EDTA对土壤渗滤液中TOC和重金属动态变化的影响

Leaching of TOC and Heavy Metals from a Polluted Soil as Affected by Addition of EDTA

通过盆栽试验研究了EDTA对土壤渗滤液中总有机碳(TOC)和重金属动态变化的影响。结果表明,施用EDTA极显著地增加了土壤渗滤液中TOC含量,土壤渗滤液中TOC含量随淋洗量呈指数曲线下降。在加入EDTA48天后,土壤渗滤液中TOC含量仍然高于对照处理。施用EDTA大幅度地增加了土壤渗滤液中Cd、Ni的浓度,其浓度在1个月内迅速下降,以后趋于稳定。用EDTA强化重金属污染土壤的修复存在淋溶迁移的环境风险。防止因EDTA施用而引起地下水污染的关键时期在EDTA施入后的2周内。

A pot experiment was conducted to study effect of addition of EDTA on leaching of the Total Organic Carbon (TOC) and heavy metals from a polluted soil. Results indicated that, EDTA extra-remarkably increased the concentration of TOC in the soil leachate. The concentration, however, declined, showing an exponential curve, along with the increasing volume of leachate. On day 48 after the addition of EDTA, it was still higher than that in the control. EDTA increased the concentrations of Cd and Ni by a large margin; but they dropped rapidly within 1 month and then leveled off. The use of the EDTA technology does have an environmental risk of heavy metals migrating into the groundwater. The crucial time to prevent pollution of ground water in applying the EDTA technology is the first two weeks after its addition.