Red Soil Adsorb Cu, Zinc Properties And Heavy Metal Migration In The Red Soil Under The Action Of Three Kinds Of Phosphate

This paper researched red soil adsorb Cu, Zn properties and heavy metalmigration in the red soil under three kinds of phosphate (KH2PO4,(NH4)H2PO4andCa(H2PO4)2).The Phosphate adsorption experiment mainly studied the isothermalbalance adsorption of heavy metals and freundlich fitting model under the actionphosphate. Leaching experiment mainly studied the heavy metal migration in the redsoil under different phosphate and different phosphorus content. The experimentdetermine PH, Electricity conductivity, heavy metal concentration in the leachate andspeciation of heavy metals in the soil after leaching experiment, the experiment resultcould provide basic reference frame for soil and groundwater pollution prevention.(1) The adsorption experiment result showed that the adsorbing capacity of threekinds of phosphate was Ca(H2PO4)2＞(NH4)H2PO4＞KH2PO4. The adsorptionefficiency of three kinds of phosphate was above90%. The soil adsorbed Cu2+, Zn2+can be fitting through freundlich model, and the correlation coefficient was above0.9,which means significant correlation. The red soil adsorption effects of copper arelager than Zn under action of phosphate.(2) Leaching experiments with different phosphoric showed phosphateapplication in red soil are contributed to stable heavy metal Cu and Zn. At the sametime applying phosphate in the soil could raise soil pH in continuous rainy days, soilpH could affect heavy metal species distribution in the soil. Only a little Cu and asmall amount of Zn migrate into the deep soil，and it is harmless to shallowgroundwater. Heavy metals in the soil mainly existed in the form of residual state. TheMF value of Zn was high. Hence, Zn would bring more harmful to environment.(3) Leaching experiments with different anmount of KH2PO4application showedthat application of potassium dihydrogen phosphate into soil could reduce the pH ofleachate, but different amount phosphate has little effect on leachate pH. The pH inleachate kept rising in the whole leaching process. Under the action of KH2PO4, Cumigration is mainly in the surface layer while Zn migrated into deeper soil.Concentrations of Cu、Zn in deep soil leachate were low indicated that it was harmlessto the shallow groundwater. After leaching, heavy metals mainly exist in the residualform in soil, the proportion of residual form of Cu was around60%and the proportion of residual form of Zn was around40%. High concentration of KH2PO4is contributedto change of Zn from residual organic combination state to exchange state.The pH of soil increased with different phosphate implication. Phosphate in soilwere contribute to adsorption the heavy metal and the Ca(H2PO4)2adsorption effectwas best. Phosphate in soil could fix heavy metal Cu、Zn and the Ca(H2PO4)2fixingeffect was best. High concentration of phosphate increases the exchange state ofheavy metal zinc.