Atmospheric gaseous elemental mercury (GEM) concentrations in the Arctic exhibit a clear summertime maximum, the origin of which is debated. Using summertime observations from the MOSAIC expedition and a modeling approach, this study investigates atmospheric Hg sources in the central Arctic. A generalized additive model (GAM) shows that long-range transport is a minor contributor (<2%), while oceanic evasion explains >50% of GEM variability. PSCF analysis reveals that oceanic evasion is significant mainly in the Marginal Ice Zone (MIZ). This regional process is suggested as the leading contributor to the summertime GEM maximum. With Arctic warming and MIZ expansion, oceanic Hg evasion may become even more significant.

Fange Yue, Hélène Angot, Byron Blomquist, Julia Schmale, Clara J. M. Hoppe, Ruibo Lei, Matthew D. Shupe, Liyang Zhan, Jian Ren, Hailong Liu, Ivo Beck, Dean Howard, Tuija Jokinen, Tiia Laurila, Lauriane Quéléver, Matthew Boyer, Tuukka Petäjä, Stephen Archer, Ludovic Bariteau, Detlev Helmig, Jacques Hueber, Hans-Werner Jacobi, Kevin Posman, Zhouqing Xie