Master thesis defense by Erik Warming – Niels Bohr Institute - University of Copenhagen

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Master thesis defense by Erik Warming

A Technique for Continuous Detection of Drill Liquid in Ice Cores

Abstract
When drilling ice cores deeper than 100 meters, drill liquid is required to limit bore-hole deformation. Due to pressure differences in the ice, in Greenland typically between 800 to 1200 meters depth, the ice cores can crack during drilling. Ice from this ”brittle zone” can be contaminated by drill liquid that seeps into cracks and this potentially contaminates chemical analysis of ice core samples. The Continuous Flow Analysis (CFA) system melts a subsection of the ice core, and analyses the ice for chemical impurities. Drill liquid can potentially interfere with the measurements or damage instruments. An optical detector was constructed to identify drill liquid in CFA tubing by UV absorption spectroscopy at a wavelength of 290 nm. To distinguish air bubbles from drill liquid, absorption was also monitored at 435 nm. The setup was successfully field tested in the frame of the NEEM ice core drilling project in Greenland. During 158 measuring runs, 27 proved positive for drill liquid. The instruments affected by drill liquid contamination were: the insoluble dust particle, the electrolytic conductivity, the ammonium, the hydrogen peroxide, and the sulfate detectors.

Supervisors:
Anders Svensson, associate professor, Centre for Ice and Climate
Paul Vallelonga, associate professor, Centre for Ice and Climate