The Effect Of Earthworms On The Dissipation Of 2,7-Dibromocarbazole In Soil And Its Oxidative Stress Effect

Halocarbazole is a new type of persistent organic pollutant.Its structure is similar to polychlorinated dibenzofuran.It has the properties of dioxin-like toxicity,bioaccumulation,and persistence.Its pollution to the environment has only attracted people's attention in recent years.As a new type of organic pollutant,it is very important to study the fate of halogenated carbazole in the environment and assess its potential risks to the ecological environment.Earthworms,as a very important type of non-target soil organisms,also have a strong ability to transform soil properties.Therefore,earthworms are widely used in environmental safety assessment of soil ecosystems and remediation of contaminated soil.In this experiment,2,7-dibromocarbazole was used as the object,and Eisenia fetiida was selected as the model organism to study the effect of earthworms on the migration and transformation of halogenated carbazole in the soil and the toxic effect of halogenated carbazole on earthworms.(Oxidative damage),the research content includes:(1)To investigate the bioconcentration of earthworms and the intestinal microorganisms on the soil 2,7-dibromo by measuring the content of2,7-dibromocarbazole in soil,earthworms,and earthworm feces The effect of carbazole migration and transformation;(2)Detecting the degradation products of2,7-dibromocarbazole in soil by GC/MS,and preliminary judgment of its degradation pathway;(3)High-throughput analysis of soil,vermicompost,and earthworm gut microbial communities;(4)Determination of superoxide dismutase(SOD)in earthworms,Catalase(CAT),malondialdehyde(MDA)content of2,7-dibromocarbazole oxidative damage to the earthworm body.Research indicates:(1)The introduction of earthworms significantly increased the migration and conversion rate of 2,7-dibromocarbazole in the soil;the bioconcentration level of earthworms was very low during the experimental period,indicating that the intestinal microorganisms played a larger role;the effect of the low concentration group was more The high concentration group is more obvious,indicating that higher concentration will inhibit the activity of microorganisms and have a toxic effect on earthworms.(2)The degradation pathways of 2,7-dibromocarbazole in soil are mainly debrominated and halogenated carbazole molecules with angled dioxygen ring-opening cracking,and the main degradation product is 2-amino-5-bromobenzene Formic acid.(3)The introduction of earthworms will change the composition of the microbial community in the soil environment.Part of the anaerobic bacteria in the intestine of the earthworms will be discharged into the soil environment with the feces,and the mucus on the surface of the earthworms will also stimulate the reproduction of dominant species in the environment.The introduction of 2,7-dibromocarbazole will also change the diversity and abundance of species in the soil environment,and Proteobacteria and Patescibacteria will significantly increase as dominant species.As the exposure time increases,the species diversity and abundance in soil and vermicompost are approaching(4)Different concentrations of 2,7-dibromocarbazole also have different degrees of oxidative damage to earthworms.The SOD,CAT,MDA content in the earthworms of the high concentration experimental group is higher than that of the low concentration group,and the dynamic changes of the three biological indicators are roughly presented The trend of increasing first and then decreasing.