Master thesis defense by Alexander Erik Friisnæs

Title: Measurements of δ¹⁵N and δ ⁴⁰Ar of NEEM air with oxygen removal from a perovskite membrane

Abstract: Isotopes of nitrogen and argon are stable in the atmosphere over long periods of time but the isotopic abundances is subject to change in a firn column. Measurements of δ¹⁵N and δ⁴⁰Ar from ice cores contain information about climate parameters such as temperature change through the firn and firn column width. With this information the past site temperature firn column height can be modelled. In this thesis a measurement system was built that could measure δ¹⁵N and δ⁴⁰Ar as well as the zero-enrichment, pressure imbalance and chemical slope needed to analyze the δ values. A new oven was built to remove oxygen from the sample stream. The oven was found to have an oxygen  removal rate of 99.4%. Four acquisition runs were carried out to test the stability of the setup. δ¹⁵N was found to be: 4.787 ±0.0120‰, 4.785 ±0.0060‰, 4.649 ±0.0070‰ and 4.503 ±0.0689‰. The δ⁴⁰Ar‰ was found to be: 6.078 ±0.1581‰, 6.064 ±0.0991‰, 5.8465 ±0.0722‰and 5.8519 ±0.3687‰.

Supervisor Thomas Blunier

Censor Jens Oluf