Study On Ecotoxicity Of Nano-Fe3O4on Chlorella Vulgaris In Aquatic Environment

Nanomaterials have unique physicochemical properties, high strength, and good magnetic properties. Rapid development of nanotechnology and nanomaterials, and continual expansion of their applications have resulted in widespread biosafety concerns.In this paper, the photosynthetic toxicity and oxidative damage induced by nano-Fe3O4on a model organism, Chlorella vulgaris (C. vulgaris) in aquatic environment, were studied. The results showed that nano-Fe3O4was toxic to C. vulgaris and affected its content of chlorophyll a, malonaldehyde and glutathione, CO2absorption, net photosynthetic rate, superoxide dismutase activity and inhibition of hydroxyl radical generation. Results are as follows:1. Determination of photosynthetic toxicity With the increased of nano-Fe3O4concentration, the chlorophyll a content, the amount of CO2absorbed during photosynthesis and net photosynthetic rate in C. vulgaris decreased. Compared with the control group, at nano-Fe3O4concentrations of200mg·L-1to1600mg·L-1, the chlorophyll a concentration decreased significantly (p<0.05). The net photosynthetic rate decreased significantly (p<0.01) in all exposure groups except for the lowest concentration (50mg·L-1) exposure group.2. Determination of oxidative damageWith the increased of nano·Fe3O4concentration, the MDA content increased, the GSH content and the inhibition of·OH generation decreased, the SOD activity first increased then decreased. Compared with the control group, at nano·Fe3O4concentrations of800mg·L-1(p<0.05) and1600mg·L-1(p<0.01) the increases in the MDA content were significant. In the400-1600mg-L"1groups the GSH content decreases were significant (p<0.01). When the nano-Fe3O4concentration<400mg-L"1, the SOD activity significantly increased (p<0.01). With nano-Fe3O4concentrations>400mg-L-1, the SOD activity decreased, and in the1600mg·L-1group the SOD activity was significantly lower than that of the control group (p<0.05). When the nano-Fe3O4concentration<200mg·L-1, inhibition of·OH generation slightly increased. With>200mg·L-1nano-Fe3O4, inhibition of·OH generation decreased. In the400mg·L-1and800mg·L-1groups (p<0.05) and1600mg·L-1group (p<0.01) the inhibition of·OH generation was significantly lower than that of the control group.At higher concentrations, compared with the control group, the toxicity of nano-Fe3O4was significantly different. It suggested that nano-Fe3O4is ecotoxic to C. vulgaris in aquatic environment.