Characteristics of gaseous elemental mercury and its corresponding source contributions to regional transport in Hefei, China

Abstract

The characteristics of atmospheric gaseous elemental mercury (GEM) in Hefei, China in winter, spring, and autumn 2016 were investigated in this study. Higher GEM concentrations in spring were associated with more abundant anthropogenic emissions and biomass burning before spring plowing. GEM concentrations in the three seasons decreased significantly compared to 2013–2014 levels (22.2%–49.2%), which may to some extent reflect the effectiveness of air quality control measures for coordinated control of atmospheric Hg. The Potential Source Contribution Function (PSCF) analysis show that areas to the north are major contributors of GEM to Hefei in winter because of the effect of the East Asian winter monsoon. In spring and autumn, the major contributors are primarily concentrated in regions to the south. The relative contributions of three categories of anthropogenic GEM sources to their regional transports in each season was further quantified in this study. The results showed similar patterns. Industrial sources accounted for the highest contribution (56%–59.6%), followed by intentional use and product waste associated sectors (24.5%–27.1%), and stationary combustion sources (15.6%–16.9%), implying that control of industrial Hg emissions should be prioritized in future measures. This study compared the simulated results of GEM by the GEOS-Chem model with the field observations. It is found that the GEOS-Chem model significantly overestimated GEM by 75% in general, suggesting that timely update of mercury emission inventory data is needed to improve the accuracy of atmospheric mercury simulations under the background of implementing “Minamata Convention” and a series of air pollution control policies in the future.