Variation in polycyclic aromatic hydrocarbons and nitropolycyclic aromatic hydrocarbons in airborne particulates collected in urban Kanazawa, Japan, in last 12 years

Abstract

Airborne particulates were collected at a roadside site in Kanazawa, Japan, in the summer and winter, 1999, 2004/2005, 2007/2008 and 2010. The polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs) were determined by HPLC with fluorescence and chemiluminescence detections, respectively. The total concentration of six PAHs (pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene and benzo[a]pyrene) decreased by the factor of 63.9% in the winter and 75.6% in the summer from 1999 to 2010. The total concentration of seven NPAHs (1,3-, 1,6-, 1,8-dinitropyrenes, 1-nitropyrene, 6-nitrochrysene, 7-nitrobenz[a]anthracene and 6-nitrobenzo[a]pyrene) significantly decreased by the factor of 88.0% in the winter and 89.2% in the summer during the same period. The concentration ratio of 1-nitropyrene to pyrene also significantly decreased in this period, suggesting a decrease in the emission amount. As the main reason for the significant decrease in the PAHs and NPAHs, the regulation of exhaust gas/particulates from automobiles was considered.