| High-performance water-based mud is mainly used in shale gas exploration,and there are few studies on its influence on soil physicochemical properties and microbial characteristics.In this paper,high-performance water-based mud was added into paddy soil and purple soil,colected from different sites in Sichuan province,at a ratio of 2: 1,and then incubated at 25°C.Samples were taken at day 0,30,90,and day 180,to explore the impact of waste high-performance water-based mud(WHWM)on the soil physicochemical properties and microbial characteristics includes diversity of soil microbial communities and enzyme activities,and to provide a theoretical basis for biotreatment of WHWM.The results obtained were as following:(1)After WHWM was added into different soil,the total nitrogen content of each sample decreased with the increase of culture time,and the different between treatment samples was not significant.The alkali-hydrolyzed nitrogen content of T1 and T2(paddy soil + WHWM)changed greatly,while the alkali-hydrolyzed nitrogen content of T3-T5(purple soil + WHWM)changed little.The alkali-hydrolyzed nitrogen content in T1 and T2 showed an increase-decrease-increase trend,while in T3-T5 showed a gradually decreasing trend.The contents of organic matter and available phosphorus in all treatment samples decreased gradually,and COD of soil extract decreased first and then increased significantly.(2)The addition of WHWM has a significant effect on soil enzyme activity.The soil activities of urease and alkaline phosphatase were significantly increased,while the activities of sucrase were significantly decreased.The activities of polyphenol oxidase and catalase were increased at first and then decreased.The soil urease activities and polyphenol oxidase activities in T3,T4 and T5 were more responsive to WHWM.(3)The number of culturable microorganisms in each treatment decreased at first and then increased,the number of actinomycetes increased at first and then decreased,and the number of fungi decreased.Fifty-one bacterial strains were isolated and purified from soil collected at day 30 to day 80.Their 16 S r DNA sequence analysis indicated that these bacteria mainly belonged to Bacillus.(4)The gas chromatographic analysis of organic pollutants in the soil leaching solution of different treatments showed that the main pollutants were volatile cyclosiloxane,aliphatic hydrocarbon,aromatic hydrocarbon and phthalate ester,and soil microorganisms could degrade these organic pollutants effectively.(5)The results of high-throughput sequencing showed that the soil microbial diversity,richness and homogeneity in different treatments were significantly reduced after the addition of waste high-performance water-based mud.The microbial communities had siminar evolved trend in different soils,and the similarity of microbial folora was increased.The stability of bacterial community structure in paddy soil was better than that of purple soil after the addition of WHWM.The fungal community was less affected by WHWM compared with bacterial community,and the structure of the fungal community in the tested soil has not significant change.At the level of phylum classification,the dominant bacteria in the soil were Proteobacteria and Actinobacteria,and the dominant fungi were Ascomycota and Basidiomycota.At the genus level,the dominant bacteria in the soil are Alcanivorax,Idiomarina,Marinobacter,Thalassospira,and Halophilus,etc.The dominant genus of fungi were Aspergillus,Mortierella,Fusarium,etc. |
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