High-resolution acidity in Antarctic ice cores over the past two millennium

Ice core acidity is a proxy for acid deposition and atmospheric acidity, where pH controls many chemical reactions. It is also a valuable indicator of changes within global geochemical cycles, since it reflects changes in the concentration of any of the contributing acid or base species. A novel technique for continuous, high-depth-resolution measurements of pH and acidity in ice core samples has been developed and applied to the array of ice cores collected during the Norwegian-US Scientific Traverse of East Antarctica. The technique provides both high resolution accuracy and efficiency that cannot be found with the existing techniques of electrical conductivity measurement (ECM) and Gran titration. Comparison of the acidity measurement with the major ion chemistry reveals the individual acid and base species that are contributing to the acidity. Spatial trends in the acidity across East Antarctica and temporal trends over the last ~2000 years are discussed, along with trends in the concentrations of each of the acid and base species. Changes in the concentration of acid and base species are interpreted in the context of global geochemical cycling and climate variability.