Distribution of polycyclic aromatic hydrocarbons on atmospheric particles in winter in Xi'an City

This paper is aimed to present a report on the authors' investigation and analysis of 13 mainly controlled PAHs in the atmospheric particles collected from the different function zones of Xi' an City in winter. We choose heavy traffic, industrial, agricultural, student-occupied campus, commercial, cultural and civilian-resident zones as the typical sampling sites. In doing our investigation and analysis, we adopted HPLC-UV detector as our data collection and sampling device and analyzed the PAHs concentration, which has widely been adopted in the world in recent years. The results of our investigation and analysis demonstrate that the PAHs pollution of Xi' an corresponds on the whole to Xuzhou and Tianjin with heavy industry, while it is more serious than that in some cities abroad and at home in atmospheric quality, such as London, Hongkong and Hangzhou etc. The total sum of 13 PAHs varied in different function zones are 121.61—302.25 ng/m~3 with their mean concentrations of PAHs and BaP (factors of high carcinogenesis) are 188.44 ng/m~3 and 12.63 ng/m~3, respectively. As to the concentrations of particle-associated PAHs in ambient air, they are found standing in the order of heavy traffic areas student aparments with heavy coal-burning emission agricultural areas high-tech industrial zones commercial center college campus in the corresponding function zones. On the other hand, BaP concentration is varied with function zones in the order of heavy traffic areas agricultural areas campus with parking lots commercial zones student-living campus areas high-tech industrial zones. As to the origins of such forms of pollution particles, it can be said that PAHs in atmospheric particles primarily come from the vehicle exhausts and coal-burning emissions. For example, the distribution of various rings of PAHs proves consistent in different function zones, where middle and high ringsare dominant. Last of all, the fractions of PAHs with various rings are found to be in the order of 4 rings (38.64%) 5 rings (25.17%)6 rings (18.83%)3 rings (10.25%) digressively.