Abstract

The isotopic and chemical composition of soil waters in a periglacial environment was studied during a 2 month period (89-10-07 to 89-11-09). The experimental site chosen is located near Ny Ålesund, Svalbard (79°N, 12°E). The profile studied is situated on a fluvioglacial terrace made up essentially of silicate material, which, however, contains secondary calcite that is crystallized at the base of the coarse fraction. During the summer season, an active layer of about 1.5 m thick is developed over the continuous permafrost. During the refrosting stage, two freezing waves advance through the profile, one from the surface and one from the permafrost. At the system closure at depth 0.6–0.7 m, a residual solution is generated, which evolves toward selective solute enrichment and stable isotope (18O, 2H) depletion. The chemical and isotopic data coupled with physicochemical measurements taken in situ show that during refrosting this solution is oversaturated relative to calcite. The resulting crystallization of calcite takes place in a closed system in the presence of soil-derived CO2, but is not in isotopic equilibrium with the solution. [Journal Translation]

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