简介:
简介:TheNanshaIslands,China,haveextremelyhighmarinebiodiversityandhundredsofmolluskshavebeenreportedthere.BenthosresourcesinvestigationsoftheintertidalandsubtidalzonearoundtheNanshaIslandshavebeencontinuouslyperformedfordecades,andrecently,dozensofnewspeciesandnewrecordsofmolluskshavebeenreportedfromthisarea.ThispaperdealtwiththreenewrecordspeciesoftheGastropodafromChinesewaters:CerithiumsalebrosumSowerbyII,1855,Vexillummilitare(Reeve,1845)andVexillumbizonale(DautzenbergetBouge,1923),respectivelybelongingtothreefamilies:CerithiidaeFleming,1822,andCostellariidaeMacDonald,1860.AllspecimenswerecollectedfromtheNanshaIslandsduringthebenthosresourcesinvestigationsontheintertidalzoneofislandsandreefsintheSouthChinaSeainrecentyears.Diagnosisandgeographicdescriptionsofbothgenusandspecies,illustrationsofeachspeciesweregiveninthiscontribution,anddiscussionoftaxonomy,identificationfeaturesandfaunalcharacteristicswerepresented.AllexaminedspecimensweredepositedintheMarineBiodiversityCollectionsofSouthChinaSea,ChineseAcademyofSciences.
简介:Thediffusionattenuationcoefficientfordownwellingirradiance,Kd(490),isanimportantopticalparameterofseawater.Theopticalproperty,Kd(490),aroundNanshaIslandsintheSouthChinaSeawasanalyzedbasedonopticaldataprofilesmeasuredwithSPMR(SeaWiFSProfilingMultichannelRadiometer)andSMSR(SeaWiFSMuitichannelSurfaceReference)instrumentinAprilandMay,1999.TheresultsshowthatKd(490)iscloselycorrelatedwithchlorophyll-aconcentration,Cchl.a,andthattheverticaldistributionofKd(490)showsthestrongstratificationofthewatercolumninthisarea.Kd(490)hasasimilarverticalco-variationasKL(490),thediffusiveattenuationcoefficientforupwellingradiance.Bothcoefficientsincreasewithdepthintheupperlayer,whereKL(490)isgreaterthanKd(490);andafteradepth,approximativelyatthechlorophyllmaximum,theydecreasewithdepth,withtheformerbeingsmallerthanthelatter.
简介:BasedontheSSTandwavedataobservedbyvesselspassingthroughtheNanshaIslandswaters,thispaperanalysesElNinoevent’seffectonhydrologicalfactorsintheabovewaters.Thepaperconcludes(1)SSTintheNanshaIslandswatervarieswiththatoftheEasternEquatorialPacificOceaninsynchronousphase,butvarieswiththatoftheWesternEquatorialPacificOceaninoppositephase;(2)theseastateinNanshaIslandswatersisrough,thefrequencyofgreatwaveincreasesintheyearofElNino,especiallyinthenextyearoftheyearofElNino.Thepaperdiscussesthereasonsfortheabovephenomena.
简介:Onthebisisofdeterminingthethereelementsofthemocline(depth[upperbounddepth],thicknessandintensity)andthemaximumverticaltemperaturegradientofthesurveyingstation,thepapercalculatesthemeantemperatureoftheNanshadeep-watersurveyingstationwithintheupper-bounddepthlayerofthermoclineandthemeantemperaturebelowthelowerbounddepthofthermoclinebetweenthe300mand800mlayers,respectively.AnalysisindicatesthatthehorizontaldistributionofmeanseawatertemperatureshowsadistincttrendofthelowtemperatureseawaterslowlymovingfromtbenortheasttothesoutheastofNansha,whichseemstohavebeendrivenbytheNortheastMonsoon.Thelargertheverticaltemperatureradientis,thegreaterisitscapabilityofpreventingtheheatoftheupperseawaterfromdiffusingintothedeeperlayersontheverticaldirection.
