复合污染条件下莴苣对Zn、Cd的吸收与富集

Absorption and Enrichment of Zinc and Cadmium by Lettuce in Complex Contaminated Soil

采集莴苣及根际土壤样品,分析Cu、Zn、Cd、Pb复合污染条件下莴苣对Zn、Cd的吸收与富集规律。结果表明:复合污染条件下,莴苣不同部位对4种重金属元素的吸收积累表现为根>叶>茎,莴苣中重金属含量为Zn>Cu>Cd>Pb,富集系数为Cd≈Zn>Cu>Pb;不同采样区莴苣对重金属的吸收积累与富集能力存在明显差异。用于描述Zn和Cd在土壤-莴苣系统中迁移的响应模型均为非线性方程,模型类型在2种元素之间以及莴苣不同部位存在一定差异,但2种元素在不同部位中的响应均可用3次曲线方程来描述。莴苣对Cd、Zn的吸收除了受到元素自身性质的影响外,还受到共存元素的影响,这种影响与共存元素的含量有关。

It is important for safe use of polluted soils and amendment of the soil environment quality standard to study absorption and enrichment of heavy metals by crops. Samples of lettuce （Lactuca sativa vat. angustana Irish） plants and their rhizospheric soils were collected for analysis of accumulation of Cu, Zn, Cd and Pb in lettuce, and absorption and enrichment of Zn and Cd by lettuce in complex contaminated soil. Resuhs show that in terms of accumulation, contents of the four elements in lettuce was in the order of root 〉 leaf 〉 stem, and Zn 〉 Cu 〉 Cd 〉 Pb, with the bioconcentration factors （BCF） being Cd≈Zn 〉 Cu 〉 Pb. The ability of the lettuces of absorbing and accumulating heavy metals varied significantly with the sampling sites. The response models that may depict transfer of Zn and Cd in the soil-lettuce system are nonlinear ones; and somewhat differ between the two elements and between parts of the lettuce plant. However, all the responses of the two elements in various parts of the lettuce plant can be described with a cubic curve equation. The absorption of Zn and Cd by lettuce is not only affected by elements themselves, but also by co-existent elements, and the effect of the co-existent elements depends on their concentration in the soils.