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Global Simulation of Atmospheric Mercury Concentrations and Deposition FluxesResults from a numerical model of the global emissions, transport, chemistry, and deposition of mercury (Hg) in the atmosphere are presented. Hg (in the form of Hg(O) and Hg(II)) is emitted into the atmosphere from natural and anthropogenic sources (estimated to be 4000 and 2100 Mg/ yr, respectively). It is distributed between gaseous, aqueous and particulate phases. Removal of Hg from the atmosphere occurs via dry deposition and wet deposition, which are calculated by the model to be 3300 and 2800 Mg/ yr, respectively. Deposition on land surfaces accounts for 47% of total global deposition. The simulated Hg ambient surface concentrations and deposition fluxes to the Earth's surface are consistent with available observations. Observed spatial and seasonal trends are reproduced by the model, although larger spatial variations are observed in Hg(O) surface concentrations than are predicted by the model. The calculated atmospheric residence time of Hg is -1.7 years. Chemical transformations between Hg(O) and HG(II) have a strong influence on Hg deposition patterns because HG(II) is removed faster than Hg(O). Oxidation of Hg(O) to HG(II) occurs primarily in the gas phase, whereas HG(II) reduction to Hg(O) occurs solely in the aqueous phase. Our model results indicated that in the absence of the aqueous reactions the atmospheric residence time of Hg is reduced to 1.2 from 1.7 years and the Hg surface concentration is -25% lower because of the absence of the HG(II) reduction pathway. This result suggests that aqueous chemistry is an essential component of the atmospheric cycling of Hg.
Document ID
20000011662
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Shia, Run-Lie
(Atmospheric and Environmental Research, Inc. Cambridge, MA United States)
Seigneur, Christian
(Atmospheric and Environmental Research, Inc. San Ramon, CA United States)
Pai, Prasad
(Atmospheric and Environmental Research, Inc. San Ramon, CA United States)
Ko, Malcolm
(Atmospheric and Environmental Research, Inc. Cambridge, MA United States)
Sze, Nien Dak
(Atmospheric and Environmental Research, Inc. Cambridge, MA United States)
Date Acquired
August 19, 2013
Publication Date
October 20, 1999
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 104
Issue: D19
ISSN: 0148-0227
Subject Category
Environment Pollution
Report/Patent Number
Paper-1999JD900354
Funding Number(s)
PROJECT: EPRI Proj. 3218-08
PROJECT: EPRI Proj. 8221-01
CONTRACT_GRANT: NAS5-97039
Distribution Limits
Public
Copyright
Other

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