纳米ZnO与TiO_2对赤子爱胜蚓(Eisenia foetida)的毒性效应

Ecototoxicological Effect of ZnO and TiO_2 Nanoparticles on Earthworm(Eisenia foetida)

以赤子爱胜蚓(Eisenia foetida)为受试生物,研究纳米TiO2与ZnO两种纳米颗粒的毒理学效应及环境释放风险。实验采用滤纸法(浓度组:0、0.15、0.75、1.5和3.0mg.cm-2)和溶液法(浓度组:0、10、50和100mg·mL-1),染毒时间为48h,以抗氧化系统的响应和DNA损伤作为毒理效应的评价指标。结果表明:0-3.0mg.cm-2浓度范围内,纳米颗粒以滤纸法染毒48h未引起蚯蚓死亡;浓度为1.5mg.cm-2的纳米ZnO处理后,蚯蚓体内丙二醛(MDA)含量和谷胱甘肽过氧化物酶(GPX)活性较空白组显著上升(p<0.05),分别升高58.25%和43.30%;而对于TiO2处理组,过氧化氢酶(CAT)与GPX活性和MDA含量均出现低浓度促进和高浓度抑制的现象。溶液法中,经浓度为0-100mg·mL-1的TiO2或ZnO处理后,MDA和各抗氧化酶活性未出现明显的变化趋势(p>0.05),但彗星实验结果发现,分别以100mg·mL-1的TiO2和ZnO染毒48h,蚯蚓均出现明显DNA损伤。实验结果说明:纳米TiO2与ZnO在较低浓度下对蚯蚓无明显毒性效应;在溶液法最高的实验浓度(100mg·mL-1)下,纳米ZnO对蚯蚓产生一定程度的毒性;DNA损伤可作为检测环境中纳米污染物对蚯蚓胁迫程度较为灵敏的指标。

In this study,the ecotoxicological effects and the risk of environmental releases of nano-TiO2 and nano-ZnO were evaluated using earthworm（Eisenia foetida）as tested biological subjects.The contact filter paper test（with doses of 0,0.15,0.75,1.5 and 3.0 mg cm-2）and solution test（with doses of 0,10,50 and 100 mg L-1）were used to determine toxicities of the two nanoparticles.After 48-h administration,response of the antioxidant systems and DNA damage of the earthworm were selected as assessment indicators.The results indicated that no earthworm death was observed after exposure to 0-3.0 mg·cm-2 of the two nanomaterials using filter paper test to contact administrate earthworm;1.5 mg·cm-2 administration with nano-ZnO led to significant increases of content of malonaldehyde（MDA）and activity of glutathione peroxidase（GPx）with 58.25% and 43.30%,respectively（p0.05）;treated with nano-TiO2,activities of catalase（CAT）and GPx and content of MDA in earthworm were promoted under low concentrations of nano-TiO2,while these were inhibited under high concentrations of nano-TiO2.Earthworm administrated with solution test,no significant changes of activities of CAT and GPx as well as content of MDA were detected after exposure to 0-100 mg·L-1 of nano-TiO2 or nano-ZnO.However,the results of the comet assay of the solution test showed that DNA of the earthworm was damaged markedly after 48-h exposure to 100 mg·L-1 of nano-TiO2 or nano-ZnO（p0.05）.The results suggest that nano-TiO2 and nano-ZnO have no toxicological effects under relative low concentrations,while they do have toxicological effects under the highest concentration（100 mg·L-1）.In addition,comet assay could be used as a sensitive indicator to evaluate the toxicities of the nanomaterials disposed in the environment to earthworm.