Effects of Nano-Sized Titanim Dioxide (nTiO<sub>2</sub> ) on the Growth and Biophysical Characteristics of Chlorella sp.

Abstract

The study was conducted to investigate the effects of nano-sized titanium dioxide (nTiO2 )on the growth and biophysical characteristics of Chlorella sp.. Chlorella sp. was cultured in HB-4 medium and exposed to 7 levels(0,1,5,10, 20, 40 and 80mg/L)of nTiO2.The results showed that EC50 of nTiO2 was 26.52 mg/L after 96-hr exposure. In 5 levels (0,10, 20, 30 and 40mg/L)of nTiO2 after 96-hr exposure, the content of Chl-a and the soluble protein was reduced with the increasing concentrations. Because of nTiO2 caused the increase of permeability of Chlorella sp.'s membrane, some soluble materials got out of Chlorella sp.'s cell, such as polysaccharide.The value of conductivity and polysaccharide content was increased with concentrations. When the concentrations of nTiO2 were higher than 20mg/L, the physiological function of Chlorella sp. was inhibited obviously, and the activity of peroxidase and dehydrogenase decreased. As a result, there was the potential harm to the aquatic environment by using nTiO2.So the toxicity of nTiO2 and the mechanism of aquatic lives deserved special concern.