Cd-HA-TiO2联合胁迫对小球藻致毒效应的研究

以小球藻为受试生物，研究Cd-HA-TiO2联合暴露体系对小球藻的毒性作用.实验结果表明，Cd单独作用、Cd-HA和Cd-TiO2联合作用下，Cd的96h-EC50分别为:0.166、0.185~0.207和0.185~0.199mg/L，以上结果说明当HA或TiO2存在情况下，可以降低Cd对小球藻的生物毒性，这主要是由于HA或TiO2可以吸附水中Cd，降低体系中自由金属离子的浓度，进而减弱了Cd的生物毒性.但在Cd-HA-TiO2三者联合作用下，Cd的96h-EC50降低到0.063~0.089 mg/L.表明当HA、TiO2同时存在时，Cd对小球藻的生物毒性显著增强. 通过检测暴露后的丙二醛(MDA)、过氧化氢酶（CAT）和超氧化物(KAT)水平，发现Cd-HA-TiO2联合作用时，小球藻的CAT水平显著高于其他暴露条件(P0.05)；细胞内Cd分布实验结果显示三者联合暴露显著促进了小球藻细胞内的Cd的生物累积量（P0.05）.因此，小球藻的氧化性损伤（CAT水平）和Cd的生物积累水平可能解释了三者联合暴露导致Cd毒性显著增强的原因.

Combined Toxicological Effects of Cd-HA-TiO2 on Chlorella

Chlorella was selected to test the combined toxicological effects of Cd-HA-TiO2.The present results showed that the 96h-EC50 of single Cd，Cd-HA and Cd-TiO2 were 0.166， 0.185~0.207 and 0.185~0.199mg/L， respectively，indicating that the toxicity of cadmium would be attenuated in the presence of HA or TiO2. This was mainly due to the reduction of free Cd ion through combination of HA and TiO2. However，the 96h-EC50 of Cd-HA-TiO2 was decreased to 0.063~0.089 mg/L，indicating that the toxicity of cadmium was significantly increased in the presence of HA and TiO2 existed. Chlorella showed highest CAT level after exposure to Cd-HA-TiO2 compared to other conditions. In addition，the bio-accumulation level of Cd was highest after exposure to Cd-HA-TiO2. This may explain that the highest toxicity was observed on the Cd-HA-TiO2 exposure group.