Distribution Of PAHs In Zhoushan Sea Area And Screening Of Phenanthrene Efficient Degrading Bacteria

Polycyclic aromatic hydrocarbons(PAHs)are a class of hydrophobic persistent organic pollutants that are widely distributed in the environment.They are easily accumulated in the soil and transported through the food chain.Their "three effects" and biological toxicity are very harmful to the ecological environment and human health.Big.Through various studies,microbial degradation is the most important way to repair polycyclic aromatic hydrocarbons in the environment.Therefore,the use of bioremediation to degrade PAHs in the environment can provide theoretical basis and technical guidance for the use of microbial remediation of PAHs to pollute the environment.In this paper,28 samples were collected from the sea near Zhoushan,and the distribution characteristics of pollution degree of PAHs in Zhoushan City were analyzed.Then,a strain of phenanthrene-degrading bacteria was isolated and screened from the soil of the sewage outlet polluted by the petrochemical plant near Zhoushan.The degradation effect of the strain on the contaminated soil of PAHs was explored,and the optimal conditions for the degradation of phenanthrene were explored.Degrading bacteria are better used in actual soil bioremediation.The main findings are as follows:(1)16 kinds of PAHs were detected in addition to terpenes,and the highest detection rates were naphthalene,anthracene,benzo[k]fluoranthene and benzo[g,h,i] perylene.100%,the lowest detection rate is acenaphthene and fluoranthene,both are 4%.The total content of PAHs in the soil ranged from 2.71 ng/g to 52.05 ng/g with an average concentration of 16.64 ng/g.The proportion of PAHs in the 2-3 ring is large,with an average ratio of 69.15%.From the regional distribution,the soil PAHs concentration near Peach Blossom was the highest,with an average total content of 32.41 ng/g,followed by Jintang,with an average total concentration of 26.03 ng/g,and the lowest concentration was near the Lushan Mountain.The average total content was 10.53 ng/g.(2)Screening and isolating a highly efficient degrading strain HJ2 which can be used to degrade phenanthrene from the sediment-soil soil of petrochemical pollution.The morphological observation,physiological and biochemical analysis and 16 s rDNA gene sequence identification confirmed that HJ2 belongs to Staphylococcus.Basically,it can be identified as Staphylococcus warneri strain,but the specific species is still uncertain.(3)The final degradation rate of HJ2 was 73.66% under the initial temperature of 30 °C,initial pH 7.0,initial salinity 0 and initial concentration of 1 mg/L.(4)The strain HJ2 has strong adaptability to the environment and good temperature.The degradation rate is between 48% and 74% in the temperature range of 20 °C-35 °C.The degradation rate ranges from 65% to 74% in the range of pH 6.0 to pH 8.0,but the peracid or overbased environment inhibits the action of the strain.The degradation rate was good at a salinity of 5-20,and the degradation rate of salinity of 20 was 75.61%.The initial concentration of phenanthrene was better in the range of 1 mg/L-10 mg/L.When the initial concentration was 5 mg/L,the degradation rate was 76.91%.By comparison,it was found that the degradation of phenanthrene was the best under the conditions of temperature 30 °C,pH 7.0,salinity 20,phenanthrene initial concentration 5 mg/L,and the degradation rate of phenanthrene was 86.66% after 48 h.