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

Fate of Mercury in the Arctic 24
research team indeed does suggest reactive bromine as one step in the mercury depletion
mechanism and shows that Hg deposition has been decreasing. This researcher however, is not
ready to directly correlate the measured increase of Hg in Arctic biota directly to ozone depletion
events. This is a hypothesis that must be tested with future research.
The work done in this Ph.D. on peat in fact suggests that global Hg deposition has peaked, and
that net deposition is in decline. With an appropriate archive, the high resolution dating technique
developed as a part of this work will provide a useful tool for investigating in detail, deposition to
the Arctic coast since 1960. The chance of finding an appropriate high Arctic archive for this time
period are however, slim, due to freeze thaw destruction of the upper layers of soil.
The post snow melt flux into the marine environment is not yet well described, nor is the total
mass balance for mercury cycling in the Arctic, though it is known that once deposited, the RGM is
methylized, primarily by microbial metabolism, to methylmercury, which has the capacity to collect
in organisms i.e., bioaccumulate, and to concentrate up food chains i.e., biomagnify or
bioconcentrate, especially in the marine food chain.
Atmospheric mercury has been of interest since the 60’s with an overview of mercury in the
atmosphere published by Williston in 1968. Slemr et al., 1985, and Lindqvist and Rodhe (1985)
give one of the first comprehensive distribution, speciation and budget of atmospheric mercury.
Since then, two major reviews of the atmospheric chemistry of mercury have been published:
Schroeder and Munthe, 1998; and Lin and Pekhonen, 1999. These studies are cardinal references
with respect to atmospheric mercury. Lin and Pekhonen establish the lifetime of gaseous elemental
mercury to be about 1 year, given what is known of the atmospheric chemistry of mercury at the
time. The work in this Ph.D. suggests that globally, this may need to be re-evaluated, taking into
consideration the extremely short lifetime of Hg (0) during Arctic polar sunrise.