Heavy Metal Uptake by Rape

Abstract

In pot experiments, the effect of single and combined pollution of soil by lead (Pb), cadmium (Cd), and zinc (Zn) and uptake of heavy metals in Brassica napus L. were investigated. There were two main factors that affected the assimilation of Pb, Cd, and Zn by rape: (i) level of soil pollution by the particular element and (ii) the combined influence of Pb, Cd, and Zn. In general, with the increase of the concentrations of Pb, Cd, and Zn in the soil, there were increases in the concentrations of those elements in the roots, stems, and seeds. The main part of the Pb and Zn amounts taken up by the roots from the soil are fixed and accumulated in the roots, and small amounts of them move through the conductive system to the seeds. Cadmium moves relatively easily from root to stem and is accumulated in higher concentrations in the top of the plant.

There is a well‐expressed synergistic interaction between Pb²⁺ and Cd²⁺, as well as of Cd²⁺ and Zn²⁺. Zinc has a highly depressing effect on the assimilation of Cd²⁺, as does Pb²⁺ on the assimilation of Zn²⁺. The combined pollution by Pb, Cd, and Zn stimulated the assimilation of these elements by the roots and foliage and eliminated the effect of Zn²⁺ on Cd²⁺ and of Pb²⁺ on Zn²⁺.