The study of the mercury cycle in polar regions: An international study in Ny-Alesund, Svalbard

Mercury (Hg) is a toxic pollutant and it can be strongly accumulated in the food chain, especially in Polar Regions. This paper presents a part of the work that has been on-going for 3-4 years in Ny-Alesund, Svalbard within the frame of an international collaboration. In Ny-Alesund in spring 2003, the atmospheric chemistry of mercury has been studied so as to better understand the formation of oxidized mercury species in the atmosphere that could be deposited onto snow surfaces. The role of snow as a potential source of mercury to the atmosphere or as a sink has also been approached to better understand the behavior of this metal. Chemical and biological processes seem to play a major role in Hg storage in snow. When melting, snow could be a major source of Hg into the various ecosystems and this toxin could therefore be accumulated into the food chain

Étude d'un processus singulier d'oxydation du mercure atmosphérique en zone polaire : les « Atmospheric Mercury Depletion Events »

Environmental pollution caused by mercury has been a cause of concern for decades. In Arctic, it undergoes during polar spring special reactions and can then be deposited onto snow packs leading to contamination of sensitive ecosystems. These special events are called Atmospheric Mercury Depletion Events (AMDEs).During field experiments in Arctic, we observed seven AMDEs and we then tried to understand which physical and chemical parameters are necessary to produce such events. The roles of low temperatures and frozen surfaces as iced clouds are mentioned. The consequences of AMDEs onto mercury levels in surface snow samples have also been studied. We showed that such events do not always lead to important contamination in surface snow samples, and that we lack of knowledge to precisely quantify the toxic effect of AMDEs in Arctic.Le mercure est un composé toxique. En zone polaire, au printemps, une chimie extrêmement particulière est à l'origine, après oxydation, de son dépôt en surface du manteau neigeux. Ces phénomènes appelés « Atmospheric Mercury Depletion Events » (AMDEs) ou « pluies de mercure » sont à la base d'une contamination encore mal renseignée des écosystèmes polaires. Lors de campagnes de terrain en Arctique, nous avons observé sept AMDEs, et avons étudié les paramètres physico-chimiques susceptibles de gouverner l'apparition de ces événements. Le rôle des basses températures et l'implication des nuages glacés parmi les surfaces gelées actives sont évoqués. L'impact de ces AMDEs en terme de teneurs en mercure dans la neige de surface a également été examiné. Les dépôts résultant de ces phénomènes n'aboutissent pas forcément à une contamination marquée de la neige de surface, et nos connaissances sont aujourd'hui trop limitées pour pouvoir quantifier l'apport toxique des AMDEs sur l'Arctique

Étude d'un processus singulier d'oxydation du mercure atmosphérique en zone polaire (les Atmospheric Mercury Depletion Events )

Le mercure est un composé toxique. En zone polaire, au printemps, une chimie extrêmement particulière est à l'origine, après oxydation, de son dépôt en surface du manteau neigeux. Ces phénomènes appelés Atmospheric Mercury Depletion Events (AMDEs) ou pluies de mercure sont à la base d'une contamination encore mal renseignée des écosystèmes polaires. Lors de campagnes de terrain en Arctique, nous avons observé sept AMDEs, et avons étudié les paramètres physico-chimiques susceptibles de gouverner l'apparition de ces éve nements. Le rôle des basses températures et l'implication des nuages glacés parmi les surfaces gelées actives sont évoqués. L'impact de ces AMDEs en terme de teneurs en mercure dans la neige de surface a également été examiné. Les dépôts résultant de ces phénomènes n'aboutissent pas forcément à une contamination marquée de la neige de surface, et nos connaissances sont aujourd'hui trop limitées pour pouvoir quantifier l'apport toxique des AMDEs sur l'Arctique.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Analysis of ^7Be and ^(210)Pb air concentrations in Ny-Alesund, Svalbard: CHIMERPOL II project, preliminary results

International audienceHalf-daily high volume aerosol particles samples have been collected onto cellulose and glass fiber filters at Ny-Alesund, Svalbard, from April 14th to May 7th 2004, in the framework of CHIMERPOL II program. The filters have been analyzed for ^(210)Pb (22.3y) and ^7Be (53 d) by semiconductor gamma spectrometry. The median concentration values were 70μBq m^(-3) STP (8-264μBq m^(-3)STP) for ^(210)Pb, and 404μBq m^(-3)STP (35-824μBq m^(-3)STP) for ^7Be respectively. The ^7Be and ^(210)Pb activity concentrations measured are relatively "low" compared to those measured in Svalbard and in other Arctic sites for the same period time (April-May) during previous studies. The ^(210)Pb atmospheric concentration and atmospheric pressure are positively correlated, which may indicate that the ^(210)Pb atmospheric concentration increase as a function of air mass exchange over the Svalbard region. The results of ^7Be and ozone concentrations show also the absence of direct ^7Be stratospheric injections during our sampling campaign, in the low troposheric air masses. The performed backward trajectory analysis showed that collected aerosols and associated radionuclides concentrations were associated to three different air masses, originating from Atlantic ocean, Artic ocean and Barents Sea, and continental areas (North Finland-Russia) respectively

The fate of mercury species in a sub-arctic snowpack during snowmelt

received 12 MArch 2003;revised 1 may 2003; accepted 15 May 2003An extensive mercury study was conducted in April 2002 prior to and during the annual melting of a snowpack in a sub-arctic site along the Hudson Bay (Canada). Gas-phase measurements show that the snowmelt coincides with an elemental mercury (Hg°) pulse in the snowpack air far above ambient levels. Additional measurements of inorganic mercury (Hg2+) and methylmercury (MeHg+) in snow pits, in surface snow and in a meltwater sample clearly reveal that most of Hg is removed from the snow during the first days of snowmelt. We estimate that gas-phase exchanges contribute poorly to remove Hg from the snowpack; consequently during a snowmelt day more than 90% of Hg present in the snow surface is likely released with the meltwater. In arctic areas, where Hg accumulates at an accelerated rate in the snow surfaces [Lu et al., 2001] during mercury depletion events (MDE), the discharge of this toxic and bio-accumulating pollutant in water systems could be a threat to ecosystems and local indigenous populations

Diurnal Cycles of Gaseous Mercury within the Snowpack at Kuujjuarapik/Whapmagoostui, Québec, Canada

International audienc

Fast depletion of gaseous elemental mercury in the Kongsvegen Glacier snowpack in Svalbard

International audienceGaseous elemental mercury (GEM, Hg°) was measured in the snowpack interstitial air on the Kongsvegen Glacier (Svalbard) between the surface and 190 cm depth. A rapid depletion of GEM from ∼5 to 0.4 ng.m−3 in the snowpack air was measured in less than 8 hours at a calculated depletion rate of ∼0.5–0.7 ng.m−3.h−1 while concentration of GEM above the snow stayed constant about 1.7 ng.m−3. This depletion could only be explained by chemical processes and this study suggests that Br. could be the most important reactant for the oxidation of GEM in the interstitial snow air. The lifetime of GEM was estimated to be ∼10 minutes with second order reaction rate constant between GEM and Br. of about ∼2 × 10−11 cm−3.molecule−1.s−1. These first experimental kinetic values for GEM oxidation in the snow air are in good agreement with both theoretical and modelling studies previously reported