1Department of Civil Engineering, Lamar University, Beaumont, TX 77710, USA
2School of Environmental Science & Engineering, South China University of Technology, Guangzhou, 510006, Guangdong, China
3Department of Mechanical Engineering, Lamar University, Beaumont, TX 77710, USA
4Decision and Information Sciences Division, Argonne National Laboratory, Argonne, IL 60439, USA
5Department of Chemical Engineering, Lamar University, Beaumont, TX 77710, USA
6Office of Air Quality Planning and Standards, USEPA, Research Triangle Park, NC 27711, USA
7State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China
Abstract. East Asia contributes nearly 50% of the global anthropogenic mercury emissions into the atmosphere. Recently, there are concerns for the long-range transport of mercury from East Asia to North America, which may lead to enhanced dry and wet depositions in North America. In this study, we performed four monthly simulations (January, April, July and October in 2005) using CMAQ-Hg v4.6 in an East Asian model domain. Coupled with a mass balance analysis and a number of emission inventory scenarios, the chemical transport of atmospheric mercury, the seasonal mercury transport budgets and mercury emission outflow from the East Asian region were investigated. The total annual mercury deposition in the region for the modeling year is estimated to be 821 Mg, with 396 Mg contributed by wet deposition and 425 Mg contributed by dry deposition. Regional mercury transport budgets show strong seasonal variability, with a net removal of RGM (7~5 Mg mo−1) and PHg (13~21 Mg mo−1), and a net export of GEM (60~130 Mg mo−1) from the study domain. The annual outflow caused by the East Asian emission is estimated to be in the range of 1369~1671 Mg yr−1, primarily in the form of GEM. This represents about 75% of the total mercury emissions (anthropogenic and natural) in the region. The emission outflow from this source region would contribute to 20~30% of mercury deposition in areas remote from anthropogenic emission sources.