Periodic Reporting for period 4 - deepSLice (Deciphering the greenhouse gas record in deepest ice using continuous sublimation extraction / laser spectrometry)
Reporting period: 2020-04-01 to 2021-03-31
However, the use of the paleo atmospheric archive in polar ice cores is currently limited in terms of temporal coverage, resolution and sample availability in the bottom-most part of the Antarctic and Greenland ice sheets where extreme thinning of the ice by glacier flow occurs. The overarching goal of deepSLice is, therefore, to develop a new analytical method that overcomes these limitations, opening the window for high quality gas records, for example for a future Oldest Ice ice core from Antarctica covering the Mid Pleistocene Transition 0.9-1.5 million years ago.
Accordingly, deepSLice is developing
1) a Quantum Cascade Laser Absorption Spectrometer (QCLAS) to measure CO2, CH4 and N2O concentrations as well as the carbon isotopic signature of CO2 (δ13CO2) in small ice core samples from highly thinned ice.
2) a quantitative, contamination free, and non-fractionating extraction system for the air enclosed in such small ice samples using Continuous Sublimation Extraction (CSE).
A complete CSE system for ice core samples was built, comprising near infrared (NIR) irradiation of ice rods under vacuum conditions, efficient removal of water vapor to allow for high sublimation speed and cryogenic sampling of the complete air for further analysis. At the beginning of the project a IR light bulb (black-body emitter) was used as infrared light source, which is now being replaced by a high power, monochromatic NIR laser source. Currently adsorption/desorption effects within the extraction device and the sample fingers are tested. Completion of the system is planned in 2019 after coupling of the CSE and the QCLAS system.
First ice core measurements are envisaged in the last year of the project including publication of first ice core results.