[Toxicity of leachate of different landfill ages and different seasons].

Leachates from 7 landfill of Wuhan, China were selected to determine the toxicity of leachates of different landfill age and different seasons, and relationships between physical-chemical parameters and toxicity of leachates were also study. Bioassays were conducted recording toxicity against Tetrahymena thermophila as median lethal concentrations (LC50 values) after 24h exposure and growth inhibition. The results show that LC50 values of leachates of different landfill age oscillate between 0.84% and 12.15%, and LC50 values increase and growth inhibitions do not decrease with increase of landfill age. No clear regularity is observed from LC50 values of leachates of different seasons, and LC50 values of leachates of summer are comparatively lower. Growth inhibitions of leachates of spring are the lowest. Physical-chemical parameters of leachates do not correlated with LC50 values, whereas growth inhibitions are dependent on COD, BOD5, NH4+ -N and concentrations of diethylhexyl phthalate (DEHP).