Study On Toxicological Effect Of DEHP On Soil Microbe

With the industrial and agricultural plastic products of large production and use, DEHP and other PAEs compounds into the soil. DEHP and other PAEs compounds long residue in the soil will produce a certain degree of impact to soil ecological system. Effects of different concentrations (1,5,10,20,50,100,200,400mg·kg-1) of di-(2-ethylhexyl) phthalate (DEHP) on the number of soil microorganism, soil enzyme activity, soil microbial biomass, soil microbial functional diversity and genetic diversity have been researched under laboratory condition in this paper. A preliminary analysis of its mechanism has been made so as to provide a theoretical basis for the evaluation of its ecotoxicological effects of phthalates. The findings are as follows:1. Effects of DEHP pollution on soil microbial quantity1.5,10and20mg·kg-1DEHP had little effect on the number of soil bacteria, fungi, actinomyces, ammonifying bacteria, nitrogen fixing bacteria, nitrifying bacteria, inorganic phosphorus and organic phosphorus bacteria, but50,100,200and400mg·kg-1DEHP on the number of soil bacteria, fungi, actinomyces, ammonifying bacteria, nitrogen fixing bacteria, nitrifying bacteria, denitrifying bacteria, organic phosphorus and inorganic phosphorus bacteria had obvious inhibition effects, along with the increase of concentration, the inhibition enhanced.10and20mg·kg-1DEHP on the number of soil denitrification bacteria have a certain activation effect.2. Effects of DEHP pollution on soil enzyme activity1,5and10mg·kg-1DEHP had little effect on soil invertase activity, but20,50,100,200and400mg·kg-1had obvious inhibition effect on soil invertase activity.1,5,10and20mg·kg-1DEHP had little effect on soil urease, phosphatase and protease activity, and50,100,200and400mg·kg-1DEHP on soil urease, phosphatase and protease activity had certain inhibiting effect. With the concentration increased, the inhibition of high DEHP level enhanced.1,5and10mg· kg-1DEHP had little effect on the activity of polyphenol oxidase, and20mg·kg-1DEHP had a stimulating effect on soil polyphenol oxidase activity and other concentration treatments had an obvious inhibitory effect on the activity of polyphenol oxidase.3. Effects of DEHP pollution on soil microbial biomass1,5,10and20mg·kg-1DEHP had little effect on soil microbial biomass carbon, nitrogen and phosphoru, but50,100,200and400mg·kg-1showed an inhibitory effect on soil microbial biomass carbon, nitrogen and phosphorus, treatments of soil microbial biomass carbon, nitrogen and phosphorus compared with the control group, the difference was significant. In the initial stage of culture (5d),50,100,200and400mg·kg-1treatments had an obvious inhibitory effect on soil microbial biomass carbon, but little influence on soil microbial nitrogen and phosphorus. Throughout the culture period, the change trend of soil microbial nitrogen and phosphorus are basically the same,50,100,200and400mg·kg-1DEHP on soil microbial biomass nitrogen and phosphorus show a tendency with decreased-increased-decreased and stable.4. Effects of DEHP pollution on soil microbial functional diversity1,5,10and20mg·kg-1DEHP would not affect microbial activity of the whole soil community, but50,100,200,400mg·kg-1DEHP on the whole community of soil microbial activity had obvious inhibition. Variation trend of Shannon, Simpson and Mclntosh index were basically consistent,50,100,200and400mg·kg-1treatment make the three indices decreased significantly. During the whole experimental period,50,100,200and400mg·kg-1DEHP and control group in the figures of principal component analysis has a good separation, further proof that the higher concentration of DEHP pollution of soil microbial community structure had changed.5. Effects of DEHP pollution on soil bacterial community structureIn the whole experiment cycle, soil microbial community richness and Shannon index were little influenced by1,5,10and20mg·kg-1DEHP, but50,100,200and400mg·kg-1DEHP made the soil bacterial community richness and Shannon index dropped significantly, with the increase of concentration, the greater the decrease. PC A analysis further proved that50,100,200and400mg·kg-1DEHP have changed soil microbial community structure. Through the rubber cutting recycle strip, links, transformation and the sequencing analysis, we found the predominant microbes which were represented by bacteria DGGE strip were mainly belong to three categories, they were Proteobacteria, Firmicutes, Actinobacteria.