The effect of heavy metal salts on the maximum and steady-state fluorescence intensity of algae was investigated. Different influence of copper, manganese and cobalt ions on these parameters was shown. The photosynthetic activity coefficient (PAC) calculated on the basis of these parameters correlates with the concentration of heavy metal salts and physiological state of algae. It was found that natural phytoplankton in polluted areas has a lower CFA value than in ecologically clean areas.
