实际污染土壤和模拟污染土壤垂直电动修复效果对比

为加深对电动修复技术理论的理解及提供实际污染土壤修复技术科学依据，以实际污染土壤和人为污染土壤为研究对象，采用垂直电动修复技术，着重对比了实际污染土壤和人为污染土壤的电流强度、pH和土壤中重金属迁移率。结果表明:1）电动修复过程中，实际污染土壤和人为污染土壤具有相似的电流峰形，但是人为污染土壤电流值约为实际污染土壤电流值的2倍，指示人为污染发生了更多的离子迁移。2）电动修复结束后，距离阳极越近的土壤pH越低，阴极附近区域的土壤pH显著升高，实际污染土壤和人为污染土壤pH变化规律相似，阴极pH的升高可起到深层固定重金属的效果。3）对于实际污染土壤，垂直电动修复技术对0~5 cm土层Cd、Pb、Cu和Zn造成一定的向下迁移，Cd和Zn在5~10 cm土层也有一定迁移，但该土层中Pb和Cu产生积累，其余土层变化不明显。4）对于人为污染土壤，Cd迁移明显且在最底层（35~40 cm）积累，Zn、Cu在表层（0~20 cm）有一定迁移，但是Pb只在最表层（0~5 cm）有一定迁移，其余土层变化不明显。5）对比实际污染土壤和人为污染土壤，实际污染土壤具有明显较低的重金属迁移率，人为污染土壤重金属由于老化时间较短（2个月），Cd和Zn具有较高的迁移率。因此，人为污染土壤的研究结果不一定适用于实际污染土壤。

REMEDIATION PERFORMANCE OF REAL AND ARTIFICIAL SOIL CONTAMINATED BY HEAVY METALS WITH VERTICAL ELECTROKINETIC TECHNOLOGY

In order to understand the theory of electrokinetic remediation (EKR) and provide scientific basis for the remediation of the contaminated sites, the vertical electrokinetic remediation technology was used to the real and artificial contaminated soil and compared the current intensity, pH and heavy metal translocation between the two types of soil. The main experimental results could be listed as follows:1) During the process of EKR, the real and artificial contaminated soil had similar current peak shape, but the current value of artificial soil was about twice of that of the real soil, indicating that the artificial soil contained more mobile ions than the real soil. 2) After the EKR, the real and artificial contaminated soil had similar pH changing trend:the soil pH near the anode was lowered, but the soil pH near the cathode was increased. The increase of the cathode pH could fix the heavy metals in deep layers of soil. 3) For the real soil, the vertical EKR removed Cd, Pb, Cu and Zn from 0~5 cm to deeper layers, and similarly from 5~10 cm soil layer for Cd and Zn, but Pb and Cu accumulated in the 5~10 cm soil layer, and the other soil layer did not change significantly. 4) For the artificial soil, Cd migrated obviously and accumulated at the deepest layer (35~40 cm). Zn and Cu were removed from the 0~20 cm layer, but Pb was only removed from the 0~5 cm layer. The other soil layers did not significantly change. 5) The real soil had a significantly lower heavy metals translocation rates than the artificial soil, probably due to the heavy metals in artificial soil had shorter aging time (for 2 months), and Cd and Zn had a high mobility. Therefore, the experimental results obtained from artificial soil might not be able to be applied to the actually contaminated soil.