蓄电池拆解区铅、镉复合污染农田土壤钝化修复

Remediation of lead and cadmium contaminated farmland soil in battery dismantling area

为了揭示复配及改性钝化材料对农田土壤中重金属的钝化效应,通过土壤培养和田间试验相结合的方式,研究了镁基矿物材料、土壤调理剂、巯基改性海泡石、钙镁磷肥对Pb、Cd复合污染土壤的修复效果,并以油菜为供试作物,研究了施用土壤调理剂和巯基修饰海泡石对油菜吸收累积Pb、Cd的影响.同时,通过扫描电子显微镜(SEM),傅里叶变换红外光谱(FTIR)和孔结构分析(BET)来表征不同材料的形态、表面官能团和比表面积.试验结果显示,土壤调理剂、巯基改性海泡石、钙镁磷肥均能降低土壤DTPA提取态Pb、Cd的含量,镁基矿物材料效果不明显;不同材料对Pb的钝化效果如下:土壤调理剂>巯基改性海泡石>钙镁磷肥>镁基矿物材料,对Cd的钝化效果如下:巯基改性海泡石>土壤调理剂>钙镁磷肥>镁基矿物材料.田间试验条件下同时施用土壤调理剂和巯基修饰海泡石,油菜可食部分Pb、Cd含量分别降低了67.6%、75.9%.通过测定土壤pH、CEC,结合SEM、BET和FTIR所得表征图像探讨不同材料钝化修复的机理,土壤调理剂主要通过离子交换吸附固定土壤中的重金属,而巯基修饰海泡石主要通过物理吸附和提高土壤阳离子交换量固定土壤中的重金属.

In order to investigate the availability and the stability of lead(Pb)and cadmium(Cd)in soil affected by the compound and the modified materials,this study was conducted to evaluated the effect of magnesium-based mineral materials(MB),compound soil amendment(CA),mercapto-modified sepiolite(MP),and calcium-Magnesium phosphate(CM)on Pb and Cd contaminated farmland soil by soil incubation experiment.Meanwhile,the effect of CA and MP on Pb and Cd accumulation in pak choi was evaluated through field experiments.Materials characterization,including SEM(Scanning Electron Microscopy),FTIR(Fourier Transform Infrared Reflectance Spectroscopy)and BET(Brunauer-Emmett-Teller)specific surface area measurements,were applied to test morphology,surface functional groups,and specific surface area of different material.The results showed that CA,MP,CM reduced the content of Pb and Cd extracted by DTPA,whilst MB showed little effect on both Pb and Cd.The efficiency of different materials of available Pb followed the order of CA>MP>CM.The efficiency for Cd followed the order of MP>CA>CM.According to the field experiment,the reduction of Pb and Cd on aboveground part of pak choi were 67.6%and 75.9%after the application of mixed CA and MP,respectively.The results of soil pH,CEC,SEM,BET and FTIR showed that heavy metal ions were mainly adsorbed and fixed in by CA through ion exchange,while heavy metals were mainly stabilized by MP through physical adsorption and increasing the soil cation exchange capacity.