Measurement of electrical conductance in ice cores by AC-ECM method

A relation between ice electrical conductance and impurity ions incorporated in ice was investigated from several samples of Antarctic and Arctic ice cores. Conductance was measured using the AC-ECM method. The aim of this study was to assess the possibilities and limitations for rapid detection of impurity ions in polar ice cores through measurements of electrical conduction. We are in particular interested in higher spatial resolution with which we can investigate if there is a contrast of electrical conductivity, between ice-grain boundaries and within the ice-lattice. We found that there is a proportional relation between the highfrequency conductance and molarity of sulfuric acid in the ice cores. In addition, the observed relation (molar conductance) was consistent with the molar conductivity found in earlier studies at LF and microwave frequencies. Moreover, we found that sodium chloride can also increases the conductance. The results suggest that AC-ECM is a useful method for rapid, quantitative, and high-resolution detection of these constituents in ice cores. A preliminary high-resolution analysis using doped ice showed that electrical conductance is localized in the vicinity of grain boundaries in case of doped ice. Based on these tests, the method was recently used for ice analysis of the 2504-m-deep Dome Fuji station ice core.