Size fractionated speciation of nitrate and sulfate aerosols in a sub-tropical industrial environment

Size fractionated chemical speciation of acidic aerosols were performed for ammonium sulfate, other sulfates, ammonium nitrate and other nitrates in a sub-tropical industrial area, Bina, India during December 2003 to November 2004. Analysis of variance (ANOVA) revealed highly significant temporal variations (p > .001) in the concentrations of nitrate and sulfate aerosols in all the three size fractions (fine, mid-size and coarse). Winter demonstrated utmost concentrations of ammonium sulfate, which ranged from 3.2 to 26.4 μg m−3 in fine particles and 0.20–0.34 μg m−3 in coarse particles. Ammonium sulfate was chiefly in fine mode (43.77% of total particulate sulfate) as compared to coarse particles (28.60% of total particulate sulfate). The major fraction Ammonium sulfate existed in different forms in atmospheric aerosols, for example NH4Fe(SO4)2, (NH4)2SO4, (NH4)3H(SO4)2 in fine particles, and image in coarse particles. Other sulfate concentrations were also higher during winter ranging from 1.89 to 14.3 μg m−3 in fine particles and 0.12–0.65 μg m−3 in coarse particles. Ammonium nitrate constituted the major fraction of total particulate nitrate all through the year and was principally in fine particles (the highest concentration in January i.e. 14.2 μg m−3). Other nitrates were mainly distributed in the fine particles (highest concentration in January i.e. 11.2 μg m−3) All the sulfate and nitrate species were mainly distributed in fine mode and have significant impact on human health.