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1、WATERRESOURCESRESEARCH,VOL.44,W02423,doi:10.1029/2007WR006120,2008BehaviorofthemasstransfercoefficientduringtheMADE-2experiment:Newinsights12334JianyongGuan,FredJ.Molz,QuanlinZhou,HuiHaiLiu,andChunmiaoZhengReceived16April2007;revised7August2007;accepted4October2007;p
2、ublished19February2008.[1]Usingadual-porositytransportmodel,amorecompleteanalysisoftheMADE-2experiment,anaturalgradienttracer(tritium)test,ispresented.Resultsshowthatafirst-order,masstransferratecoefficientisscale-dependentanddecreasingwithexperimentduration.Thisisin
3、agreementwithpreviousstudiesandpredictions.Factorscontributingtothescale-dependencyareerrorsorapproximationsinboundaryconditions,hydraulicconductivity(K)measurementsandinterpolations,masstransferrateexpressionsandconceptualerrorsinmodeldevelopment.Inordertoformulatea
4、self-consistent,dual-porositymodel,itwasnecessarytoassumethattheinjectedtracerwastrappedhydraulicallyinthevicinityoftheinjectionsite.ThiswasaccomplishedbyloweringallKvaluesneartheinjectionsitebyafactorof30,whileholdingallotherKvalues,boundaryconditionsandparametersat
5、theirmeasuredorestimatedmagnitudes.Resultingsimulations,usingthesamescale-dependentmasstransferratecoefficient,werethenabletoreasonablymatchthemovementofthecenterofmass,overallplumegeometryandtheanomalousmassrecoveryratiosobservedateachsnapshot.Thedual-porositymodeli
6、sconceptuallysimple,relativelyeasytoapplymathematicallyanditsimulatesdifferencesinadvectionthatareprobablytherootcauseofdispersioninnaturalheterogeneoussediments.Also,asmallmorerealisticamountoflocalhydrodynamicdispersionisnotprecluded.Citation:Guan,J.,F.J.Molz,Q.Zho
7、u,H.H.Liu,andC.Zheng(2008),BehaviorofthemasstransfercoefficientduringtheMADE-2experiment:Newinsights,WaterResour.Res.,44,W02423,doi:10.1029/2007WR006120.1.IntroductionseveralgroupstoconcludethatGaussiandispersiontheorywasnotconsistentwiththetransportprocesstakingplac
8、ein[2]Between1986and1992,aseriesofwell-knowntheMADEaquifer[BerkowitzandScher,1998;Harveyandtracertestswereperformedatasitelocatedon