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

Fate of Mercury in the Arctic 21
hydrological and geochemical conditions it is exposed to, there may also be post depositional
vertical or horizontal transport.
Working with environmental archives is therefore extremely dynamic and complex, with
several functions that should be taken into consideration: the transfer function from air to plant, soil,
ice, water or snow, the sedimentation function, which describes what happens to the mercury as it
undergoes sedimentation, the fixation function or how the mercury is preserved in the archive, the
diagenesis function which is how the mercury is chemically or physically affected over time and the
reemission function which accounts for losses from the depositional area under consideration. We
have therefore no way of knowing what the actual concentration of atmospheric gaseous elemental
mercury was prior to the industrial age, or through the Holocene and previous geologic history.
However, we can, by studying environmental archives such as lake, marine sediments, peat
sediments and ice cores or historical records (e.g. Hylander and Meili, 2003) relatively determine
that anthropogenic activities have increased levels of mercury in the atmosphere by a factor of 3
(Munthe et al., 2001) or more, as noted in this work.
As also seen from this work, actual spatial loading of mercury over geologic time is very
consistent between different regions, thus indicating the global character of mercury transport and
deposition.
Based on emission inventories from 1995, it is seen that the majority of mercury being released
to the Northern hemisphere and thus most burdening the Arctic is coming from anthropogenic
emissions from coal fired combustion plants in Asia with primary burden in Asia coming from
China (Pacyna and Pacyna, 2000).
The total annual load of mercury transported to the Arctic, is a significant burden to the fragile
and pristine environment. The Arctic weather system and cold as well as the highly productive and
efficient post snow melt marine ecosystem, may represent the ultimate sink for mercury.