Toxicological Effects And Risk Assessment Of Nano-Ferriferrous Oxide On Aquatic Organisms

In order to understand the risk of nano-ferriferrous oxide on the aquatic environment,the superoxide dismutase?SOD?,metallothionein?MT?,malondialdehyde?MDA?,free radicals?ROS?and phosphorylated histone H2AX??H2AX?were analyzed by the toxicity test of nano-ferriferrous oxide on zebrafish and tubificid worms to determine their toxic effects.Ecological risk assessment was carried out using the Integrated Biomarker Index?IBR?method.The experimental results are as follows.1)In the 96h acute toxicity experiment,the nano-ferriferrous oxide suspension appeared precipitation.Nano-ferriferrous oxide enters the zebrafish body by breathing or ingesting it.The 96h median lethal concentration of tubificid worms in the exposed group of 5²00mg·L^-1 was 47.507 mg·L^-1.2)In the 13d zebrafish subacute toxicity test,the high concentration group ROS content reached the maximum value of the concentration group earlier than the low concentration group.The trend of SOD activity in the blank group was“M”type,and the exposed group was inverted“N”type.The MDA content of the blank group and the low concentration group changed little,and the trend of high concentration group is"V"type.The MT content was more sensitive to nano-ferriferrous oxide stress of 25 mg·L^-1.The content of?H2AX in the blank group changed smoothly,and the exposure group showed a change trend of“?”type.And the content of?H2AX was higher than that of the blank group.DNA double bond breaks are obvious,and the damage caused is not repairable.3)In the 13d subacute toxicity test of S.hydrophylla,the ROS content was more sensitive to nano-ferriferrous oxide stress of 20mg·L^-1 and 40mg·L^-1.In order to resist foreign substances,the body protects itself and the activity of SOD fluctuates.The MDA content of the 20mg mg·L^-1 exposure group was the first to reach the minimum value of the test period.The MDA content in the 40mg·L^-1 exposed group reached the maximum value during the test period(2.081nmol·mgrot^-1),which was the most damage to the zebrafish body.The change trend of the MT content in the blank group was"V"type,and the exposed group was"?"type.The trend of?H2AX content in the blank group and the exposed group was“?”type,and the DNA double bond breaks were obvious.4)In the IBR analysis,the most sensitive biomarker of zebrafish is MDA,and the most sensitive biomarker of tubificid worms is?H2AX.As the concentration increases,the risk of exposure increases.