Understanding sources and processes using chemistry of fine and coarse particles simultaneously collected from different windward locations in N-NW India

Abstract

PM2.5and PM2.5-10 particles, simultaneously collected from Bikaner (BKR) and New Delhi (DEL) through Jhunjhunu (JHJ) located along S-SW wind pathduring summer in N-NW India were chemically characterized to understand their sourcesand related processes.Winds preferentially picked and trasnported PM2.5 compared to PM2.5-10 in windward direction. Ratios of mass concentrations and WSII in PM2.5 and PM2.5-10 were three or more at all sites. Thermal power plants, vehicles, and plastic burning were major contributors of SO42-, NO3- and Cl- ionsat DEL. Crustal materials, salt lakes/playas and contaminated aged particles were sources of WSIIs in PM2.5 over BKR and JHJ. In PM2.5, burning of wood and cow dung resulted in high OC/EC ratio (6.9) at BKR whereas EC emissions from vehicles lowered this ratio (3.5) at DEL. EC was dominated by char-EC compared to soot-EC. Major elements showed similar concentrations in both size particles but were depleted compared to Upper Continental Crustal (UCC) due to silica dilution effect. Ba and Sr, and Ba, Cr, Sr and Zn content showed site specific variations in PM2.5 and PM2.5-10, respectively. Trace elements in PM2.5 showed high enrichment compared to UCC at DEL due to re-suspension of roadside dust and vehicle related emissions.