Study on the Acute Toxicity of Rare Earth Yttrium to Earthworms under the Stress of Leaching Agent Ammonium Sulfate

This study aimed to investigate the toxicity of rare earth ion yttrium under the stress of leaching agent ammonium sulfate (NH^sub ^)^sub 2^ SO^sub 4^. By using earthworms as indicator organisms of environmental pollution, acute toxic effects of rare earth yttrium on earthworms under the stress of ammonium sulfate were investigated with filter paper contact method. Under single stress of rare earth yttrium, the semi-lethal concentration after 48 and 24 h was LC^sub 50^=213.41 mg/L and LG^sub 50^=322.63 mg/L, respectively. Under single stress of ammonium sulfate, the semi-lethal concentration after 48 h and 24 h was LC^sub 50^=13.89 g/L and LC^sub 50^ =15.05 g/L, respectively. Low concentration of ammonium sulfate could reduce the toxicity of rare earth yttrium to earthworms and produce certain antagonism against rare earth yttrium; middle concentration ammonium sulfate increased the toxicity of rare earth yttrium to earthworms and produced relatively significant synergistic effects; high concentration ammonium sulfate significantly increased the toxicity of rare earth yttrium to earthworms.