[A-CG42] Science in the Arctic Region

[ACG42-P03] Vertical Distribution of Mercury Concentrations in the Permafrost of Palsa Along the Alaska Denali Highway and Their Mercury Emission Rates

*Osamu Nagafuchi¹, Koyomi Nakazawa², Go Iwahana³, Tetsuo Sueyoshi⁴, Kazuki Oura⁵, Osamu Shikino⁶ (1.Fukuoka Institute of Techology, 2.Toyama Prefectural University, 3.University of Alaska, 4.JAMSTEC, 5.Graduate School, Toyama Prefectural University, 6.PerkinElmer Japan)

Keywords:Mercury, Palsa, Permafrost, Active layer, Mercury Re-emission

The rapid warming of polar regions has raised concerns about the re-emission of mercury stored in permafrost into the atmosphere as a significant environmental issue. In this study, the authors collected samples from the active layer (50cm-70cm) and the underlying permafrost (3m-5m) at 10m intervals from palsa mounds along the Denali Highway at the end of August in 2022 and 2023. Additionally, a simple chamber test was conducted to measure the flux of mercury released from the active layer. The 2022 samples included the active layer from 0 to 57cm and permafrost from 57cm to 317cm, with the active layer cut every 10cm and the permafrost cut every 1-2cm to measure mercury concentrations and LOI. Age dating of the 2022 core is currently being conducted using the 14C method on two samples from the active layer and nine samples from the permafrost. The samples used for age dating are also being analyzed for carbon, nitrogen, and metal components. Results from the chamber test showed that the concentration of atmospheric mercury at the site was several times higher than the ambient air mercury concentration when the temperature rose during the day, confirming the re-emission of mercury. Detailed data will be presented in the poster on the day.