Metal content in street dust as a reflection of atmospheric dust emissions from coal power plants, metal smelters, and t
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RESEARCH ARTICLE
Metal content in street dust as a reflection of atmospheric dust emissions from coal power plants, metal smelters, and traffic Gorazd Žibret & Danel Van Tonder & Lea Žibret
Received: 10 August 2012 / Accepted: 2 December 2012 / Published online: 18 December 2012 # Springer-Verlag Berlin Heidelberg 2012
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 dust was 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 16 km) from the main pollution sources in each direction. The length of both profile lines is around 80 km with 35 samples collected (18 samples along the E-W direction and 17 samples along the N-S direction). Additional samples were taken in the vicinity of major industrial facilities and in densely populated areas of Witbank. The total number of street dust samples was 46. Figure 1 shows the sampling plan, as well as the locations of major atmospheric dust pollution sources. Sampling begun with the careful selection of microlocations to avoid sampling of sand particles, plant remains (leaves, pollen, seeds or similar), or soil and rock material (soil, mud, debris falling from trucks, dirt from wheels, etc.). Larger parking areas, playgrounds, larger road intersections, bridges, or other similar infrastructure were found to be the most suitable surfaces for sampling. After the selection of sampling surface, unwanted coarse-grained material (sand, asphalt remains, etc.) was cleared away with a soft plastic brush after which, electrostatically connected dust particles inside holes and pores in the asphalt or concrete were collected with a hard plastic brush. Fine-grained material was collected and sealed in a plastic bag. Approximately 200 to 500 g of composite sample material was collected from at least 15 different sampling surfaces at each sampling point. Samples were dried at 303 K for XXX minutes/hours and sieved through a 0.125-mm mesh to obtain the fine-grained fraction. A subsample of 5 g of the 30 % of samples) below the detection limit, were discarded from further
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Environ Sci Pollut Res (2013) 20:4455–4468
Table 2 Comparison of maximum content of selected metals in street dust found in world literature with maximum 75th percentile value (P75) in Witbank area, and with South A
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