Multi-GHG analysis with the BigCIM: a novel system for fast and discrete ice core reconstructions

Deep Antarctic ice cores can contain thousands of years of past climate history stored in a meter of ice. This limited sample availability demands experimental setups to extract the maximum amount of information while using the minimum amount of sample. Here we present the BigCIM (Big Centrifugal Ice Microtome), a novel system for discrete ice core measurements of atmospheric CO2, d13C-CO2, CH4 and N2O. Combining the fast dry extraction principle from the Centrifugal Ice Microtome (CIM; Bereiter et al., 2013), and the analytical capabilities of the Quantum Cascade Laser-based Absorption Spectrometer (QCLAS; Bereiter et al., 2020), the BigCIM requires 16-g cuboid samples and throughputs 5 samples/day. Blank measurements using standard gas over gas-free ice achieve precisions (1s) of 0.3 ppm for CO2, 0.06 permil for d13C-CO2, 2 ppb for CH4 and 1 ppb for N2O, comparable to other dry-extraction methods (Mächler et al., 2023). Preliminary results from the EDC ice core shows general agreement with previously published data. The ability to measure multiple gas species simultaneously on small samples at a relatively quick pace makes the BigCIM a suitable instrument for measuring late Pleistocene greenhouse gas records on BE-OI ice core.

REFERENCES 

 Bereiter, B., Stocker, T. F., and Fischer, H., A centrifugal ice microtome for measurements of atmospheric CO2 on air trapped in polar ice cores. Atmos. Meas. Tech., 6, 251-262 (2013). 

Bereiter, B. et al., High precision laser spectrometer for multiple greenhouse gas analysis in 1 mL air from ice core samples. Atmos. Meas. Tech., 13, 6391–6406 (2020). 

Mächler, L. et al., Laser-induced sublimation extraction for centimeter-resolution multi-species greenhouse gas analysis on ice cores. Atmos. Meas. Tech., 16, 355–372 (2023).