Impact of exhaust emissions on chemical snowpack composition at Concordia Station, Antarctica

• Published in: The Cryosphere
• Main Authors: Helmig, Detlev, Liptzin, Daniel, Hueber, Jacques, Savarino, Joel
• Other Authors: Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Concordia Station; Antarc*; Antarctica; The Cryosphere
• Online Access: https://hal.science/hal-03402319; https://hal.science/hal-03402319/document; https://hal.science/hal-03402319/file/Helmig-2020-Impact%20of%20exhaust%20emissions%20on%20che.pdf; https://doi.org/10.5194/tc-14-199-2020

International audience Continuous measurements of reactive gases in the snowpack and above the snowpack surface were conducted at Concordia Station (Dome C), Antarctica, from December 2012-January 2014. Measured species included ozone, nitrogen oxides, gaseous elemental mercury, and formaldehyde, for study of photochemical reactions, surface exchange, and the seasonal cycles and atmospheric chemistry of these gases. The experiment was installed ~ 1 km from the station main infrastructure inside the station clean air sector and within the station electrical power grid boundary. Air was sampled continuously from three inlets on a 10 m meteorological tower, as well as from (two) above and four below the surface sampling inlets from within the snowpack. Despite being in the clean air sector, over the course of the 1.2-year study, we observed on the order of 15 occasions when exhaust plumes from the camp, most notably from the power generation system, were transported to the study site. Highly elevated levels of nitrogen oxides (up to 100 x background) and lowered ozone (up to ~50%), most likely from titration with nitric oxide, were measured in the exhaust plumes. Within 5-15 minutes from observing elevated pollutant levels above the snow, rapidly increasing and long-lasting concentration enhancements were measured in snowpack air. While pollution events typically lasted only a few minutes to an hour above the snow surface, elevated nitrogen oxides levels were observed in the snowpack lasting from a few days to one week. These observations add important new insight to the discussion if and how snowphotochemical experiments within reach of the power grid of polar research sites are possibly compromised by the snowpack being chemically influenced (contaminated) by gaseous and particulate emissions from the research camp activities. This question is critical for evaluating if snowpack trace chemical measurements from within the camp boundaries are representative for the vast polar ice sheets.