Ion chemistry and source identification of coarse and fine aerosols in an urban area of eastern central India

This work focuses on size segregated atmospheric aerosol mass concentrations and water soluble inorganic components in Chhattisgarh, the eastern central India. Investigation on the monitoring of ambient air levels of atmospheric particulates were done around a large source of primary anthropogenic particulate emissions: the industrial area and coal based power plants. Chemical characterization was carried out for aerosol samples collected in urban area, Raipur, (21°14′N, 81°38′E) of Chhattisgarh region over a period of one year, using cascade impactor. Annual mean of mass concentration for coarse (PM2.5–10) and fine (PM2.5) aerosols were monitored to be 238.1 ± 89.9 and 167.0 ± 75.3 µg m− 3 respectively This work deals with the seasonal variation and meteorological influences of inorganic components of the aerosols viz. NO3−, Cl− and SO42−, Mg2+, Na+, K+, Ca2+ and NH4+. The annual mean concentration of the inorganic components were monitored to be 3.8 ± 2.5, 8.9 ± 2.7, 10.2 ± 1.5, 2.6 ± 0.6, 8.7 ± 7.2, 4.6 ± 1.8, 16.4 ± 6.9 and 0.4 ± 0.5 µg m− 3 respectively in coarse particles and 8.2 ± 7.1, 6.8 ± 3.6, 46.5 ± 32.8, 1.7 ± 0.6, 7.4 ± 3.6, 5.9 ± 3.4, 10.2 ± 2.9, and 8.8 ± 7.7 µg m− 3 respectively in fine particles, for the above ions. The average distribution of nitrate and sulphate in PM2.5–10 were found to be 1.6 and 4.2% and in PM2.5 were 4.9 and 27.9% respectively indicating the dominance of sulphate in both PM2.5–10 and PM2.5 particles. Here, industrial emission plays important role for contribution of PM2.5 particle loading in the atmosphere. The cation–anion rational analysis indicated that the PM2.5–10 particles were mostly neutralized and PM2.5 particle were acidic. The major ions were mainly in the form of NaCl > CaSO4 > K2SO4 > MgSO4 > KCl > NH4Cl > Ca(NO3)2 > KNO3 > MgCl2 > Mg(NO3)2 > NH4NO3 > (NH4)2SO4 in coarse aerosol particles and (NH4)2SO4 > K2SO4 > CaSO4 > NaCl > NH4NO3 > CaCl2 > KNO3 > MgCl2 > Ca(NO3)2 > KCl > NH4Cl in fine particles.