Aliphatic and polycyclic aromatic hydrocarbons of atmospheric aerosols in five locations of Nanjing urban area, China

A comprehensive campaign had been performed from 2001 to 2002 in five urban sites of Nanjing, a typical mega-city of China, in order to fully understand the state, characteristics and sources of the air pollution. As part of the work, 18 n-alkanes (C₁₅-C₃₂) and 15 PAHs in PM₁₀ and PM_2.5 aerosols were chemically characterized in this study by GC and GC/MS. The potential sources of pollutants were reconciled using carbon preference index (CPI) values of n-alkanes and diagnostic ratios of PAHs. Concentrations of the total n-alkanes varied from 53.6 to 733 ng m^{- 3} with mean value of 260 ng m^{- 3} for PM10 and from 39.1 to 709 ng m^{- 3} with mean value of 206 ng m^{- 3} for PM2.5, respectively, while average concentration of the total PAHs was 86.0 ng m^{- 3} for PM10 and 62.6 ng m^{- 3} for PM_2.5, respectively. BaP was detected in all samples and at much higher concentrations than in Los Angeles and London. Strongly linear relationship of concentrations of the target compounds between PM₁₀ and PM_2.5 was found and indicated that n-alkanes and PAHs are mainly enriched in fine particles. Concentrations of n-alkanes and PAHs presented the highest values at the traffic center, where huge amount of vehicle emissions was the main source of the pollutants. The CPI values and the diagnostic ratios of PAHs further suggested that fossil fuel combustions were the most important source of organic aerosols in the urban area.