Acute Toxicity of Leachate of Manganese Sulphate Waste Residue to Brachydanio rerio and Toxic Effect on Its Antioxidant Enzymes Activities
硫酸锰废渣浸出液对斑马鱼的毒性及抗氧化酶活性的影响

Previous work indicated that a large amount of manganese sulphate waste residue (MSWR) was piled up along the bank of Huayuan River in the west of Hunan Province and that MSWR contains some heavy metals, which has led to the pollution of the river water and sediment. In order to evaluate the potential ecological risk and the toxic effect of MSWR on aquatic animals, the metal composition of MSWR leachate was analyzed. Brachydanio rerio was exposed to the leachate of MSWR and their physical signs were observed in the acute toxic test. Moreover, the variations of biochemical parameters of Brachydanio rerio were measured at sub-lethal concentration of the MSWR leachate. The results demonstrated that the main heavy metals of MSWR leachate include Mn, Cd, Pb, Cu and Zn. In the acute toxic test, a series of toxic effects on Brachydanio rerio occurred, including breathing slowly, staying still, and the disappearance of their body stripes and final death. The activities of four antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) and glutathione peroxidase (GPx), were investigated in the liver, gill and muscle of Brachydanio rerio exposed to a sub-lethal concentration of the MSWR leachate. No obvious relationship between the activities of SOD and CAT enzymes and the concentrations of MSWR leachate was observed in the exposed liver, gill and muscle of Brachydanio rerio, while the variations of GST and GPx enzymes activities may serve as an indicator of the damage of Brachydanio rerio from the leachate of MSWR. It is concluded that the response mechanism of four studied antioxidant enzymes may be different in the three tissues of Brachydanio rerio exposed to the leachate of MSWR.