AsenicPPT课件

Arsenicinmarinehydrothermalfluids,OceanCollege,ZhejiangUniversity,1,.,Arsenicinthehydrothermalfluids:Why?,Arsenic:environmentaltoxinore-formingelementrarelyinvestigated,2,.,TheamountofAsindifferentsettings,3,.,FactorscontrollingtheamountofAs,TemperaturePressurePHAsmobilityandspeciationreactiontimeandmaturityofthesystemdiversechemicalreactions,4,.,5,.,Therelationshipbetweenthedistributionofhydrothermalventsandthedepth,Hydrothermalventsaredistributedintherangeofhundredsofmetersto5000m,Thehydrothermalventsinthemid-oceanridgeareaaredistributedinthewaterdepthof2000-3000m,6,.,Phaseseparation,Results:ProduceahighCl“brine”phaseandalowCl“vapor”phaseElementsarefractionatedbetweenthebrineandvaporphasesAstendtoenterintothevaporphase，itisduetothedominationoftheunchargedarsenitespeciesattheprevailingpHandredoxconditions,additiontoSulfurcyanide(HS)complexation.,7,.,AdditionalinputofAs,ThesystemoffshoreinMontserrat:enrichmentofAsheremaybecausedbyenhancedmagmaticinput(intheformofmagmaticvolatiles)duringtheeruptivecycle.Sediment-fluidinteraction:anadditionalcauseforAsenrichmentcouldbeleachingfromAs-richsediments,priortodischarge.(noevidence),8,.,ConcentrationofAsindifferentmarinerocksandsediments,ThedifferenceinAsconcentrationbetweenandesitesanddacites(0.5-5.8)fromtheIAsystemsandtheMORBs(1.0)isslight,9,.,Conclusions,Hydrothermalfluidsfromshallow-waterisland-arc(IA)settingsaremostlyveryhighinAs，followedbyfluidsfromdeep-waterhydrothermalsystemsinback-arcbasins(BAB)，andAsconcentrationofmid-oceanicridges(MOR)iscomparablymuchlower.TheonlyslightlyhigherbulkrockconcentrationofunderlyingacidicdacitesandandesitesfromIAsystemscannotberesponsiblefortheoverallmuchhighervaluesofAscomparedtodeep-watersystemsunderlainbyMORB.PhaseseparationproducesahighCl“brine”phaseandalowCl“vapor”phase.ItisoneofthemostimportantfactorscontrollingtheconcentrationofAs.AdditionalinputofAsduetomagmaticvolatilesandsediment-fluidinteractionhastobeconsidered.,10,.,Followingplan,Conversionprocessofarsenate(AsV)andarsenite(AsIII)insubmarinehydrothermalfluidTheinfluenceofpHandbiologicaleffectsonthechangeofthevalencestateofarsenic,11,.,Reference,1ChristianBreuer,ThomasPichler.Arsenicinmarinehydrothermalfluids.ChemicalGeology348(2013)214.2马力.基于地球化学模型对低温热液中Au、As赋存状态的研究D.中国地质大学(北京),2017.3杨振林,丘宝国.砷元素