Characterization of Modern and Fossil Mineral Dust Transported to High Altitude in the Western Alps: Saharan Sources and Transport Patterns

Figure 2

(Left Insert) Aerial view of the Jungfraujoch (JFJ) research station. The record of black carbon (BC) concentration and the associated δ ¹³C_BC composition (data from [4]), as a function of age (calendar year AD; left axis) and depth (meter water equivalent, m weq.; right axis). Trace element concentrations (Pb, Ti, Ba, Cs, U, and La) normalized to conservative crustal elements (Sc, Ta, Hf, or Th) and crustal enrichment factors (EFs) after normalization to the mean concentration ratios in the upper continental crust [23]. The total aerosols surface (cutoff level of 30 mm² kg⁻¹) and the mean diameter of the mineral fraction [4] compared to Sr and Nd isotopic ratios. The analyses of analog samples collected during the years 2008/2009 at the JFJ are reported in the upper part. ⁸⁷Sr/⁸⁶Sr error bars (2 standard errors of the mean) have been multiplied by 5 for CG samples and by 10 for JFJ samples. The horizontal grey-shaded area highlights the largest Saharan dust event deposited ~10 years before the Laki eruption in 1783.