出版社：Chinese Association for Aerosol Research in Taiwan
摘要：Water-soluble inorganic ions (WSII), organic carbon (OC) and elemental carbon (EC), and metals in the residue of the water-soluble fraction were studied in fine (PM2.5) and coarse (PM2.5-10) particles during winter over two urban cities, Amritsar (AMS) and New Delhi (DEL), in northern India. The PM2.5/PM2.5-10 mass ratios at DEL and AMS were 3.6 and 2.79, respectively. ∑WSIIs was nearly 25% of the total mass in two size fractions and was higher in PM2.5 than PM2.5-10 at both sites. The secondary ions SO42− and NH4+ were dominant at both sites. The adsorption of fine particles onto larger ones may be a possible source of soluble ions in PM2.5-10. SO42− and NO3− were neutralized by NH4+, and the formation of (NH4)2SO4 dominated over NH4NO3 in PM2.5, and by Ca2+ in PM2.5-10 over DEL. Coal burning, and agricultural and livestock emissions were potential sources of precursor gases of SO42− and NH4+. Plastic burning and the brick kiln industry contributed Cl− in the PM2.5. OC dominated over EC above both sites, and the total carbon (OC + EC) was higher over AMS than DEL. Emissions from low-temperature rather than high temperature combustion processes were dominant, as indicated by the higher quantity of char-EC than soot-EC. OC, EC, and K+ resulted from biomass burning over AMS, whereas they originated in multiple sources over DEL. The Al normalized ratios of elements in the samples compared to the crust were higher in PM2.5 than PM2.5-10. Fe, Ti, and Mn ratios of < 1 were attributed to the silica dilution effect. The Pb, Cu, and Zn ratios in PM2.5 were 63, 18, and 13 over DEL and 2, 11, and 31 over AMS, respectively. Ba and Zn were contributed by vehicular emissions. A coefficient of divergence of > 0.5 indicated the spatial heterogeneity in the particle chemistry between the two sites. To improve the air quality and safeguard human health, biomass burning and the re-suspension of dust must be restricted.
