Comparative study of aluminum and copper transport and toxicity in an acid-tolerant freshwater green alga

The effects of aluminium (10-50 ppm) or copper (1-10 ppm) additions on the growth of Chlorella saccarophila cultures at pH 3 were examined. Aluminium caused toxic effects at 10 ppm with increasing growth inhibition to 50 ppm. Copper caused similar toxicity profiles but at lower concentrations than aluminium. Fast-exchange ions, calcium, magnesium, potassium and sodium, offered some protection against both aluminium and copper toxicity. Potassium protected against aluminium toxicity but enhanced copper toxicity. Plasma emission spectroscopy was used to investigate bioaccumulation of aluminium, copper and iron from culture media and acid mine water. The metals were accumulated at different levels with significant iron accumulation. Cytoplasmic changes in cell walls and chloroplasts resulted from metal stress.