Aerosol measurements at the Sonnblick observatory - analysis of elements and evaluations regarding the chemical composition

Abstract

Desert areas contribute significantly to the global aerosol load, with Saharan dust also reaching the Alpine region in Austria. The influx of minerals is of interest due to the associated impact on the radiation balance in glacier areas and also the nutrients included in the dust. The sampling of atmospheric aerosol (PM10, particles with aerodynamic diameter below and including 10 μm) is done on quartz fiber filters in a High Volume Sampler with weekly resolution at the Sonnblick Observatory. Aliquots of these filters are taken and subsequently digested with the aid of microwave irradiation. The solutions generated are analyzed by ICP-MS and ICP-OES.Within this work, the analysis of eleven elements (Mg, Al, Ca, Ti, Cr, Mn, Fe, Co, Ni, Sr, Pb) was feasible. The results could be evaluated as temporal trends. We see that elevated concentrations mainly occur in the spring, summer and fall. Even more apparent is the correlation of elemental concentrations with Saharan dust events (SDEs). We see that highest elemental concentrations of relevant elements such as Fe, Al and Ca coincide with the weeks that are most affected by mineral dust. Based on approximations taken from literature, the mineral dust load could be calculated from the elemental concentrations. This estimates the mineral dust proportion of the total suspended particle mass concentration as up to 71% in weeks with relatively high Sahara dust occurrences.The results allow an estimation of the contribution of long-range transport of mineral dust to the overall aerosol mass. Furthermore, the change in aerosol composition during SD occurrences in the region around Sonnblick Observatory can be described. Thus, the data provides the basis to estimate effects on the ecosystem.