微胶囊EDTA对2种土壤中铅释放的影响

选用不同铅污染程度及pH值的土壤,采用连续批浸提实验和土柱淋溶实验,比较研究微胶囊EDTA（Cap-EDTA）和未微胶囊化EDTA（Ncap-EDTA）对不同土壤溶液中pH值和铅离子浓度动态变化影响,以及土壤渗滤液中铅离子淋失特征。结果表明：施加2种不同形式的EDTA,可极显著地增加土壤溶液中铅离子浓度,Cap-EDTA能控制土壤溶液中铅浓度的突增幅度,且使土壤溶液中的铅持续保持在适度浓度的时间更长。同一种土壤不同处理间土壤pH值的变化趋势基本一致,无显著差异。施用2种不同形式EDTA可极显著地增加土壤渗滤液中铅离子含量,土壤铅累积淋失量呈对数曲线上升,但施用Cap-EDTA处理能显著降低土壤中铅的初始淋失量和淋失总量。在相同浓度及形式的EDTA下,高铅浓度和高pH值的土壤铅更易活化和淋失。因此,在进行污染土壤植物修复的EDTA调控时,采用微胶囊化EDTA,能降低其带来的污染地下水风险。

Extraction and leaching of Pb from two polluted soils as affected by addition of microencapsulated EDTA

Incubation batch and leaching experiments were conducted to study effect of microencapsulated EDTA（Cap-EDTA） on extraction and leaching characteristics of Pb and pH changes in two heavy metal polluted soils.The results showed that pH showed similar change pattern in all treatments in the same type soils.EDTA effectively increased the mobility of Pb in the soil,the cumulative amount leaching of Pb,showed a logarithmic curve,along with the increasing volume of leachate.In comparison with EDTA,Cap-EDTA showed similar leaching pattern but provided lower and more constant water-soluble concentrations of Pb in the soil solution with less cumulative amount of leaching of Pb,indicating that Cap-EDTA application may alleviate the risk of groundwater contamination.