Characterization of atmospheric aerosols by SEM-EDX in a rural-continental environment-a seasonal approach

Abstract

The vital information on the morphology and composition of the atmospheric aerosols over any region is critical to understand their climatic and health effects. This work aims at the physicochemical characteristics of atmospheric aerosols at a rural continental site in northeastern India. We collected the aerosol samples from January to December 2018 and applied a seasonal approach to investigate the physical and elemental characteristics of aerosol particles. A Scanning Electron Microscope (SEM) has been used to examine the morphology of particles that, includes shape, size, and structure information. Energy-dispersive X-ray analysis (EDX) is used to investigate the elemental composition information. By using the SEM-EDX, we have noticed a variation in the morphology of particles and elemental composition from season to season. The different particle shapes vary from regular to irregular, including spherical, nearly spherical, triangular, capsule-like, and platy shapes have been observed. We have seen a variety of particle clusters, including chain-like structures, porous textures, soot structures, and irregular structures. A size range of particles with a diameter ranging from 100 nm to 30 µm has been observed. The presence of elements C, Si, O, B, K, Ca, P, S, Fe, Na, N, Cl, Mg, and Al has been examined in different seasons. We have noticed that road dust, crustal origin particles, and carbonaceous particles dominate the study region. We have observed a clear seasonal variation in the percentage of different elements. A small contribution by sea salt origin elements has also been noticed during the pre, monsoon, and post-monsoon seasons when winds flow from the marine region, and air mass back trajectory results support this.