In order to study the effects of postdepositional processes on snow chemistry a surface snow experiment was performed on the Cerro Tapado summit glacier in northern Chile, a subtropical glacier site presumably influenced by strong sublimation. Chemical species irreversibly trapped in the snow were significantly enriched in the surface layer by sublimation of the water matrix (Cl-, SO42-, and K+) and by sublimation and dry deposition (Ca2+, Mg2+, Na+, CH3SO3-, and C2O42-). Species present in a volatile form, such as HCOOH, CH3COOH, and HNO3, were released from the snow. This indicates that not only particular meteorological conditions influence the modification of snow composition but so does the chemical form of the studied species (salts or volatile). From the enrichment in concentrations of irreversibly deposited chemical species the sublimation rate was quantified as 1.9 mm weq d-1, which agrees with the sublimation rates determined by lysimeters and by mass balance modeling. ¿ 2001 American Geophysical Union