Remediation Effect Of Solidification/stabilization Of Several Mineral Materials On A Heavy Metal Contaminated Farmland Soil

Heavy metal pollution in farmland soilbecomes more and more serious,because it reduces soil fertility,grain production,and causes the pollution of groundwater.such environmental issues harmful to the sustainable development and the survival of human beings.Solidification/stabilization remediation are gradually applied to deal with soil heavy metal pollution,and they are effective methods to solve this problem.In this study,selected a farmland soil in Jiyuan for research object.Based on the plenty surveys and the acquaintance of which were the rule of space variation and the character of soil pollution,the three mineral materials were used to deal with soil which was polluted by heavy metal.The proportion of added three mineral materials were further screened and optimized,and its effect of solidification/stabilization were compared and evaluated.The main results of experiment showed that:(1)From the data which was acquired and inspected in tested farmland soil,in the surface soil,Pb,Cd,As average values: 170±15,2.33±0.31 and 21.8±4.3mg?kg-1.From the section data,the distribution of heavy metals in the soil section showed that the phenomenon of surface accumulation,With the increase of soil depth,the concentrations of Pb and Cd decreased gradually in soil,but the content of As was even and not varied with soil depth.On the whole,the main polluted metals was Cd,and the all soil contaminated by heavy metals.(2)In the experiment which screened extracting agents(EDTA?HCl?CaCl2),The extraction effect of 0.1 mol·L-1EDTA solution was the best in the screened test of extracting agents,the minimum content of As,Cd,Pb were: 0.68,0.70 and 50.58 mg·kg-1,which were extracted by 0.1 mol·L-1EDTA solution that were higher than those maximum value of other 2 types of solution.the content of As was even and not varied with soil depth.(3)Selected three mineral materials(Acid-modified attapulgite is a typical Magnesium-aluminosilicate clay mineral,Fixall is a typical Calcium-iron-sulphate mineral,and MAG is a typical mineral material of magnesium oxide.)for recovering the polluted soil,the result showed that: soil pH increased with MAG material treated,for heavy metals,both available contents were decreased with MAG-3%(C3)or MAG-5%(C5)treated,and which can also reduce the exchangeable content of Cd.With Fixall treated,soil pH decreased and maintain alkalinity.The effect of Fixall-3%(B3)was the best in terms of reducing available contents of As,Cd,Pb.On the forms of heavy metals,exchangeable contents of As,Cd,Pb decreased with Fixall-5%(B5)treated.Soil pH decreased with Acid-modified attapulgite material treated,too.The available contents of Cd and Pb decreased with Acid-modified attapulgite-1%(A1)treated,on the forms of heavy metals,exchangeable contents of As reduced with Acid-modified attapulgite(A1,A3,A5)treated.(4)In the field test,the solidificated/stabilized effect of Fixall material was the best for Pb and As in soil,and MAG was an effective material to solidificate/stabilize Cd;For the roots and grain of wheat,the content of Pb was decreased with Acid-modified attapulgite and Fixall treated;For the above ground part of wheat,all the materials failed to reduce the content of heavymetals,the reason is that the pollution of heavy metals in the region comes from atmospheric deposition,it may be the leading factor which cause the result.