Effects of Cd, Cr, and Zn on growth and metal accumulation in an aquatic macrophyte, Nitella graciliformis
M. Hawa Bibi,
The effect of heavy metals (Cd, Cr, and Zn) on the growth of the freshwater macrophytic Nitella graciliformis J. was observed under laboratory conditions and their accumulations in the plant were measured. The experimental plant was exposed to three different concentrations of Cd (25, 50, 150 μg L-1), Cr (150, 500, 1000 μg L-1), and Zn (150, 500, 1000 μg L-1) for 35 days. The heavy metal concentrations in the plant increased with the increasing Cd, Cr, and Zn concentrations in the mediums. The highest concentration of Zn that accumulated in the plant tissues was 2540 μg g-1 Zn at 1000 μg L-1 medium compared to 547 μg g-1 Cr at 1000 μg L-1 and 290 μg g-1Cd at 150 μg L-1 mediums. As a result, negative growth occurred and the internode elongation was reduced when exposed to these metals at any concentration. We concluded that under experimental conditions, intracellular green alga Nitella graciliformis has a potential for accumulating Cd, Cr, and Zn.