Study On The Remediation Effects Of Three Herbaceous Plants On Crude Oil Polluted Soil

The rapid development of industry has made crude oil pollution problems more and more serious.As the most basic activity area of human beings,the pollution situation is even more severe.At present,crude oil pollution has become one of the global environmental problems,and crude oil polluted soil needs to be repaired.The advantages of phytoremediation,such as green,environmental protection,and compliance with sustainable development requirements,which have quickly attracted widespread attention and become the primary choice for remediating crude oil polluted soil.In order to understand the mechanism of phytoremediation more deeply,and to screen plants with strong tolerance and high degradation efficiency to crude oil,three herbaceous plants with theoretical growth advantages were selected,such as Pennisetum purpureum Schum ev.Taiwan,Festuca arundinance L.,and Amaranthus hypochondriacus L..We explored their remediation ability through the 60 days greenhouse pot experiment.The phytoremediation mechanism is a process in which plants,soils and microorganisms are interconnected and interacted,so this study analyzed and evaluated the repair process of plants in three aspects.Firstly,P.purpureum had the strongest tolerance to petroleum,A.hypochondriacus is second,and F.arundinance is the worst.The germination rate of F.arundinance was the most poisonous by crude oil pollution.And under 20%crude oil pollution level,the germination rate of F.arundinance decreased by 14.2%,A.hypochondriacus decreased by 8.34%,P.purpureum only decreased by 3.33%.The biomass of F.arundinance is the most negatively affected by crude oil pollution,and the biomass decreased with the increase of crude oil pollution level.A.hypochondriacus and P.purpureum both increases with crude oil pollution level.P.purpureum grows the most.During the whole experiment,F.arundinance showed obvious poisoning phenomenon.The higher crude oil pollution level is,the more the number of withered leaves appears,the larger the withering area gets.At the same time,the physiological mechanisms of plants also show great differences.The NPK content,soluble protein content and soluble sugar content of F.arundinance decreased with the increase of crude oil pollution level.The NPK content,soluble protein content and soluble sugar content in P.purpureum and A.hypochondriacus increased with the increase of crude oil pollution level,both of the two plants showing strong adaptability and tolerance.The tolerance of P.purpureum was stronger.Secondly,P.purpureum has the highest degradation efficiency to crude oil,and it has the greatest influence on the physical and chemical parameters of the soil.Under high crude oil pollution level,the soil planted with P.purpureum changes from acidic to alkaline.Under 5%,10%and 20%crude oil pollution level,the degradation efficiencies of P.purpureum were 30.93%,34.51%and 45.37%,respectively.The degradation efficiencies of A.hypochondriacus were 28.44%,34.94%,and 37.00%,respectively.The degradation efficiencies of F.arundinance were 25.06%,19.46%and 10.24%,respectively.It was found that the P.purpureum had the highest degradation efficiency,A.hypochondriacus is second and F.arundinance is the worst.Finally,under crude oil pollution,Alcanivorax,Perlucidibaca,Sphingomonas,Luteimonas,Pseudomonas and Flavobacterium which belongs to the genus of dominant bacteria are beneficial to phytoremediation in the rhizosphere bacterial community..The crude oil pollution stimulates the directional changes of the community composition of the rhizosphere bacteria,resulting bacterias which are not existed in the non-polluted soil.In the crude oil polluted soil,it produces Perlucidibaca which is beneficial to plants,and Flavobacterium which is beneficial to degrading the crude oil.These bacteria can dominate the rhizosphere environment and improve the efficiency of crude oil degradation directly or indirectly.The effect of crude oil pollution on the rhizosphere bacterial community structure is different by the influence of plant species.The abundance of Flavobacterium and Perlucidibaca in the rhizosphere soil of F.arundinance is greater,which indicating that the cultivation of F.arundinance is more conducive to the growth of these two types of bacteria.And the fecal remediation potential of F.arundinance is greater.