Trace elemental composition and source identification of PM2.5 in the metropolitan area of Bangkok, Thailand

The trace elements in PM2.5 samples collected in Pathum Thani province, the metropolitan area of Bangkok were determined and their possible sources were analyzed. PM2.5 samples were monitored from January to December in 2022. The mass concentration of PM2.5 ranged from 4.33 to 66.02 μg/m3 with and an average (± std.) value of 24.64 ± 13.97 μg/m3. The concentrations of trace elements (Na, Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Zn, Ni and Cu) were measured using accelerated based ion beam analysis (IBA) methods, particle-induced X-ray emission (PIXE). Elements such as K, Ca, Fe, S, Si and Cr were found to be the dominant elements in PM2.5 across all seasons. The Pearson correlation coefficients between Fe-Cr, Ni-Cr, Fe-Ni, Mn-Cr, Fe-Mn and Ni-Mn were all above 0.893 with p < 0.01. The enrichment factor indicated that S, Cl, V, Cr, Mn, Fe, Zn, Ni and Cu came mainly from anthropogenic emissions; Ca, Ti and Fe were generated from natural and anthropogenic sources; Na, Mg, Al and Si originated from natural sources. These findings suggested that biomass burning, industrial and soil dust emissions were the major sources of PM2.5 in the study area.