干旱区绿洲受污染土壤中Cd和Pb在油菜中的累积与迁移

Accumulation and Migration of Cd and Pb in Cole Grown in the Arid Oasis Soil

运用Tessier五步连续提取法研究干旱区绿洲受污染土壤中重金属Cd、Pb在油菜中的积累与迁移。结果表明,①原状土中Cd主要以碳酸盐结合态为主,Pb主要以残留态为主,随着外源性Cd投加量的增加,交换态、碳酸盐结合态、铁锰氧化物结合态含量增大,有机结合态、残留态含量随投加量的增加有所减少,且残留态呈锐减趋势,各形态Pb含量均随投加量的增加而升高,碳酸盐结合态、铁锰氧化物结合态Pb的含量增幅较大。②随着外源性Cd、Pb投加量的增加,油菜根和叶中累积的Cd、Pb含量随之增加。用土壤中各形态Cd、Pb的含量与油菜叶和根部累积的Cd、Pb含量做逐步回归分析,发现土壤中的碳酸盐结合态Cd、Pb与油菜叶和根部累积的Cd、Pb含量呈极显著相关。表明碳酸盐结合态对油菜各器官Cd、Pb的累积有最大贡献。③油菜叶和根部Cd的富集系数均大于1,Pb的富集系数均小于1。Cd的富集系数大于Pb,表明油菜吸收Cd的能力大于Pb,其毒害作用也相应大于Pb;Cd的富集系数叶部均大于根部,表明Cd在油菜中的迁移性较强;Pb叶部的富集系数小于根部,表明Pb主要在油菜根部累积,迁移性较差。

Tessier＇s five-step sequential extraction procedure was used to study the accumulation and migration of Cd and Pb in the cole grown in arid oasis soil.The results showed that：（i） Cd existed almost in carbonate fraction in uncontaminated oasis soil existed almost in carbonate fraction and Pb existed in residual fraction,with the increase of Cd concentrations added increased,Cd contents of exchangeable fraction,carbonate fraction and Fe-Mn oxide fraction also increases in the soil,but those of organic fraction and residual fraction decrease.with Pb concentrations added increased,all fractionations content increase in the soil.carbonate fraction and Fe-Mn oxide fraction have obviously increased.（ii） With Cd and Pb concentrations added increased,content of cole organs also increase correspondingly.And significant correlationship between the concentration of Cd and Pb fractionations in soil and the amount of Cd and Pb uptake by cole organs was detected by step regression analysis between the concentration of Cd and Pb fractionations in soil and Cd and Pb contents in by cole organs,which showed that the carbonate fraction in soil have the greatest contribution to Cd and Pb on the accumulation in the cole organs.（iii）The Bio-concentration Factors（BCF） of Cd in the cole leaves and roots were all greater than 1,but BCF of Pb were all smaller than 1.BCF of Cd was greater than BCF of Pb.It shows that Cd has stronger accumulation ability in the cole,but its toxicity also greater than Pb.BCF of Pb in the cole leaves was greater than in the cole roots,it shows Cd has stronger migration ability;BCF of leaves were smaller than in roots.Its shows that Pb major accumulate roots of cole,and has poor migration ability.