Concentrations Of Nitropolycyclic Aromatic Hydrocarbons Research Articles

Considerations of Atmospheric Behaviors of Polycyclic Aromatic Hydrocarbons, Nitropolycyclic Aromatic Hydrocarbons and Inorganic Pollutants Based on Their Interrelationships.

Airborne particulates were collected during the same periods in downtown Kanazawa, Sapporo and Tokyo and polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs) were determined together with several heavy metal elements and water-soluble inorganic ions. The mean concentrations of metal elements and inorganic ions were the highest in Tokyo, followed by Sapporo and the lowest in Kanazawa both in winter and summer, and were strongly dependent on the amount of airborne particulates. These tendencies were different from the cases of PAHs and NPAHs. Correlations between the organic compounds (PAHs and NPAHs) and several inorganic pollutants were strong only in winter samples of Sapporo, but not so strong in Kanazawa and Tokyo. Because PAHs and NPAHs and several combustion-origin inorganic substances are, in general, detected mainly in the fine airborne particulates, it was reasonable that the significant correlations were found only in the winter samples of Sapporo where the generation of the coarse and crustal particulates were suppressed by snow or ice. Though the atmospheric concentrations of PAHs and NPAHs in Kanazawa were much lower than in Sapporo, the correlation among the NPAH compounds and between PAHs and NPAHs were surprisingly similar in these two cities. The strong correlations indicated that the atmospheric behaviors of the PAHs and NPAHs studied were similar in the two cities and that the source of PAHs and NPAHs might be the same. On the contrary, strong correlations were not observed in Tokyo, suggesting the possibility of multiple sources or formations/degradations of PAHs and

Comparison of Polycyclic Aromatic Hydrocarbons and Nitropolycyclic Aromatic Hydrocarbons in Airborne and Automobile Exhaust Particulates

Polycyclic aromatic hydrocarbons (PAH) and nitropolycyclic aromatic hydrocarbons (NPAH) in airborne particulates collected simultaneously at downtown and suburban sites and in exhaust particulates from diesel and gasoline engine vehicles were determined. The mean concentrations of all compounds in the atmosphere were lower at the suburban site. The differences between the two sites were smaller in airborne particulates than in the atmosphere. However, the difference in NPAH concentrations in particulates between the two sites was greater than the difference in PAH concentrations, suggesting that the NPAH were less stable than the PAH. The concentrations of 1-nitropyrene and 1,3-, 1,6- and 1,8-dinitropyrenes were generally much higher in automobile exhaust particulates than in airborne particulates because the former were collected directly. However, 2-nitrofluoranthene and 2-nitropyrene were observed in airborne particulates but not in automobile exhaust particulates. The diurnal concentrations showed that 2-nitrofluoranthene and 2-nitropyrene might be formed by a hydroxyl radical-initiated reaction followed by nitration.

Comparison of Atmospheric Polycyclic Aromatic Hydrocarbons and Nitropolycyclic Aromatic Hydrocarbons in Kanazawa, Sapporo and Tokyo

Air samples were collected at the sides of busy traffic roads in downtown Kanazawa, Sapporo and Tokyo during the same periods both in the daytime and in the night, in winter and summer. We determined the levels of polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs), which are known to be carcinogenic and/or mutagenic. PAHs and NPAHs were analyzed simultaneously with an HPLC system with fluorescence detection for PAHs and another HPLC system with chemiluminescence detection for NPAHs, respectively. The amounts of airborne particulates were larger in the daytime than in the night in all three cities. This result was thought to reflect the diurnal change of such urban activities as traffic volume. Many of the PAH and NPAH compounds showed higher concentrations in the daytime than in the night, and also showed higher concentrations in winter than in summer in the three cities. This result coincided with the trends observed in our continuous surveys in downtown Kanazawa for several years. However, 5-ring PAHs, such as benzo [a] pyrene, and dinitropyrenes in Tokyo did not show such diurnal or seasonal differences. The composition ratio of NPAHs and the contribution of diesel-engine vehicles to the atmospheric concentrations of NPAHs were calculated from all the data of this survey. The concentration ratio of dinitropyrenes to 1-nitropyrene became larger with an increase in the ratio of diesel-engine vehicles to the total vehicles registered, suggesting a large contribution of diesel-engine vehicles to the concentrations of these NPAHs in urban air.