采用植物仿生与化学淋洗联合修复技术对重金属Cd污染的工业场地进行修复,使用H2O、1%乳酸、5%乳酸和0.03 mol·L-1EDTA溶液作为化学淋洗剂进行原位淋洗,通过改变土壤重金属存在形态以增加植物仿生修复技术的效率。同时研究了植物仿生修复装置大小及修复装置填料组成对植物仿生修复技术效率的影响。结果表明,经过3个月的修复,3块实验田Cd含量的降低率分别为81.97%、82.67%和67.67%,均达到国家土壤环境质量标准(GB15618-1995)规定的Cd三级标准。四种淋洗剂中,以EDTA的联合修复效率最高,为82.33%,其余联合修复效率依次为5%乳酸溶液(74.33%)、1%乳酸溶液(71.67%)、H2O(67.67%)。相关性分析表明,土壤Cd含量与乳酸呈负相关,差异显著;与EDTA呈负相关,差异极显著。植物仿生修复3个月后φ=5.0 cm的植物仿生修复装置的修复效率较φ=2.5 cm的高1.21倍;填料中增加5%赤泥对植物仿生修复效率无明显影响。
Soil contaminated by Cd at an industrial site was restored using the phyto-mimic method (PMM) of plant evapotranspiration bionic repair combined with chemical leaching remediation.Solutions of H2O, 1% lactic acid, 5% lactic acid, and 0.03 mol·L-1 EDTA were used for in-situ chemical leaching to change the form of the heavy metals in the soil and increase the efficiency of the PMM technology.Meanwhile, research on effect of the device size and filler composition on the efficiency of the PMM technology was conducted.The reduction rates of Cd in the three plots were 81.97%, 82.67%, and 67.67% after 3 months of remediation, reaching the national standard Ⅲ of Soil Environmental Quality Standards (GB15618-1995).Among the four kinds of combined remediation, EDTA-PMM showed the highest efficiency at 82.33%, followed by 5% lactic acid-PMM at 74.33%, 1% lactic acid-PMM at 71.67%, and H2O-PMM at 67.67%.Correlation analysis showed that the contents of Cd and EDTA had significant negative correlations with lactic acid in the soil.The remediation efficiency of the phyto-mimic device with a 5.0 cm diameter was 1.21 times higher than that with a 2.5 cm diameter over 3 months.Additionally, there was no significant effect of the plant evapotranspiration bionic repair efficiency by 5% red mud.