Toxic Effects of Nano-TiO2 on Gymnodinium breve
纳米TiO2对短裸甲藻的毒性效应

In order to reveal the toxicity and mechanism of nano-TiO2 on algae, the inhibition effect, enzyme activity, oxygen free radicals of nano-TiO2 on the growth of G. breve were investigated. The results showed that G. breve was inhibited by nano-TiO2, and the 72 h-EC50 was 9.7 mg·L-1. With the increasing concentration of nano-titanium dioxide, the activities of SOD decrease significantly(P<0.05). The content of hydrogen peroxide radicals and the activities of CAT increase significantly(P<0.05), and the content of superoxide anion shows the increasing trend. The content of hydrogen peroxide radicals was 0.083 U·mL-1 in 0 mg·L-1nano-TiO2 suspension while that was 1.1 U·mL-1 in control after 48 h. Through the study of 20 mg·L-1 nano-titanium dioxide on G. breve at different times, the activities of SOD and CAT, the content of MDA are consistent, which the highest values is achieved at the exposure time of 12 hours and the lowest value is found at the exposure time of 48 hours. The content of hydroxyl radical increased significantly at the exposure time of 48 hours. The activity of SOD was 0.14 U·(107 cell·min)-1in G. breve at 12 h which was ten times higher than that at 48 h.