USE OF CHLOROPHYLL FLUORESCENCE TO EVALUATE THE EFFECT OF CHROMIUM ON ACTIVITY PHOTOSYSTEM II AT THE ALGA SCENEDESMUS OBLIQUUS

Industrial activities are significant sources of contamination of aquatic environments by heavy metals such as chromium. The latter occurs in two forms, trivalent or hexavalent, trivalent Cr is a trace element essential to the human body but its hexavalent form is toxic and very harmful to human health. Unfortunately, this form is found in abundance in industrial effluents and urban areas due to industrial activities, such as chromium metal and wood preservation 17 . In industrialized countries such as Quebec the use of Cr is much smaller because of its toxicity, but this will not lead to its total disappearance in the ecosystem. Maybe it will disappear from the air, soil and end up in the sea then in the fish we eat. While in developing countries its use is still present. The photosynthetic apparatus of plants represents a target sensitive to these pollutants. In this project we will study the mechanism of toxicity of chromium on chlorophyll synthesis and electron transfer between photosystem II and photosystem I in the alga Scenedesmus obliquus. The yield and kinetics of chlorophyll fluorescence were used to evaluate the photochemical alteration of photosystem II. Our results provide an indication of the degree of toxicity of chromium on the photosynthetic apparatus of algae and can also be used to develop biomarkers photosynthetic sensitive to the toxicity of heavy metals.