We present results of studies of in situ cosmogenic 14C in several ice samples from the Vostok and Taylor Dome cores, spanning the time intervals of 20 and 11 k.y. B.P., respectively. The results are in variance with our findings for the Greenland Ice Sheet Project 2 (GISP 2) samples, where near quantitative 14C retention was observed. The partitioning of 14C in the CO and CO2 phases is, however, quite similar in the GISP and two Antarctic ice samples. Noting that most of the in situ 14C is produced in the ice during its accumulation to thicknesses of up to ~10 m, we interpret the observed 14C deficiencies in Antarctic ice samples as due to grain metamorphism (recrystallization and sublimation or evaporation caused by wind ventilation). Simplified models for wind ventilation exhibit an interesting feature of the firnification processes; they differently affect the concentrations of in situ 14C and of the cosmogenic nuclides 10Be and 36Cl scavenged from the atmosphere in the accumulating firn. By studying the concentrations of in situ cosmogenic 14C and the atmospheric cosmogenic nuclides in the same ice samples, one can hope to obtain fairly realistic models of the chemical impacts of firnification processes: specifically, relationships between precipitation and accumulation and the main processes contributing to modifications in the nuclide concentrations. ¿ 2001 American Geophysical Union