Application Of Three Plants In Remediation Of Heavy Metals Mn,Cd And Pb In Cultivated Soil

Soil heavy metal pollution has a great impact on human food safety and national food security.Ecological restoration of cultivated soil heavy metal pollution is very important.In this paper,the soil of cultivated land with heavy metals of Mn,Cd and Pb in fallow state was selected.Three plants,Ligustrum vicaryi,Brucea javanica and Oxalis corniculata,were used as repair materials in pot experiment.The experiment was divided into two groups of single planting and compound planting,with 6 treatments in each group.After 180 days,the effects of three kinds of plants on the growth index,leaf tissue,plant adsorption capacity,plant enrichment index,plant transport index,and the effects of three kinds of plants on soil Mn,Cd and Pb heavy metal elements were studied.To provide scientific basis for phytoremediation of heavy metal pollution in cultivated soil.The main research results are as follows:(1)In heavy metal contaminated soil,compared with the control group,the growth rate of Ligustrum vicaryi,Brucea javanica and Oxalis corniculata was slowed down,which showed that the number and stem number of plants in high altitude and the thickness of leaf tissue were decreased.Compared with the control group,the growth amount of plant height of Ligustrum vicaryi,Brucea javanica and Oxalis corniculata decreased by 5.5cm,0.4cm and 2.3cm,respectively.The growth amount of stem and plant number of Ligustrum vicaryi,Brucea javanica and Oxalis corniculata decreased by 0.33cm,0.06cm and 0.5 per plant,respectively.The thickness of leaf tissue of Ligustrum vicaryi,Brucea javanica and Oxalis corniculata decreased in heavy metal polluted soil compared with control group.The absorption capacity of Ligustrum vicaryi,Brucea javanica and Oxalis corniculata to N,P and K in soil polluted by heavy metals was increased,and the combined planting could effectively improve the absorption of N,P and K in soil.(2)The adsorption capacity of Mn,Pb and Cd in soil varies with different cultivation combinations.The adsorption capacity of Ligustrum vicaryi was the strongest.In the mixed species of Ligustrum vicaryi and sorrel,the increase of Ligustrum vicaryi in root was the most obvious,which was 124.03g/kg-3 higher than that in the control group,and the content of Mn in root of sorrel was significantly increased,which was 100.7g/kg-3 higher than that in the control group.Therefore,it is recommended to use Ligustrum vicaryi as a remediation plant for Mn in heavy metal contaminated soil.Brucea javanica and Oxalis corniculata had the strongest adsorption capacity for Cd elements in soil,and the soil repair effect was the most obvious.The content of Cd in the roots of Brucea javanica increased by 13.62g/kg-3 compared with the control group,and the content of Cd in the roots of Oxalis corniculata increased by 27.92g/kg-3 compared with the control group.It is recommended to use brucea javanica and Oxalis corniculata combined planting as remediation plants for Cd in heavy metal contaminated soil.Brucea javanica and sorrel had the strongest adsorption capacity for Pb elements in soil,and the soil repair effect was the most obvious.The content of Pb in the roots of Brucea javanica increased by 3.61g/kg-3 compared with the control group,and the content of Pb in the roots of sorrel increased by 14.31g/kg-3 compared with the control group.It is recommended to use brucea javanica and Oxalis corniculata combined planting as remediation plants for Pb in heavy metal contaminated soil.(3)Ligustrum vicaryi,Brucea javanica and Oxalis corniculata had obvious remediation effects on Mn,Pb and Cd in soil.For the Mn element in heavy metal polluted soil,the content of heavy metal element decreased by 203.37 g/kg-3 in the soil under the combined cultivation of Ligustrum vicaryi and Brucea javanica,so the combined cultivation of Ligustrum vicaryi and Brucea javanica can be used to improve the effect of soil remediation.For Pb elements in heavy metal polluted soil,the content of heavy metal elements in soil under brucea javanica and Oxalis corniculata combined cultivation decreased by 29.13 g/kg-3.The combined cultivation of brucea javanica and Oxalis corniculata can be used to improve the effect of soil remediation.As for the Cd element in the heavy metal polluted soil,the heavy metal element content in the soil under brucea javanica and Oxalis corniculata combined cultivation decreased by 92.5 g/kg-3.The combined cultivation of brucea javanica and Oxalis corniculata can be used to improve the soil repair effect.