简介：Studyonformcharacteristicsofnitrogeninmarinesedimentsistheprimarymethodtoresearchitsbiogeochemicalcyclingandnitrogenformcharacteristicsincoresedimentscanreflecttheprocessandresultsofearlydiagenesisinacertaindegree.Inthispaper,SequentialextractionprocessinnaturalgrainsizewasusedforstudyingtheexistentformsofnitrogeninfivecoresedimentsofthesouthernBohaiSeaforthefirsttime.Nitrogenwasdividedintotwoparts-transferableandfixedbasedonwhetheritcouldbeextractedbythereagent.DistributionsandearlydiagenesisoftransferablenitrogenformsinthesouthernBohaiSeawereresearchedintegratedly.ResultsindicatethatIEF-NandOSFNarepredominantformsintransferablepartinthestudiedcoresediments.Contentsofdifferentnitrogenformsvarydifferentlywithdepth,andhavedifferentdiagenesisprocess.Decompositionconstantoforganicnitrogen(ON)andOCareabout15.51×10-3a-1and4.79×10-3a-1respectively,andthedecompositioncontentofbiogenicelementsC,N,P,SihasthesequenceN＞P＞C＞Si.OC/TN(simplifiedasC/Ninthefollowing)ratioismuchlowerthanOC/ON,whichindicatesthatsedimentpreservesplentyofinorganicnitrogen(IN)and/orfixednitrogen,andthedecreaseofOC/ONratiowithdepthisduetoONreservationinsediments.Generally,transferablenitrogenaccountsformoreproportionofTNinthesurfacelayerthaninthedeeplayerofcoresediments,whereas,somestableformsofnitrogencanactivateandbecometransferableunderappropriateenvironment,whichinducestheproportionoftransferablenitrogeninTNinthedeeplayertobealmostthesameasthatinthesurfacelayer.

简介：OnthebasisofthesoundvelocitymeasurementsofthecoralreefcorefromNanyongNo.1wellofYongshuReefintheNanshaIslands,thepaperstudiestherelationsbetweentheverticalsoundvelocitytransitionfeaturesinthecoralreefcoreandthecorrespondingstratigraphicdepositionalfacieschangeaswellasstratigraphicgapoferosion,analysesthecauseofthesoundvelocitytransition,expoundstheconcreteprocessofthesealevelchangeresultinginthestratigraphicgapoferosionandfacieschangeinthecoralreefandexplainstherelationsbetweentheverticalsoundvelocitytransitioninthecoralreefcoreandthecorrespondingstratigraphicpaleoclimateandthesealevelchange.ThisstudyisofimportantpracticalvalueandtheoreticalsignificancetotheislandandreefengineeringconstructionandtheacousticloggingforoilexplorationinthereeflimestoneareaaswellasthepaleoceanographicstudyofthemarginalseainthewestermPacificOcean.

简介：Inthispaper,wetakeDLW3101coreobtainedatthetopofthecanyon(nolandslidearea)andDLW3102coreobtainedatthebottomofthecanyon(landslidearea)onthenortherncontinentalslopeoftheSouthChinaSeaasresearchobjects.ThechronostratigraphicframeworkoftheDLW3101coreandelementalstrataoftheDLW3101coreandtheDLW3102coresinceMIS5areestablishedbyanalyzingoxygenisotope,calciumcarbonatecontent,andX-RayFluorescence(XRF)scanningelements.Onthebasisoftheinformationobtainedbyanalyzingthesedimentarystructureandchemicalelementsinthelandslidedeposition,wefoundthattheDLW3102coreshowsfourlayersofsubmarinelandslides,andeachlandslidelayerischaracterizedbyhighSi,K,Ti,andFecontents,therebyindicatingterrigenousclasticsources.L1(2.15–2.44m)occurredinMIS2,whichisaslumpsedimentarylayerwithasmallslidingdistanceandscale.L2(15.48–16.00m)occurredinMIS5andisadebrisflow-depositedlayerwithascaleandslidingdistancethataregreaterthanthoseofL1.L3(19.00–20.90m)occurredinMIS5;itsupperpart(19.00–20.00m)isadebrisflow-depositedlayer,anditslowerpart(20.00–20.90m)isaslidingdepositionlayer.ThelandslidescaleofL3islarge.L4(22.93–24.27m)occurredinMIS5;itsupperpart(22.93–23.50m)isaturbidsedimentarylayer,anditslowerpart(23.50–24.27m)isaslumpsedimentarylayer.ThelandslidescaleofL4islarge.

