Effects Of Amendment On Content And Speciation Of Cadmium And Lead In Soil-crops Systems

In recent years,heavy metals contaminating is more and more serious in calcareous soil and some methods are needed to manage it effective.This paper based on the number of amendments screened out a kind of amendment,and wheat and maize pot experiment,the effects of amendment and after-effect on content and speciation of Cadmium(Cd)and Lead(Pb)in calcareous soil were investigated.The main results are as follows:1、The effect of amendment and after-effect can significantly increase wheat and maize yields,when the amount of amendment was 24 g kg-1to 48 g kg-1,the yield of wheat and maize increased by 35.92% to 96.92% and 16.39% to27.02%,respectively.2、The amendment can significantly reduce the content of heavy metals wheat roots,straw-leaves,glumes and grains.When applied at a rate of 24 g kg-1 to 48 g kg-1,the Cd content decreased by 13.80% to 36.03%,39.62% to 61.15%,40.22% to 64.35%,40.86% to 67.34%,respectively,the Pb content decreased by 23.81% to 29.74%,27.77% to 39.72%,30.98% to 51.22%,36.95% to 60.13%,respectively,remediation effects Cd>Pb.3、The coefficient of Cd migration in different parts of wheat was TF grain /glume>TFglume/straw-leaves>TFstraw-leaves/root,while Pb was TF grain /glume,TFglume/straw-leaves>TFstraw-leaves/root.With the increase of the dosage of amendment,the migration coefficient of Cd at each site was significantly reduced,and the TF grain /glume,TFglume/straw-leaves,TFstraw-leaves/root were decreased 6.92% to 15.68%,5.98% to 11.27% and 30.20% to 38.87%,respectively.4、The change of soil p H value was different in each wheat growth period,but the soil p H decreased with the increase of the dosage of the amendment.And the size of the p H value and the soil in the form of heavy metals have a certain impact.5、When applied at a rate of 24 g kg-1 to 48 g kg-1,Cd exchangeable and carbonate bound forms decreased by 33.66% to 63.24% and 12.67% to 25.30%,respectively,while two Pb forms by 17.20% to 19.38% and 41.90% to 52.70%.By contrast,Cd weak organic bound,Fe-Mn oxide bound,strong organic bound and residual forms increased by 24.52% to 62.93%,53.10% to 88.75%,31.12% to 87.61% and 4.13% to 41.30%,respectively,while four Pb forms by 13.94% to 24.99%,35.30% to 39.90%,3.46% to 30.15%,37.70% to 65.00%,remediation effects Cd>Pb.And there was a certain correlation between heavy metal forms.There is a certain correlation between the various forms of heavy metals.6、The amendment can significantly reduce the contents of Cd and Pb of roots,stems,leaves and grains in maize,and the after-effect is obvious.The Cd content decreased by 40.00% to 62.32%,46.82% to 70.45%,47.05% to 69.89%,51.51% to 75.27%,respectively.The Pb content reduced by 30.50% to 53.90%,35.78% to 63.17%,51.04% to 82.84%,52.63% to 86.80%,the after-effect of amendment remediation effects Cd<Pb.And the accumulation of heavy metals in each part and plant showed a significant reduction effect.7、The migration coefficient of Cd in each part of maize is larger than that of Pb in the after-effect of amendment test,the translocation factor of Cd and Pb in each region showed a decreasing trend.And the effect of Pb is stronger than that of Cd.8、In the after-effect of amendment test,the soil p H decreased by 0.23 to 0.50 units in the maize mature period,and the DTPA-Cd/Pb content decreased by33.70% to 59.08%,21.44% to 37.78%,respectively.There was a significant positive correlation between p H and DTPA-Cd/Pb.And there was a significant positive correlation between DTPA-Cd/Pb and grain heavy metal content in maize.9、In the after-effect of amendment test,the content of exchangeable Cd and Pb in soil decreased significantly,the content of carbonate bound forms of Pb decreased significantly,the content of Cd and Pb in weak organic bound,Fe-Mn oxide bound,strong organic bound and residual forms increased significantly.And the contents of Cd were varied from 40.96% to 63.21%,6.64% to 9.63%,-38.88% to-106.69%,-26.59% to-47.39%,-7.74% to-48.98%,-23.48% to-42.64%,respectively;the Pb were 11.52% to 20.35%,24.82% to 42.18%,-9.63% to-22.03%,-43.24% to-69.49%,-11.92%to-25.02%,-28.36% to-68.83%,respectively.There was a significant positive correlation between exchangeable and carbonate bound forms of Cd and Pb contents in soil and heavy metal content in maize grain,and there is a certain correlation between the forms of heavy metals.