Distribution Characteristics Of Polycyclic Aromatic Hydrocarbons On PM_2.5 In Urban Traffic Road

Polycyclic aromatic hydrocarbons?PAHs?are a class of organic contaminants containing two or more benzene rings..n the urban traffic road,the PAHs in the atmospheric particles are seriously polluted by the emission of motor vehicles.Studying the distribution characteristics of PAHs in the atmospheric particles of urban traffic roads plays a positive role in the control and management of PAHs.In this paper,four kinds of typical traffic roads in Tianjin were sampled and meteorological information statistics were collected.Temporal and spatial distribution characteristics of PAHs were analyzed.The main conclusions of the dissertation are as follows:?1????PAHs?of PM_2.5.5 in Baidi Road was 34.09±9.91ng/m³,while Jianyang Road was31.49±14.10ng/m³,Fukang Road was 22.38±9.48ng/m³,and Waihuan Road was 15.98±4.66ng/m³.The proportions of the total PAHs in rings 5⁷ were Jianyang Road>Baidi Road>Fukang Road>Waihuan Road.?2?The concentrations of all PAHs in Jianyang Road and Waihuan Road were higher at night,while Baidi Road and Waihuan Road were higher in the daytime.Theconcentrations of all PAHs in Jianyang Road were higher in non-working days than in the working day,while Fukang Road remained unchanged in a week.Part of PAHs of high-cyclic in Waihuan Road were were higher in non-working days,which part of PAHs of low-cyclic in Waihuan Road were higher in the working days.?3?There were significant positive correlations between mass concentration of PAHs and vehicle flow rate,significant negative correlation with vehicle speed and poor correlation with meteorological factors.There was a significant positive correlation between high PAHs and vehicle flow rate.Low PAHs were significantly and negatively correlated.There was no significant correlation between PAHs and meteorological factors.?4?The ILCR model was used to evaluate the PAHs risk in four traffic roads.The risk of PAHs exposure for children and adults in the four roads were:0.30×10^-6,0.24×10^-6,0.23×10^-6and 0.05×10-6;0.46×10^-6,0.39×10^-6,0.28×10^-66 and 0.24×10^-66 respectively,health risks for children and adults within acceptable limits,adults have a greater health risk in transportation than children because of exposure time to traffic on roads longer than children.