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

Abstract

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 NH 4Fe(SO 4) 2, (NH 4) 2SO 4, (NH 4) 3H(SO 4) 2 in fine particles, and ( NH 4 ) 4 ( NO 3 ) SO 4 + 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.