Effect of short term exposure of ZnO and TiO2 nanoparticles on algae: Chlorella pyrenoidosa & crustacean: Daphnia sp.

Abstract

Zinc oxide (ZnO) and Titanium dioxide (TiO 2 ) nanoparticles are some of the widely used nanoparticles (NPs) in commercial industry. Thus the chances for the particles to get run off to the aquatic environment and to there by affect the aquatic life are very high. The present study evaluates the short term toxicity of ZnO NPs and TiO 2 NPs on Chlorella pyrenoidosa, which is a fresh water algae and on Daphnia sp. which is a common crustacean found in fresh water bodies. NPs were synthesized via chemical co-precipitation technique and characterized using UV-visible spectroscopy, X Ray Diffraction, Scanning Electron Microscope, particle size sizer and zeta sizer. The dosage of the particles was from 0.001 mg/L to 100 mg/L. The study evaluated the chlorophyll content, lipid peroxidation, intracellular protein and extracellular protein as a measure of toxicity against C. pyrenoidsa. The study found that the algae produced excessive amount of extracellular polysaacharides when it gets interacted with the NPs. The light microscopic evaluation also found agglomeration of algal cells when interacted with NPs. The mortality of Daphnia sp. was also studied both in the dark condition and as well as after the irradiation of visible light. The interacted organisms were observed under phase contrast microscope and the images were taken.