Modelling of Cadmium Transport in Soil—Crop System

(整期优先)网络出版时间:2000-01-11
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Amodelforsimulatingcadmiumtransportinasoil-plantsystemwasbuiltusingacommercialsimulatingprogramnamedPowersimonthebasisofinput-outputprocesseshappeninginthesoil-plantsystem.COnvectiveanddispersivetransportprocessesofcadmiuminsoilprofileareembedded.Simulationsonadailybasehavebeendoneuptoatotalsimulatingtimeof250years,Resultsshowthatapplicationsofsewagesludgeandfertilizeratthesimulatedrateswouldonlycauseslightcadmiumaccumulationsineachlayerofthesoil,andcadmiumaccumulationwouldbelevellingoff,reachinganequilibriumconcentrationslayerbylayerdownwardaftercertaintime.Thetimescaletoreachanequilibriumconcentrationvariesfrom10yearsforthetopthreelayerstoover250yearsforthebottomlayers.Plantcadmiumuptakewouldincreasefrom52umm^-2underinitialsoilcadmiumconcentrationsto65ugm^-2underequilibriumsoilcadmiumconcentrations,whichwouldnotexceedthemaximumallowablecadmiumconcentrationinwheatgrains.Mainparameterswhichinfluencecadmiumaccumulationandtransportinsoilaretotalcadmiuminput,rainfall,evaporation,plantuptakeandsoilproperties.