Pollution And Evaluation Of Polycyclic Aromatic Hydrocarbons (PAHs) On The Surface Of Taigu County Coking Site

Polycyclic aromatic hydrocarbons(PAHs)widely exist in various environments on which human beings live.China is a major PAHs polluter,and the PAHs pollution in China is also serious.Shanxi Province is a large coal-burning province in China,in which the coking industry plays a crucial role in the industrial structure of Shanxi Province.The coking process causes a large number of PAHs production and emission every year,which seriously pollutes the environment.Through the study of PAHs pollution status and carcinogenic risk in soil of coking plant,scientific basis can be provided for local soil PAHs pollution prevention and control,and it is helpful to implement land consolidation measures.The paper takes a coking plant ground surface 0?20 cm depth soil in Taigu county of Shanxi Province jinzhong city as the research object,and analysis of ground surface content of 16 kinds of optimal control of PAHs.According to the established Maliszewska-Kordybach PAHs pollution degree classification standard and the domestic coking plant PAHs pollution concentration data,the pollution level is analyzed.According to the dose-effect evaluation TEQBaP toxicity equivalent?the exposure effect method the article assesses health risks and the screening value and control value of industrial land(M)in the second category of land used for urban construction(GB36600-2018).Finally,microbioremediation,combined phytoremediation with microbioremediation and other physical,chemical restoration measures are recommended for land consolidationThe research results show that:1.The content range of 16 polycyclic aromatic hydrocarbons(?16PAHs)in the six sampling sites was 171.4-1099.57ng/g,with an average of 749.32ng/g.The content of 7 kinds of carcinogenic PAHs(?7Car PAHs)ranges from 80.02-557.74ng/g,with an average of 382.35ng/g,accounting for 51.03%of 16PAHs.The highest concentrations of carcinogenic BaP in 16 PAHs monomers ranged from 6.72-40.53ng/g,with an average of 24.98ng/g.2.According to the grading standards of 16 optimal control PAHs pollution levels in soil suggested by Maliszewska-Kordybach,it is concluded that the sampling points of clean,moderate,and severe pollution are respectively 16.67%,66.67%and 16.67%.The site pollution level is mainly moderate3.Compared with PAHs pollution concentration data of coking plants in recent years,the average concentration of 16 PAHs is ranked from high to low:A coking plant in Beijing>A steel plant in northeast China>A large steel enterprise in the northeast>The paper>Beijing suburbs>Farmland near a coking plant in jinzhong.4.The risk values of 7 types of carcinogenic PAHs were 0.45x10-9-3.02×10-9.BaP is the most carcinogenic in 16 PAHs,and its risk range is 2.18×10-10-1.31×10-9,which reaches the maximum at point S2.5.Relative to the Dutch soil quality standard,the content of BkF,BaP and IcdP exceeded the standard value,and the risk values were 52.305ug/kg,143.14ug/kg and 54.272ug/kg,respectively2.09 times,5.73 times and 2.17 times of the standard value.There were potential risks.The 16TEQBaP of 16 PAHs is 359.53216ug/kg,the sum of 7CarTEQBaP of 7 carcinogenic PAHs is 353.1465ug/kg,accounting for 98.22%of the total 16TEQBaP,and the carcinogenic PAHs is the main contributor to the total TEQBaP,and takes the highest proportion of BaP.6.The content of 8 PAHs monomers is less than the reference value of industrial land(M)in the second category of land used for urban construction(GB36600-2018)in the standard for soil environmental quality control and control of soil pollution risk for construction land(GB36600-2018),which does not pose any health risk to human bodyThe conclusions of this study are as follows:(1)the total amount of PAHs in the surface soil of the coking plant site is at a moderate pollution level.Microbial remediation is carried out by using white-rot fungi,rhodococcus,leaf bacillus and burkholsiella,or by combining plant and microbial remediation with corn,ryegrass,rape and alfalfa.In terms of physical measures,electric repair was adopted to reduce PAHs concentration;In terms of chemical measures,hydrogen peroxide,potassium permanganate and TiO2 were used to repair soil contaminated by PAHs in coking plants.(2)According to the results of health risk assessment,the carcinogenic risk of PAHs in the surface soil of the coking plant site is lower than the acceptable human level(1 × 10-6),which will not cause carcinogenic risk to human body.