Studyon Physicochemical Property And Microbial Diversity Of Soil Contaminated With Combined Petroleum And Salinization

As the cornerstone of modern economic development,oil has been exploited and utilized in large quantities,which leads to increasing oil pollution.Oil pollution and salinization are the main problems in the coastal wetland in the Yellow River delta.Therefore,the soil in this study area was taken as the research object,and the effects of salinization on soil physical and chemical properties and microbial communities were explored through indoor simulation experiments.The tolerance of microorganisms and salinity was determined,respectively.Using oil-enriched soil and high-throughput sequencing,the potential degradation mechanism of degradation microorganisms in soil was explored,and changes of p H,conductivity and TOC were determined respectively.Through soil experiments under the combined action of petroleum and salinization,the change rules and influencing factors of sensitive microorganisms in soil under the combined effect of oil and salinization were explored,and the changes of microbial community,TPHs and salinity were determined.(1)The variations of soil physical and chemical properties(p H,TOC,TPHs,salinity)and soil microbial diversity were studied with the increase of petroleum content;(2)To study the changes of soil chemical properties(p H,TOC,TPHs,salt content)and soil microbial diversity with the increase of salt content under a certain amount of oil pollution;(3)With the rise in soil salinity and the amount of salt added,the correlation analysis of soil physical and chemical properties(p H,TOC,TPHs,saltcontent)and the change of microorganisms,the sensitive organisms with apparentdifferences in response were screened.The study of soil physical and chemical properties found that the addition of petroleum significantly increased soil TOC from 2.31±0.59 mg/kg to 7.04±0.42 mg/kg(r>0.95,p<0.1,R2>0.9),and TPHs from 9.18±0.07 mg/kg to 33.09±4.61 mg/kg(r>0.9,p<0.05,R2>0.9),and led to the increase of soil salinity and the decrease of p H in the initial stage.Soil salinity increased from 2.46±0.13g/kg to 15.12±0.21g/kg(r>0.8,p>0.1,R2>0.95),but it did not directly affect other physical and chemical properties.In the study of microbial diversity,it was found that Gemmatimonadaceae showed a noticeable trend of growth under the two conditions of increased dosage of additives and increased salinity.However,other bacteria,such as Bacteroidetes,have a distinct growth trend under the condition of growing salt content.In contrast,the increase of adding salt has an inhibitory effect on their growth.Lactobacillus and Halorhodospiraceae,the nitrate-reducing bacteria with potential oil degradation,appeared after the addition of crude oil.Halobacillus and Immundisolibacter appeared in high and low salt environments,respectively.Aerobic bacteria Acidimicrobiaceae,Peptoccaceae,Hyphomonas and cannot use oil in the process of salinization and oil pollution.Among them,Lactobacillaceae can produce lactic acid,acetic acid and fumaric acid by fermentation of carbohydrates,lipidic acids,or esters to provide metabolic substrates for other microorganisms.The above results provide the theoretical basis for further understanding of the pollution mechanism of oil and salinization combined stress on the soil.A large number of sensitive organisms in the soil can act asindicative and degraders for salinized sludge.