Lead speciation of PM2.5 collected from Greater Cairo, Egypt and Zarqa, Jordan: An energy dispersive X‐ray fluorescence and X‐ray absorption near edge structure study

Abstract

Fine aerosol particles with an aerodynamic diameter equal or less than 2.5 μm (PM2.5) have been collected from two sites (residential and industrial) in Greater Cairo, Egypt and one site in Zarqa, Jordan. Based on the elemental quantitative analysis of PM2.5 using energy dispersive X‐ray fluorescence with Mo secondary target, Pb concentrations increased remarkably during winter season regardless of the sampling location. Moreover, it reached the maximum concentration at the industrial location of Greater Cairo, Egypt, and it equals 415 ± 485 ng/m3. The remarkable high standard deviation is due to the significant variation of Pb concentration from time to time during that winter season. Depending on the energy dispersive X‐ray fluorescence results, specific PM2.5 samples that have the highest concentration of Pb (two samples/location) have been selected for the X‐ray absorption near edge structure measurements to estimate the oxidation state of Pb species. The X‐ray absorption near edge structure measurements including 13 Pb references have been carried out at Pb‐L3 absorption edge (13.039 keV) using fluorescence mode. It was shown that PM2.5 contains divalent and tetravalent lead in both industrial site in Greater Cairo, Egypt and urban site of Zarqa, Jordan although that of a residential area of Greater Cairo‐Egypt is almost divalent lead.