Single and joint toxic effects of cadmium and phenanthrene on enchytraeid Fridericia bulbosa

The toxic effects of single and joint stress of Cd (cadmium) and Phe (phenanthrene) on enchytraeid Fridericia bulbosa were investigated by natural soil tests. Mortality of single and joint stress of Cd and Phe was significant (p < 0.01) except the lowest concentration of single pollutant. There was a positive correlation between mortality and the concentration of pollutant added to soil. Also, the more exposed to single or joint Cd and Phe, the more morality. For joint pollution, Cd was the main contributive factor of toxic effects, the different concentration and interaction of Cd and Phe significantly influenced mortality (p < 0.01). The joint effects of Cd and Phe were additive, after a 14-d exposure. When Phe was 0.1 mg kg−1 and 1.6 mg kg−1, the interactive effects between Cd and Phe were synergistic. When Phe was 25.6 mg kg−1, the interactive effects were antagonistic. It suggested that morality may be considered as a valuable and sensitive biomarker to diagnose adverse effects of Cd or Phe in soil environment.