Calculating source contributions to urban atmospheric polycyclic aromatic hydrocarbons and nitropolycyclic aromatic...

A method to calculate source contributions to atmospheric polycyclic aromatic hydrocarbons (PAHs) and their nitrated congeners (NPAHs) is proposed, using pyrene (Pyr) and 1-nitropyrene (1-NP), as respective representatives of PAHs and NPAHs. This is based on the known increases in NPAH to PAH ratios as combustion temperatures increase. The fractions of 1-NP and Pyr from high temperature combustion sources in total 1-NP and Pyr are respectively calculated as a (0 < a <1) and b (0 < b < 1). By using atmospheric concentrations of Pyr and 1-NP obtained at monitoring sites, contributions of high and low temperature combustion sources were calculated. Using this method, the contributions of automobiles and coal combustion facilities/industries to atmospheric Pyr and 1-NP concentrations were calculated for atmospheric samples collected in Kanazawa, Japan during a seasonal Asian dust event. The results show that Pyr was almost entirely emitted from industries in China and transported long-range to Japan. By contrast, 1-NP was emitted primarily from automobiles in Kanazawa and its surrounding areas, with a small amount of 1-NP possibly transported from China. The proposed method can provide greater clarity on source identification compared to the typically used PAH isomer pairs.