Experimental Study on the Toxicity of Cu~(2+) and Cd~(2+) to Paramecium

[Objective] The research aimed to provide reference basis for wastewater discharge safety evaluation in the water environment monitoring. [Method] In single acute toxicity test and joint toxicity test, the acute toxicity and joint toxicity of heavy metals Cu2+ and Cd2+ to paramecium was studied.[Result] In acute toxicity test of single ion, the toxicity of Cu2+ and Cd2+ were augmented with the increasing of concentration and both of them showed obvious dose effects. The median lethal concentration (LC50) of Cu2+ in 1h was 0.32 mg/L and that of Cd2+ was 0.96 mg/L. When Cu2+ and Cd2+ coexisted, the median lethal concentration (LC50) of Cu2+ in 1h was 0.24 mg/L and that of Cd2+ was 0.19 mg/L. And 2 kinds of heavy metals showed an synergistic effect. [Conclusion] In the process of wastewater discharge, not only the toxic effect of single heavy metal ion to aquatic organisms should be considered, but also much attention should be paid to the toxic effect of 2 or many kinds of heavy metal ions on aquatic organisms when they coexisted.