The Combined Contamination Of Triclosan And Clarithromycin On Soil Enzyme Activities And Microbial Community Structure

In this study,two kinds of pharmaceutical and personal care product(PPCPs),antimicrobial(Triclosan,TCS)and antibiotic(Clarithromycin,CTC),were selected as the target pollutant to treatment the soil.The soil microorganism was selected as the treatment object,and the effects of TCS and CTC on soil microbial enzyme activity and microbial community structure were studied under laboratory conditions.The experimental results are as follows:It was found that the activity of urease,catalase and dehydrogenase of three soil with three different physicochemical properties were inhibited by the single treatment by TCS,and the activity of soil microorganism also entered the inhibition state after the transient stimulation.According to the degree of the response of the biological index to TCS,when the soil biomass content reached a certain limit,the response of urease and catalase in soil with a low biomass content were obtained.And the response of dehydrogenase and fluorescein diacetate in soil with a high biomass content were obtained.In the experiment of the gradient concentration of TCS alone and the combined CTC,it can be found that the compound pollution of the two kinds of pollutants has a strong inhibitory effect on the soil urease and catalase,in which the pollution of the soil urease is inhibited by the compound pollution.In this process,CTC has antagonistic the inhibiting effect of TCS on soil urease activities.The pollution of soil catalase by combined pollution is a low concentration inhibition effect.In the experiment of gradient concentration of CTC alone and combined with TCS,it can be found that the compound pollution of two pollutants has a strong inhibitory effect on soil urease,catalase and dehydrogenase.Among them,urease and dehydrogenase showed high concentrations of inhibitory effects;TCS showed antagonistic or synergistic effects on CTC inhibition of soil urease and catalase activity,and the microbial activity showed the change trend of inhibition and stabilization in the experiment period.The microbial activity exhibited an initial stimulus and then inhibited during the experimental period.The trend of stable and lasting inhibition was demonstrated,indicating that soil microorganisms will have more obvious changes after the contaminants have been loaded into the soil.In the analysis of high throughput sequencing results of soil samples,it was foundthat CTC and TCS compound pollution had little influence on the species and quantity of soil microbes,but had an impact on the interspecies dominance in soil microbial communities.Among them,the relative abundance of Thiobacillus,Sphingomonas and Lysobacter of the soil sample has a greater increase than that of the control group.The Truepera,Halothiobacillus and Methylobacter of the soil sample decreased significantly than that of the control group maybe because they can not tolerant the toxicity of CTC and TCS.