Fate of Springtime Atmospheric Reactive Mercury: Concentrations and Deposition at Zeppelin, Svalbard

• Main Authors: Stefan Osterwalder (4639573), Sarrah M. Dunham-Cheatham (8072282), Beatriz Ferreira Araujo (11577538), Olivier Magand (6386882), Jennie L. Thomas (2468116), Foteini Baladima (11577541), Katrine Aspmo Pfaffhuber (11577544), Torunn Berg (2052508), Lei Zhang (38117), Jiaoyan Huang (394030), Aurélien Dommergue (2193553), Jeroen E. Sonke (1472950), Mae Sexauer Gustin (1694389)
• Format: Other Non-Article Part of Journal/Newspaper
• Language: unknown
• Published: 1753
• Subjects: Cell Biology; Pharmacology; Sociology; Marine Biology; Environmental Sciences not elsewhere classified; Biological Sciences not elsewhere classified; Chemical Sciences not elsewhere classified; trajectory analysis indicated; marine boundary layer; arctic polar sunrise; arctic marine environment; hg – n; gaseous oxidized hg; enhanced atmospheric deposition; 5 – 2; hg – cl; measured dry deposition; based rm detection; modeled rm deposition; 45 %) compounds; hg – br; dry deposition; cl compounds; based methods; 51 %); reactive hg; bound hg; deposition velocities; 5 μg; 5 times; rm chemistry; predominantly advected; important component; free troposphere; exceed denuder; confidence interval; 9 μg; 49 cm; 2019 ); Arctic; Svalbard; Sea ice
• Online Access: https://doi.org/10.1021/acsearthspacechem.1c00299.s001

Mid-latitude atmospheric elemental mercury (Hg) emissions undergo extensive oxidation to reactive Hg (RM) compounds during Arctic polar sunrise, resulting in enhanced atmospheric deposition that impacts Arctic marine wildlife and humans. It has been difficult to estimate RM dry deposition, because RM concentrations, compounds, and their deposition velocities are ill-defined. Here, we investigate RM concentrations sampled with membrane-based methods and find these to exceed denuder-based RM detection by 5 times at the Zeppelin Observatory on Svalbard (March 26–July 24, 2019). Measured dry deposition of gaseous oxidized Hg was about half of the modeled RM deposition, demonstrating that particulate-bound Hg was an important component of dry deposition. Using thermal membrane desorption, RM chemistry was found to be dominated by Hg–Cl/Br (51%) and Hg–N (45%) compounds. Back-trajectory analysis indicated that Hg–Br/Cl compounds were predominantly advected from within the marine boundary layer (sea ice exposure), while Hg–N originated from the free troposphere. Weekly average RM compound-specific dry deposition velocities ranged from 0.12 to 0.49 cm s –1 , with a net RM dry deposition of 1.9 μg m –2 (1.5–2.5 μg m –2 95% confidence interval) that exceeds the mean annual Hg wet deposition flux in Svalbard. Overall, we find that springtime atmospheric RM deposition has been underestimated in the Arctic marine environment.