Estimating relative contributions of primary and secondary sources of ambient nitrated and oxygenated polycyclic aromatic hydrocarbons

Abstract

Polycyclic aromatic hydrocarbons (PAHs) derivatives like nitrated and oxygenated PAHs (nitro- and oxy-PAHs) are of growing interests due to their direct and potentially high toxic properties. PAHs derivatives can be produced from primary sources and also can derive from photochemical reactions, however, works about the quantitative contributions of primary and secondary sources are scarce. In this study, levels and seasonal distributions of ambient nitro- and oxy-PAHs were studied in a megacity Nanjing located in East China and evaluated for relative contributions of different sources. The annual average concentrations of most PAH derivatives were generally lower than the levels found in north China, but higher than the levels reported for south China. The relative contributions of secondary formation ranged from 10% to 47% for nitro-PAHs and ∼60% for oxy-PAHs. The study suggested that typical source apportionment technologies could be adopted to investigate primary and secondary sources of PAHs derivatives when derivatives are simultaneously measured with parent PAHs and other source markers. Future studies are interesting to develop, evaluate and compare different source apportionment methodologies for PAHs derivatives.