Combined application of multielement analysis—k0-INAA and PIXE—and classical techniques for source apportionment in aerosol studies

Three objectives were proposed in this work: (i) to evaluate the concentrations of Air Particulate Matter (APM) species obtained via k0-INAA and PIXE by comparison with results obtained via classical methodologies, (ii) to study the water solubility of chloride, sodium, sulfur, potassium and calcium sampled in APM filters and (iii) to analyze the importance of their solubility in the identification of emission sources. The multi-technique analytical approach, using nuclear and classical techniques, not only the results provided for a large number of APM species (essential for source apportionment studies) but also, for several elements, independent methods gave information about their solubility. Results indicated that: (1) the total Cl concentration was lower than the soluble Cl− concentration, showing that it volatilized partially during the PIXE analysis, (2) the majority of Na—provided mainly from sea salt spray—was soluble, (3) in PM10 most of the sulfur was in SO42− chemical form, (4) K exhibited aweaker solubility in the coarse fraction: in PM10−2.5, the insoluble potassium was associated with the mineral aerosol, whereas the soluble fraction resulted from the sea salt spray, (5) Ca showed a lower solubility in the coarse fraction, and the insoluble Ca was associated with a mineral origin.