10:45 AM - 12:15 PM
[ACC26-P01] Electrical conductivity and ion concentration of SE-Dome ice core, Greenland
Keywords:SE-Dome ice core, Greenland, electrical conductivity, ion concentration
Ice cores drilled in polar ice sheets preserve acid and salts as impurities deposited by snowfall and/or wind in the past. Since electrical conductivity of ice containing acids and salts is higher than that of pure ice, the electrical conductivity of ice cores has been used to detect past events such as volcanic signals. In this study, electrical conductivities at three frequencies (250, 25, and 2.5 kHz) of a 250 m-long ice core, drilled in the southeast dome (SE-Dome) of the Greenland ice sheet in May 2021, were measured using the dielectric continuous profile (DEP) method, and ion concentrations of the melted samples were measured by ion chromatography (Thermo Scientific, ICS-2100).
The 250 kHz electrical conductivity profile of the SE-Dome ice core shows two peaks at depths of 236.22 m and 143.13 m, which are identified as the Tambora (1816) and Katmai (1912) volcanic eruptions, respectively. The SE-Dome ice core has significant peaks at 19 depths in the difference of between 250 kHz and 25 kHz conductivity. These 19 depths also have peaks of either “H+”, “Na+ and Cl-”, and “NH4+ and NO3-”. Ion species such as H+, Cl-, NH4+ move relatively freely in ice crystal lattice, and the amount of these ion movement may differ in frequency.
The advantages of applying the DEP method to ice cores are rapid non-destructive analysis and can be operated in drilling site. The H+ peaks reflect volcanic signals and anthropogenic SOx and NOx contributions, the Na+ and Cl- peaks reflect sea salt events and impurity redistribution by melt-refreezing process, the NH4+ and NO3- peaks reflect forest fire events. This study suggests that future DEP measurements at multiple frequencies, not just 250 kHz, will detect multiple environmental signals such as above at the initial stage of ice core analyses.
The 250 kHz electrical conductivity profile of the SE-Dome ice core shows two peaks at depths of 236.22 m and 143.13 m, which are identified as the Tambora (1816) and Katmai (1912) volcanic eruptions, respectively. The SE-Dome ice core has significant peaks at 19 depths in the difference of between 250 kHz and 25 kHz conductivity. These 19 depths also have peaks of either “H+”, “Na+ and Cl-”, and “NH4+ and NO3-”. Ion species such as H+, Cl-, NH4+ move relatively freely in ice crystal lattice, and the amount of these ion movement may differ in frequency.
The advantages of applying the DEP method to ice cores are rapid non-destructive analysis and can be operated in drilling site. The H+ peaks reflect volcanic signals and anthropogenic SOx and NOx contributions, the Na+ and Cl- peaks reflect sea salt events and impurity redistribution by melt-refreezing process, the NH4+ and NO3- peaks reflect forest fire events. This study suggests that future DEP measurements at multiple frequencies, not just 250 kHz, will detect multiple environmental signals such as above at the initial stage of ice core analyses.