Radiocarbon and tracer for fossil CO2 Research Methods
ICOS Karl Otto Münnich Radiocarbon Laboratory (ICOS CRL)
The ICOS CRL is based on the former Heidelberg Radiocarbon Laboratory, which was operated for more than 50 years by the IUP and the Heidelberg Academy of Sciences and Humanities. The main task of the ICOS CRL is the high-precision radiocarbon analysis of CO2 samples from the ICOS atmospheric station network. These 14C measurements are used to separate the contributions of fossil fuels to atmospheric CO2 over Europe from those of biogenic sources. The ICOS CRL was named after the first director of the IUP, Karl Otto Münnich. During his doctorate in the 1950s, he established the Heidelberg Radiocarbon Laboratory. His doctoral student Ingeborg Levin continued his pioneering work on atmospheric ¹⁴CO₂ measurement, expanded it with her research group on a global scale and was a key driving force behind the founding of ICOS.
The Central Radiocarbon Laboratory uses two different analytical techniques for 14C analysis - Low Level Counting (LLC) for large volume CO2 samples and Accelerator Mass Spectrometry (AMS) for small (piston) air samples. Below you will find some impressions of our laboratory.
Spot checks of air samples (flasks)
Some of the 3-litre flask samples taken at Class 1 ICOS stations are analysed for 14CO2 using accelerator mass spectrometry after they have been tested for greenhouse gas concentrations and stable isotopes in the ICOS flask and calibration laboratory. The samples are transported between the stations and the ICOS laboratories in specially designed transport boxes.
ICOS CRL Flask CO2 extraction and graphitisation line (EGL)
A special semi-automatic CO2 extraction and graphitisation line for flask samples was developed at CRL to prepare the up to 1500 small air samples per year for AMS-14CO2 analysis. The line is designed to also produce graphite targets from pure CO2 sample aliquots of the large volume CO2 samples. For quality control of the entire flask extraction process, a laser spectrometer is integrated into the preparation line, which enables precise analysis of the stable isotopes of the extracted CO2.
ICOS CRL graphitisation ovens from EGL
A total of twelve CO2 samples can be graphitised in parallel in the extraction and graphitisation line. We use iron powder as a catalyst and hydrogen gas for the reduction of CO2 to graphite for the AMS-14C analysis.
ICOS CRL CO2 sample aliquot preparation
From each high volume integrated conventional 14CO2 sample, three aliquots are transferred to ampoules to allow parallel AMS analysis of the sample ( for comparison to low level counting and quality control) and to create an archive of CO2 air samples (for possible later analysis).
ICOS CRL laboratory for the preparation of large volume air samples for 14C analyses in low level counting tubes
The integrated large-volume 14CO2 samples, which are obtained from around 20 m3 of air by chemical absorption in sodium hydroxide solution, are extracted from the base solution in a vacuum system by adding phosphoric acid and transferred to high-pressure stainless steel containers.
ICOS CRL system for cleaning large-volume air samples
The CO2 from the extracted large-volume samples is purified over charcoal to enable direct counting in the low-level counting tubes of the underground laboratory at the IUP.
ICOS CRL underground laboratory at the IUP
A total of 19 counting tubes are available for measuring the large-volume CO2 samples in the IUP's underground laboratory. The counting tubes are shielded with low-activity lead and the samples are measured in two different counting tubes for at least one week in order to obtain sufficient 14C counting statistics and achieve the highest possible accuracy.
MICADAS 14C accellerator mass spectrometer at CEZA
Few milligrams of graphite from the CO2 of the small-volume flask samples are analysed for 14C using AMS at the Curt-Engelhorn Centre for Archaeometry in Mannheim, Germany.
