A sublimation technique for high-precision d13C on CO2 and CO2 mixing ratio from air trapped in deep ice cores

Abstract

Glacier ice represents the only direct archive to retrieve information about the composition of the paleoatmosphere. During the glacials the CO2 concentration was about 90 ppmv lower than during the warm interglacials. The task to quantitatively understand the processes behind these observed CO2 changes is of outstanding importance not only for the paleo climate community, but also to predict the CO2 concentration in the future. One crucial key to unravel the open questions about the coupling of atmospheric CO2 with the dynamics of the global carbon cycle is the stable carbon isotope ratio of CO2 (d13C). This thesis introduces a new analytical method allowing a quantitative extraction of air from small ice core samples coupled to a high precision gas chromatography-isotope ratio mass spectrometry system to determine d13C. Additionally, this technique precisely determines the CO2 concentration on the same sample. This new technique makes it possible to surmount major analytical limitations and shortcomings encountered during previous studies.