Dear listmembers, We are working on water chemistry of closed-basins in the Andean cordillera of Northern Chile. Precipitations occur mainly as snow. Our concern is about isotopic composition of infiltrating melt-water. The snow cover evaporates during the day. Under an arid climate, does the condensation during the night offset evaporation enrichment of 18O and 2H which occurs during the day? Does anyone know studies already done in such environments ? Many thanks for you help. Francois Risacher Centre de Géochimie de la Surface-CNRS. Strasbourg. France