The uptake of zinc (Zn) by the duckweed Lemna gibba L., native to the north-east region of Algeria, was investigated in quarter Coic solutions enriched with 6.0, 10.0, 14.0 and 18.0 mg l(-1) of Zn supplied as zinc sulphate (ZnSO(4)). 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 degrees 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. (C) 2009 Elsevier Ltd. All rights reserved.