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简介：Calibrationsbetweensodium(Na+)concentrationsfromaMt.Loganicecoreandsealevelpressure(SLP)seriesshowthatNa+concentrationsarecloselycorrelatedwiththeautumn-time(SeptemberOctober-November)Aleutianlow(AleuLow).AdeepeningoftheAleuLowstrengthensthetransportofsea-saltaerosolsfromtheNorthPacifictotheMt.Loganregion.TheMt.LoganNa+recordisusedtodevelopa292a(1688～1979)reconstructionoftheAleuLowrevealingadramaticintensificationofatmosphericcirculationovertheNorthPacificregionsincethe20thcentury.MeanSLPoftheAleuLowwasabout1hPalowerduringthe20thcenturythanduringpriorperiods.ThestrongestdeepeningoftheAleuLowappearedinthe1950s.SignificantcorrelationsarealsofoundbetweentheMt.LoganAleuLowproxyseriesandthePacificdecadaloscillation(PDO)andPacificcirculation(PC)indexduringthe20thcentury.Evolutionaryspectralanalysisoftheproxyrecordshowssignificantperiodicitiesfrom15to30aconsistentwithPDOfluctuationsandthebidecadaloscillationofNorthPacificatmosphere-oceancirculation.Aperiodof11aintheAleuLowrecordmaybeassociatedwiththeSchwabe11-acycleofsunspotactivity.AdditionallongericecorerecordsfromthisregionwillaidintheeffortstofurtherunderstandtheclimaticchangeovertheNorthPacificregion.

简介：Horizontalandverticaldistributionsofδ18Oandδ13Cwereinvestigatedinshellsoffourplanktonicforaminiferalspecies,Globigerinoidesruber,Globigerinoidessacculifer,PulleniatinaobliquiloculataandNeogloboquedrinadutertrei,fromatotalof62core-topsedimentsamplesfromtheIndonesianthroughflowregion.Resultswerecomparedtomodernhydrologicconditionsinordertoexplorepotentialofproxiesinreconstructingfluvialdischargeandupperoceanwatercolumncharacteristicsinthisregion.Ourresultsshowthat,intheMakassarStrait,bothofdepletedδ18Oandδ13Cofthesefourspecieswerelinkedtofreshwaterinput.IntheBaliSea,however,depletedδ18Oandδ13Cforthesespeciesmaybeduetodifferentreasons.Depletedδ18Owasaresultoffreshwaterinputandaswellinfluencedbyalong-shorecurrentswhiledepletedδ13CwasmorelikelyduetotheJava-Sumatraupwelling.Comparisonofshellδ18OrecordsandhydrographicdataofWorldOceanAtlas2005suggeststhatG.ruberandG.sacculifercalcifywithinthemixed-layer,respectivelyat0–50mand20–75mwaterdepth,andP.obliquiloculataandN.dutertreiwithintheupperthermocline,bothat75–125mwaterdepth.N.dutertreicalcifiesatslightlydeeperwaterdepththanP.obliquiloculatadoes.Ingeneral,δ13CvaluesofbothG.ruberandG.sacculiferarelargerthanthoseofP.obliquiloculataandN.dutertreiatallsites,possiblyrelatedtodepthhabitatsofthesespeciesandverticaldistributionofnutrientsintheIndonesianthroughflowregion.