title: Isotopic Composition of Gaseous Elemental Mercury in the Free Troposphere of the Pic du Midi Observatory, France.
abstract: Understanding the sources and transformations of mercury (Hg) in the free troposphere is a critical aspect of global Hg research. Here we present one year of observations of atmospheric Hg speciation and gaseous elemental Hg (GEM) isotopic composition at the high-altitude Pic du Midi Observatory (2860 m above sea level) in France. Biweekly integrated GEM from February 2012 to January 2013 revealed significant variations in δ(202)HgGEM (-0.04‰ to 0.52‰) but not in Δ(199)HgGEM (-0.17‰ to -0.27‰) or Δ(200)HgGEM (-0.10‰ to 0.05‰). δ(202)HgGEM was negatively correlated with CO and reflected air mass origins from Europe (high CO, low δ(202)HgGEM) and from the Atlantic Ocean (low CO, high δ(202)HgGEM). We suggest that the δ(202)HgGEM variations represent mixing of recent low δ(202)HgGEM European anthropogenic emissions with high δ(202)HgGEM northern hemispheric background GEM. In addition, Atlantic Ocean free troposphere air masses showed a positive correlation between δ(202)HgGEM and gaseous oxidized Hg (GOM) concentrations, indicative of mass-dependent Hg isotope fractionation during GEM oxidation. On the basis of atmospheric δ(202)HgGEM and speciated Hg observations, we suggest that the oceanic free troposphere is a reservoir within which GEM is readily oxidized to GOM.
authors.affiliation: Observatoire Midi-Pyrénées, Laboratoire Géosciences Environnement Toulouse, CNRS/IRD/Université de Toulouse, 14, avenue Édouard Belin, 31400 Toulouse, France.|State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences , 46 Guanshui Road 550002, Guiyang, China.
authors.forename: Xuewu
authors.initials: X
authors.lastname: Fu
authors.affiliation: Observatoire Midi-Pyrénées, Laboratoire Géosciences Environnement Toulouse, CNRS/IRD/Université de Toulouse, 14, avenue Édouard Belin, 31400 Toulouse, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Marusczak
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences , 46 Guanshui Road 550002, Guiyang, China.
authors.forename: Xun
authors.initials: X
authors.lastname: Wang
authors.affiliation: Observatoire Midi-Pyrénées, Laboratoire d'Aérologie, CNRS/IRD/Université de Toulouse, 14, avenue Édouard Belin, 31400 Toulouse, France.
authors.forename: François
authors.initials: F
authors.lastname: Gheusi
authors.affiliation: Observatoire Midi-Pyrénées, Laboratoire Géosciences Environnement Toulouse, CNRS/IRD/Université de Toulouse, 14, avenue Édouard Belin, 31400 Toulouse, France.
authors.forename: Jeroen E
authors.initials: JE
authors.lastname: Sonke
mesh_terms: D005591:Chemical Fractionation; D004784:Environmental Monitoring; D005602:France; D005740:Gases; D007554:Isotopes; D008628:Mercury
chemical_list: D005740:Gases; D007554:Isotopes; D008628:Mercury