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 mi-ht 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 NPAHs.