Toxicity Of Fullerene On Daphnia Magna And Its Effects On Biotoxicity Of Cadmium

The potential environmental exposure and harm of MNMs have been paid attention to.Fullerene nanoparticle is a kind of carbon nanomaterials which has been widely used in industrial materials,catalysts,cosmetics,and anticancer drugs.To study the toxic impacts,toxic mechanisms of fullerene(nC₆₀)in aquatic organisms and its effects on toxicity,bioaccumulation and trophic transfer of environmental pollutant cadmium（Cd）,the experiments were carried on from the following aspects:1)the physicochemical properties of nC₆₀ in the tap water system;2)the effects of nC₆₀ on biological behaviors of Daphnia magna,and the responses of several related biomarkers;3)the negative impacts of nC₆₀ on the digestive enzyme systems in D.magna;4)the effects of nC₆₀ on the biological toxicity,bioaccumulation and food chain transfer behaviors of Cd in aquatic organisms.The as-obtained results are showed below:1)Once entered into the aerated tap water system,nC₆₀ would form lots of large aggrrgates with hydrodynamic diameters ranging from 200⁹00 nanometers.A number of nC₆₀ aggregates could suspend in tap water with the zeta-potential ranging from-40^-17mV.2)The 72h EC₅₀ and LC₅₀ values of nC₆₀ in D.magna were 14.9±1.2 mg·L^-1 and16.3±0.8 mg·L^-1,respectively.nC₆₀ could change the behaviors including hop,heartbeat,and feeding of D.magna,which were closely related several biomarkers（AChE,SOD,and LPO）.3)There was a significant accumulation of nC₆₀ in the tract of D.magna.nC₆₀would be embedded in the surface of epithelial cells,causing damage to the intestinal tract.There were significant protrusions and microvilli shedding around epithelial cells.Moreover,the activities of amylase,cellulose,trypsin,β-galactosidase and ATPase decreased after exposure to nC₆₀ with concentration of 5 and 20 mg·L^-1 for 24 h.4)The presence of nC₆₀ could significantly enhance the acute toxicity of Cd to D.magna.Additionally,the bioaccumulation amount of Cd in daphnia would increase under the exposure of 10 mg·L^-1 nC₆₀。But with the presence of nC₆₀,the trophic transfer amount of Cd to zebrafish would decrease and the depuration of Cd by zebrefish would also be facilated.The results showed that the damage of digestive system and oxidative stress was a possible explanation for the toxic effect of nC₆₀ on D.magna.In addition,nC₆₀ could enhance the acute toxicity of Cd to D.magna,increase the bioaccumulation of Cd in D.magna and affect the trophic transfer amount of Cd to zebrafish.The results evaluate the complex environmental effects of nanomaterials entering the natural water environment,which provides basis for the development of reasonable environmental standards.