Enrichment Characteristics And,Physiological Response In The Anodonta Woodiana Under Low Concentration Cadmium

In this paper,the laboratory experiments were carried out to place the Anodonta woodiana in the Cd²⁺solution,and the concentration of Cd²⁺ were 0,5,10,20,40μg/L respectively.The enrichment characteristics of heavy metal cadmium and antioxidant enzymes（SOD,CAT,GPx）activity and lipid peroxidation（MDA）in each tissue of Anodonta woodiana（gill,viscera,mantle,foot）were studied.The oxidative damage stress effect of Anodonta woodiana was studied by using IBR index method,it was used to discuss the bioavailability and oxidative damage stress effect because of the cadmium pollution.The results were as follows:1.Cd²⁺ enrichment characteristics of Anodonta woodiana showed that Cd²⁺ had significant enrichment ability,and the order of cadmium content in the tissues were gill>visceral>mantle>foot tissues.After 30 days of enrichment,the bioconcentration factor（BCF）of each tissue decreased gradually with the increase of Cd²⁺ concentration.On the contrary,the average enrichment rate and enrichment ratio of each tissue were-all decreased continuously.At the end of the enrichment,the contents of cadmium in the mantle and foot tissues were not higher than the edible safety standard in the 5 μg/L and 10 μg/L dose groups.However,the cadmium content was above standard in the visceral and gill tissues.2.The Cd²⁺ stress effects on antioxidant enzyme activities of Anodonta woodiana was analyzed,it showed that the effect of low concentration of Cd²⁺ on the activities of SOD,CAT and GPx in the each tissues was similar:they were induced in the lower concentration group,and inhibited in the higher concentration group.However it also had some differences between tissues.CAT and GPx were complementary to each other,but they were relatively independent of SOD.SOD,CAT and GPx showed a significant time-effect and dose-effect relationship with Cd²⁺ concentration.With the increase of exposure concentration and time,the content of MDA in the tissues of Anodonta woodiana was increasing,so the damage degree of the tissues was increasing.And the damage degree of the gill and visceral tissues was greater than that of mantle and foot tissues.Among them,the content of MDA in the 5 μg/L dose groups was not increased significantly.It was proved that 5 μg/L was reasonable for the cadmium limit in fishery aquaculture water,and cadmium pollution above the surface water Class V water standard（10 μg/L）could cause different degrees of damage to the organisms.3.Integrated biomarker response was a approach that can integrate all kinds of biomarkers and evaluate the conditions of pollution comprehensively and objectively.The correlation analysis showed that damage degree was different with the difference of Cd²⁺ concentration.The higher the concentration of Cd²⁺ in the same enrichment time,the greater the IBR value of each tissue,the higher the damage degree.The IBR value in 5 μg/L dose group was relatively lower,so the damage degree was smallest.The IBR value of viscera was higher than other tissues,it showed that damage degree of viscera was higher and more sensitive to Cd²⁺ oxidative stress,it could be used as the vector of aquatic ecological risk assessment.During the short time of Cd²⁺exposure,there was a good correlation between the IBR values and the Cd²⁺concentrations in the each tissue of Anodonta woodiana,and the correlationcoefficients were from high to low in turn is:gill>mantle>visceral>foot tissues,so CAT,GPx,MDA as markers for the IBR analysis could be used for the monitoring analysis of environment pollution in the short time.