Item: Major element chemistry of inner-alpine snowpacks, aosta valley (nw italian alps)
Title: Major element chemistry of inner-alpine snowpacks, aosta valley (nw italian alps)
Proceedings: International Snow Science Workshop, Davos 2009, Proceedings
Authors: G. Filippa, M. Freppaz, M.W. Williams, E. Zanini, Di. V.P.R.A. Chimica Agraria e pedologia, University of Torino, Grugliasco (TO), Italy Institute of Arctic and Alpine Research, University of Colorado, Boulder (CO), USA
Abstract: Snowmelt is the dominant hydrologic event on an annual basis in high-elevation areas. Liquid water, particulates, and solutes stored over the winter period are released in a relatively short time period, and initial stages of snowmelt often have ionic concentrations many times higher than averages for the whole snowpack, and ionic pulse. The rapid release of water and solutes from the seasonal snowpack has a potentially significant impact on terrestrial and aquatic ecosystems. Major element chemistry of the snow cover was investigated at 15 samplings sites at about 2000 m a.s.l. in the Aosta valley, and inner-alpine region, during late winter '05-06. Snowfall was primarily westerly, due to Atlantic air flows, while southerly flows were not a significant source of snowfall. The inner-alpine topography and the peculiar air flow patterns determined a unique ion distribution compared to the rest of the Alps. Calcium and magnesium concentrations in snowpacks were low, consistent with the absense of Saharan dust events and local geological sources. Sodium and chloride concentrations were higher than the average for the Alps, supporting the influence of the Atlantic air masses on the ionic composition of snowfall. Sulfate concentrations were in the range of background concentrations reported for high altitude and latitude sites, indicating that industrial emissions were not a main source of chemicals for winter '05-06. Ammonium and nitrate values were comparable to concentrations found in other sites for the Alps for low-emission winters. Here we show that the distribution of chemicals in the snowpacks of inner-alpine valleys may have a different behavior, compared to the rest of the Alps, resulting in potential differences in the effects of N and S depositions in such sites. Given the not negligible extent of inner-alpine valleys in the Alpine chain, such pattern should be taken into account while modeling N and S deposition at a global scale.
Keywords: inner-alpine, nitrogen deposition, snowmelt, water quality
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