dc.description.abstract | Resuspended street dust is a source of inhalable
particles in urban environments. Despite contaminated street
dust being a possible health risk factor for local population,
little is known about the contribution of atmospheric dust
emissions and other factors to the content of toxic metals in
street dust. The impact of smelting, traffic, and power plants on
metal contaminates in street dust is the focus of street dust
sampling at 46 locations in the Witbank area (Republic of
South Africa). This area is characterized by numerous openpit
coal mines in the Karoo coal basin, which provides a cheap
source of energy to numerous metallurgical smelters and ironworks
and supplies coal to the coal-fired power plants located
nearby. Street dustwas collected on asphalt or concrete surfaces
with hard plastic brushes, avoiding collecting of possible sand,
soil, or plant particles. Chemical analysis was done on the
<0.125 mm fraction using inductively coupled plasma mass
spectrometry subsequent to total digestion. Exceptionally high
concentrations of metals were detected with concentrations of
Fe reaching 17.7 %, Cr 4.3 %, Mn 2 %, Ni 366 mg/kg, and V
4,410 mg/kg. Factor analysis indicates three sources for the
pollution. Road traffic which contributes to the high concentrations
of Cu, Pb, Sb, and Sn, with the highest impacts
detected in the town of Witbank. The second source is associated
with the metal smelting industry, contributing to Fe, Co,
Mn, and Vemissions. The highest factor scores were observed
around four metallurgical smelter operations, located in the
Ferrobank, Highveld, and Clewer industrial areas. Impact of
vanadium smelter to street dust composition could still be
detected some 20 km away from the sources. Exceptionally
high concentrations of Cr were observed in four samples collected
next to the Ferrobank industrial area, despite Cr not
being loaded in factor 2. The last source of the pollution is
most probably fly ash associated with the coal-fired power
plants and fly ash dumps. Elements which are associated with
this source are Al, Sr, and Li. This factor is abundant in the coal
mining part of the study area. | en_US |