[A-CC29] Ice cores and paleoenvironmental modeling

[ACC29-P03] Dielectric profiling (DEP) of the ice core from south-east dome, Greenland

*Mahiro Sasage^1,2, Iizuka Yoshinori², Shuji Fujita^3,4, Kaoru Kawakami^1,2, Takeshi Saito², Mai Matsumoto^1,2, Keita Takasugi⁵, Sumito Matoba², Akira Hori⁵, Sakiko Ishino⁶, Shohei Hattori⁷ (1.Graduate School of Environmental Science, Hokkaido University, 2.Institute of Low Temperature Science, Hokkaido University, 3.National Institute of Polar Research, Research Organization of Information and Systems (ROIS), 4.Department of Polar Science, The Graduate University for Advanced Studies (SOKENDAI), 5.Kitami institute of Technology, 6.Institute of Nature and Environmental Technology, Kanazawa University, 7.Nanjing University)

The electrical conductivity of snow and ice increases by electrolytes such as dissolved ions. Therefore, the concentration of dissolved ions in snow and ice sample can be estimated by measuring the electrical conductivity. The electrical conductivity measurement in ice cores is a non-destructive analysis and therefore widely used (e.g., Wolff et al., 1997; Fujita et al., 2016). In May 2021, a 250-meter-long ice core (SE-Dome ice core) was drilled from the Southeastern Greenland Dome (67°11′30.14328″N, 36°28′12.77075″W, 3160.7 m a.s.l.) (Iizuka et al., 2021). To estimate the amount of dissolved ions in SE-Dome ice core, we measured electrical conductivity by dielectric profiling (DEP) method (Fujita et al., 2016). The DEP was carried out at four different frequencies of electrical conductivities (250 kHz, 25 kHz, 2.5 kHz, 0.25 kHz) for the entire ice core with 20 mm resolution in -22℃. As a result, 46 peaks with an intensity of more than twice the standard deviation from the 3 m moving average were detected between 0 m and 88.52 m depth (correspond to the past 55 years) at 250 kHz. These peaks change periodically, which may indicate a summer season with high sulfate and nitric acid ion concentrations (Oyabu et al., 2015). The three most significant peaks were detected at depths of 43.39 m (1990s), 37.52 m (1990s), and 66.00 m (1970s), in ascending order of magnitude, which were all before 2000. Even in the DEP result of a 90.45-meter-long ice core drilled in May 2015 in the southeast dome of Greenland (67°10’ 48″N, 36°22’ 11″W, 3170 m a.s.l.), significant electrical conductivity peaks have been detected in 1968, 1987, 1992 (Iizuka et al., 2017). In the presentation, we will report the electrical properties of the SE-Dome ice core, including the identification of the volcanic signal with improved accuracy of dating.