G01_06

Radiocarbon Inventories of Switzerland (RICH) : Source apportionment of atmospheric CO₂, sampling strategy and first results

Geissbühler D^1,2, Laemmel T^1,2, Gautschi P³, Wacker L³, Szidat S^1,2

¹Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland, ²Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland, ³Laboratory of Ion Beam Physics, Institute for Particle Physics and Astrophysics, Federal Institute of Technology Zurich (ETHZ), Zurich, Switzerland

Anthropogenically-induced climate change is strongly linked with perturbations of the carbon cycle causing the emission of greenhouse gases into the atmosphere, especially carbon dioxide (CO₂). Radiocarbon (¹⁴C) measurements of atmospheric CO₂ are unique in their capabilities to provide information on carbon source apportionment and transport, especially of fossil-fuel derived CO₂ which is ¹⁴C-free.

The Radiocarbon Inventories of Switzerland (RICH) project aims to build a comprehensive database and model of the distribution and cycling of radiocarbon in Switzerland across the atmosphere, soils, rivers and lakes. The project presented here will serve to specifically construct an inventory of atmospheric ¹⁴CO₂ in this larger scope. This will be achieved by sampling air in strategic ways, and measuring its ¹⁴CO₂ content, as well as CO₂ concentration. This will bring information on the radiocarbon signature of concentrated anthropogenic emissions in air masses, the spatial representation of diffuse natural emissions in multiple ecosystems, as well as their subsequent atmospheric transport. One of the main challenge in this work is to develop a robust sampling method allowing us to effectively capture ¹⁴CO₂ signatures. Graphitization of air samples will be done by using the Air Loading Facility developed at ETHZ (Gautschi, 2017). Measurements from leaf biomass are also planned, which will allow an insight into the integration of ¹⁴CO₂ to the vegetation, and ultimately to soils.

Presented here are the current status of the sampling methods and strategy development, as well as results from the first campaigns.