| In recent years,with the acceleration of urban development and the improvement of social economy,the concentration of living activities,population and productivity are higher than before.The traffic and industrial activities generate a large amount of pollutants,which are persistent and toxic,caused some destruction to the ecological environment.Polycyclic aromatic hydrocarbons(PAHs)is a kind of persistent organic pollutants,and widely exists in the atmosphere,the human activities pollution and most of the industrial activities can produce this pollution.Because of its three effects–carcinogenic,teratogenic and mutagenic,which has got more attention in the world.In this study,we take the northern alpine city – Harbin,as an example,study on the 16 PAHs which are the US EPA priority controlled in two snowfalls event in winter of 2014.The research contents include: analysis of the general characteristics of the PAHs concentration,characteristics of the monomer PAHs concentration;discussthe spatial distribution characteristics of PAHs contents in each function;using the source analysis method to analyze the sources of PAHs,and evaluate the ecological risk by PAHs.(1)Study on the pollution status of PAHs in Harbin,the detection rate of 16 PAHs was 100% in 9 sample points in the first snow event.The concentration range from 437.9 ng·L-1 to 23167.3 ng·L-1,the average value of 11549.5ng· d L-1,3-4 ring PAHs were accounted for the major part,accounting for 77.3% of total contents of PAHS detection,Phe was highest monomer in 16 PAHs.The distribution of each functional area: rural(17349.4 ng·L-1),commercial-traffic mixed area(16727.9 ng·L-1),industrial area(11078.4 ng·L-1),urban park(8426.6 ng·L-1),residential area(5390.7 ng·L-1)and suburban(437.9 ng·L-1),and the PAHs concentration of rural commercial-traffic mixed zone is about 50 times as the suburbs.The pollution sources and atmospheric diffusion condition that affect the concentration of PAHs in the snow,and it may be the main reason for existing regional differences.(2)Study on the different forms of PAHs in Harbin City The PAHs in snowfall were separately analyzed by particle phase and dissolved phase.The concentration of PAHs ranged from 10670.0 ng·L-1 to 351792.3 ng·L-1,the average concentration of 6188.89 ng·L-1,the content of 2-3 rings PAHs accounted for about 88% in the particle phase.The PAHs concentration range of 153.8-1684.6 ng·L-1,the average concentration of 4879.6 ng·L-1,the 2-3 ring mainly accounted for 77.3% of the total PAHs in dissolved phase.The monomer of Naphthalene(Na P)and Acenaphthylene(Acy)have the highest content in the two phase,solid-dissolved distribution coefficient Kp was in the range of 1.21×10-5.85×102,PAHs concentration of dissolved phase was significantly lower than that of particle phase.The content of PAHs in the mixed traffic-commercial area was significantly higher than those in other areas,that shows the pollution is serious in this functional area.(3)In the correlation analysis of each monomer PAHs,it was found that the low molecular weight PAHs and the high molecular weight PAHs had poor correlation,because of the two components may coming from different sources;most of the PAHs had a good correlation with the ?PAHs.(4)By using the method of characteristic compound ratio,it was found that the PAHs could be derived from the combustion of coal and biomass,and others from the emission of motor vehicle exhaust in two snowfall event Harbin.(5)In further study,we qualitative and quantitative analyzed of PAHs,by using the method of factor analysis and multiple regression analysis: the analysis of 12.01 samples,we get two main factors,explains the information of the original data 84.3%.The source of the main factor 1 represents the combustion of coal and biomass,the main factor 2 was from the traffic emission.The contribution rate of the main factor 1,was 77.49%,calculated by regression analysis.The contribution rate of the main factor 2 was 22.51%.2 main factors were obtained in the particle phase,explains the information of the original data of 91.6% in second snow event.The main factors 1 was from the traffic emission,the main factor 2 was from coal and biomass combustion.3 main factors were obtained in the dissolved phase,explains the information of the original data of 84.2%,The main factors 1 was from mixed sources of pollution: traffic emission,coal and biomass combustion.The main factor 2 represents natural gas emission sources,the main factor 3 for coal and biomass combustion.The contribution rate of the traffic source was 55.49%,the contribution rate of coal and biomass combustion emission source was about 44.51% in the particle phase.The contribution rate of the traffic source increased compared in snowfall in first snow event.(6)The average content of Ba P were 375 ng· L-1 in two snow event,Ba P were detected in comparison with other city,and the polar glacier snow in the American city of St Paul,the research results similar to this study,may be due to the two city industrialization is more concentrated;human activities may be caused by the content of Ba P in the far city and the reasons for higher polar glacier.(7)By using Benzopyrene(Ba P)toxic equivalent method for ecological assessment,TEQ concentrations were 798.37 ng·L-1 and 572.84 ng·L-1 in each snow event.It was found that commercial-traffic mixed area and industrial area had higher TEQ value than other functions,which had the highest risk grade.While the concentration of TEQ in rural and residential area were little,which had weak ecological risk.After calculated the hazard quotient of the PAHs in two snow events,the HQ value of Ba P in two events were very large.Because of the high carcinogenic risk of Ba P,we should pay enough attention to it.Then we used the risk quotient(RQ)value method for ecological risk assessment,the results showed that RQ value is higher in the second snow event,which had significant risks,and the pollution was more serious.Besides the Neanthes arenaceodentata,the other two organisms both had higher risk,it illustrated that the pollution from two snow events for the ecological impact can not be ignored.The research results will provide reference value and scientific basis for the numerical simulation of the secondary emission of PAHs during the snow melting process,the snowmelt runoff numerical simulation and the formulation of environmental pollution control measures and its management policies. |
PDF Full Text Request