Characterization of PM2.5 by X-ray diffraction and scanning electron microscopy–energy dispersive spectrometer: its relation with different pollution sources

Atmospheric PM_2.5 samples were collected by using Mini-Vol TAS air sampler. Samples were characterized directly on the collecting substrate using X-ray diffraction and scanning electron microscopy–energy dispersive spectrometer. From the analysis, it was found that Si dominate over other elements which follows the trend as Si>S>Zn>Cu>Na>Al>K>Ca>P>Fe>Mg >Ti. Based on the measurements of a population of 840 particles, particle morphology was determined by quantitative image analyzer and value of roundness (R) varies from 0.23 to 1.0 (mean 0.75) which suggests that particles vary in shape from nearly irregular to perfectly spherical shape. The mineral particulate matter identified in the atmosphere of Pune was made up of: silicates (52 %), oxides (22 %), sulfates (8 %), phosphates (7 %), carbonates (3 %) and others. A factorial analysis was carried out to determine the main elements related to the emission sources such as soil and building material erosion (∼44.6 %); oil combustion (20.6 %) and fuel and biomass burning (18.3 %). Besides these factors, soot particles are abundantly present in all studied samples. Mineral particles such as sulfates aggregated to soot could have produced localized climatic effect in Pune. The emphasis of the present study is to give insight and detailed analysis of morphological and chemical composition of atmospheric particles at discrete level.