In-situ Bioremediation Of Petroleum-contaminated Soil By Agropyron Cristatum And Arbuscular Mycorrhizae Fungi In Northern Shaanxi

The economic development in the Northern Shaanxi and even the whole Western China has been vigorously promoted by the oil extraction and refining industries.However,the processes of oil industry,such as exploration and development,oil and gas storage and transportation,chemical production and so on,causes soil to be polluted by crude oil,which poses a serious threat to the fragile ecological environment in the Northern Shaanxi.As an effective technology of soil remediation,bioremediation has attracted more and more attentions on its friendly,economical and effective characteristics.In this study,the soil polluted by crude oil was extracted from the outside,and the in-situ plant-microorganism combined remediation experiment was conducted.As a potential bioremediation material,the remediation capacity of A.was investigated.Besides,the concentration of soil polluted by petroleum hydrocarbon was 0mg/kg,5000mg/kg,10000mg/kg,15000mg/kg,20000mg/kg,respectively,and the effects of arbuscular mycorrhizae fungi(AMF)inoculation on the A.biomass(height,dry weight,weight,death rate),the changes of polluted soil properties and the synergistic effect of petroleum hydrocarbon degradation rate was also carried on in order to develop a bioremediation technology for petroleum contaminated soil in Northern Shaanxi by the study on the symbiotic effects of A.and AMF.The main contents of this study could be summarized as follows:(1)The laboratory-scale experiment showed that a certain petroleum degradation capacity,which is 2.87%-12.15% can be reached only by the effect of A..When the concentration of petroleum hydrocarbons was less than 10000mg/kg and inoculated with 150 AMF/basin,the best degradation rate of petroleum hydrocarbons can be achieved.Under the four different petroleum hydrocarbon concentrations,with 150 AMF/basin were inoculated,the degradation rate were 52.14%,67.81%,47.26% and 38.52%,respectively.The average degradation rate of petroleum hydrocarbons could be increased by 44.93% when compared with AMF,which indicated that the A.and AMF symbiotic remediation of crude oil contaminated soil had a certain potential.Compared with control check(CK),the average degradation rate of petroleum hydrocarbons could be increased by 44.93% after the inoculation of AMF,which indicating that A.and AMF symbiotic remediation method has a great potential on the oil polluted soil treatment.(2)In the in-situ experiment,by comparing and analyzing the effects of different AMF inoculation on soil physical and chemical properties,it was found that organics and rapidly available phosphorus in soil showed a deference decrease with the growth of A..On the contrary,there were merely changed in total nitrogen content and pH value.After the inoculation of AMF,the organics and rapidly available phosphorus were sharply decreased,the pH value tended to be neutral and it was no significant changed in total nitrogen.(3)In the in-situ experiment,with the analysis on the changes of plant height,biomass and death rate,it was showed that the tolerance of A.to pollutant was increased after the inoculation of AMF.Under the 4 different petroleum hydrocarbon concentrations,with 150 AMF per plant were inoculated,the A.height were 52.14%,67.81%,47.26% and 38.52%,about 15.73% higher than CK.Meanwhile,the death rate of A.was the lowest in the whole time.While the concentration of petroleum hydrocarbon was 20000mg/kg,and the death rate of A.growed at 150 d was 37.67%,which was 6.81 times than CK.(4)In the in-situ experiment,A.showed a degradation rate of 49.01% in average.The degradation rate of petroleum decreased with the increase of petroleum concentration in soil by the symbiotic remediation of A.and AMF.However,under the same concentration of pollutants,the higher the inoculation amount of AMF was,the higher degradation rate of petroleum hydrocarbons was.And the appropriate extension of the remediation time is helpful to the degradation of petroleum hydrocarbons.While the inoculation amount was 200 and the remediation time was 150 d,the petroleum hydrocarbons degradation rate reached the highest level,which were 74.98%,70.61%,53.38%,43.47% with the initial concentration between 5000~20000mg/kg,and it was 23.67% higher than the CK experiment in average.(5)The correlation analysis showed that the biodegradation rate of petroleum hydrocarbon was significantly positive correlated with AMF inoculation,soil organics and the dry weight of A..It was significantly native correlated to the concentration of petroleum hydrocarbons and the death rate.