Pce And The Polluting Effects Of Cadmium On Research

The single and joint toxicity of cadmium (Cd²⁺) and perchloroethylene (PCE) acting on grass carp (Ctenopharyngodon idellus) was observed. The additive index method was applied to evaluate the joint toxicity. The result showed that both of the two tested chemicals had their high toxicity on the grass carp population, and the single toxic sequence of the chemicals was Cd²⁺ > PCE. The LC₅₀ of 24, 48, 72 and 96 h for Cd²⁺ toxic to grass carp was 45.58, 34.81, 28.63 and 24.23 mg·L^-1, respectively; and LC₅₀ of 24, 48, 72 and 96 h for PCE toxic to grass carp was 49.12, 41.68, 36.37 and 34.30 mg·L^-1, respectively. The safety concentration for Cd²⁺ and PCE toxic to grass carp was 0.242 and 0.343 mg·L^-1, respectively. The joint toxicity of Cd²⁺ and PCE showed that when the exposure time was 24, 48, 72 and 96 h and their toxicity was at the rate of 1:1, the joint toxicity of Cd²⁺ and PCE was Synergistic. And the Synergistic effect was increasing with time. When the exposure time was 24, 48, 72 and 96 h and their concentration was at the rate of 1:1, the joint toxicity of Cd²⁺ and PCE was Synergistic.In this paper, the activities of superoxide dismutase (SOD) and Peroxidase ( POD) of liver, kidney and gill tissues in 168 h was also observed. The result of the experiment indicates that the activities of SOD in liver, kidney and gill tissues have been inhibited at low Cd²⁺ and PCE concentrations in a short time. The activities of SOD, however, would increase with the exposure time going on, which may probably come about as a result of the "Toxic excitement effect". With the high concentrations Cd²⁺ and PCE inhibiting the activities of SOD in liver, kidney and gill, the inhibiting strength will increase with the prolonging of the exposure time and the concentration enhancing. Thus, the harm caused by active oxygen due to the decrease of the activities of SOD is an important reason that leads to the mass death of grass carp exposed to Cd²⁺ and PCE. The activities of POD in liver, kidney and gill haven't made the same regular change as the activities of SOD when the grass carp were exposed to Cd²⁺ and PCE. But the activities of POD in liver, kidney and gill tissues have been increased in different degree at low Cd²⁺ and PCE concentrations. It is also the "Toxic excitement effect". Thus, the activity of POD could be considered a biomarker for adversity physiology of fish. The experiment also indicates that the activities to Cd²⁺ and PCE of SOD and POD in liver are higher than those in kidney and gill, which maybe associated with their physiological functions.