Abstract
Abstract. Measurements of gaseous elemental mercury (GEM) fluxes over snow surfaces using a relaxed eddy accumulation (REA) system are carried out at the High Arctic site at the Villum Research Station, Station Nord, in North Greenland. Simultaneously, CO2 fluxes are determined using the eddy covariance (EC) technique. The REA system with dual inlets and dual analyzers is used to measure fluxes directly over the snow. The measurements were carried out from 23 April to 12 May during spring 2016, where atmospheric mercury depletion events (AMDEs) took place. The measurements showed a net emission of 8.9 ng mâ2 minâ1, with only a few minor episodes of net depositional fluxes, from a maximum deposition of 8.1 ng mâ2 minâ1 to a maximum emission of 179.2 ng mâ2 minâ1. The data support the theory that gaseous oxidized mercury (GOM) is deposited during AMDEs followed by formation of GEM on surface snow and is re-emitted as GEM shortly after the AMDEs. Furthermore, observation of the relation between GEM fluxes and atmospheric temperature suggests that GEM emission partly could be affected by surface heating. However, it is also clear that the GEM emissions are affected by many parameters.
Highlights
Mercury (Hg) is a toxic element found in the atmosphere primarily as elemental mercury
The large emission events were connected to increased wind speed and resultant increase in turbulent transport (Fig. 9)
Mercury is primarily transported in the atmosphere in the form of gaseous elemental mercury (GEM) and it is ubiquitous in the atmosphere
Summary
Mercury (Hg) is a toxic element found in the atmosphere primarily as elemental mercury. PBM and GOM are removed faster from the atmosphere than. GEM and have atmospheric lifetimes on the order of days (SĂžrensen et al, 2010; Goodsite et al, 2004, 2012; Valente et al, 2007). GOM and PBM generally deposit near emission sources. The lifetime of GEM, determined by the reaction between GEM and Br (Goodsite et al, 2004, 2012), spans from 1 to 2 months (Holmes et al, 2006; SĂžrensen et al, 2010). GEM can be transported over longer distances to areas with low natural and anthropogenic emissions. GEM concentrations in the Arctic are mainly due to long-range transportation from lower-latitude sources (Dastoor et al, 2008; Pandey et al, 2011; Christensen et al, 2004)
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