Master thesis defense by Mirjam Martina Läderach – Københavns Universitet

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Master thesis defense by Mirjam Martina Läderach

Title: Continuous flow analysis on EastGRIP ice core: Optimization of optical dye method and results from acidity measurements on the EastGRIP ice core

This study presents continuous flow analysis (CFA) acidity data obtained from the EastGRIP ice core and contributes to the climate record of past volcanic activity. A restructured setup for the optical dye acidity technique developed by Kjær et al. (2016), enabling a lower signal to noise ratio, is presented and evaluated. Within this new setup, the optimal concentration of the two pH-indicator dyes bromophenol blue and chlorophenol red for the reagent used in this technique is assessed and estimated at 0.04 mg/mL to 0.06 mg/mL. Further, the method is applied to the EastGRIP ice core section of 350.35 m to 904.75 m depth, roughly corresponding to a time range spanning from 3 ky to further than 7.6 ky before 2000 CE. The evaluation of the standard data from this ice core section concludes that the EastGRIP acidity data obtained as part of this study is of reasonable quality and can thus be trusted in future investigations of climatic events. To this end, a selection of the EastGRIP measurement data for acidity combined with CFA meltwater electrolytic conductivity, dust, calcium and ammonium data, showcases selected indications for volcanic activity at the time.