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简介：WaterandsedimentqualitiesarestudiedbyanalyzingsamplestakingfromthemouthsoftheHaihe,Duliujian,NewZiyaandBeipairiversintheHaiheriverbasininnorthChinain2005and2001,inordertofindthechangesofwaterandsedimentpollutions.Theconcentrationsofheavymetals,arsenic,totalnitrogen(TN)andtotalphosphorus(TP)areanalyzedandresultshavebeencomparedforthetwotimes.Thein-situmeasurementforDissolvedOxygen(DO)andSedimentOxygenDemand(SOD)rateswerecarriedattheHaiheandDuliujianrivermouthsin2006.Theresultsshowthatthewatersofthe4rivermouthsarestillseriouslypolluted,thoughmuchimprovedinthecaseoftheHaiheandDuliujianrivers.ThemainpollutantsareTPandTNintheNewZiyaandBeipairiversandmercury(Hg)atall4rivermouths.Comparedwiththosein2001,theconcentrationsofalmostallmetalsandarsenicinthe4rivermouthshavedecreased.WaterqualityatHaiheandDuliujianshowsanimprovingtrend,whilethewaterqualityatBeipaiissimilartothatof2001.Incontrast,waterattheNewZiyarivermouthismoreseverelypolluted.Thesedimentsinthe4rivermouthsarenotseriouslypollutedbyheavymetalsbutarepollutedbynitrogenandphosphorus.Mostofthepollutantcontentsinthesedimentsshowlittlechangebetween2001and2005.Thein-situDOandSODmeasurementshowsthatthewatersattheHaiherivermouthisinthestateofoxygendepletion,andSODisimportantconsumerofDOattherivermouths.Theoverallanalysisshowsthatincreasingwaterpollutionandeutrophicationinwatersfarfromcitiesareongoingcausesofconcern.

简介：TheUnitedStatesDepartmentofAgriculture(USDA)AnnualizedAgriculturalNon-PointSourcePollutionmodel(AnnAGNPS)isusedtohelpevaluateawatershedresponsetoagriculturalmanagementpracticestocontrolwaterquality.However,AnnAGNPSversion3.5doesnotcontainfeaturestoestimatetheeffectofariparianbuffer(RB)systemonwaterquality.TheRiparianEcosystemManagementModel(REMM)isusedtosimulatetheimpactofriparianbuffersystemsonwaterquality.However,frequentlythelackofmeasureduplandloadingsthatarerequiredbyREMMsimulationlimitstheapplicationofREMM.Toaddressthisdatagap,astudywasconductedtointegrateAnnAGNPSwithREMMforRBsystemsimulation.AnnAGNPSwasusedtosimulatewaterandsedimentloadingsfromanuplandfieldintoathree-zoneRBsystemattheGibbsFarmlocatedintheGeorgiacoastalplain.TheseAnnAGNPSoutputswereusedastheinputstoREMM.REMMwasusedtosimulatewaterandsedimentmovementalongtheriparianbuffers.TheAnnAGNPSsimulatedamountofannualrunoffattheedgeofthefieldwasclosetoobservedamounts(Nash-Sutcliffeefficiencyof0.92).Itisbelievedthatasubstantialportionofsandwasremovedfromtherunoffonemeterintothegrassbufferwherethesamplerswerelocated;therefore,sandwasexcludedfromtheAnnAGNPSsimulationforcomparisonwithobservedsediment.Excludingsand,theAnnAGNPSpredictedamountofannualsedimentmatchestheobservedamountfairlywell(Nash-Sutcliffeefficiencyof0.46).Inaddition,basedonevaluatingthepercentreductionofsedimentateachzonalinterface,theAnnAGNPS/REMMmodelwellsimulatedthefunctionoftheRBsystemtoreducesediment.

简介：Thisresearchdevelopsageneralized,one-dimensional,finitedifferencemodelforsimulatingthedistributionoftoxicsubstancesinariver-estuarinesystem.Thethreesub-modelsforunsteadyflow,sedimenttransport,andthereactionoftoxicsubstancesarealsopresentedusinganuncouplednumericalmethod.Thepaperalsoincludesexperimentalworkforsorption/desorption,fieldmeasurementsoforganiccarboncontentintheheavilypollutedKeelungRiver,andalaboratorystudyofcohesivesedimenttransportforthemodelcalibrationandverification.Inaddition,thisstudysimulatesthepolycyclicaromatichydrocarbons(PAHs)intheKeelungRiverinnorthernTaiwanasacasestudy.Encouragingresultsareobtained,andsuggestthatthemodelingapproachcouldbeextendedtosimulatethefateandtransportofsorbedpollutantsintidalriver.

