Aerosol deposition, trace elements and black carbon, over the highest glacier of the Eastern European Alps (Mt. Ortles, 3905 m) during the last 3000 years: environmental and climatic impacts

Abstract

An ice core from one of the highest summit of the Eastern European Alps has been analysed for the first time through the use of a brand new melting and de-contamination system. The melting system was prepared and tuned in order to achieve the highest level of de-contamination, stability of the melting speed and fluxes and to allow a simultaneous double high-resolution discrete sampling. The continuous flow analyses system (CFA) methodology was tested as well as the results repeatability. The firn and ice were drilled in 2011, processed at the University Ca’ Foscari of Venice and stored at -20°C. The ice core was melted on a heated aluminium letting head and the melt water from innermost part was pumped to the CFA tubing system. Four different channels were set up after the de-bubbling system. The first line was connected to the SP2 for refractory black carbon (rBC) concentration and diameter; the second to an ICP-QMS for trace elements (TE); the third to a conductivity micro-cell and an on-line particle counter with 32 dimensional classes and subsequent sampling; the last line finally is used for sample the melt water in pre-cleaned vials for TE and ultra-TE analyses (ICP-QS with CRC) and further analyses. The results show the elemental profiles over the last 3000 years. For some heavy metal the first human pollutions were released in the atmosphere about 2000 years before present, during the Roman Empire and the mining activities were the sources. Other significant contaminations were found around 1400 and 1600 where an increase of the concentrations of Pb, As, Ag and Sb were measured. The strongest contamination was observed during the 1960s where the industrial activity in the European region was at its maximum level. In the upper part of the core the climatic and environmental signal is less clear but a strong decrease in concentration for the anthropogenic emitted heavy metals is observed. The BC concentration started to increase at the beginning of the 18th century and reached the highest values during the 1930s and the 1960s. The radiative influence on the glaciers was significant.