石灰对Cu、Cd、Pb、Zn复合污染土壤中重金属化学形态的影响

EFFECTS OF LIME ON CHEMICAL FORMS OF HEAVY METALS UNDER COMBINED POLLUTION OF Cu,Cd,Pb AND Zn IN SOILS

通过室内模拟试验,研究了石灰对不同处理(轻度、中度、重度)水平下土壤典型重金属Cu、Cd、Pb、Zn化学形态的影响。结果表明:添加石灰60 d后土壤pH值、有机质含量均明显升高,4种重金属化学形态总体呈现由水溶态、交换态等活性态向有机态、残渣态等非活性态转化的趋势,其生物活性、迁移能力及淋溶能力均有不同程度下降,表明石灰是土壤重金属复合污染的有效修复剂。同时,不同处理水平下土壤4种重金属对石灰添加量的响应有差异,其中土壤Cu、Cd生物活性受石灰添加量影响较小,但中度、重度处理下土壤Pb、Zn生物活性和Cd、Zn迁移能力以及轻度处理下土壤Pb迁移能力均随着石灰添加量增加而显著降低,轻度处理下重金属淋溶能力在0.2 g石灰时最低,在中度、重度处理下随着石灰添加量增加而降低。

The research was constructed to investigate the effects of lime on heavy metal chemical forms under combined pollution of Cu, Cd, Pb and Zn in soils with different treatment levels(mild, moderate, severe) based on results of simulated experiment. The heavy metals fractions in soils were analyzed by using Tessier method. The results showed that the pH values and organic matter contents of the soils increased obviously 60 days later after adding lime. The chemical morphology of four heavy metals presented the trend of the transformation from the active state(such as the water soluble state and the exchange state) to the non-active state(such as the organic state and the residue state). In general, the biological activity, migration ability and leaching ability of the four heavy metals declined, which indicated that lime was an effective modifier for soil heavy metal compound pollution. Meanwhile, the response of the heavy metals of different treatment levels to the addition of lime was different. The biological activity of Cu and Cd was less affected by adding lime. However, the biological activity of Pb, Zn under moderate and severe treatment, the mobility ability of Cd and Zn under moderate and severe treatment, and Pb under mild treatment were all significantly reduced with the increase of lime. Four heavy metal leaching ability value were lowest under mild treatment with 0.2 g lime, and decreased with the increase of lime in moderate and severe treatment.