new developments in marine nitrogen cycle.pptx

NewDevelopmentsintheMarineNitrogenCycle,1.Basicknowledge&Introduction2.Increasedindenitrificationestimatesanditsconsequence3.Difficultiesinthemarinenitrogencycleresearch4.Newtechniquestoexplorenitrogencycle4.1FISHandworkinghypothesis4.2Nano-SIMSworkinghypothesis,Outline,1.Basicknowledge&Introduction,N,NO3,NO2,NH4,N2,Organicnitrogen,FixedN,Classicnitrogenreactionweb(Brandes,2007),sixtermstodescribethemarinenitrogencycle:N2fixation,riverineinputs,atmosphericfallout,sedimentorganicmatterburial,andwatercolumnandsedimentarydenitrification.,EarlymarinenitrogenstudiesfocusedontheroleofNasaprimaryproductivity-limitingelement.RedfieldRatioprovidedasimplemetrictodeterminewhethernitrogenorphosphoruswouldlimitoveralllevelsofprimaryproductivityinaparticularecosystem.N*=NO3-16PO4+2.9RepresentsthedeviationsfromRRreflectnon-Redfieldbiologicalnutrientinputs,1.Basicknowledge&Introduction,N*,Nitrogenfixation,denitrification,2.Increasedindenitrificationestimatesanditsconsequence,Classicnitrogenreactionweb,Diagramofthenitrogencycleasitisunderstoodtoday.,(Brandesetal,2007),DenitrificationistheonlywaytolossN,ManyprocesseswerefoundtocontributedforNloss,2.Increasedindenitrificationestimatesanditsconsequence,Alogicalconsequenceoftheincreaseindenitrificationestimateshasbeentocreatedifficultiesinachievingbalancedmarinefixednitrogenbudgets,whichwouldrequirehighergloballyintegratednitrogenfixationrates.Futureworkwillpayspecialattentiontothreeareas:1.newprocessesleadingtonitrogenlosses,2.sitesofnitrogenfixation,3.anassessmenttobalancethepreindustrialmarineNbudget.,1.MarinemicrobesotherthanTrichodesmiummaycontributesubstantialinputsofnewlyfixedNthatwouldnotberepresentedinanypreviousbiologicalestimates,whichleadstounderestimateofnitrogenfixation.Butitisdifficulttosortthedifferentalgae,untiltheadventofFISH(fluorescenceinsituhybridization).,2.Difficultiesinthemarinenitrogencycleresearch,3.Newtechniquestosolvetheproblems,Threegroupsofcells(Prochlorococcus,Synechococcusandpicoeukaryotes)canbedistinguished.ForexampleSynechococcusischaracterizedbythedoublefluorescenceofitspigments:orangeforphycoerythrin(PE)andredforchlorophyll.,/wiki/Photosynthetic_picoplankton,Autofluorescentcells,SYTO-13stainedcells,Fluorescence-activatedcellsorting(FACS),CellSorting(ink-jetgraphicprintingandelectrostaticdeflection),Dropletsorting25,000/s,Fawcettetal.(2011)Naturegeoscience4:717-722.,AssimilationofupwellednitratebysmalleukaryotesintheSargassoSea(Fawcettetal.,2011),8Lwatersamples,47mm0.4mmPCmembranes,Step1.Cells(particulatenitrogen)collectionandflowcytometricsorting,Collection(100mmHg),Agitation,Step2:OxidationofPNtoNO3-,(Elementalanalyzer)(Gaschromatography-isotopeMassspectrometer),Removethefilter,Filtration,(FlowCytometer)sorting,4mL(2million)Intricatetoperform,NanoSIMS:Appliedonmanyfields,BiomineralizationEnvironmentalMicrobiologyNitrogenfixationinthedeep-seaAssimilatoryabilityoforganiccarboninautotrophicAOAPlant/SoilCellBiologyMaterialsGeology&EnvironmentThesulphur-basedmetabolismsforPalaeoarcheanmicrobialecosystems.CosmochemistryIntrumentation-FISH(fluorescenceinsituhybridization),Deep-seaanaerobicmethane-oxidizingarchaeafixN2,Incubatedwith15N2,(Dekasetal.,Science,2009),SedimentassociatedprocessesMn+/MnO2participation,Workinghypothesis,Suspendedparticlecreateshugeamountsofparticulatemicro-nichewithvariousredoxdegreeinoxyg