THE UPTAKE AND DISTRIBUTION OF HEAVY-METALS BY SPRING WHEAT

Pot experiments were carried out with two soils from long-term field experiments to examine heavy metal distribution in spring wheat. The soils (Luvisol pH 6.5 and Cambisol pH 5.5) were manured with sewage sludge for 18 ys and now show heavy metal contamination. The Cd-, Zn-, Pb- and Cr-contents of the grain were appreciably lower than those of straw. Nickel and Cu levels in the grain, however, exceeded those of the straw. In the unpolluted control the grain was enriched in Zn. Grain with a Cd-content lower than the German guide value was produced only with Cd concentrations of the soil lower than 0.5 mg kg-1 and a pH value greater than 5.7. Higher Ni and Pb contents were found in the chaff than in the straw. Roots were enriched in Cd, Zn, Ni and Cu, as compared with the soil. However, Pb and Cr were hardly taken up by the roots. Liming decreased the Cd-, Zn- and Ni-content in the plant. pH variation was found to have a negligible effect on the uptake of Cu, Pb and Cr.