Characterization and Morphological Analysis of Summer and Wintertime PM 2 . 5 Aerosols Over Urban-Rural Locations in Delhi-NCR

Present study investigates the urban-rural variation of aerosols morphological and chemical characteristics. Summer and winter time 24 hourly sampling for PM2.5 was carried out at an urban and rural location in Delhi and National Capital Region (NCR) using a Mini-Volume Air Sampler. High PM2.5 concentrations were observed at the urban site (87.3μg/m, 155.56μg/m) compared to those at the rural (39.46μg/m, 91.62μg/m) in summer and winter seasons respectively. Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX) were used to characterise the PM2.5 aerosols in the urban and rural area in the two seasons. SEM images shows different particle shapes at the urban and rural site in summer and winter seasons. SEM results showed the presence of flaky, aggregates and irregular shaped particles dominated in the urban area in summer season whereas rural area was relatively cleaner. In the winter season, rural site was observed to be dominated by spherical and irregular shaped particles indicating the combustion sources whereas particles were observed in a more concentrated form at the urban site. EDX analysis indicates the varying percentages of C, Cu, Zn, Co, Ni, Fe (representative elements) at both the rural and urban sites in both the seasons. Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) three day backward air mass trajectories Characterization and Morphological Analysis of Summer and Wintertime... 1010 indicated the influence of Western and N-W air masses over Delhi-NCR for both the summer and winter seasons respectively. Further, this study reveals the variability of PM2.5 particles morphological and elemental composition in different seasons at urban and rural locations and highlighted the different probable sources associated with them.