Passivation remediation of cadmium-lead-copper-zinc composite polluted soil by phosphate fertilizer
In order to explore the passivation effect of different phosphate fertilizers and their application amounts on the soil contaminated by heavy metals,the paddy soil contaminated by heavy metals a-round a mining area in Tongling,Anhui was selected for indoor cultivation experiments.The passiva-tion characteristics of soil heavy metals cadmium(Cd),lead(Pb),copper(Cu),and zinc(Zn)with time changes of 4 kinds of phosphorus fertilizers(diammonium hydrogen phosphate DAP,potassium dihydrogen phosphate MPP,tricalcium phosphate TCP and calcium magnesium phosphate fertilizer CMP)and 5 kinds of phosphorus application rates were studied.The results showed that the four kinds of phosphorus fertilizers increased soil pH to different degrees,and the order of increase was DAP,CMP,TCP,MPP.All four kinds of phosphorus fertilizers can passivate Cd and Pb in soil to a certain extent,and the overall passivation effect increases with the increase of time and phosphorus application amounts.The passivation efficiencies of DAP,MPP,TCP and CMP to Cd reached 42.77％,41.74％,30.37％and 28.31％,respectively,and the passivation efficiencies to Pb reached 48.55％,60.57％,37.58％and 35.03％,respectively.The passivation effect of phosphate fertilizer on Cd and Pb is mainly the transformation of weak acid extraction state and reducible state to residue state;water-soluble phosphate fertilizers have the risk of activation on Cu and Zn in compound polluted soil,while citric acid-soluble phosphate fertilizers are at the same phosphorus application level.The passivation effect of Pb and Cd in polluted soil is poorer than that of water-soluble phosphate fertilizer.Therefore,phosphate fertilizer is suitable for the remediation of Pb and Cd polluted soil,and has good stability,but the remediation effect of Cu and Zn polluted soil is poor.
soilcomplex heavy metalsphosphate fertilizerpassivation characteristics
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维普
