Effects of combined phthalate acid ester contamination on soil micro-ecology.

The impacts of combined phthalate acid ester(PAE) contamination,including dimethyl phthalate(DMP),diethyl phthalate(DEP),and di-n-octyl phthalate(DOP),on farmland soil basal respiration and microbial diversity were studied by monitoring soil respiration,soil PAEs concentration and random amplified polymorphic DNA(RAPD) marker under laboratory simulation testing.The results showed that the soil basal respiration was activated by PAEs at an early stage,reaching a maximum value at 400 mg /kg PAEs treatment.However,this type of activation effect decreased with prolonged PAE exposure time.In addition,the concentration of PAEs in the soils decreased,especially the DEP concentration.The number of specific RAPD bands increased in all PAE treatments at the end of incubation,reaching 13% higher than that of the early stage of incubation.The Shannon-Weaver index of soil microbial community DNA sequence in all treatments was:0 mg /kg 50 mg /kg 100 mg /kg 200 mg /kg 400 mg /kg.Overall,the results indicated that the combined PAE contamination in soil may stimulate soil basal respiration,but decrease soil microbial diversity.