Investigation of the relationship between atmospheric mercury and concentrations of key greenhouse gases at a mountainous monitoring site

The concentration of total gaseous mercury (TGM) was monitored, together with some key greenhouse gases (GHGs: carbon dioxide (CO₂), methane (CH₄), and water (H₂O) vapor) at hourly intervals at a mountainous monitoring site close to the highly industrialized city of Seoul, Korea. Correlations between the concentrations of Hg and those of the greenhouse gases were examined to assess their source characteristics and responses to changes in meteorological conditions. The mean Hg levels in this study (3.58 ± 2.13 ng m^-3) were considerably lower (by, e.g., 24.3%) than those measured previously in other comparable sites during 1999-2006 (4.73 ± 1.34 ng m^-3). Accordingly, such a reduction in Hg levels suggests the effectiveness of the regulatory measures enforced over the years. The mean Hg level observed in this study is also lower (by approximately 5%) than those in other Asian locations. In contrast, the mean concentrations of the two most important GHGs (CO₂ and CH₄) were moderately higher than those of other locations across the world (by approximately 4-9%). The results of our analysis indicate that the behavior of Hg is strongly correlated with water vapor and CH₄ in terms of their source characteristics, despite notable differences in their diurnal patterns.