Atmospheric mercury concentration variations at Syowa Station, Lützow-Holm Bay, East Antarctica and contributing factors†

In January 2022, gaseous elemental Hg (GEM) concentrations were continuously monitored at Syowa Station on East Ongul Island, located ∼4 km from the continent on the eastern coast of Lützow-Holm Bay, to examine atmospheric Hg concentrations during the summer in the southeastern Antarctic region. Atmospheric GEM ranged from 0.36 to 1.83 ng m⁻³ average value: 1.01 ± 0.21 ng m⁻³ and increased during the day and decreased at night. While maintaining these diurnal variations, GEM concentrations increased to 1.99 and 1.55 ng m⁻³ on January 2–3 and 17–20, 2022, respectively. During both events, the low-pressure system approached the Syowa Station, and the 72 hours backward trajectory analysis revealed that the air mass originated from open water surfaces, implying that Hg evasion from the sea surface increased the atmospheric GEM concentration. To investigate the causes of diurnal variation causes—excluding these two events mentioned—Hg concentrations in the soil [n = 102, 2.61 ± 3.16 (0.14–19.0) ng g⁻¹], snow, glacier, and ice sheet around Syowa Station (n = 19, 0.45–5.60 ng L⁻¹), as well as in the atmosphere on the fast ice around the station (0.54–1.10 ng m⁻³), were measured. The results revealed that sources such as ornithogenic soil from the penguin rookery around the station, open water surfaces, and the gaseous oxidized Hg transported inland by katabatic winds did not contribute to the daytime GEM concentration increases. The cause of the summer diurnal variation at Syowa Station was unidentified and warrants further investigation.