Circumpolar transport and air-surface exchange of atmospheric mercury at Ny-Ålesund (79° N), Svalbard, spring 2002

International audienceMercury in different environmental compartments has been measured at Ny-Ålesund (78°54' N, 11°53' E) during an intensive campaign, 17 April to 14 May 2002. Time-resolved speciated determination of mercury in the atmosphere and snow was conducted at the Norwegian research station at the Zeppelin mountain, 474 m above the sea level, and at the Italian research facility Dirigibile Italia, 12 m above the sea level. Total Gaseous Mercury (TGM) was present in the range ?3 during the campaign. Three mercury depletion events, identified as periods with decreased TGM concentrations, were observed. At the lower altitude, TGM concentrations following such events were found to exhibit both higher magnitude and larger variability in comparison to results from the Zeppelin station. Oxidised mercury species in air and fall-out with snow as well as mercury attached to particles were also measured and their concentrations were found to be anti-correlated with TGM in air. concentrations of total Hg in snow (Hg-tot) showed a large (~15×) increase in response to Gaseous Elemental Mercury Depletion Events (GEMDEs, range 1.5?76.5 ng L?1). Solid evidence for photo-stimulated emissions of Hg0(g) from the snow pack in conjunction to depletion events were obtained from gradient measurements as well as from flux chamber measurements. Steep diurnal concentration variations of Hg0(aq) in surface seawater were also found to concur with changing solar radiation. The concentration of Hg0(aq) in seawater was found to be in the range 12.2?70.4 pg L?1, which corresponds to supersaturation. Hence, the seawater surface constituted a source emitting elemental mercury. The concentrations of RGM (reactive gaseous mercury), Hg-p (particulate mercury), and BrO column densities (detected by DOAS) were very low except for a few individual samples during the major Hg0 depletion event. BrO vertical column densities obtained by the remote satellite ESR-2 and trajectory analysis indicate that the air masses exhibiting low Hg0 concentrations originated from areas with high BrO densities

Circumpolar transport and air-surface exchange of atmospheric mercury at Ny-Ålesund (79° N), Svalbard, spring 2002

International audienceMercury in different environmental compartments has been measured at Ny-Ålesund (78°54? N, 11°53? E) during an intensive campaign, 17 April to 14 May 2002. Time-resolved speciated determination of mercury in the atmosphere and snow was conducted at the Norwegian research station at the Zeppelin mountain, 474 m above the sea level, and at the Italian research facility Dirigibile Italia, 12 m above the sea level. Total Gaseous Mercury (TGM) was present in the range ?3 during the campaign. Three mercury depletion events, identified as periods with decreased TGM concentrations, were observed. At the lower altitude, TGM concentrations following such events were found to exhibit both higher magnitude and larger variability in comparison to results from the Zeppelin station. Oxidised mercury species in air and fall-out with snow as well as mercury attached to particles were also measured and their concentrations were found to be anti-correlated with TGM in air. The strongest modulation was observed for total mercury concentration (Hg-tot) in snow (range 1.5?76.5 ng L?1). Solid evidence for photo-stimulated emissions of Hg0(g) from the snow pack in conjunction to depletion events were obtained from gradient measurements as well as from flux chamber measurements. Steep diurnal concentration variations of Hg0(aq) in surface seawater were also found to concur with changing solar radiation. The concentration of Hg0(aq) in seawater was found to be in the range 12.2?70.4 pg L?1, which corresponds to supersaturation. Hence, the seawater surface constituted a source emitting elemental mercury. The concentrations of the transient mercury forms RGM (Reactive Gaseous Mercury) and PM (Particulate Mercury) respectively and BrO column densities detected using a zenith and off-axis sky viewing DOAS instrument were very low except for a few individual samples during the major depletion event. An evaluation of trajectories for selected events and comparisons with BrO vertical column densities obtained by the GOME (Global Ozone Monitoring Experiment) instrument aboard the earth remote sensing satellite ESR-2 indicates that the air masses exhibiting low Hg0 concentrations originated from areas with high BrO densities. It was concluded that the observed depletion events at Ny-Ålesund were a results of transport from areas with high photochemical activity around the polar region

Comparison of two measurement methods of dissolved gaseous mercury concentrations and estimations of supersaturation grade and mercury fluxes during a research campaign at the Mediterranean Sea

Dissolved gaseous mercury (DGM) concentrations and gaseous elemental mercury (GEM) concentrations were measured during an oceanographic campaign in the Mediterranean Sea. The DGM concentrations were measured using two different methods, a manual- and an automated method. The manual method was used to obtain DGM depth profiles at several stations throughout the campaign. The automated device measured DGM concentrations continuously at a depth of 4 m. Gaseous elemental mercury (GEM) concentrations in air were measured continuously at the bridge deck. The objectives were to achieve DGM depth profiles, compare the manual- and automated DGM measurement methods, to calculate the supersaturation grades of the sea and the evasional fluxes from the sea surface. Depth profiles of the four measured stations show no diurnal variations. The manual- and the automated method show good compliance. Supersaturation grades are high due to high DGM values and low GEM concentrations. Fluxes of Hg from the sea surface are more dependent on the wind speed than on the supersaturation grade according to the flux models used

Airborne mercury species at the Råö background monitoring site in Sweden: distribution of mercury as an effect of long-range transport

Within the EU-funded project, Global Mercury Observation System (GMOS) airborne mercury has been monitored at the background Råö measurement site on the western coast of Sweden from mid-May 2012 to the beginning of July 2013 and from the beginning of February 2014 to the end of May 2015. The following mercury species/fractions were measured: gaseous elemental mercury (GEM), particulate bound mercury (PBM) and gaseous oxidised mercury (GOM) using the Tekran measurement system. The mercury concentrations measured at the Råö site were found to be low in comparison to other, comparable, European measurement sites. A back-trajectory analysis to study the origin of air masses reaching the Råö site was performed. Due to the remote location of the Råö measurement station it receives background air about 60 % of the time. However, elevated mercury concentrations arriving with air masses coming from the south-east are noticeable. GEM and PBM concentrations show a clear annual variation with the highest values occurring during winter, whereas the highest concentrations of GOM were obtained in spring and summer. An evaluation of the diurnal pattern of GOM, with peak concentrations at midday or in the early afternoon, which often is observed at remote places, shows that it is likely to be driven by local meteorology in a similar way to ozone. Evidence that a significant part of the GOM measured at the Råö site has been formed in free tropospheric air is presented