T03_P07

DIC radiocarbon measurements at the AWI-MICADAS facility, current method developments and improvements

Grotheer H^1,2, Gentz T¹, Hammes J³, Hefter J¹, Mollenhauer G^1,2

¹Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany, ²University Bremen, Dept. of Geosciences and MARUM, Bremen, Germany, ³University Bonn, Dept. of Geosciences, Bonn, Germany

Reliable radiocarbon ages of dissolved inorganic carbon (DIC) are a perquisite to obtain improved understanding of current carbon cycle dynamics. With the advance of small-scale radiocarbon measurements, it became possible to analyze samples in unprecedented spatial resolution and increasing precision obtained by replicate analysis. Small sample requirements allow reliable dating of DIC samples from even the most remote places on Earth, where access is challenging, and available material limited in quantities. Reliable high precision methodologies for these precious sample sizes are required, and due to the lack of accepted Δ¹⁴C DIC standard material a sample processing consensus must be developed within the community.

We will report on ongoing method improvements for processing marine dissolved inorganic carbon samples. Our developments utilize the standard MICADAS peripheral carbonate handling system (CHS) coupled via the gas interface system (GIS) to the AWI-MICADAS . We report on reproducible ¹⁴C dates measured on DIC samples as small as 2 mL sea water. We describe our method improvement pathway including testing of different acids for DIC outgassing, sampling duration and volume dependency on ¹⁴C replicability.