الخلاصة

The current research was an experimental conducted in vitro to examine some heavy metals; (Cd+2, Co+2, and Cr+6) for uptake capacities of Lemnagibba .The selected macrophyte was taken to the laband exposed to solution enriched with 0.5, 1.0, 3.0, and 6 mg/lof cadmium, 0.5,1.0, 2.5 ,and 5 mg/l of cobalt and chromium and were separately harvested after day 1, 7, and 15. Measurements were calculatedin the study period; (Total chlorophyll, Chlorophyll a, Chlorophyll b, Total protein, Superoxide dismutase enzyme and Catalase enzyme). Concentrations of heavy metals in plant and water were measured and thus, bioconcentration factor (BCF) was calculated. The results showed that for cadmium, BCF was higher as 59.2 at 1 mg/l on day 15 and low as 0.8at 0.5 mg/L on day 1.Cobalt and chromium concentrations on the other hand, were (0.5,1,2.5 and 5) mg/L and BCF higher value was 61.5 and 5.4 at 1 mg/L and0.5 mg/L on day 15 and day 1respectively. Removal ratio of Cd and Co at 1 mg/L onday 15 were 78 % and 79 % respectively, but recorded 60% at 2.5 mg/L for Cr+6 on day 15. Accumulation for the Cd metal increased gradually with day 7 and day 15 and its highest value was at 3 ppm onday 15, while Cd concentration in the medium decreased gradually throughout the experiment period without producing any toxicity or reduction in growth. Accumulation of cobalt and chromium in plant increased during day 7 and day 15 and its highest value was at 2.5 ppm on day 15 and at 5 ppm onday 7 respectively. The results of the study showed a decrease in protein content in plants during the experiment period, and decreased in the amount of chlorophyll onday 15. The results in the current study showed an increase in the effectiveness of SOD enzyme but a decrease of catalase enzyme during the period of stress of metals on day 15.