Joint Toxicity of Cu~(2+),Zn~(2+)and Cd~(2+) to Tadpole of Bufo bufo gargarizans

The joint toxicity of copper(Cu),cadmium(Cd) and zinc(Zn) ions to tadpole of Bufo bufo gargarizans was determined using additive index method.The acute toxicities of Cu~(2+),Zn~(2+) and Cd~(2+) were in the sequence of Cu~(2+)Cd~(2+)Zn~(2+).The 48 h median lethal concentrations of Cu~(2+),Cd~(2+) and Zn~(2+) were 0.514,9.224 and 33.56 mg L~(-1),and the 96 h median lethal concentrations of Cu~(2+),Cd~(2+) and Zn~(2+) were 0.288,8.142 and 30.76 mg L~(-1),respectively.When the tadpoles were exposed to equitoxic mixtures,the results showed that the joint toxicities of Cu~(2+) with Zn~(2+) and Zn~(2+) with Cd~(2+) were antagonistic,while the joint toxicity of Cu~(2+) with Cd~(2+) was synergistic.The joint toxicity was synergistic when Cu~(2+),Cd~(2+) and Zn~(2+) were together.Tab 6,Ref 18