Variations in Atmospheric Mercury Concentration in Kagoshima City During 2010 – 2012

Abstract

The atmospheric mercury (Hg) concentration was determined during Aug. 2010 – Jun. 2012 in Kagoshima City and compared with values reported for 1996 – 2002. The average concentrations were 10.8 ng m−3, 13.4 ± 10.1 ng m−3, 5.52 ± 3.85 ng m−3 and 1.9 ± 0.5 ng m−3 for 1996 – 1997, 1997 – 1998, 1999 – 2002 and 2010 – 2012, respectively. The recent atmospheric Hg level in Kagoshima City was the same as the Japanese background levels. The Hg concentration was higher in the summer than other seasons and a significant correlation was obtained between the Hg concentration and the air temperature. These results suggested that the evaporation of Hg from surfaces according to temperature was an important factor to increase the Hg concentration in ambient air. On the other hand, the atmospheric Hg concentration could not be enhanced directly by the fumarolic activity of the Sakurajima volcano located in Kagoshima City. In this study, 3.5 ng m−3 (= mean + 3 standard deviation) was defined as a background level in the Kagoshima City. The days were observed to have higher values than the background level in Kagoshima City; there were 5 days during the investigation period. From the back-trajectory over China, it could be considered that the observed high concentration of Hg in air showed the possibility of long-range transportation from the East Asia region.