Effect of acute toxicity of phenanthrene, pyrene and 1,2,4-trichlorobenzene on earthworms in soils.

The effects of acute toxicity of phenanthrene,pyrene and 1,2,4-trichlorobenzene in single or combined form on earthworms in meadow brown soils were determined.The results indicated that concentration of the three chemicals was significantly related to lethal rate of the earthworms (α=0.05,r PHE=0.87,r PY= 0.85,r TCB=0.95).However,the relationship of pollutant concentration with sub-lethal rate was not as significant as with acute lethal rate (α=0.05,r PHE=0.75,r PY=0.72,r TCB= 0.85).Tolerance of some individual earthworms to the toxicity of some individual pollutants varied greatly.The threshold value causing death of individual earthworm was 20 mg·kg -1 for phenanthrene and 1,2,4-trichlorobenzene,and 2 000 mg·kg -1 for pyrene.The threshold value resulting in weight loss of individual earthworms was 20 mg·kg -1 for phenanthrene,300 mg·kg -1 for 1,2,4-trichlorobenzene, and 1 000 mg·kg -1 for pyrene.LC 100 was 100 mg·kg -1 for phenanthrene and 350 mg·kg -1 for 1,2,4-trichlorobenzene,and non-calculatable for pyrene due to its low water solubility and low toxicity.The experiment also revealed that combined pollution resulted in both synergism and antagonism.