简介：TheadsorptionkineticsofPb^2+ondifferentsoilsandmineralswithvariablechargeswasstudiedbythetwoion-selectiveelectrodetechniqueatdifferentpHandconcentrations.Theresultsshowedthatmorethan95%ofadsorptiononallthesamplesoccurredduringthefirst5minutes.Alladsorptiontime-dependentdatacouldfitthesurfacesecond-orderequationverywell.ThevaluesofXmweregoethite>kaolinite,andlatosol>redsoilatthesameinitialreactionconcentration.Thevaluesofkwerekaolinite>>goethite,andlatosol>redsoilatthesamereactionpHandinitialconcentration.ThehigherthesuspensionpH,thefastertheadsorptionoccurred.ThemeaningofXmgotbythetwoion-selectiveelectrodetechnique(onekindofbatchtechnique)wasdifferentfromthatbythemiscibledisplacementtechniqueinthattheformerwasonlytheequilibriumadsorptionamountatadefiniteconcentrationandpH,butthelatterwasalmostequaltotheadsorptioncapacityatadefinitepHwithmuchlessinfluenceofconcentration.OnePb^2+wassupposedtooccupytwoadsorptionsitesastheadsorptionmechanismisconcerned.

简介：Dustemissionsfromsmelters,asamajorcontributortoheavymetalcontaminationinsoils,couldseverelyinfluencesoilquality.Downwindsurfacesoilswithin1.5kmofazincsmelter,whichwasactivefor10yearsbutceasedin2000,inMaguTown,GuizhouProvince,ChinawereselectedtoexaminePb,Zn,andCdconcentrationsandtheirfractionationalongadistancegradientfromazincsmelter,andtostudythepossiblee?ectsofPb,Zn,andCdaccumulationonsoilmicroorganismsbycomparingwithareferencesoillocatedatadownwinddistanceof10kmfromthezincsmelter.Soilswithin1.5kmofthezincsmelteraccumulatedhighlevelsofheavymetalsZn(508mgkg-1),Pb(95.6mgkg-1),andCd(5.98mgkg-1)withlowratiosofZn/Cd(59.1-115)andPb/Cd(12.4-23.4).Compositepollutionindices(CPIs)ofsurfacesoils(2.52-15.2)were3to13timeshigherthanthereferencesoils.Inmetalaccumulatedsoils,exchangeablepluscarbonate-boundfractionsaccountedformorethan10%ofthetotalZn,Pb,andCd.Thesaturationdegreeofmetals(SDM)insoilswithin1.5kmofthesmelter(averaging1.25)wassixtimeshigherthanthatofthereferencesoils(0.209).Asmallersoilmicrobialbiomasswasfoundmorefrequentlyinmetalaccumulatedsoils(85.1-438μgCg-1)thaninreferencesoils(497μgCg-1),andanegativecorrelation(P<0.01)ofsoilmicrobialbiomasscarbontoorganiccarbonratio(Cmic/Corg)withSDMwasobserved.Microbialconsumptionofcarbonsourceswasmorerapidincontaminatedsoilsthaninreferencesoils,andashiftinthesubstrateutilizationpatternwasapparentandwasnegativelycorrelatedwithSDM(R=-0.773,P<0.01).Consequently,dustdepositedPb,Zn,andCdinsoilsfromzincsmeltingwerereadilymobilized,andweredetrimentaltosoilqualitymainlyinrespectofmicrobialbiomass.