Preliminary results from a continuous record of atmospheric gaseous mercury at the coastal station Dumont d’Urville in Antarctica

A Dommergue,N Vogel,M Barret,O Magand,C P Ferrari,Nicola Pirrone

doi:10.1051/e3sconf/20130127005

Abstract

While the tropospheric reactivity of mercury (Hg) in the Arctic is more and more documented only a few attempts were made to study the Hg cycle in the Southern Polar Regions. The role of the Antarctic continent and its influence on the global geochemical cycle of mercury is unclear today, and is certainly under evaluated by current models. Here, we present the first continuous high-time-resolution measurements of atmospheric gaseous elemental mercury (GEM) in East Antarctica from February 2010 to March 2011 at the coastal research station Dumont d’Urville (DDU) (66°40’S, 140°01’E, 43 m asl). We report an annual mean level of 1.062 ± 0.321 ng/m3 with well-marked daily fluctuations from October to January. An intense reactivity originated from the atmospheric boundary layer of the Antarctic plateau under sunlight conditions is observed at DDU. Partly GEM-depleted air masses are exported from the continent and dramatically influence the GEM record at DDU. From November to January, surface waters of the Southern Ocean are an important source of GEM.

Highlights

Polar Regions, like other regions of the planet, are impacted by long-range transport of man-made emissions of mercury (Hg)
An intense reactivity originated from the atmospheric boundary layer of the Antarctic plateau under sunlight conditions is observed at Dumont d’Urville (DDU)
The high stability of gaseous elemental mercury (GEM) measured during fall and winter is mainly explained by an export of continental air masses

Summary

Introduction

Polar Regions, like other regions of the planet, are impacted by long-range transport of man-made emissions of mercury (Hg). Hg is mostly transported as Gaseous Elemental Mercury (GEM), which has a lifetime of about 1 year in the troposphere. In Antarctica, gross Hg input is probably controlled by Southern Hemisphere emissions. The tropospheric reactivity of Hg in the Arctic is more and more documented (Steffen et al, 2008) due to the occurrence of springtime fast GEM oxidation processes called Atmospheric Mercury Depletion Events (AMDE). In the Southern Polar Regions, only a few attempts were made to study the Hg cycle. Observations retrieved from central Antarctica (elevation > 2500 m, coldest place of the Earth with long polar nights) and coastal stations are distinctly different (for a review see Dommergue et al, 2010)

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Conclusion