Talk by Marie Bölsche, Centre for Ice and Climate – Niels Bohr Institute - University of Copenhagen

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Talk by Marie Bölsche, Centre for Ice and Climate

Talk by Marie Bölsche, Centre for Ice and Climate 



Air bubbles found in polar ice cores preserve a record of past atmospheric composition up to 800 kyr back in time. Carbon dioxide concentrations measured in Greenland ice samples show anomalous peaks compared to Antarctic values of the same age.

Nowadays an in situ production of CO2 from either organic material or carbonate reactions is considered very likely (Tschumi and Stauffer, 2000; Guzman et al., 2007). Neither the pathway nor the potential location of this chemical reaction within the ice have been identified so far. This in situ CO2 (CO2 excess) increases not only the CO2 concentration, but also impacts the isotopic composition of the atmospheric CO2 in the ice.

We aimed to link the CO2 excess found in Greenland ice and the related shifts of δ 13 C of CO2 relative to the values measured in Antarctic ice, with chemical impurity data measured on parallel ice sections. For this purpose we measured CO2 and δ 13 C − CO2 in high resolution (approximately 2.5cm) of GRIP and NGRIP ice samples.

In general, the results reveal that the in situ produced CO2 mainly originates from an oxidation process of organic impurities in the ice, for example formaldehyde, but a contribution from an acid-carbonate reaction cannot be fully excluded.

We found that correlations improved for our calculated contributions of CO2org and CO2carb with the related impurities (formaldehyde and dust particles) compared to the correlation of the total CO2 excess which is not divided into the two sources based on δ 13 C measurements.