Zinc and Cobalt Bioconcentration and Toxicity in Selected Algal Species

Abstract

This investigation was concerned with toxicity and bioconcentration of zinc and cobalt in three species of algae as reflected by growth inhibition, algal accumulation of metal, and percentage uptake. Although there was generally an overall growth decrease from lower to higher metal concentrations (with the exception of the 2x zinc concentration), increased uptake and concentration of metals occurred in all three algal species. Therefore, the lower cellular weights resulting from high metal concentrations were more effective in accumulating zinc and cobalt. Chlorella vulgaris had a higher percentage uptake of zinc but a lower percentage uptake of cobalt than did Euglena viridis and Pediastrum tetras. Chlorella vulgaris thrived in surprisingly high concentrations of zinc. Euglena viridis concentrated the greatest amount of zinc, while both P. tetras and E. viridis had a higher affinity for cobalt than did C. vulgaris. Concentration of metal to an extreme degree was evident in all species studied. The three species, therefore, could accumulate trace metals to an extent that might make them toxic in the food chain. Moreover, all test species could be effective as biological filters to help remove zinc and cobalt from polluted water.