Atmospheric mercury observations from Antarctica: seasonal variation and source and sink region calculations 1Norwegian Institute for Air Research (NILU), Kjeller, Norway
03 Apr 2012
*current address: Department of Chemistry, Norwegian University of Science and Technology, Trondheim, Norway
**current address: Centre for Environmental and Climate Research (CEC), Lund University, Lund, Sweden
Received: 11 Oct 2011 – Published in Atmos. Chem. Phys. Discuss.: 28 Oct 2011 Abstract. Long term atmospheric mercury measurements in the Southern Hemisphere are
scarce and in Antarctica completely absent. Recent studies have shown that
the Antarctic continent plays an important role in the global mercury cycle.
Therefore, long term measurements of gaseous elemental mercury (GEM) were
initiated at the Norwegian Antarctic Research Station, Troll (TRS) in order
to improve our understanding of atmospheric transport, transformation and
removal processes of GEM. GEM measurements started in February 2007 and are
still ongoing, and this paper presents results from the first four years.
The mean annual GEM concentration of 0.93 ± 0.19 ng m−3 is in good
agreement with other recent southern-hemispheric measurements. Measurements
of GEM were combined with the output of the Lagrangian particle dispersion
model FLEXPART, for a statistical analysis of GEM source and sink regions.
It was found that the ocean is a source of GEM to TRS year round, especially
in summer and fall. On time scales of up to 20 days, there is little direct
transport of GEM to TRS from Southern Hemisphere continents, but sources
there are important for determining the overall GEM load in the Southern
Hemisphere and for the mean GEM concentration at TRS. Further, the sea ice
and marginal ice zones are GEM sinks in spring as also seen in the Arctic,
but the Antarctic oceanic sink seems weaker. Contrary to the Arctic, a
strong summer time GEM sink was found, when air originates from the
Antarctic plateau, which shows that the summertime removal mechanism of GEM
is completely different and is caused by other chemical processes than the
springtime atmospheric mercury depletion events. The results were
corroborated by an analysis of ozone source and sink regions.
Revised: 20 Jan 2012 – Accepted: 09 Mar 2012 – Published: 03 Apr 2012
Citation: Pfaffhuber, K. A., Berg, T., Hirdman, D., and Stohl, A.: Atmospheric mercury observations from Antarctica: seasonal variation and source and sink region calculations, Atmos. Chem. Phys., 12, 3241-3251, doi:10.5194/acp-12-3241-2012, 2012.