FATE OF MERCURY IN THE ARCTIC Michael Evan ... - COGCI

Fate of Mercury in the Arctic 20
Given the amount of RGM measured in this study, when extrapolated to the Arctic by the
Danish Eulerian Hemispheric Model, the amount of mercury deposited to the Arctic doubles to
about 200 tons per year, or approximately 4.5% of the global total emissions as a result of the
springtime arctic mercury depletion episode (Skov et al., 2003, Appendix C).
It is hypothesized that in the Arctic, this mercury is thereafter released at snowmelt into an
ecosystem starving for nourishment. It is therefore subject to immediate uptake into the marine food
web with subsequent methylation and bioaccumulation to follow.
Little is known of the magnitude of the transformation and subsequent re-emission of mercury
as Hg (0). Reactive species, operationally known as reactive gaseous mercury (RGM) identified as
HgXY are typically HgCl2 from power plants, in industrial areas, as well as total particulate
mercury (TPM) will eventually deposit via dry or wet deposition. The true product or products,
HgXY, have not yet been identified in the Arctic region. A summary of what is known with respect
to Arctic atmospheric mercury, as well as identified needs and data gaps are found in Schroeder et
al., 2003.
2.3 Mercury recorded in environmental archives
Post depositional processes for Hg or HgXY include biological or physical fixation, i.e.
adsorption, and subsequent diagenesis, to include chemical oxidation or reduction and subsequent
reemission of at least a portion of the mercury. Gaseous reemission, especially in tropical areas, or
physical reemission through aeolian transport, adsorbed to particles. Reemission of mercury is one
of the ongoing research areas and is very relevant to the global cycle.
Due to a portion of the deposited mercury being reemitted, it must be understood that
environmental archives of mercury represent a net record of accumulation, one that has been subject
to the deposited mercury being subjected to physical and chemical processes that affect the overall
amount of mercury that remains in the archive from year to year. Depending on the archive, and the