Abstract
A trend analysis of the benzo[a]pyrene (BaP) concentrations in Japan during the period from 2002 to 2012 was conducted using the monitoring data from the Ministry of the Environment of Japan. The sites are classified into three categories, i.e., general environment (I), stationary industrial region (H), and road site (E). It was found that the BaP trend values, [BaP], decrease in time with the associated seasonal variation, i.e., high in the autumn-winter and low in the summer. The contribution of emissions from the stationary industrial sources to [BaP] was found to be higher than that from mobile sources. The decreasing rate of [BaP] was 6.0%/yr for I, 4.6%/yr for H, 6.6%/yr for E for all of Japan. The higher [BaP] was found in H in Kyusyu and Setouchi, whereas [BaP] in the coastal area of the Sea of Japan was the lowest. It was found that the annual decreasing rate in I in all of Japan (6.8%/yr) during the period from 2005 to 2012 was 2.3 times higher than that (2.9%/yr) at the Noto monitoring site, facing the Sea of Japan. The contribution of the transboundary transport was estimated to be 11–34% in the coastal site of the Sea of Japan and 4–44% in the northern coastal sites of Kyusyu.
