Carbon dioxide concentration in bubbles of natural cold ice

• Published in: The Journal of Physical Chemistry
• Main Authors: Neftel, A., Oeschger, H., Schwander, J., Stauffer, B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Chemical Society 1983
• Subjects: 530 Physics; Greenland; Dye 3; Dye-3; Ice Sheet
• Online Access: https://boris.unibe.ch/158748/1/neftel83jpc.pdf; https://boris.unibe.ch/158748/

The bubble pressure in an ice sheet is increasing with depth, due to the hydrostatic pressure of the surrounding ice. Below a certain depth, which depends on the ice temperature, bubbles are shrinking faster than expected, due to formation of air clathrates. After recovery and decompression of ice cores from below this depth, new bubbles start to form again. Within 1 year most of the air is collected again in newly formed bubbles. We measured by means of an infrared laser spectrometer the CO2 concentration in gas extracted by mechanically crushing small ice samples at -20 ⁰C. We analyzed samples from a depth of 1600 m below surface from the recently drilled Dye 3 core (South Greenland), a few days, a few weeks, and a few months after recovery. This allows us to investigate the influence of clathrate formation and incomplete back-diffusion to the measured CO2 concentration. The formation of CO2 clathrates and the back-diffusion process is certainly influenced by the solubility of CO2 in the ice structure. Earlier measurements published by our laboratory overestimated this solubility. New measurements of the CO2 concentration in laboratory grown single crystals allow a better estimate of the solubility of CO2 in ice. The seasonal variations of the COP concentration measured on ice samples from the Dye 3 core allow us to estimate an upper limit for the diff&on constant of CO2 in natural polycrystalline ice at -20 ⁰C.