[Study on the effect of enzymatic activity and acute toxicity of three PAEs on Eisenia foetida]

The acute toxic effects of DMP, DEP and DBP to earthworms (Eisenia foetida) were examined in this study. The two pollutants are tested by filter paper contact method and natural soil method, results indicated that they were both poisonous to earthworms. Earthworms were exposed to DMP and DEP for 48 h by filter paper contact method, LC50 (DMP) is 129.603 microg x cm(-2) and LC50 (DEP) is 145.336 microg x cm(-2). Earthworms were exposed to DMP and DEP for 14 d by natural soil method, LC50 (DMP) is 1 560. 120 mg x kg(-1) and LC50 (DEP) is 1516. 186 mg x kg(-1). While non-calculatable for the LC50 of DBP due to its low water solubility, penetrating into the skin and cells of earthworm is not easy. The natural soil test method was used to study the effects of DMP, DEP and DBP on enzyme activities of earthworms, activities of superoxide dismutase (SOD), catalase (CAT) and acetylcholinesterase (AChE) were measured. SOD activity was induced by DMP and DEP, CAT is the most sensitive and the activity was induced by DEP and DBP at the low concentration and inhibited at the high concentration. AChE activity was inhibited by DEP and DBP at the low concentration and induced at the high concentration, finally exhibited a tendency to recover to the control level at 28 d.