Effects Of Cd²⁺ And Hg²⁺ On Physiological And Biochemical Characteristics Of Aquatic Organisms In Multiple Media

The physiological and biochemical characteristics of organisms can usually characterize the living conditions and vital signs of organisms.In recent years,a large number of domestic sewage and industrial wastewater containing heavy metal pollutants have been discharged into the water body,causing damage to the aquatic ecosystem and affecting the physiological and biochemical characteristics of aquatic organisms.In order to study the effects of heavy metal pollution on the physiological and biochemical characteristics of aquatic organisms,water,sediment,Vallisneria,Ceratophyllum and zebrafish were selected to build a micro ecosystem.The static exposure method was used,and Cd and Hg heavy metal ions were used to single and compound exposure to sediment and water,The acute toxicological effects of Cd and Hg ions on aquatic organisms and their effects on antioxidant enzymes in organisms were explored,and the toxic effects of heavy metals were evaluated more comprehensively,so as to provide effective toxicological basis for ecological risk management of heavy metal ions pollution.The results show that:(1)Acute toxicological test:the 96h-LC₅₀of Cd ion to zebrafish was 0.414 mg/L,and the 96h-LC₅₀of Hg ion to zebrafish was 0.340 mg/L.(2)Zebrafish were exposed to two kinds of heavy metal ions(0.138 mg/L of Cd and0.113 mg/L of Hg)for 7 days.The enrichment factor of Cd in the viscera of zebrafish was 818×10^-3mg/g,which belonged to moderate enrichment.The enrichment factor of Hg was 54×10^-3mg/g,which could be regarded as no enrichment.The muscle of zebrafish had no enrichment of two kinds of heavy metal ions.(3)With the increase of heavy metal ion concentration,the content of MDA in Vallisneria and Ceratophyllum demersum gradually increases.When the concentrations of Cd and Hg ions are 1mg/L,respectively,the content of MDA in Vallisneria and Ceratophyllum demersum reaches the highest point in the concentration gradient.The content of chlorophyll in Vallisneria and Ceratophyllum decreased with the increase of Cd and Hg concentration.This indicates that Cd and Hg ions can affect the producers in the ecosystem and even the whole ecosystem.(4)Different concentrations of Cd and Hg ions had different effects on the soluble protein content of Vallisneria,Ceratophyllum and zebrafish,but on the whole,it showed a downward trend with the increase of ion concentration.(5)The effects of different concentrations of Cd and Hg on the activities of antioxidant enzymes in Vallisneria,Ceratophyllum and zebrafish showed a low concentration promoting high concentration inhibiting effect.(6)The results showed that Cd and Hg ions had synergistic effects on physiological and biochemical characteristics of Vallisneria,Ceratophyllum and zebrafish.