PIXE and statistical analysis of fine airborne particulate matter (PM2.5) in Damascus

Abstract Air particulate matter (PM) samples were collected over the period from May 2017 to January 2018 for determination of chemical elements. Sampling campaign is realized in Damascus, the capital of Syria, and conducted twice per week. PM samples were taken as two size fractions (PM2.5 and PM2.5-10) using ISAP air sampler. The results showed that the mass concentrations for PM2.5 were higher than those for PM10-2.5. The overall mean mass concentrations were 32.48 ± 14 μg/m3 and 18.9 ± 10 μg/m3 for PM2.5 and PM10-2.5, respectively. The PM2.5 samples were subjected to PIXE analysis in order to determine the major (Ca, S, Si, Fe, Al, K, Mg and Na) and trace elements (Cl, Pb, Zn, Ti, P, Mn, Cu, Sr, Zr, Br, V and Ni). Elemental composition data were modelled using cluster analysis and principal component analysis to determine particle source categories contributing to the air pollution. The identified sources of PM2.5 were (1) resuspended soil characterized by high concentrations of Si, Al, Fe and Mg; (2) traffic source identified by the presence of Pb, Br, and S; (3) heavy oil combustion characterized by association between Ni and V; (4) a mixed industrial source; and (5) agriculture activities (K, Ca and P). The concentrations of elements initiated from anthropogenic sources are much lower than those induced naturally from earth’s crust.