Source apportionment of major ions and trace elements in the atmospheric deposition of Palermo (Sicily, Italy)

Abstract

In Palermo, (Sicily, Italy), a year-long study was conducted to analyse the chemical composition of atmospheric deposition samples. The research was carried out at four urban sites and one semi-rural site. The atmospheric deposition samples were analysed both for major ions and trace elements. Abundances of major ions, on meq L⁻¹ basis, followed the sequence Cl⁻ > HCO₃⁻ > NO₃⁻ > SO₄²⁻ > F⁻ > Br⁻ for anions, and Na⁺ > Ca²⁺ > NH₄⁺ > Mg²⁺ > K⁺ for cations. The statistical technique of Confirmatory Factor Analysis (CFA) was used to identify the main sources of origin of some of the main species and trace elements studied. Ions such as Cl⁻, Na⁺, Br and I were attributed to the marine source, whilst NH₄⁺ and NO₃⁻ to the anthropogenic source, as well as Mo, Cd, Cu, As, Pb, Sb and V among the trace elements. On the other hand, Ca²⁺, K⁺, Li, Fe, Al, and Sr were mainly of crustal origin. The seawater fractions of Mg²⁺ and SO₄²⁻ were of marine origin, whereas the non-seawater fractions of the same ions were of crustal and anthropogenic origin, respectively. Anthropogenic sources, such as internal-combustion vehicle, domestic heating, and plant emissions, must be considered for Cu, Cr, Ba, Mo, Sb, Zn, As, Ni, and V. This study produced a previously unpublished dataset on the chemical composition of atmospheric deposition that made it possible to identify the main sources influencing air quality in the metropolitan area of Palermo (Italy).