BIO-CHEMICAL BIOMARKERS IN ALGAE SCENEDESMUS OBLIQUUS EXPOSED TO HEAVY METALS CD, CU AND ZN

Laboratory studies were conducted to determine the effects of different concentrations of Cu, Cd, Zn and mixture (equal concentrations from the three heavy metals) on growth and some oxidative stress (catalase and glutathione resuctase) on Scenedesmus obliquus (microalgae) after exposure to 24, 48, and 96 h. In addition, the uptake of Cu, Cd and Zn were determined in the culture medium after 24, 48 and 96h of exposure. The catalase and glutasthion resuctase enzyme activities were used as biomarkers to evaluate the toxic effects of Cu, Cd, Zn and mixture (equal concentrations from the three heavy metals) on the microalgae. Enzymatic activities were measured in the presence of each compound alone after 24, 48 and 96 h and also inmixture after the same time of exposure. The results showed that Cu, Cd, Zn and mixture induced antioxidative enzyme activities (CAT and GR) at different concentrations. Catalase activities (CAT) in both heavy metals treatedalgae were significantly increased. Additionally, a decrease in Chl.a, Chl.b and caritenoids was observed in algae after 24, 48 and 96 h of exposure to both Cu, Cd, Zn and mixture (equal concentrations from the three heavy metals).