Cobalt‐copper and cobalt‐zinc effects on duckweed growth and metal accumulation

Abstract

Zn⁺², Cu⁺² and Co⁺² were added to Jacob nutrient medium with constant pH value at concentrations ranging from 0.10–10.0 ppm, 0.20–2.00 ppm and 0.20–20.0 ppm, respectively. The IC50's for these metals as well as their effects on the growth and the accumulation efficiency by Lemna minor L. were determined. The IC50's for Co⁺², Zn⁺²and Cu⁺² were 16.90, 10.00 and 1.54 ppm, respectively. At 0.20–2.00 ppm concentrations, the potential of Lemna minor L. to accumulate these metals with respect to their inital concentrations in the medium was in the following order: Co⁺² > Zn⁺² > Cu⁺². The effects of the metal pairs of Co⁺²‐Cu⁺² and Co⁺²‐Zn⁺² at concentration levels ranging from 0.10 to 2.00 ppm were also tested. The accumulation of Zn⁺² was stimulated by Co⁺² and the accumulation of Co⁺² was inhibited by Zn⁺². Also a decrease in the growth of Lemna minor L. was observed, especially at 2.00 ppm. The accumulation of Co⁺² was suppressed by Cu⁺², whereas the accumulation of Cu⁺² was slightly promoted by Co⁺². The growth Inhibition effect of Cu⁺² was not changed by Co⁺² at 0.10 through 1.00 ppm, but at 2.00 ppm, Co⁺² reduced the growth Inhibitory effect of Cu⁺².

Key words:

• L.minor L., copper
• zinc
• cobalt.

Notes

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