简介：

简介：NitrogenandphosphoruscontentsareanalyzedintheoverlyingwatersandporewaterstakenfromtheChangjiangEstuaryandShanghaicoastaltidalflatsinthisstudy.Inaddition,thediffusionfluxesofnitrogenandphosphorusacrossthesediment-waterinterfaceintidalflatsareestimatedaccordingtothenutrientconcentrationgradientsattheinterface.Ithasbeenindicatedthattheconcentrationsofammonium,nitrite,nitrateanddissolvedphosphorusinoverlyingwatersrangefrom0.0082～2.56,0.03～0.58,0.69～5.38and0.035～0.53mg/L,respectively,while0.0025～1.35mg/LforNH4+-N,0.0055～0.20mg/LforNO2--N,0.61～1.14mg/LforNO3--Nand0.11～0.53mg/LforDPinsurfaceporewaters.Thefindingshaverevealedthatammonium,nitrite,nitrateanddissolvedphosphorusdiffusionfluxesacrossthesediment-waterinterfacearebetween-0.024～0.99,-0.39～-0.0019,-3.09～thesourceofphosphorusandanimportantsinkfornitrogeninthewaters.

简介：OnthebasisofdatacollectedintheJiaozhouBayinJuneandJuly2003,theDICdistributioninseawaterisstudied,andanaverageair-seafluxofCO2isestimated.TheresultsshowthatthecontentofDICinsidethebayismarkedlyhigherthanoutsidethebayinJune,butthecontentofDICoutsidethebayismarkedlyhigherthaninsidethebayinJuly.ThetrendofDICdistributioninsidethebayissimilar,viz.thecontentisthemaximuminthenortheast,thendecreasesgraduallytowardthewest,andthecontentistheminimuminthewest.Thetotaltrendofverticaldistributionistoincreasegraduallyfromsurfacetobottom.ThischaracteristicofDICdistributionisdeterminedbyJiaozhouBayhydrologyandthereisacloserelationbetweenDICandparticulateN,P.AverageCO2fluxacrossthesourceforatmosphericCO2inJuneandJuly,andthetotalCO2fluxfromseawaterintoatmosphereisabout740tinJuneand969tinJuly.

简介：SurfacesedimentsamplestakenfromtheEastChinaSeaofftheChangjiangestuaryareusedasrawmaterialsforphosphorusreleasingexperiment.Itisfoundthatafterbeingthoroughlymixedwithseawaterforabout10minutes,phosphorusreleasedfromthesedimentsreachesitsmaximumvalue.AdsorptionkineticscanbefittedwithbothElovichequationandtwo-constantrateequation.Thereleasingamountiscloselyrelatedtothecompositionofthesediments.Phosphorusreleasefromsiltyandmuddysedimentishigherthanfromthatdominatedbysandycomposition.Forthedesorptionreaction,iron-phosphorus(Fe-P)isthemostactiveone,withareleasingratiohigherthanotherphosphorusforms,followedbyabsorbed-phosphorus(Ad-P)andorganicboundphosphorus(OP).Allofthemcanbereferredtoasbio-availablephosphorus.Theresultsdemonstratethatphosphorusinsedimentscanbereleasedintoseawaterundersuitablehydrodynamicconditions,andhaveagreatimpactonthenutritionstateandprimaryproductivityofmarinebiosphere.