EFFECT OF COPPER AND ZINC ON MICROALGAE

ABSTRACT

This study investigated the effects of copper and zinc on Chlorella vulgaris and Dictyosphaerium pulchellum and was carried out in the laboratory. Concentrations of the test heavy metals were 0mg/l, 2mg/l, 4mg/l, 6mg/l, 8mg/l, 10mg/l and 20mg/l. The growth of the test microalgae was determined optically every two days for 14 days. The results showed that the effects of the test  heavy metals were generally concentration-dependent. In subsequent tests with lower concentrations of zinc, Chlorella vulgaris exhibited growth, but with lesser dynamics than in the case of the control sample. From the two microalgae species tested,  Chlorella vulgaris alone showed growth up to 8mg/l concentration of zinc metal. It was observed that in Dictysphaerium pulchellum, different copper concentrations  had minimal growth except the 2mg/l which seemed to have a relatively higher growth. In contrast, the zinc concentrations all had comparable growth. The growth of the control was remarkably higher than all the other concentrations. Generally the above heavy metals inhibited the growth of Dictyosphaerium pulchellum and Chlorella Vulgaris. Comparatively, copper generally inhibited the growth of both test algae than zinc. Chlorella vulgaris can be used for high concentrations zinc.