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To explore the possibility of using ground ice archives for studies of the cosmogenic radionuclide 10Be, we analyzed the beryllium isotopes in ice wedges exposed in the Cold Regions Research and Engineering Laboratory (CRREL) Permafrost Tunnel and the Barrow Permafrost Tunnel in Alaska. We determined the concentrations of 10Be and 9Be in samples pretreated following two procedures: acidification before (procedure A) and after (procedure B) removal of particles. The 10Be and 9Be concentrations spanned wide ranges. Concentrations in procedure A samples were higher than those in procedure B samples. The 10Be/9Be ratios fell within a narrow range, and values from CRREL (about 8.5 × 10−9) and Barrow (about 7 × 10−9) were of the same order of magnitude. Further studies are needed to validate our findings and assess the feasibility of using the 10Be/9Be ratio of syngenetic ice wedges for reconstruction of 10Be variations due to cosmogenic and environmental changes, and radiometric dating of ice-wedge sequences that contain very old (beyond 1 Ma) ice. [ABSTRACT FROM AUTHOR]

For atmospheric gases and aerosols, snow and ice provide a useful archive of paleoenvironmental history. In the northern hemisphere, this archive has been largely limited to Greenland ice, but promising pioneering work has been done recently using chronology of an ice wedge in Barrow, northern Alaska. Here, we investigate past aerosols at the same ice-wedge sampling site, reconstructing the sea-ice fluctuations in the adjacent Beaufort Sea during the Bølling/Allerød (BA) and Younger Dryas (YD) periods. We confirm the integrity of methanesulfonate ion (MS−) concentrations in the BIWS as marine proxies, and then find that the ice wedge has a high MS− concentration through the beginning (coldest) YD periods. The high MS− concentration indicates that even during the coldest YD periods (12,900–12,700 yrBP), the near-shore region in the Alaskan Beaufort Sea near Barrow may not have been completely filled by permanent sea ice. • This is the first investigation of Pleistocene marine environment using an ice wedge. • Bromine and methanesulfonate ions are proxies of sea-ice fluctuations. • Permanent sea ice might not cover the near-shore Beaufort Sea during Younger Dryas. [ABSTRACT FROM AUTHOR]