Toxic Effect Of Several Heavy Metals On Guppy

With the rapid development of industry and agriculture and the growth of population, environmental pollution have become increasingly prominent, especially to the water pollution, which have become a serious social problem. Kinds of heavy-metal pollutants are discharged into environment due to domestic sewage and industrial wastewater, and the environmental risk results from it shloud be concerned.The single and joint acute toxicity of Cu²⁺, Cd²⁺ and Cr⁶⁺ to Poecilia rericula was investigated by static test method. The result of single acute toxicity showed that the LC₅₀ of Cu²⁺ in 24, 48, 72 and 96h were 5.70, 4.02, 2.95, 2.36 mg/L; LC₅₀ of Cd²⁺ were 23.24, 20.15, 18.07 and 17.71 mg/L; Cr⁶⁺ were 88.56, 65.21,47.81 and 43.40mg/L respectively. Cu²⁺, Cd²⁺ and Cr⁶⁺ all had high acute toxicity on Poecilia rericula with the order of Cu²⁺>Cd²⁺>Cr⁶⁺. The joint acute toxicity showed that the joint toxicity of Cu²⁺ and Cd²⁺, Cu²⁺ and Cr⁶⁺, Cd²⁺ and Cr⁶⁺ and Cu²⁺ with Cd²⁺ and Cr⁶⁺ were all synergistic with Poecilia rericula exposed to mixtures of 1:1 or 1:1:1 in concentration.Further more, the effects of Cu, Cd and Cr on CAT, SOD and GSH-PX of Poecilia rericula were studied from three different sublethal concentrations in 96h exposure duration in order to make sure the feasibility of using these biomarkers monitoring heavy metal pollutants. Results obtained from the study showed that CAT of Poecilia rericula can be uesed as a good biomarker for monitoring the exposure of Cu²⁺, Cd²⁺ and Cr⁶⁺. SOD could also be a good biomarker for test heavy metal pollutants, however, the response of GSH-PX to heavy metal pollutants was not as good as CAT or SOD. Changes of GSH-PX activities in all exposure levels of heavy metal pollutants were not obvious. GSH-PX activity changed significantly only in high concentration of Cu, Cd.We also made research on the acute toxicity of wastewater from paper mill, dyeing plant and oil refinery. Brachydanio Rerio and Poecilia Reticulates were chosed to search the feasibility of assessing the toxic effect of industrial wastewater based on fish acute lethalit test. The response of both fishes to different concentrations of wastewater is obvious. The LC96h-50 of wastewater from paper mill to Brachydanio Rerio were 59.16%; LC96h-50 of that from dyeing plant to Brachydanio Rerio and Poecilia Reticulates were 7.63% and 14.84%; LC96h-50 of wastewater from oil refinery to Poecilia Reticulates was 37.02%. The results showed that it is feasible to make Poecilia Reticulates as an indicator organism, though it is not the recommended one in fish acute toxicity test.