Biological Toxicity of Five Metal Ions on Marine Algea

Abstract

Internationally validated methods (ISO standards) for the determination of toxic effects were used in this study to evaluate the toxicity of metals [i.e. Hg, Cu, Zn, Pb and Cd] to a kind of marine algae, namely Chlorella autotrophica. In the test, the no observable effect concentration (NOEC) and the effective concentration for 50% of test algae (EC50) were obtained after 96-h of incubation at 25±1°C, by comparing the growth of the Chlorella autotrophica in the test samples and in the control. Among the 5 metal ions, mercury (Hg) was found to be the most toxic metal in the test (EC50=1.04 mmol/L), while cadmium (Cd) was the least toxic (EC50=151.37 mmol/L). The results from the Chi-square test of each dose-response equations showed that 96h-EC50s calculated were all precise and credible. According to both NOEC and 96h-EC50, the toxic sequence of these metals from high to low on the inhibition of Chlorella autotrophica’s growth was Hg2+, Cu2+, Zn2+, Pb2+ and Cd2+.