Atmospheric nitrogen isotopes of the Marine Isotope Stage 6 period (190-135 ka) from the EPICA Dome C ice core

Isotopes of molecular nitrogen in air bubbles were measured from EDC at the Laboratoire des Sciences du Climat et de l'Environnement (LSCE), France. The gas was extracted from the ice by a wet extraction technique and the released air was analysed by a dual-inlet mass spectrometer (Delta V Plus; Thermo Scientific) (Bréant et al., 2019). In total, 151 samples from 88 depth intervals (63 duplicates) between the depths of 2124.7 and 1875.0 m below the surface were measured, corresponding to the time interval from 205 to 154 kyr BP.

We improved the relative age uncertainties between ice and gas in the EDC core using δ15N-based estimates of firn column thickness, see doi:10.1594/PANGAEA.929698. A new chronology was established using new δ15N data during the early MIS 6 in this study and published data from Landais et al. (2013).