Abstract
Studies on toxicity and bioaccumulation of lead, cadmium and zinc in the blue-green alga Chroococcus minutus and the green alga Chlorococcum aegyptiacum were conducted by short-term bioassays using toxicity symptoms, scientific growth rate, chlorophyll a, removal % and bioaccumulation factor parameters. The toxicity symptoms of the studied metals include increasing in crystalline inclusions, aggregation of thylakoid membranes at the sides of the cell and partial disorganization of the cell wall in the case of Chroococcus minutus and a major change in shape of cell wall, damage of chloroplasts, reduction in number of chloroplasts, complete disorganization of the cell components and formation of granules and disintegrated cell wall and cell death in the case of Chlorococcum aegyptiacum. There were significant decreases in the specific growth rate and chlorophyll a contents when the metal concentrations were increased. The removal % and bioaccumulation factor (BCF) of Zn were higher than that of Cd and Pb suggesting that the accumulation potential of the studied two microalgae for Zn was higher than that for Cd and Pb.