绿洲油菜根际土壤中Cd,Pb赋存形态特征及其互作影响

The characteristics and interaction effects of Cd,Pb in oasis cole soil

采用盆栽试验,设计了Cd、Pb以及Cd/Pb复合胁迫三种污染情景模式种植油菜,利用Tessier连续提取法对绿洲油菜地土壤重金属元素的形态含量及比例特征进行了分析。结果表明:干旱区绿洲油菜地原状土壤中Cd和Pb分别主要以铁锰氧化物结合态及残渣态形式存在,而添加可溶性Cd和Pb后,两金属的主要赋存形态均为碳酸盐结合态。在任何浓度添加水平,可交换态Cd,Pb对外界浓度胁迫响应最大,残渣态响应最小。三种污染情景模式下油菜根际土壤中Cd,Pb形态拟合方程及生物活性系数的对比分析表明:两金属的互作对各元素活性的影响为:Pb的加入抑制Cd的土壤活性,而Cd的共存则促进Pb的土壤活性。

Pot experiments were conducted on coles（Brassica） grown in oasis soils jointly treated with traces of two heavy metals： cadmium（Cd） and lead（Pb）.Three scenarios of Cd,Pb and Cd-Pb were designed to compare the interaction of speciation between the Cd and Pb.The results obtained from Tessier＇s sequential extraction schemes indicated that Cd and Pb were mainly separately bounded with Fe-Mn fraction and residual fraction in controlled soil,while the carbonate fraction in amended soil.Under the control and stress of exotic Cd and Pb,exchangeable fractions of these two metals were always the most sensitive to the changes.However,residual fractions showed less influence.Comparing study which focused on regression equations and Mobility Factor（MF） of Cd,Pb under three scenarios revealed that Pb could weaken the availability of Cd,and Cd could facilitate the availability of Pb in cole＇s soil.