Geochemistry of natural and anthropogenic fall-out (aerosol and precipitation) collected from the NW Mediterranean: two different multivariate statistical approaches

The chemical characteristics of the mineral fractions of aerosol and precip itation collected in Sardinia (NW Mediterranean) are highlighted by means o f two multivariate statistical approaches. Two different combinations of cl assification and statistical methods for geochemical data are presented. It is shown that the application of cluster analysis subsequent to Q-Factor a nalysis better distinguishes among Saharan dust, background pollution (Euro pe-Mediterranean) and local aerosol from various source regions (Sardinia). Conversely, the application of simple cluster analysis was able to disting uish only between aerosols and precipitation particles, without assigning t he sources (local or distant) to the aerosol. This method also highlighted the fact that crust-enriched precipitation is similar to desert-derived aer osol. Major elements (AI, Na) and trace metal (Pb) turn out to be the most discriminating elements of the analysed data set. Independent use of minera logical, granulometric and meteorological data confirmed the results derive d from the statistical methods employed. (C) 1999 Elsevier Science Ltd. All rights reserved.