Toxicity Evaluation of Metals and Metal-oxide Nanoparticles based on the Absorbance, Chlorophyll Content, and Cell Count of Chlorella vulgaris

In this study, toxicities of seven metals (Cu, Cd, Cr, As(III), As(V), Zn, Ni) and five metal oxide nanoparticles (NPs: CuO, ZnO, NiO, TiO2, Fe2O3) were evaluated based on the growth of Chlorella vulgaris. Effect on algae growth was evaluated by integrating the results of absorption, chlorophyll content, and cell count. The toxicity rankings of metals was observed as Cr (0.7 mg L) > Cu (1.7 mg L) > Cd (3.2 mg L) > Zn (3.9 mg L) > Ni (13.2 mg L) > As(III) (17.8 mg L) ≫ As(V) (> 1000 mg L). Slightly different orders and sensitivities of metal toxicity were examined depending on endpoints of algal growth. In case of NPs, regardless of endpoints, similar toxicity rankings of NPs (TEC50) were observed, showing ZnO (2.4 mg L) > NiO (21.1 mg L) > CuO (36.6 mg L) > TiO2 (62.5 mg L) > Fe2O3 (82.7 mg L). These results indicate that an integrating results of endpoints might be an effective strategy for the assessment of contaminants.