简介:BasedonthesurveydatafromtheprogramMultidisciplinaryExpeditiontoNanshaIslandsSeaArea,thedistributionofdissolvedinorganicphosphate(PO43--P)intheseawaterofNanshaIslandsSeaAreaiscomprehensivelyanalyzedinthispaper.TheresultsshowthatPO43--PconcentrationintheseawaterofsoutheasternNanshaIslandsSeaAreaiscommonlyhigherthanthatintheotherseaareas;theverticaldistributionofPO43--Pconcentrationvariesinconspicuouslyindifferentseasons;theconcentrationofPO43--Pincreaseswithwaterdepthandchangesmostgreatlyinthelayerof50~100m.ThediurnalvariationofPO43--Pconcentrationdiffersindifferentseasonsandatdifferentobservationstations.ThedistributionandvariationofPO43--Pconcentrationresultfromthephysicalandbiologicalprocessestogether.
简介:Onthebasisofinterpretationofcomprehensivegeophysicaldataandforeigndataanalysis,thereexistedalotofoverburdendetachmentshearthrustfaultsalongthesoutheasternmarginofNanshaTrough,whichcomposedimbricatedoverthrustnappestructure.Thrust-faultednappestructurepatternisdeterminedinthisarea,whichconsistsoffrontalfaultzone,thrustfault-foldedzoneandrootzonestructures,andpresentsregularlyzonationonplane.Thedetaildescriptionofthestructuralgeometricalcharacteristicsisgiveninshallowthrustfaultzone,andthekinematicalmechanismofthrustfaultnappestructureisfurtherlydiscussed.Overthrnstnappestructureinthisareaisresultedfromislandarc-continentcollisionandorogenicactivities.
简介:Concentrationsoforganicmatter,ironandmanganeseinthedeepseasurfacesedimentsintheNanshaIslandsseaarea,SouthChinaSeaaremeasured.Horizontalandverticaldistributionsofironandmanganesearediscussed.Theverticaldistributionofironandmanganeseinthesedimentsresultsfromreduction,diffusion,andredepositionofmanganese(oriron)oxideandhydroxideinthesediment.Therearethemaximaofironandmanganeseinsolidphaseinthetopofthesediment,whichiscausedbythepenetrationofO2andtheupwardfluxofMn2+(orFe2+).Manganesebacteriaplayaveryimportantroleinthecycleofsolid-phaseironandmanganeseintheoceanenvironment.ManganesebacteriaoxidizeMn2+(orFe2+)indissolvedstatetoMn4+(orFe3+)inoxidizedstateundertheaerobiccondition,whereastheyreduceironandmanganeseinanaerobicconditions.
简介:AdetailedsurveyofthereefsintheNanshaIslands’seathatareofstrategicimportanceisconducivetotheirfuturedevelopment.Inthisstudy,atotalof50Landsat8operationallandimager(OLI)imageswereusedtoanalyzethegeologicalfeaturesandspectralcharacteristicsoftheNanshareefs.Theexposedislands/sandbanks,reefflatsandsub-tidalreefswereidentifiedwiththenear-infraredband,theredandgreenbands,andtheblueband,respectively.BasedontherelationshipsamongvariouscharacteristicsandbandsillustratedintheOLIimages,themaximumbetween-clustervariancethresholdalgorithm(OTSUmethod)andthemathematicalmorphologywereemployedtoextractcharacteristicparametersofthespatialgeometryofthereefsfromtoptobottom,whichweresubsequentlyoperatedbyaseriesofpost-processingmethodssuchasvectorization,simplificationandtopologicalanalysis.Amongthe132standalonereefsand16atollsthatareidentifiedinthestudy,fourreefshaveyettobenamedintheStandardNamesofVariousIslandsintheSouthChinaSeaandthewebsiteNanshaIslandsOnline(http://www.nansha.org/).Another24onesareexposedtotheatmosphereevenduringhightides.TaipingIslandwithanareaof0.57km~2representsthelargestexposedgeologicalfeature.Thisstudydemonstratedtheapplicabilityofmedium-resolutionsatelliteimagestoderivethecoralreefinformationeffectivelyandthusprovidedinformationfortherelateddepartmentsthatareresponsibletomanagethecoast.Animprovedresolutionofmultispectralbandswiththepanchromaticbandinhigherspatialresolution(15mforOLIimage)isexpectedtoprovideanoptimumsatellitebasedapproachtomapmarinehabitats.