Seasonal impact of natural and anthropogenic emissions on the highest glacier of the Eastern European Alps
1Institute for the Dynamics of Environmental Processes IDPA-CNR, University of Venice, Dorsoduro 2137, 30123 Venice, Italy
2Department of Environmental Sciences, University Ca' Foscari of Venice, Dorsoduro 2137, 30123 Venice, Italy
3Department of Land, Environment, Agriculture and Forests, Agripolis, University of Padua, Viale dell'Università 16, 35020 Legnaro, Italy
4School of Earth Sciences and Byrd Polar Research Center, The Ohio State University, 108 Scott Hall, 1090 Carmack Road, 43210 Columbus, USA
5Ripartizione Protezione Antincendi e Civile – Provincia Autonoma di Bolzano, Viale Drusio 116, 39100 Bolzano, Italy
6Ripartizione Protezione Antincendi e Civile, Ufficio Idrografico – Provincia Autonoma di Bolzano, Via Mendola 33, 39100 Bolzano, Italy
7Earth Science Department, University of Pavia, Via Ferrata 1, 27100 Pavia, Italy
Abstract. In June 2009, we conducted the first extensive glaciological survey of Alto dell'Ortles, the uppermost glacier of Mt. Ortles which at 3905 meters above sea level (m a.s.l.) is the highest summit of the Eastern European Alps. We analyzed snow samples collected from a 4.5 m snow-pit at 3830 m a.s.l. Here, we present a comprehensive data set including a large suite of trace elements and ionic compounds that comprise the atmospheric depositions over the past few years.
Trace element concentrations measured in snow samples are extremely low with mean concentrations at pg g−1 level. Only Al and Fe present median values of 1.8 and 3.3 ng g−1, with maximum concentrations of 21 and 25 ng g−1. The median EFc values for Be, Rb, Sr, Ba, U, Li, Al, Ca, Cr, Mn, Fe, Co, Ga and V are lower than 10 suggesting that these elements originated mainly from soil and mineral aerosol. EFc higher than 100 are reported for Zn (118), Ag (135), Bi (185), Sb (401) and Cd (514), demonstrating the predominance of non-crustal depositions and suggesting an anthropogenic origin.
Our data show that the physical stratigraphy and the chemical signals of several species were well preserved in the uppermost snow of the Alto dell'Ortles glacier. A clear seasonality emerges from the data as the summer snow is more affected by anthropogenic and marine contributions while the winter aerosol flux is dominated by crustal sources. For trace elements, the largest mean EFc seasonal variations are displayed by V (with a factor of 3.8), Sb (3.3), Cu (3.3), Pb (2.9), Bi (2.8), Cd (2.1), Zn (1.9), Ni (1.8), Ag (1.8), As (1.7) and Co (1.6).
The chemical data are also discussed in light of the atmospheric stability and back-trajectories analyses in order to explain the observed seasonal variability and how human activities impact the high altitude environment in the Eastern Alps. The origin and behavior of air masses as inferred from the evaluation of 48-h back-trajectories show significant seasonal differences. However, the large changes in trace elements concentrations seem to be more related to the vertical structure of the troposphere at a regional scale rather than the synoptic weather patterns.