Continental outflow shapes the circum-Antarctic pattern of summertime atmospheric mercury depletion zones

Atmospheric mercury depletion events (AMDEs) are a unique phenomenon in polar mercury cycling, involving intense atmospheric mercury oxidation and deposition that amplify marine mercury sinks. The Southern Ocean, a critical hotspot for environmental mercury exposure, exhibits AMDEs whose characteristics and distribution patterns remain unclear. This study presents the observational dataset of atmospheric gaseous elemental mercury (GEM) across the circum-Antarctic Southern Ocean. We observed pronounced summertime AMDEs that drove high spatial heterogeneity in circumpolar GEM distribution. By combining Generalized Additive Models (GAM) simulations with multi-platform observational evidence, we demonstrate that the Antarctic continental outflow largely shapes the circumpolar distribution of summertime AMDEs, concentrating these events within the convergence zones of katabatic winds. This work highlights the critical role of land-sea coupling effects in Antarctic atmospheric chemistry, and underscores the need to systematically assess the implications of these processes for mercury bioavailability across Southern Ocean ecosystems.