简介：Soilerosionatthehilly-gullyregionoftheLoessPlateauhasobviousverticalerosionzonationfromwatershedboundarytogullyedge.Meanwhile,upsloperunoffandsedimenthaveasignificantimpactonthedownslopeerosionprocess.Butduetothelimitsofresearchmethods,thereisnotmuchdataavailabletoquantifytheeffectsofupsloperunoffandsedimentonthedownslopeerosionprocessunderdifferentconditions.Theobjectiveofthisstudywastoquantifytheeffectsofupsloperunoffandsedimentonthedownslopeerosionprocessusingadual-boxsystemwitha15°gradientconsistingofa2m-longfeederboxanda5m-longtestboxunderdifferentrunoffratesandsedimentconcentrationsinupsloperunoff,rainfallintensitiesandsoilsurfaceconditions.Theresultsshowedthatthesedimentregimewasdetachment-transportdominantatsteephillslopes.ThenetsedimentdeliveryScausedbyupsloperunoffwascontrolledbysedimentconcentrationinupsloperunoff,especiallybyinteractionoftherainfallintensity,runoffrate,surfaceconditionanddominanterosionprocess.ThenetsedimentdeliverySaccountedforthetotalsedimentdeliverySftatdownslope31.7%to97.3%and27.8to89.7%forbothlooseandcompactsurfacetreatments,respectively.Rainfallintensity,slopegradient,surfacecondition,andrillerosiondevelopmenthadimportantinfluencesonthedownslopeerosionprocess.

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简介：Aquasi-2Dunsteadyflowandsedimenttransportmodelsuitableforthesimulationoflargelowlandriversystems,includingtheirfloodplains,ispresented.Thewaterflowandsedimentequationsarediscretisedusinganinterconnectedirregularcellsscheme,inwhichdifferentsimplificationsofthe1DdeSaintVenantequationsareusedtodefinethedischargelawsbetweencells.Spatially-distributedtransportanddepositionoffinesedimentsthroughouttheriver-floodplainsystemaresimulated.Themodelisappliedovera208-kmreachoftheParanaRiverbetweenthecitiesofDiamanteandRamallo(Argentina)comprisingariver-floodplainareaof8100km~2.Aftercalibrationandvalidation,themodelisappliedtopredictwaterandsedimentdynamicsduringsyntheticallygeneratedextraordinaryfloodsof100,1000,and10,000yearsreturnperiod.Thepotentialimpactofa56-kmlongroadembankmentconstructedacrosstheentirefloodplainissimulatedandcomparedtomodelresultswithouttheembankment.Theembankmentresultsinincreasesinupstreamwaterlevels,inundationextent,flowduration,andsedimentdeposition.

简介：Upwellingcoastalsystemscanbeusedtounderstandhowdissolvedoxygenandbiologicalproductivitycontroltheaccumulationofredox-sensitivemetalsinmarinesediments.Thealuminium(Al),cadmium(Cd),iron(Fe),nickel(Ni),molybdenum(Mo),vanadium(V),totalorganiccarbon(TOC),totalnitrogen(TN)andtotalsulfur(TS)contentsinsurficialsedimentcollectedfromdifferentwaterdepths(30,70,and120m)inthreenorthernChileanbaysinfluencedbycoastalupwellingandoxygenminimumzones(OMZs)weremeasured.Principalcomponentanalysis(PCA),clusteranalysis,andSpearman'srankcorrelationwereusedtoidentifythemechanismsresponsiblefortheredox-sensitivemetalaccumulation.Thecontentofredox-sensitivemetalsandorganiccomponentsinsedimentincreasedwithincreasingwatercolumndepth,whereaslithogenicmetalsdecreased.IntheMejillonesdelSurandCalderabays,theenrichmentfactorsoftheredox-sensitivemetalsshowedenrichmentforallmetalswithdepth.TheCdandVenrichmentsaremainlytheproductofbiogenicflowtotheseabed,andtheMoandNienrichmentsareduetopreservationunderlowsubsurfaceoxygenconditions.Sulfatereductionisnotanimportantmechanismintheaccumulationofredox-sensitivemetalsinthesedimentofthethreebays.ThePCAshowedthatthebehaviorsoftheredox-sensitivemetalsandorganiccomponentsreflectdifferencesintheeffectsoftheOMZinsedimentalongthecoastofnorthernChile,withamoreintenseOMZinMejillonesdelSurbayandweakerOMZsinCalderaandInglesabays.However,thehighdegreeofenrichmentinredox-sensitivemetalsinCalderaBaycanbeattributedtotheintenseactivityoftheminingindustrynearthebay,asituationthatproducesgeochemicalbehaviorsimilartothatobservedinMejillonesdelSurBay.

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简介：以阿姆河盆地右岸地区碳酸盐岩台内滩气田为例,运用基于图论的多分辨率聚类分析法开展了以常规测井资料为基础的测井相聚类及岩相定量预测研究。该方法不需要分析数据体的结构及聚类数等先验知识为指导,能够自动优选最佳聚类个数,并允许按照实际需求控制聚类级别,进行聚类合并。依据岩芯资料岩相识别及测井相标定结果,本文最终建立了包含5个聚类的测井相划分模型及岩相定量解释图版,其中,聚类测井相1~5分别对应于泻湖泥、石膏坪、滩间、低能滩及高能滩,取芯段符合率达85%以上,能够较好的运用于非取芯段岩相预测研究。据此,我们进行了连续的聚类测井相划分及岩相预测,并对层序地层格架内岩相分布及物性特征进行了分析。