Characterization of African dust over southern Italy A. Blanco1, F. Dee Tomasi1, E. Filippo2, D. Manno2, M. R. Perrone1, A. Serra2, A. M. Tafuro1, and A. Tepore2 1Istituto Nazionale di Fisica della Materia, Dipartimento di Fisica, Universita’ di Lecce, Lecce, Italy 2Istituto Nazionale di Fisica della Materia, Dipartimento di Scienza dei Materiali, Universita’ di Lecce, Lecce, Italy
Abstract. Dust samples from rainfall residues have been collected in southeast Italy
(40º 20' N, 18º
6' E) during dust outbreaks occurred from April to June 2002 to characterize
morphological and elemental particle composition by different techniques, and
investigate the dependence of particle properties on source regions. Four-day analytical
back trajectories and satellite images have been used to infer source regions of the
investigated dust samples.
It has been found that the TOMS absorbing aerosol index was in the range
0.7-2.2 over Southern Italy when samples have been collected. The particle-size and -shape analysis
by a scanning electron microscope (SEM) has revealed either that the particle-diameter
distribution was between 0.3 and 30 mm with median-diameter values between
and that the particles were characterized by a roundness factor varying from 0.8 to
2.5. The infrared transmission spectra have allowed recognizing that all dust samples
contained a significant amount of illite. The X-ray energy dispersive (EDX)
measurements have revealed that the Al/Si ratio of the transported dust varies from 0.41
to 0.50, and that the Al/Si, Ca/Al, K/Ca, and Fe/Ca ratios differ according to source
regions and therefore can be used as indicators of dust source regions. Indeed, it has been
found that dust samples with larger Ca/Al and Si/Al ratios and lower Fe/Ca and K/Ca
ratios, have been collected along dust events with a source region in northwestern
Sahara. On the contrary, the samples collected along dust events with the origin mainly
in Chad, Niger, Algeria and Lybia were characterized by larger Fe/Ca and K/Ca ratios.
Citation: Blanco, A., Dee Tomasi, F., Filippo, E., Manno, D., Perrone, M. R., Serra, A., Tafuro, A. M., and Tepore, A.: Characterization of African dust over southern Italy, Atmos. Chem. Phys., 3, 2147-2159, doi:10.5194/acp-3-2147-2003, 2003.