DETERMINATION OF ATMOSPHERIC NITRO-POLYCYCLIC AROMATIC HYDROCARBONS AND THEIR PRECURSORS AT A HEAVY TRAFFIC ROADSIDE AND AT A RESIDENTIAL AREA IN OSAKA, JAPAN

Abstract

Concentrations of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) and polycyclic aromatic hydrocarbons (PAHs) in airborne particles collected at two sites, a residential area and a roadside with high traffic density in Osaka, Japan, in summer and winter were quantified. Five nitro-PAHs, 1-nitropyrene (1-NP), 2-nitropyrene (2-NP), 2-nitrofluoranthene (2-NF), 3-nitrofluoranthene (3-NF), and 2-nitrotriphenylene (2-NTP) and five PAHs, pyrene (Py), fluoranthene (Fl), triphenylene (Tp), benzo[k]fluoranthene (B(k)F), and benzo[a]pyrene (B(a)P) were determined by high-performance liquid chromatography with chemiluminescence and fluorescence detection. At both sites, the mean concentration of 1-NP was higher in winter than in summer. On the contrary, the mean concentrations of 2-NF and 2-NP were higher in summer than in winter. Observed 2-NF/2-NP ratio in the range from 0.40 to 16 suggests that 2-NF and 2-NP were dominantly formed via OH radical initiated reaction in the atmosphere. Nitro-PAH and PAH concentrations were generally higher at a roadside area than at a residential area due to extremely higher concentration of particles at a roadside area. 1-NP/B(k)F ratio was higher at a roadside area than at a residential area, while 2-NF/B(k)F, 2-NP/B(k)F, and 2-NTP/B(k)F ratios were higher at a residential area than at a roadside area. The diurnal changes of 2-NF/B(k)F, 2-NP/B(k)F, and 2-NTP/B(k)F ratios were slightly different from those of 1-NP/B(k)F and 3-NF/B(k)F ratios. Thus, the differences in the patterns of nitro-PAHs/B(k)F ratios may be due to the disparity in formation pathways of each nitro-PAH.

Keywords:

• airborne particles
• atmospheric reaction
• nitrofluoranthene
• nitropyrene
• nitrotriphenylene
• polycyclic aromatic hydrocarbons

Notes

^a Concentrations were revalued to 3 h mean, that is coincident with the sampling period of airborne particles every 3 h, and listed in this table.

^b Values were obtained from 21:00 to 6:00.

^c Measured as oxidant of which O₃ amounts up to more than 90%.