PhD Candidate: Malavika Sivan

Defence date: 29-10-2024
Time: 14:00
Institute: Utrecht University
Location: Academiegebouw, Domplein 29, Utrecht
Online: Livestream

PhD supervisors:
prof. dr. Thomas Röckmann
prof. dr. Caroline P. Slomp
dr. Maria Elena Popa

Title thesis: Clumped isotopologues of methane: measurements and modelling

Abstract:

Methane is a potent greenhouse gas with a high global warming potential, making it a critical focus in climate studies. The clumped isotopologues of methane have emerged as valuable tracers for identifying methane sources and sinks. This thesis presents the development and optimization of extraction and measurement techniques to measure the clumped isotopologues of methane accurately and precisely across various sample types, including the atmosphere.

The first measurements from atmospheric samples and Greenland’s firn layers revealed significant changes in methane’s isotopic composition over time. This data was used to develop a two-box atmosphere model to constrain the clumped isotope budget of atmospheric methane. Furthermore, our studies of biogenic methane production in marine sediments show distinct isotopic signatures linked to different methanogenic pathways, providing insights into microbial contributions to the isotopic composition of atmospheric methane.