Elemental composition and sources of atmospheric particulate matter in Dar es salaam, Tanzania
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Date
2010
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Publisher
Ethiopian Journal of Environmental Studies and Management
Abstract
An intensive aerosol field campaign was carried out from 16 August to 16 September 2005 (dry season) at a
kerbside in Dar es Salaam, Tanzania. A Gent PM 10 stacked filter unit sampler with coarse and fine Nuclepore
polycarbonate filters, providing fine (0.4 μm) and coarse (8 μm) size fractions, was deployed. A total of 64
parallel collections were made. All samples were analysed for the PM mass by weighing. A further analysis was
performed for 25 elements by particle-induced x-ray emission spectrometry. The PM 10 mass, as derived from the
3
stacked filter unit samples, was, on average, 58 μg/m . The concentrations of the heavy metals were lower than
those for the elements of crustal origin. Nevertheless, some typical anthropogenic metals, such as Zn and Pb,
exhibited much higher median PM 10 levels, suggesting strong local sources for these elements in Dar es Salaam.
The results also showed very strong day/night differences for the crustal elements (Al, Si, Ca, Ti and Fe). Most
elements exhibit strong correlations in the coarse size fraction and somewhat weaker ones in the fine size
fraction suggesting that they may originate predominantly from the same source. Principal component analysis
with VARIMAX rotation was applied to the data set. Five and four components were identified for the fine and
coarse fractions and explained 86.5% and 90.8% of the variance in the data set respectively.
Description
Journal Article
Keywords
PIXE, Atmospheric Aerosols, Elements, Size Fractions, PCA, Kerbside