纳米ZnO与TiO2对赤子爱胜蚓(Eisenia foetida)的毒性效应

摘要

In this study, the ecotoxicological effects and the risk of environmental releases of nano-TiO2 and nano-ZnO were evaluated using earthworm (Eiseniafoetida) as tested biological subjects. The contact filter paper test (with doses of 0,0.15,0.75,1.5 and 3.0mg 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 alter exposure to 0-3.0mg·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 5825％ and 4330％, respectively (p ＜ 0.05); 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 changns 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 (p ＜0.05). 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.%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3.0 mg·cm-2)和溶液法(浓度组:0、10、50和100 mg·L-1),染毒时间为48 h,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:0-3.0 mg·cm-2浓度范围内,纳米颗粒以滤纸法染毒48 h未引起蚯蚓死亡;浓度为15 mg·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·L-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·L-1的TiO2和ZnO染毒48 h,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·L-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.