10Be variations in polar ice cores

• Main Authors: Beer, J., Andrée, M., Oeschger, H., Stauffer, B., Balzer, R., Bonani, G., Stoller, Ch., Suter, M., Wölfli, W., Finkel, R. C.
• Other Authors: Langway Jr., C.C., Dansgaard, W.
• Format: Book Part
• Language: English
• Published: American Geophysical Union 1985
• Subjects: 530 Physics; Antarc*; Antarctica; Dye 3; Dye-3
• Online Access: https://boris.unibe.ch/160972/1/Beer_10Be_variations_in_polar_ice_cores.pdf; https://boris.unibe.ch/160972/

10Be is produced in the atmosphere by cosmic radiation and has a half life of 1.5 · 106 years. The produced 10Be atoms are attached to aerosols and washed out by precipitation. The mean residence time in the atmosphere is about one year. Annual snow layers with their 10Be contents are ideally preserved in polar ice sheets. With the new accelerator based mass-spectrometry technique it is possible to measure the natural 10Be concentrations in ice samples of 1 kg each. 10Be, with its short residence time and long half life, is very well suited for the study of variations of the interaction of cosmic radiation with the atmosphere. We measured firn samples from Dye 3 from the surface to about 100 m depth, representing the precipitation of the last 140 years. One sample per 2 years has been measured. The results are compared with the sunspot-number record. A clear indication of the 11 year cycle modulation has been obtained. In addition the 10Be activities of ice samples from 1600 m-1900 m depth have been measured. Samples from this depth interval represent precipitation from about 13,000 yrs B.P. to 6000 yrs BP. The results are compared with results from Antarctica, published by Raisbeck. By measuring the 10Be/36Cl ratio, it should be possible to date ice older than about 50,000 yrs.