干旱区绿洲土壤外源Cd、Pb的形态分布及再分配

Special distribution and redistribution of Cd,Pb added in arid oasis soil

以干旱区绿洲土壤为研究对象,采用Tessier连续提取技术对外源Cd和Pb的形态分布与再分配进行了研究。结果表明:在盆栽试验完成后,Cd和Pb主要以碳酸盐结合态和铁锰氧化态存在。Cd的全量是影响其可交换态、碳酸盐结合态和铁锰氧化态含量的主要因素,而有机物结合态和残渣态受其它因素的影响也较大。Pb的全量是其各种形态含量的主要影响因素。随着Cd和Pb添加量的增加,其土壤总的再分配系数呈增加趋势,结合强度系数则相反,表明Cd和Pb各形态间的稳定性下降。随着时间的推移,二者各形态会继续发生变化,但这一过程缓慢。因此,土壤重金属污染具有长期性。

Soil samples were collected from the arid oasis region and studied. Special distributions and redistributions of Cd and Pb added were investigated using Tessier sequential extraction. The results showed that Cd and Pb exist mainly in carbonate - bound forms and Fe - Me oxide bound forms. The total concentration of Cd is the main influence factor for exchangeable form, carbo -nate - bound form and Fe - Me there may exist other influencing fac - tors for organic - bound form and residual form. oxide - bound form, and The total concentration ofPb is the the main influence factor of all forms. The redistribution index of the studied soil presented the increas- ing trend, and the binding intensity index of the studied soil is on the opposite side of it as the con - centrations of Cd and Pb added increase. This indicates that the stability between various forms descend under the same con- ditions. As time goes on, all forms of Cd and Pb continue to change, but this process is slow. So the pollution of heavy metals exist long time.