Metal Composition and Source Identification of PM2.5 and PM10 at a Suburban Site in Pathum Thani, Thailand

Abstract

This study reports the mass concentrations, elemental characterization and identification of the possible sources of PM2.5 and PM10 at a suburban site in Pathum Thani, Thailand. The sampling was done from 18 February 2021 to 14 September 2021. PM2.5 concentrations were between 0.39 μg/m3 and 174.26 μg/m3, while PM10 concentration ranged from 12.75 μg/m3 to 242.02 μg/m3. The average concentration of PM2.5 in the wet season (61.96 μg/m3) in the study area exceeded the national ambient air quality standards (NAAQS). Particle-induced X-ray emission (PIXE) was used to measure the element concentrations. The main elements, namely Fe, K, Cr and Ca, in both PM2.5 and PM10 showed significantly higher concentrations in the summer season. A qualitative inter-elemental correlation analysis, principal component analysis (PCA) and cluster analysis (CA) were applied for source identification of PM2.5 and PM10. The results for the three procedures were in good agreement. Four and three factors of sources were isolated by the PCA for PM2.5 and PM10, respectively. The main sources identified by PCA were, for PM2.5, soil dust and biomass burning (32%), road dust and industrial emission (25%), vehicle and industrial emission (10%) and soil dust (9%); for PM10, road dust and industrial emission (36%), crustal and biomass burning (30%) and industrial sources (10%).