氧化锌和二氧化钛纳米颗粒对淡水绿藻的单一及联合毒性研究

以氧化锌纳米颗粒(ZnO NPs)和二氧化钛纳米颗粒(TiO_2 NPs)为研究对象,考察了ZnO NPs和TiO_2 NPs对两种淡水绿藻(斜生栅藻和蛋白核小球藻)的单一及联合毒性。结果表明:在不同的暴露时间下,ZnO NPs对淡水绿藻的生长抑制毒性均明显高于TiO_2 NPs,且溶解释放的Zn~(2+)在ZnO NPs对斜生栅藻毒性效应中的贡献高于其在ZnO NPs对蛋白核小球藻毒性效应中的贡献。ZnO NPs和TiO_2 NPs对斜生栅藻的联合毒性大于其对蛋白核小球藻的联合毒性,且ZnO NPs的毒性在二元混合物毒性中占主要贡献。ZnO NPs与TiO_2 NPs对斜生栅藻的联合毒性作用方式在混合暴露浓度小于1 mg·L~(-1)时表现为加和,而在混合暴露浓度大于1mg·L~(-1)时表现为拮抗;二元混合物对蛋白核小球藻在24 h的联合毒性作用方式表现为协同,而在48 h和72 h的联合毒性作用方式表现为拮抗。不同的暴露时间下独立作用模型对二元混合物毒性的预测能力均强于浓度加和模型,另外ZnO NPs和TiO_2 NPs对淡水绿藻的联合毒性机制与纳米颗粒诱导活性氧物种生成,引起藻细胞氧化应激有关。

Single and joint toxicity of zinc oxide and titanium dioxide nanoparticles for freshwater algae

In this work the single and joint toxicity of zinc oxide(ZnO) nanoparticles(NPs) and titanium dioxide(TiO₂) NPs to two freshwater green algae, namely Scenedesmus obliquus and Chlorella pyrenoidosa, were investigated. Results showed that at different exposure durations, the growth inhibition toxicity of ZnO NPs to freshwater green algae was significantly higher than that of TiO 2 NPs. In addition, the contribution of dissolved Zn²⁺-ions to the toxicity of ZnO NPs to S. obliquus was higher than that of dissolved Zn²⁺-ions to the toxicity to C. pyrenoidosa. The joint toxicity of ZnO and TiO₂ NPs to S. obliquus was greater than their joint toxicity to C. pyrenoidosa, and the toxicity of ZnO NPs accounted for a higher contribution to the toxicity of the binary mixtures. The joint toxicity of ZnO and TiO 2 NPs to S. obliquus was additive when the mixed concentration was less than 1 mg·L^-1 and was antagonistic when the mixed concentration was more than 1 mg·L^-1. The joint toxicity of the binary mixtures to C. pyrenoidosa was synergistic at 24 h and antagonistic at 48 h and 72 h. The prediction power of the independent action model for the joint toxicity of the binary mixtures of ZnO and TiO₂ NPs was better than that of the concentration addition model. Furthermore, the mechanism of the joint toxicity of ZnO and TiO₂ NPs to the two freshwater green algae species was related to the generation of intracellular reactive oxygen species induced by the NPs, which resulted in oxidative stress on the algal cells.