An investigation of water and ice chemistry in a fast-retreating glacier in the Dolomites (NE Italy): the Fradusta glacier

Abstract

Fradusta glacier (Pale di San Martino massif), the second largest icefield in Italian Dolomites, is evidencing a fast retreat, with a surface area reduction of about 90% in the last 100 years, and a negative variation of glacier front of 115.5 m between 1926 and 2000. Analytical chemical studies, conducted on the field with portable instrumentation for physicochemical parameters and in the analytical laboratory for main ion determination via IC, suggested the occurrence of strong chemical interactions between melting waters and the dolomitic bedrock. The presence of ammonium ion in snow and ice samples is indicative of long-range global anthropogenic impact, which might be related to «red snow» events. Accordingly, no correlation of ammonium is found with alkalinity, indicating the absence of local pollution, as confirmed by low concentrations of sulphate and nitrate ions in snow and ice. Ammonium had a particular significance in this study, since it was proposed as an «in-situ», environmentally-friendly chemical tracer for a better understanding of hydrological karstic circulation.