Sources and distribution of trace species in Alpine precipitation inferred from two 60-year ice core paleorecords

Abstract

Abstract. The Alps represent the largest barrier to meridional air flow in Europe, strongly influencing the weather and hence the distribution of atmospheric trace components. Here for the first time, chemical records from two ice cores retrieved from glaciers located in the northern and southern Swiss Alps were compared in conjunction with an analysis of "weather type", in order to assess geographical and seasonal trends in the deposition of trace species and to identify source regions and transport patterns. Using a correlation analysis, investigated trace species (NH4+, NO3−, SO42−, Ca2+, Mg2+, Na+, K+, and Cl− were grouped into classes of different origin (anthropogenic, sea salt, or Saharan dust). Over the last 60 years, precipitation chemistry at both sites was dominated by NH4+, NO4−, and SO42−, all of anthropogenic origin and deposited mainly in summer by way of convective precipitation. The similarity of the SO42− profiles with historical records of SO4 emissions from France and Italy indicated these two countries as key source areas for the anthropogenic species. In contrast, sea salt and Saharan dust showed major differences in transport pattern and deposition across the Alps. Currently, the sea-salt constituents Na+, K+, and Cl− are transported to the northern site during advective westerly-wind situations, independent of Saharan dust events. At the southern site, sea salt and Saharan dust are deposited simultaneously, indicating a coupled transport active mainly in summer during south-westerly wind situations.

Temporal variations of perfluoroalkyl substances and polybrominated diphenyl ethers in alpine snow

“…The pollution signal trapped in the net Colle Gnifetti accumulation represents non-winter deposition. The enhanced atmospheric mixing during the summer results in increased trace species deposition (Eichler et al, 2004), and we assume that this relationship applied to PFAS and PBDE deposition. Thus the derived deposition is assumed to reflect annual deposition.…”

“…We therefore assume that PFAS contamination has completely resulted from atmospheric wet and dry deposition. In general, Colle Gnifetti is influenced by the westerly wind systems (Eichler et al, 2004). During summer months the majority of precipitation arrives by convective activity.…”

“…The Alps are the largest natural air barrier in central Europe and a potential trap for European anthropogenic atmospheric pollution (Eichler et al, 2004). Here, we use a 10 m firn core (Colle Gnifetti, Monte Rosa massif, Swiss/Italian Border, 4455 m above sea level; a.s.l.)…”

Temperature and precipitation signal in two Alpine ice cores over the period 1961–2001

“…Systems advected from the north or the south are also frequent (see e.g. Eichler et al, 2004;Barry, 2008). In this case, precipitation affects especially one flank, often accompanied by Foehn situations on the other side.…”

“…The northern Alps are dominated by the influence of North Atlantic air masses in winter and land evaporation in summer whereas the southern Alps are characterized by higher intraseasonal precipitation variability and substantial contribution from the Mediterranean, especially in spring and autumn (Frei and Schär, 1998;Eichler et al, 2004;Sodemann and Zubler, 2009).…”