mMalmesburyDissolveofPyriteOxidationofsulphideminerals99Detailedreactions(1)FeS2+7/2O2+H2O=>Fe2++2SO42-+2H+

(2)Fe2++1/4O2+H+=>Fe3++1/2H2O(ratelimitingstep)(3)Fe3++3H2O=>Fe(OH)3(yellowboy)+3H+

(4)FeS2+14Fe3++8H2O=>15Fe2++2SO42-+16H+

BOTTOMLINE=Sulphides+water+oxygen(+bacteria)giveacidity(4H+)+sulphatesIfthisisnotneutralizeditcanresultinheavymetalmobilisationwhichcanhavedisastrousenvironmentalconsequencesDetailedreactions(1)FeS2+7100ModelofpyriteoxidationModelofpyriteoxidation101aunreactedpyriteb