The Study Of Rhizoremediation Potential Evaluation For Remediation Plants In Petroleum Contaminated Soil

With the exploitation petroleum increasing each year,petroleum pollution has gradually become a remarkable environmental issue.As a novel technology for the remediation of contaminants,the purpose of phytoremediation is to use plants and their rhizosphere microorganisms to interact with the environment to remove toxic substances from the environment or to render them harmless.The aim of this study is to investigate the ability to repair petroleum of three plants including Mirabilis jalapa L.,Lolium perenne and Zea mays,and optimize the candidate plants for petroleum pollution,explore the response of root exudates and rhizosphere microorganisms to petroleum pollution in phytoremediation,and provide the theoretical basis for phytoremediation of petroleum pollution.The results are as follows:1.The results showed that petroleum pollution had a significant inhibitory effect on plant growth,and the inhibition get stronger when the petroleum concentration is higher through monitoring plant growth status and soil total hydrocarbon content.But the three plants have different degree of tolerance to petroleum pollution,Lolium perenne is the strongest,followed by Mirabilis jalapa L.and the Zea mays is the weakest.The results of petroleum hydrocarbon content show that the presence of plants could effectively remove the petroleum hydrocarbons in the soil,the three plants have the greatest degradation ability at the petroleum concentration of 10 g/kg,and on the basis of 10 g/kg,it is more difficult to repair contaminated soils with the increase of petroleum concentration.2.The purpose of determining the content of organic acids in root exudates through high performance liquid chromatography(HPLC)is to investigate the relationship between contents and species of organic acid and degradation ability.The results showed that the total contents of four organic acids decrease gradually with the increase of repair time and tend to be stable finally,and was the highest at 10 g/kg petroleum concentration with maximum degradation rate.Ethanoic acid was the highest in the early stage of repair and citric acid was the highest in the later stage of repair among the four organic acids.It was also found that there was a significant positive correlation between the degradation rate of petroleum hydrocarbons and the content of citric acid after 45 days of phytoremediation.3.This study select the Lolium perenne and Mirabilis jalapa L.for the test plants because their highter organic acid content and stronger tolerance at 10 g/kg petroleum concentration after 45 days to explore the effect of petroleum stress on the diversity of rhizosphere bacteria through high-throughput sequencing technology.The results show that petroleum stress significantly reduce the abundance and diversity of soil bacteria.And Mirabilis jalapa L.can stabilize the abundance of bacteria in the contaminated soil compared Lolium perenne.The abundance of Proteobacteria,Actinobacteria and TM7 increase significantly under petroleum stress,the presence of two plants can promote the growth of Proteobacteria significantly,and Mirabilis jalapa L.also enhances the abundance of TM7.?-Proteobacteria,TM7-3 and Actinobacteria are the main classes of Proteobacteria,TM7,Actinobacteria respectively and their abundance increase after petroleum stress.In terms of genus level,the abundance of Pseudomonas,Alcanivorax and Perlucidibaca in?-proteobacteria and lamia,Nocardia in Acidimicrobiia increase under petroleum pollution.Mirabilis jalapa L.has a stabilizing and enhancing effect on the abundance of Alcanivorax,Perlucidibaca and Flavobacterium,and Lolium perenne can prompt Pseudomonas to grow heavily.