Polar firn air reveals large-scale impact of anthropogenic mercury emissions during the 1970s

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Fain, Xavier, Ferrari, Christophe, Dommergue, Aurélien, Albert, Mary R., Battle, Mark, Severinghaus, Jeff, Arnaud, Laurent, Barnola, Jean-Marc, Cairns, Warren, Barbante, Carlo, Boutron, Claude
• 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), Politech' Grenoble, Polytech' Grenoble, Université Joseph Fourier - Grenoble 1 (UJF), Geophysical Sciences Division Hanover, ERDC Cold Regions Research and Engineering Laboratory (CRREL), USACE Engineer Research and Development Center (ERDC)-USACE Engineer Research and Development Center (ERDC), Department of Physics and Astronomy Brunswick, Bowdoin College Brunswick, Scripps Institution of Oceanography (SIO - UC San Diego), University of California San Diego (UC San Diego), University of California (UC)-University of California (UC), Institute for the Dynamics of Environmental Processes-CNR, University of Ca’ Foscari Venice, Italy, Environmental Sciences Department, Unité de Formation et de Recherche de Physique, Funded by the U.S. National Science Foundation Office of Polar Programs project NSF-OPP 0520445, the French Atmospheric Chemistry Program “Exchanges Neige Polaire,” the French Ministry of Research (Action Concertée Incitative Jeunes Chercheurs 3012), the Laboratoire de Glaciologie et Géophysique de l'Environnement, and the Institut Universitaire de France (to C.F. and C.B.).
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: atmosphere; Greenland; past century; pollution; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Arctic
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-00497912; https://doi.org/10.1073/pnas.0905117106

International audience Mercury (Hg) is an extremely toxic pollutant, and its biogeochemical cycle has been perturbed by anthropogenic emissions during recent centuries. In the atmosphere, gaseous elemental mercury (GEM; Hg°) is the predominant form of mercury (up to 95%). Here we report the evolution of atmospheric levels of GEM in mid- to high-northern latitudes inferred from the interstitial air of firn (perennial snowpack) at Summit, Greenland. GEM concentrations increased rapidly after World War II from ≈1.5 ng m−3 reaching a maximum of ≈3 ng m−3 around 1970 and decreased until stabilizing at ≈1.7 ng m−3 around 1995. This reconstruction reproduces real-time measurements available from the Arctic since 1995 and exhibits the same general trend observed in Europe since 1990. Anthropogenic emissions caused a two-fold rise in boreal atmospheric GEM concentrations before the 1970s, which likely contributed to higher deposition of mercury in both industrialized and remotes areas. Once deposited, this toxin becomes available for methylation and, subsequently, the contamination of ecosystems. Implementation of air pollution regulations, however, enabled a large-scale decline in atmospheric mercury levels during the 1980s. The results shown here suggest that potential increases in emissions in the coming decades could have a similar large-scale impact on atmospheric Hg levels.