河北主要土壤中Cd和Pb的形态分布及其影响因素

采用网室盆栽试验和大田取样 ,运用连续提取方法 ,研究了河北平原潮土和潮褐土两种土壤中Cd、Pb的化学形态特征及与其影响因素的关系。结果表明 :随着Cd、Pb污染程度的增加 ,其交换态有增加趋势。当高浓度重金属污染土壤时 ,Cd(潮土 >1mgkg- 1、潮褐土 >5mgkg- 1)主要以交换态存在 ,并表现为 :交换态 >碳酸盐结合态 >铁锰氧化物结合态 >有机结合态 >残留态 ;Pb主要以碳酸盐结合态和铁锰氧化物结合态存在。在低浓度重金属污染的土壤中 ,Cd (潮土 <1mgkg- 1、潮褐土 <5mgkg- 1)的残留态、有机结合态成倍增加 ,甚至超过交换态 ,表现为 :残留态 >碳酸盐结合态 >有机结合态 >交换态 >铁锰氧化物结合态 ;Pb主要以铁锰氧化物结合态和残留态存在。Cd、Pb在土壤中的分布与土壤的pH值 ,有机质含量密切相关。

DISTRIBUTION OF CADMIUM AND LEAD FORMS AND ITS AFFECTING FACTORS IN SOILS OF HEBEI PROVINCE

Successive extraction method was adopted to study the characteristics of chemical forms of Cd and Pb in alluvial meadow soil and meadow cinnamon soil in the plain of Hebei, and the relationship between the forms of Cd, Pb and factors affecting it by pot experiment and field sampling. The results showed that Cd, Pb contents of exchangeable form increased and those of carbonate combined and residual forms decreased with the increase of pollution extent in field soils. Cd, Pb contents of exchangeable and carbonate combined forms increased and those of organic and residual forms decreased with the increase of Cd, Pb added concentration in pot soils. Most of Cd was present in the exchangeable form(the order is: EXC>CAB >OXI>ORG>RES), and the most amount of Pb was associated with the carbonate and Fe-Mn oxide combined forms in heavy metal highly polluted soils. In lowly polluted soils, the residual and organic forms of Cd increased significantly (the order is: RES>CAB >ORG >EXC>OXI), and most of Pb was present in Fe-Mn oxide combined and residual forms. The concentration and proportion of the exchangeable and Fe-Mn oxide combined forms in alluvial meadow soil were lower than in meadow cinnamon soil.The major factor which effect on the chemical forms of Cd, Pb in soils were pH and the organic content.