Bioremediation Of Typical Polycyclic Aromatic Hydrocarbons (PAHs)contaminated Soil

Nowadays soil pollution has become more and more serious, and more attention has been paid to the remediation of soil organic pollutants. Monitoring methods of anthracene and benzo[a]pyrene in soil and plant was established in this paper, high efficiency PAHs degradation bacteria strains were separated from contaminated soil,and phytoremediation and plant-microbial repairition were conducted according to the experimental research, the main conclusions are as follows:The monitoring method of anthracene and benzo[a]pyrene in soil was composed by soxhlet extractor, silica gel column cleanup, and analysis of GC-MS-SIM. Method used for plant including ultrasonic extraction, silica gel column cleanup and analysis of GC-MS-SIM. The recovery rate and precision conformed to the standard of US EPA, so anthracene and benzo[a]pyrene in soil and plant can be accurately detected by these methods.Through the separation and cultivate of strains repeatedly, three kinds of high efficiency PAHs degradation bacteria strains were obtained. The degradation bacteria strains were identificated by MALDI-TOF-MS, and they belong to Sphingomonas and Burkholderia. For the degradation strains, their optimum growth temperature was30?, the optimum growth pH was 7.0, and the optimum substrate concentration was50mg/L. The strain R had the strongest adaptability to pollution of the substrate, the strain W had the strongest adaptability to temperature, and the strain Y had the strongest adaptability to pH.After 15 days, there was 70.98%~87.04% of anthracene and 62.00%~70.44% of benzo[a]pyrene was degradated by the three kinds of degradation strains.There is no effect of PAHs on biomass of plant. The degradation rate of anthracene and benzo[a]pyrene in soil by growing alfalfa was higher than that of festuca ruudinacea scherb, and the degradation rate of anthracene was higher than that of benzo[a] pyrene. After adding the mixed bacteria liquid containing three kinds of strains to the soil that alfalfa was planted, the degradation rate of anthracene and benzo[a]pyrene was improved significantly, and the gap was greater along with the lower level of pollution. The concentrations of anthracene and benzo[a]pyrene in plant decreased gradually. The quantity of degradation bacteria strains in soil waslarger by growing alfalfa than by in blank. The result indicated that plant can promote the increase the number of rhizosphere degradation bacteria, it also showed that plant-microbial remediation was playing a role.The activity of polyphenol oxidase in the rhizosphere of alfalfa was increasing over time, which meant that the activity of polyphenol oxidase was improved.Meanwhile, in the certain concentration range of pollutants, the activity of polyphenol oxidase in soil had positive or negative correlation with the number of degradation bacteria or the content of anthracene and benzo[a]pyrene.