Mercury isotope evidence for Arctic summertime re-emission of mercury from the cryosphere

Beatriz Ferreira Araujo (1) , Stefan Osterwalder (2, 3) , Natalie Szponar (4) , Domenica Lee (4) , Mariia V Petrova (5) , Jakob Boyd Pernov , Shaddy Ahmed (3) , Lars-Eric Heimbürger-Boavida (5) , Laure Laffont (1) , Roman Teisserenc (6) , Nikita Tananaev (7) , Claus Nordstrom (8) , Olivier Magand (3) , Geoff Stupple (9) , Henrik Skov (8) , Alexandra Steffen (9) , Bridget Bergquist (4) , Katrine Aspmo Pfaffhuber (10) , Jennie L Thomas (3) , Simon Scheper (11) , Tuukka Petäjä (12) , Aurélien Dommergue (3) , Jeroen E Sonke (1)

1 GET - Géosciences Environnement Toulouse
2 Institute of Agricultural Sciences [Zürich]
3 IGE - Institut des Géosciences de l’Environnement
4 University of Toronto
5 MIO - Institut méditerranéen d'océanologie
6 LEFE - Laboratoire Ecologie Fonctionnelle et Environnement
7 Melnikov Permafrost Institute
8 Aarhus University [Aarhus]
9 ECCC - Environment and Climate Change Canada
10 NILU - Norwegian Institute for Air Research
11 Unibas - Université de Bâle = University of Basel = Basel Universität
12 INAR - Institute for Atmospheric and Earth System Research

During Arctic springtime, halogen radicals oxidize atmospheric elemental mercury (Hg0), which deposits to the cryosphere. This is followed by a summertime atmospheric Hg0 peak that is thought to result mostly from terrestrial Hg inputs to the Arctic Ocean, followed by photoreduction and emission to air. The large terrestrial Hg contribution to the Arctic Ocean and global atmosphere has raised concern over the potential release of permafrost Hg, via rivers and coastal erosion, with Arctic warming. Here we investigate Hg isotope variability of Arctic atmospheric, marine, and terrestrial Hg. We observe highly characteristic Hg isotope signatures during the summertime peak that reflect re-emission of Hg deposited to the cryosphere during spring. Air mass back trajectories support a cryospheric Hg emission source but no major terrestrial source. This implies that terrestrial Hg inputs to the Arctic Ocean remain in the marine ecosystem, without substantial loss to the global atmosphere, but with possible effects on food webs.

Mots clés: Atmospheric chemistry; Element cycles; Mercury

Domaines: Océan, Atmosphère

Beatriz Ferreira Araujo, Stefan Osterwalder, Natalie Szponar, Domenica Lee, Mariia V Petrova, et al.. Mercury isotope evidence for Arctic summertime re-emission of mercury from the cryosphere. Nature Communications, 2022, 13, pp.4956. ⟨10.1038/s41467-022-32440-8⟩. ⟨hal-03761752⟩