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A study of water-soluble inorganic ions in size-segregated aerosols in atmospheric pollution episode
Leiva G., M. A.; Toro, R.; Morales, R. G. E.; R´os, M. A. & Gonz´lez, M. R.
Abstract
Particulate matter, the main pollutant in the
atmospheric environment of the Santiago city in winter,
was analyzed by means of the major water-soluble ionic
species obtained under critical episodes of pollution in
2003. The particulate matter samples were collected using
the Micro-Orifice uniform deposit impactors, with eight
impactor stages connected in series, and the ionic species
in particulate matter samples at each stage was analyzed by
ion chromatography. While sulfate ion and nitrate ion
showed bi-modal distributions, peaking in the fine and
coarse mode, ammonium ion displayed a bi-modal size
distribution, peaking in the fine and ultra fine mode. The
equivalent concentration ratio of ammonium to sulfate was
2.03 ± 0.09, indicating the complete neutralization of
sulfuric acid by ammonia. The excess ammonium ion was
associated to nitrate ion. The study of the size distribution
of water-soluble inorganic ions in particulate matter supports
the notion that secondary aerosols play a significant
role in the urban atmosphere.
Keywords
Ammonium; Nitrate; Particle-size distribution; Seconday particles; Sulfate
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