中文摘要：

为了揭示纳米TiO2对藻类的毒性作用和机制,研究了纳米TiO2对短裸甲藻的抑制特性及对酶活性、氧自由基等生理指标的影响.结果表明,纳米TiO2对短裸甲藻的生长有抑制作用,72 h半数致死浓度（EC50）为9.7mg·L-1.在受试范围内随着纳米TiO2浓度的升高,超氧化物歧化酶（SOD）的活性显著性下降（P〈0.05）,随TiO2浓度增加,羟自由基的含量和过氧化氢酶（CAT）的活性显著性增加（P〈0.05）,超氧阴离子自由基含量也呈现升高的趋势.对照组羟自由基的含量是0.083 U·mL-1,而在30 mg·L-1的纳米TiO2作用下,羟自由基的含量上升到1.1 U·mL-1.在20 mg·L-1纳米TiO2作用下,随着时间的延长,SOD活性、CAT活性和MDA（丙二醛）在暴露时间为12 h时达到最大,而48 h时降低到最小.12 h SOD的活性是0.14 U·（107 cell·min）-1,而48 h SOD的活性为0.01 U·（107cell·min）-1,而羟自由基只在48 h处呈显著性上升（P〈0.05）.纳米TiO2对抗氧化体系和自由基的影响可能与其抑藻机制有关.本研究为揭示纳米材料的环境生态效应提供了基础.

英文摘要：

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.