不同初始氧化还原条件下土壤中重金属的运移研究Ⅰ：单一Cd、Cu、Zn的土柱实验

以重金属离子镉、铜、锌为研究对象,通过室内土柱混合置换实验,分析了五种不同氧化还原电位对Cd、Cu、Zn在土壤中运移的影响。结果表明,氧化条件的土壤中Cd的穿透曲线(BTCs)峰值大小的顺序为Eh=490 mV>350 mV>240 mV;还原条件的土壤中Cd的BTCs的峰值为Eh=20 mV>100 mV>240 mV。在氧化条件下,高Eh能明显促进Cu在土壤中的迁移;还原条件下,低Eh会抑制Cu的迁移,抑制程度与还原剂浓度无关。与原土(氧化还原电位240 mV)相比,氧化性土壤中Zn运移较快,表现为相对浓度峰值较高,而不同的还原条件对Zn的迁移影响并不明显。三种重金属Cd、Cu、Zn出流液的pH均表现为先下降后上升最后趋于平缓,氧化条件土壤出流液的pH小于还原条件;而Eh正好相反。

THE TRANSPORT OF HEAVY METALS IN SOILS WITH DIFFERENT INITIAL REDOX POTENTIAL I.SINGLE Cd, Cu, Zn IN THE SOIL COLUMN EXPERIMENTS

Heavy metal cadmium , copper and zinc were used to study single and the effect of five different redox potential for transport amounts through an outflow experiment using saturated soil column. The results indicate that oxidizing conditions in the soil, the sequence of the cadmium in the BTCs was Eh = 490mv> 350mv> 240mv. Reducing conditions in the soil, the sequence of the cadmium in the BTCs was Eh = 490mv> 350mv> 240mv. In oxidizing conditions, high redox potential of soil can significantly promote the transport of copper. In reducing conditions, low redox potential of soil can inhibit the transport of copper, which has nothing to do with the reducing agent concentration. The BTCs peak value of zinc in the highly oxidized conditions were significantly higher than the lowly oxidation conditions; and the effect of different reduction conditions for transport of zinc is not obvious. The transport of three heavy metals ions cadmium , copper and zinc in the flow of liquid pH value decreased, then increased and final equilibrium, the flow of fluid oxidizing condition of the soil pH value is less than reducing conditions; and Eh value of just the opposite.