Radiocarbon in polar ice: The mechanism by which radiocarbon is preserved in firn grains

This work is devoted to the problem of localizing the ¹⁴C cosmogenic radionuclide in a firn layer covering glaciers. The data on ¹⁴C in ice samples from the GISP2 ice core drilled on a Greenland ice dome (Summit) are analyzed. It has been indicated that experimental values of the ¹⁴C concentration are systematically smaller than theoretically calculated values, which indicates that firn grains partially lose ¹⁴C. Diffusion of cosmogenic ¹⁴C in firn grains and hydration of ¹⁴CO₂ in a disordered ice layer, which is formed on a firn grain surface and at the boundary between ice monocrystals, are considered. It has been indicated that these processes are among the main ones responsible for the level of radiocarbon concentration in firn and ice samples.