Seasonal variation of atmospheric composition of water-soluble inorganic species at rural Background site in Tanzania, East africa
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Date
2010
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Ethiopian Journal of Environmental Studies and Management
Abstract
Samples of coarse, fine and PM10 aerosols were collected at a rural Morogoro sites, during the 2005 dry season
and 2006 wet season campaigns using a “Gent” PM10 stacked filter unit sampler with sequential Nuclepore
polycarbonate filters. A total of 80 aerosol samples were analyzed for water-soluble inorganic ions components
2-
+
-
-
using Ion Chromatography. The mean concentration for the anions Cl , NO 3 , and SO 4 and the cations Na ,
+
+
2+
2+
NH 4 , K , Mg , Ca , showed seasonal variation in all size fractions with higher levels during the 2005 dry season
campaign than the 2006 wet season campaign. The mean concentrations and associated standard deviation of
3
fine, coarse and PM10 mass were, 17±4, 52±27 and 69±29 μg/m during the 2005 dry season campaign and
3
2+
13±5, 34±23 and 47±25 μg/m for the 2006 wet season campaign, respectively. Ca was the most important
+
2-
cation and the SO 4 was the main acidifying anionic component in PM10 while NH 4 was the most abundant
-
cation in the fine fraction and Cl the main anionic species in the coarse fraction. The ion balance ratios were all
larger than 1.0; they range from 1.30 to 1.44 for the fine fraction and from 2.01 to 3.14 for the coarse fraction.
The carbonates were not measured by Ion Chromatography therefore; these missing carbonates are thought to
be largely responsible for the observed deviation from 1.0. The study suggests that primary sources such as soil
dust dispersion and biomass burning made a significant contribution to the atmospheric particulate pollution in
Morogoro.
Description
Journal Article
Keywords
Ion chromatography, Aerosol Characterization, Coarse, fine and PM10 fractions, Meteorology