纳米二氧化铈对斜生栅藻的毒性研究

Toxicities of Nanoparticulate CeO_2 on Scenedesmus Obliquus Kütz

实验研究了纳米二氧化铈(CeO2)对斜生栅藻的毒性效应。结果显示,当纳米二氧化铈浓度为5、10mg·L-1时,对斜生栅藻的生长有促进作用(P<0.01),其促进作用随着浓度增大而减小;至浓度为50mg·L-1时,开始变为抑制效应;当浓度达到100、200mg·L-1时,表现出显著的抑制作用(P<0.01),且抑制作用随着浓度增大而增大。光镜拍照和藻细胞直径的变化表现出,随着处理浓度的增大,细胞有小型化的趋势。处理7d后,纳米二氧化铈对叶绿素和SOD含量的影响和对藻密度的影响一致,而对MDA含量的影响刚好相反,说明细胞膜发生了不同程度的脂质过氧化反应。

China contains the most rare earth resources in the world. Thus, it may provide a reliable basis for the use of rare earth materials. The nanoparticulate CeO2 is widely used in numerous areas such as fuel batteries and gas sensors due to its good electrical and optical prop- erties. However, the potential for the release of CeO2 nanoparticles into the environment is also increasing. The possibility of water resources and soils being contaminated by the discharge of CeO2 nanopartieles arouses more and more concern. This study was designed to test the CeO2 nanoparticle＇s toxicity effects on aquatic ecosystems. S. obliquus was exposed to a series of CeO2 concentrations（0- 5, 10, 50, 100, 200 mg·L-l）. Five parameters were measured after 7 days of exposure which were growth rate, cell diameter, superoxide dismutase （SOD）, photosyn-thetic pigments and free malondialdehyde（MDA ）. It was shown that nanopartieulate C eO2 concentrations of 5 mg·L-1 and 10 mg. L-1 caused a significant increase in growth, while 50 mg·L-1 of nanopartieles started to inhibit the growth and high concentrations of 100 mg. L-1 and 200 mg·L-1 significantly inhibited the growth. As the concentration increased, the stimulative effect was reduced and the inhibition effect was en- hanced. The influence on the chlorophyll and SOD contents was consistent with that of cell growth, while the influence on the MDA contents was opposite with that of SOD indicating that varying degrees of lipid peroxidation occurred in the cell membrane. Optical microscopy images and changes in the diameter of the S.obliquus cells illustrated that with the increase of the concentration of the Cerium（ IV ） oxide nanoparti- cles, there was a tendency of miniaturization of the cells. This study contributes to the research on the toxicological effects of nanomaterials and can provide references for the risk assessments on issues concerning nanomaterial research.