Distribution Characteristics of Polycyclic Aromatic Hydrocarbons in Different Functional Zones of Soils from Xiqing District in Tianjin,China

Polycyclic aromatic hydrocarbons(PAHs) have been identified as serious pollutants in environment.In this paper,the distribution characteristics of sixteen PAHs in surface soils in different functional zones from four towns of Tianjin Xiqing District were investigated.The soil samples were extracted with ASE and then fractioned on GPC and SPE,at last the aromatic fractions were analyzed by HPLC-UV-FLU.The results showed that the total PAHs ranged from 67.6 ng·g-1 to 1 274.7 ng·g-1 with the average value of 422.8 ng·g-1,the concentration or-der of the PAHs in four kinds of utilization soils was:industrial areafarmlandroadsideresidential district.The highest and the lowest aver-age contents of PAHs were found in soils in Zhongbei and Xinkou towns respectively.Not all the 16 PAHs were detected in all 24 samples.Principal component analysis was used to identify the pollution sources of PAHs.The variance contribution rate of top three factors was 91.3%,High-molecular PAHs from burning sources dominated at the first principal component,while,the second principal component mainly at-tributed to the low molecular PAHs from petroleum pollution sources.Correlation of organic compound with PAHs in soils has also been stud-ied:there existed significant linear correlations between soil organic matters and PAHs(R 2 =0.613) and soil organic matters most closely cor-related with chrysen(R 2 =0.665),indicating that soil organic matter was one of the important factors affecting the PAHs in soil.However,near the serious pollution source of PAHs,the concentration of PAHs in the soils was probably determined by the pollution source and other com-plicated factors of soils.According to European PAHs risk grading standards,Zhongbei town was moderately polluted,Yangliuqing town and Zhangjiawo town were at light pollution level,Xinkou town was unpolluted.