Phytoaccumulation of zinc by the aquatic plant, Lemna gibba L.

The uptake of zinc (Zn) by the duckweed Lemna gibba L., native to the north-east region of Algeria, was investigated in quarter Coïc solutions enriched with 6.0, 10.0, 14.0 and 18.0 mg l⁻¹ of Zn supplied as zinc sulphate (ZnSO₄). Zinc concentrations were measured in the water daily and in duckweed biomass at the end of the experiments. These results showed that under experimental conditions (pH = 6.0 ± 0.1, T = 21 ± 1 °C, photoperiod = 12 h/j), L. gibba was able to accumulate in its biomass 4.23; 15.62; 23.88 and 25.81 mg g⁻¹ DM, respectively for the four initial concentrations selected. At these concentrations, the metal removed percentages were 61–71%. The mass balance performed on the system showed that about 49–68% of Zn (depending on the initial concentration in water) was removed by precipitation as zinc phosphate. The results showed that this aquatic plant can be successfully used for Zn removal.