Polycyclic Aromatic Hydrocarbons(PAHs) become an important Persistent Organic Pollutants(POPs) due to it's strong toxicity, long cycle of degradation in the environment. Soil is the storeroom of PAHs in the environment , and Polycyclic aromatic hydrocarbons pollution in soil is a grave threat on the soil ecosystem and the safety of agricultural products.The remediation with Mycorrhizal fungus and plant integrated system is an important way and the current hot research field in the field of PAHs contaminated soil remediation. Simulating pyrene polluted conditions by adding pyrene, with the method of biological experiments (soil culture and sand culture) and room analysis, this study investigated the remediating effects and its impact factors of pyrene contaminated soil with AMF (Abuscular Mcorrhizal Fungus, AMF) coming from oil-contaminated soil and corn integrated system. Furthermore, the mechinesms and the relative contribution rate of soil microorganisms,corn and AMF in the remedition effects of pyrene contaminated soil by AMF and corn integrated system was also discussed. The main results were as follows: 1. AMF and corn integrated system had significant effect on remediation of pyrene contaminated soil . AMF maintained relatively high infection activity in the soils with 5mg/kg, 10mg/kg and 50 mg / kg soil pyrene treatment .Compared with the control which had no corn growth and no sterilization,the residual pyene concentration in the soils with different pyrene treatments decreased 23%~78% ,and that the removal rate of pyrene were 1.4 to 2.3 times of control.These results indicated that AMF and corn integrated system can significantly decreased the residual pyrene concentration in the soil,and accelerate the remediation of pyrene contamination in soil. The compositive contribution rates of AMF and corn integrated systerm reached 45% ,of which corn comprehensive contribution rate was 34%, and AMF comprehensive contribution rate was 11%.2.The AMF and corn integrated systerm had significant effects on pyrene contaminated soil remidation under different levels of phosphate fertilizer in soil, and the phosphorus input in the soil with phosphorus deficiency had positive effects on that. The application of 80 mg/kg and 20 mg/kg had no significant effects on AMF inoculation rate in the soil with 50mg/kg pyrene. Compared with the control which had no corn growth and no sterilization,the residual pyene concentration in the soils under 20mg/kg and 80mg/kg P treatments decreased 53% and 58% respectively,and that the removal rate of pyrene increased 30% and 31% respectively,and the compositive contribution rates of AMF and corn integrated systerm reached 23% and 23.8% respectively.Compared with 20mg/kg P treatments,the residual pyrene concentration of soil with 80mg/kg P treatments decreased 18.4%. P input had no significant effect on the compositive contribution rates of AMF and corn integrated systerm in soil pyrene removal,but could decrease the comprehensive contribution of AMF.The microbial biomass carbon of soil had significant positive correlation with the pyrene removal rate, AMF innoculation and P can significantly increase the microbial biomass carbon,therefore ,the increase of soil microbes may be the important reasons in the removal of pyrene in soil by AMF and corn integrated systerm.3.Surfactant TW80 had noteble positive effects on the remediation of pyrene contaminated soil by AMF and corn integrated systerm,but the decreaesing extent of the residual pyrene concentration which leaded by unit concentration of TW80 input in soil exponential dropped with the increase of TW80 concentration. The residual pyrene concentration of 500 mg/kg TW80 treatment decreased 22.4% than the control without TW80,representing the best effect.TW80 can inhibit the effects of AMF in soil pyrene removal.Therefore it's necessary to contol the concentration of TW80 to use it in the remediation of pyrene contaminated soil by AMF and corn integrated systerm.4. The AMF community and the single species derived from rock oil-contaminated soil all can be combined with corn and promote the remidation of pyrene contaminated soil , the original AMF community has obvious advantages and behave best.The residual pyrene concentration of soil in the treatments with the mixed AMF community M4 (Glomus intraradices, Glomus mosseae, Glomus etunicatum and Acaulospora tuberculata) and corn integrated systerm got 0.12mg/kg,0.54mg/kg and 3.92mg/kg respectively in 1mg/kg, 10mg/kg and 50 mg/kg pyrene treatments,decreased 32.6%,58.6% and 42.2% respectively than that of the treatment of M1 (G.mossea),decreased 28.1%,59.9% and 36.6% than that of M2(G.intradices), decreased 2.7%,55% and 23.5% than that of M3 (G.intradices + G.mossea).5.Large scale reproduce overall of AMF community which coming from rud oil-contaminated soil in the absence of the original conditions will change the quantiy,composition and structure of the AMF population and may has negative impact on it's function in the remedition of soil pyrene contamination. After three times of reproduce without original conditions ,the removal rate of pyrene in the treatments with corn and AMF got 86.24%,85.73% and 82.76% respectively after each time of reproduce, and that increased 110%,97% and 85% respectively than that of the control treatments without corn and sterilization.All the results above indicated that AMF community and corn integrated systerm can signifcantly promote the remedition of pyrene contaminated soil,but the effects decreased with the increase of reproduce times. So the function of AMF may be degradated in the process of reproduce.Therefore use of the AMF and corn in remediation of pyrene contaminated soil should consider the source of AMF and it's functional stability.6.AMF inoculation can change the distribution of pyrene absorbed by root ,but had no significant effect on the total quantity of pyrene absorbed by corn. The pyrene concentrations of roots in corn were 5 to 16 times of that in shoots in the pyrene treatments of 10mg/kg,50mg/kg and 100mg/kg indicating that the pyrene absrobed by roots mainly cumulated in roots.AMF inoculation can promote the cumulation of pyrene in roots. The pyrene concentration of shoots in corn in the treatments with AMF inoculation decreased 30%~37% than that of the treatments without AMF inoculation, while that of the roots increased 19%~35% in the contrary. The pyrene concentration in the mycelium of AMF was little lower than that of roots in corn, but significantly higher than that of shoots indicating the stronger cumulative capacity of AMF mycelium. The total quantity of pyrene cumulated in corn was only 0.02% to 0.05% in the pyrene inputed in the soil,so the absorption and accumulated in corn contribute little in the remediation of pyrene polluted soil. 7.AMF inocilation had significant effects on the composition of corn's root exudates and the oxidative damage to corn caused by pyrene in the pyrene treatments. The AMF inoculation of corn had no significant impact on pH value of rhizosphere ,but can promote the secretion of succinic acid and salicylic acid and which provied the substrate for the cometabolism of pyrene.AMF inoculation can improve the activity of corn's roots ,decrease MDA concentration and CAT activity of corn's leaves, alleviate the oxidative damage caused by pyrene ,thereby enhancing the resistant ability of corn to pyrene contamination.8. AMF and corn integrated systerm can significantly increase the number of microoganism or microbial biomass carbon,enhance soil catalase and polyphenol oxidase activity, and that provide favorable conditions for the remediation of pyrene contaminated soil. |