Interaction between nickel and cobalt toxicity in Enchytraeus crypticus is due to competitive uptake

Uptake and toxicity of Ni-Co mixtures in Enchytraeus crypticus were determined after 4d, 7 d, 10 d, and 14d exposure. Generally, body concentrations of Ni and Co increased with increasing exposure concentrations. Ni body concentration was significantly reduced in the presence of Co, whereas Ni only marginally affected Co uptake. When expressed as free ion activities, individual toxicity of Ni and Co increased with time, with median lethal concentrations (LC50) decreasing from 78.3μM and 511μM at 4d to 40.4μM and 393μM at 14d, respectively. When expressed as body concentrations, LC5