EGU23-8974
https://doi.org/10.5194/egusphere-egu23-8974
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

New developments in techniques for the sampling and analysis of atmospheric 14CO2 and 14CH4 at ETHZ and UNIBE, Switzerland

Soenke Szidat1,2, Thomas Laemmel1,2, Dylan Geissbühler1,2, Sarah Rowan1,2, Philip Gautschi3, Franziska Lechleitner1,2, and Lukas Wacker3
Soenke Szidat et al.
  • 1University of Bern, Department of Chemistry, Biochemistry and Pharmaceutical Sciences, Bern, Switzerland (soenke.szidat@unibe.ch)
  • 2University of Bern, Oeschger Centre for Climate Change Research, Bern, Switzerland
  • 3ETH Zurich, Laboratory of Ion Beam Physics, Zurich, Switzerland

Radiocarbon (14C) measurements of atmospheric greenhouse gases such as carbon dioxide (CO2) and methane (CH4) are central in our capability to identify their provenance. The 14C content of these gases provides more insight into the age of their sources and mainly allows the distinction between fossil and modern ones. 14CO2 measurements can be used to analyze the nature of anthropogenic emissions (mostly fossil), or to discern on what organic matter pool respiration is taking place in a given environment. 14CH4 can also be used to detect anthropogenic emissions (from leaks of natural gas, for example) as well as natural emissions produced by methanogenesis, for example from ruminants or in wetlands.

The 14C analysis of atmospheric gases is made challenging due to their usual low concentration. Thus making the use of appropriate sampling methods, preconcentration and extraction techniques necessary to reach a sufficient amount of carbon for Accelerator Mass Spectrometry (AMS) analysis. We propose here a general view of the techniques that were developed at the Laboratory for Ion Beam Physics (ETHZ, Zurich), and at the Laboratory for the Analysis of Radiocarbon with AMS (UNIBE, Bern) for the purpose of analyzing CO2 and CH4 in atmospheric samples. We then discuss the practicability and the potential bias introduction of each of them.

The techniques are as follows :

  • Automated Graphitization Equipment with Automated Loading Facility (AGE-ALF)
  • Automated Graphitization Equipment with Cryogenic Trap (AGE-CT)
  • Methane Preconcentration and Purification System (MPPS)

Generally, samples were collected in sampling bags, either in 5-15L capacity for CO2 or larger than 60L for CH4. Types of samples that are considered are atmospheric CO2 and CH4 samples, CO2 from soil respiration, and CO2 from cave air. The different techniques are presented, and 14C results from standard gases are compared between the extraction lines and two MICADAS AMS systems at ETHZ and UNIBE.

How to cite: Szidat, S., Laemmel, T., Geissbühler, D., Rowan, S., Gautschi, P., Lechleitner, F., and Wacker, L.: New developments in techniques for the sampling and analysis of atmospheric 14CO2 and 14CH4 at ETHZ and UNIBE, Switzerland, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-8974, https://doi.org/10.5194/egusphere-egu23-8974, 2023.