Effects of heavy metals and aluminum on the root physiology of spruce ( Picea abies Karst.) seedlings.

Abstract

Toxicity of the heavy metals Zn, Cd, Hg and Pb and organic complexes of Hg and Pb to 4-wk old Picea abies seedlings was assessed by estimating the effects of these metals on root elongation. The order of toxicity was Hg > Pb > Cd > Zn, with Hg being >100 times more toxic than Zn. Methyl-Hg was considerably more toxic than HgCl2, due to its chemical form and not to a greater uptake. Lead supplied as triethyl, diethyl and dimethyl lead complexes was also more toxic than PbCl2, but there was no significant difference between the toxicity of the organic lead complexes. In short-term uptake experiments (5 h), uptake of Cd into roots of Picea abies was influenced by the ionic composition and pH of the uptake solution. Cd uptake decreased with decreasing pH, and increased with decreasing Ca supply. Al and Mn inhibited Cd uptake, whereas Hg and Zn produced a slight stimulation in uptake. -from Authors