Abstract
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.
Highlights
Antarctica is the most remote of all continents and is usually perceived as an isolated and hostile place and a symbol of the last great wilderness untouched by human disturbance
The mean gaseous elemental mercury (GEM) concentration observed at Troll Research Station (TRS) is in good agreement with other recent observations from high latitudes in the Southern Hemisphere (Ebinghaus et al, 2002; Xia et a., 2010; Temme et al, 2003b)
GEM concentrations observed in the Southern Hemisphere are lower because most of the mercury emission sources are located in the Northern Hemisphere (Pacyna et al, 2006) and in the atmosphere the lifetime of GEM (Schroeder and Munthe, 1995) is not long enough for homogeneous mixing on a global scale
Summary
Antarctica is the most remote of all continents and is usually perceived as an isolated and hostile place and a symbol of the last great wilderness untouched by human disturbance. Efforts have been initiated to study AMDEs at coastal sites (Ebinghaus et al, 2002; Temme et al, 2003a; Sprovieri et al, 2002; Brooks et al, 2008a) and more recently the Antarctic plateau has become a new focus of attention (Brooks et al, 2008b). These efforts show us that we currently underestimate the role of this continent in the global mercury cycle (Dommergue et al, 2010). Intensive measurement campaigns with extensive measurement programs provide large amounts of information that
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