Abstract
We analyzed the influence of the long-range trans-boundary air pollution (transport from the continent) on the long-term trends in the hazardous air pollutant 1,2-dichloroethane in the regions of Kyushu and Yamaguchi. In these regions, the long-term trends at the monitoring sites where low concentrations were observed apparently showed increasing trends from around fiscal 2004. Moreover, the trends in this region showed more increasing trends than those in other regions. Based on the monitoring data of this region categorized by backward trajectory classification, the cases of transport from the continent showed a much higher concentration level than those from other areas, and increasing trends of the concentration level in the later period. Based on these results, we concluded that the long-term trends reflected the increasing trends in the concentration level in the air masses transported from the continent. On the other hand, slightly increasing trends in the cases of transport from the background area suggested the possibility of an increase in the concentration in the troposphere. The authors considered that the long-term trends of the 1,2-dichloroethane concentration were consisted by adding the transport from the continent to base increasing concentration in the troposphere.
