Etude paléoenvironnementale du cycle du mercure à travers sa composante élémentaire gazeuse Hg0 : De la réactivité de surface à la reconstruction des atmosphères passées grâce aux archives glaciaires

• Main Author: Courteaud, Julien
• Other Authors: Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Joseph-Fourier - Grenoble I, Aurélien Dommergue([e-mail])
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2010
• Subjects: mercury; snow; ice; firn; antarctica; greenland:contaminant; halogens; mercure; neige; glace; névé; antarctique; atmosphère; groenland; contaminant; halogénés; archives; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; [SDU.OTHER]Sciences of the Universe [physics]/Other; Greenland; Concordia Station; Antarc*; Antarctica; Antarctique*; Groenland; ice core
• Online Access: https://theses.hal.science/tel-00625186; https://theses.hal.science/tel-00625186/document; https://theses.hal.science/tel-00625186/file/ThA_se_Courteaud_bis.pdf

Mercury is known as a global pollutant emitted by both anthropogenic and natural sources. In the atmosphere, the predominant form of mercury is gaseous elemental mercury, Hg°, (GEM), and its residence time in the atmosphere is around 1 year allowing a long-range transport. The global cycle of mercury is not well known because of its complexity. The study of Hg° in the atmosphere can provide a lot of information about its global cycle. The atmospheric Hg° concentration has been continuously measured in the atmosphere since the 1990's only. Being able to reconstruct past levels of GEMmercury would be very helpful to have a better comprehension of the mercury cycle, the anthropogenic impact, the response of the atmosphere, the importance of the sources and the links with the climate. The goal of our study is then to reconstruct past atmospheric levels of GEM by firn measurements in the frame of NEEM, an International Ice-core Drilling program from North West Greenland (camp position 77° 25.898' N, 51° 06.448'). The firn air pumping experiment was conducted through July 2009 and successfully recovered air samples from 10 m down to 80 meters below the snow surface. For Hg° measurements, air was extracted by pumps at the surface from the small space beneath the bladder and analyzed in-situ using two Tekran 2537A. The Hg° profile is noticeably different to what has been observed in firn air at Summit (Greenland) in 2006. A firn diffusion model is being applied, using a Monte Carlo approach to optimize agreement between measured and modeled GEM concentrations at all depths in the firn. Finally, GEM concentration in the atmosphere as a function of time over the last 50 years will be obtained. In a second part, Gaseous Elemental Mercury (Hg0) was investigated in the troposphere and in the interstitial air extracted from the snow at depths ranging from the surface to 1.6 meters at Dome C Concordia Station,(central Antarctica,75_060S, 123_200E, 3220 m above sea level) located 1100 km away from the nearest coast of East ...