Estimating mercury emission outflow from East Asia using CMAQ-Hg

Abstract

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.

Enhanced accumulation and storage of mercury on subtropical evergreen forest floor: Implications on mercury budget in global forest ecosystems

“…The present understanding of Hg mass budget in East Asia highlights strong anthropogenic Hg emissions but overlooks the potentially important Hg sink caused by the forest ecosystems [ Chen et al ., ; Lin et al ., ]. Based on the data sets of Hg concentration ( n = 29) and litterfall biomass production ( n = 107) in the EB forests of China, the Hg input through litterfall is estimated to be 37.0 ± 19.0 µg m −2 yr −1 .…”

Atmospheric mercury inputs in montane soils increase with elevation: evidence from mercury isotope signatures

“…Consequently, in some respects, our knowledge of the biogeochemical cycling of Hg in mountainous ecosystems remains limited. In recent decades, there has been great progress in simulations of the global/hemispheric or regional Hg distribution and examinations of the source-receptor relationship using various modelling systems (e.g., CMAQ-Hg 14 and GEOS-Chem 15 ), although surprisingly little attention appears to have been given to orographic effects. Ignoring the possibility of a mountain trapping effect on Hg may, however, hamper the validity of modelling results.…”

Evaluation of CMAQ Coupled With a State‐of‐the‐Art Mercury Chemical Mechanism (CMAQ‐newHg‐Br)

“…Similarly, GOM and PBM were overestimated by a factor of 2-10 for the Great Lakes region (Holloway et al, 2012;Zhang et al, 2012a), and overestimated by 15-257% and 82-380%, respectively, over Central and Northern Europe (Ryaboshapko et al, 2007). In East Asia, surface GOM and PBM concentrations were overestimated by 80-180% in most regions (Lin et al, 2010). Other regional and global Hg models have also found considerable overprediction of GOM and PBM compared with observations (Amos et al, 2012;Ryaboshapko et al, 2007;Seigneur et al, 2004;Selin et al, 2007;Zhang et al, 2012a).…”

“…Furthermore, regional model initial conditions (ICs) and BCs are thought to have Journal of Advances in Modeling Earth Systems 10.1002/2017MS001161 significant impacts on Hg simulations, contributing up to 99% of total Hg deposition and about 81% of total atmospheric Hg concentrations (5GEM 1 GOM 1 PBM; Baker & Bash, 2012;Holloway et al, 2012;Pongprueksa et al, 2008). Recent modeling studies have used global model output or nested simulations to provide ICs and BCs rather than using constant values for all cells as default ICs and BCs in CMAQ-Hg (Baker & Bash, 2012;Bieser et al, 2014;Lin et al, 2010Lin et al, , 2012Lu et al, 2014;Myers et al, 2013;Zhu et al, 2015).…”