Characterization and morphological analysis of airborne PM2.5 and PM10 in Agra located in north central India

PM2.5 and PM10 samples were collected from road and semirural sites of Agra, the north central part of India. The average mass concentration of PM10 was 278.67 +/- 106.58 mu g/m(3) and of PM2.5 was 90.16 +/- 7.21 mu g/m(3) at roadside while at semirural site it was 234.54 +/- 128.27 mu g/m(3) for PM10 and 89.12 +/- 37.94 mu g/m(3) for PM2.5. Scanning electron microscopy coupled with energy dispersive spectrometer (SEM-EDS) was used to understand the difference in terms of shapes, morphology, and elemental composition of aerosols in PM10 and PM2.5 and to further link them to the potential source as well as emission and transport of pollutants from different polluted areas. The SEM micrograph of PM10 was different from PM2.5 size range particles at both sites. EDS spectra indicates the three main groups of particles i.e.. C, O rich particles, Si, Na and Al rich particles and Mg, Ca, Fe, K, S, Co rich particles on the basis of their percentage contribution in PM10 and PM2.5, PM2.5 constituted C, O (95.93%), Si, Al, Na (2.63%), S, Fe, K, (1.41%) and PM10 constituted O, C (72.16%), Si, Al, Na (24.58%), S. K. Fe, Co (3.24%) respectively at roadside whereas at semirural site. PM2.5 and PM10 constituted O, C (92.8%), Si, Al, Na (4.86%), Mg, K, Ca, Fe (2.32%), and O, C, (72.14%), Si, Na, Al (23.11%) and Mg, K, Ca, Fe (4.73%) respectively. Crustal elements such as Si, Na and Al rich particles are dominant excluding C and Din PM10 and PM2.5 at roadside as well as semirural site. Correlation between element and particulate matter indicates two groups in which one group is highly significant (r > 0.90) and another group shows positive correlation (r > 0.53 to 0.90). Soot, tarballs, carbonaceous and mineral type particles were observed at roadside while aluminosilicates, quartz, fly ash and soil dust particles were observed at semirural site in PM2.5 and PM10 respectively. It was concluded that SEM-EDS is a convenient method to identify the source of emission of particulate air pollution. (C) 2011 Elsevier Ltd. All rights reserved.