水分及干燥过程对土壤重金属有效性的影响

土壤水分变化可显著改变土壤性质进而影响土壤重金属有效性。本试验通过测定土壤溶液和采用薄层凝胶梯度法(DGT)表征的Zn、Cd、Cu、Ni浓度,研究土壤含水量变化对重金属有效性的影响。结果表明,不同水分处理显著影响土壤溶液中可溶性有机碳(DOC)含量和土壤中重金属的有效性;随土壤水分降低DGT表征的Zn、Cd、Cu和Ni浓度和土壤溶液中Cu和Ni浓度呈下降趋势,且随干湿交替次数增加而降低;与长期风干土壤相比,经干湿交替后风干土壤重金属有效性降低或显著降低;与土壤溶液法相比,DGT法能反映水分变化对土壤固相金属缓冲补给能力的影响,能更好地表征土壤金属有效性的变化。在农业生产中可通过适当水分管理措施降低重金属的有效性,从而缓解重金属的毒害作用。

Influence of Moisture and Drying Process on Soil Heavy Metal Availability

Soil moisture changes can significantly affect soil properties and lead to the change of soil heavy metal availability. In this study, the effects of moisture and drying process on soil heavy metal availability were studied by investigating Zn, Cd, Cu, Ni concentrations represented by DGT and in soil solution. The results showed that soil drying process could decrease DOC concentration of soil solution and change soil heavy metal availability. Zn, Cd, Cu, Ni availability evaluated by DGT and concentrations of Cu, Ni in soil solution decreased with the soil water contend decreasing during soil drying processes; compared with the soil with long dry duration, the dry soil subjected with dry-wet cycle decreased or significantly decreased in heavy metal availability. Compared with the method evaluating metal availability by determining metal in the soil solution, DGT can reflect on the effects of soil moisture on metal buffer supply ability from the solid metal, and give much better evaluation to soil metal. In agricultural production, appropriate water management can be used to reduce the availability of heavy metal, thus alleviate the toxicity of heavy metal.