T03_P04

Update of radiocarbon analyses on dissolved inorganic carbon of seawater at ETH-Zurich

Castrillejo M^1,2, Wacker L², Bollhalder S², Casacuberta N^2,3, Kündig K^2,3, Leist L³, Scacco G², Synal H², Wefing A^2,3

¹Department of Physics, Imperial College London, London, United Kingdom, ²Laboratory of Ion Beam Physics, ETH-Zurich, Zurich, Switzerland, ³Department of Environmental Systems Science, ETH-Zurich, Zurich, Switzerland

In recent years, the Laboratory of Ion Beam Physics (LIP) has been actively involved in oceanographic expeditions to collect samples and measure radiocarbon on dissolved inorganic carbon of seawater. This work has been possible thanks to a new analytical method developed through the collaboration between oceanographers and experts in radiocarbon analysis at LIP. The fully automated method coupling the CO₂ extraction and graphitisation steps in a single line allows for rapid and precise determination of the radiocarbon content using only 50 ml of seawater. The method performs simultaneously on 7 samples and allows the processing of 21 samples a day.

Over the past two years, we have gained experience in sample collection, storage and processing allowing us to provide a substantial update on the ETH-LIP method that was first published by Casacuberta et al., (2020). We have compiled data on blanks, coral sample used as reference material, seawater replicates and data from a first interlaboratory exercise. Based on these new data, we discuss aspects related to sample collection and storage, background correction, accuracy, reproducibility and data comparability.

Casacuberta N., Castrillejo M., Wefing A.M., Bollhalder S., Wacker L. 2020. High precision ¹⁴C analysis in small seawater samples. Radiocarbon 62(1):13–24.