Metal content in street dust as a reflection of atmospheric dust emissions from coal power plants, metal smelters, and traffic

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 open-pit 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 <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 V emissions. 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.

Impact of ferromanganese alloy plants on household dust manganese levels: Implications for childhood exposure

“…For example, the outdoor mean (11700 µg/g) and median (4620 µg/g) dust Mn concentrations from Bagnolo Mella are several-fold higher than mean (2260 µg/g) and median (1440 µg/g) street dust Mn concentrations from Witbank, South Africa, (Zibret et al, 2013) site of an active ferromanganese steel plant (Tables 1 and 3), while the highest outdoor dust Mn levels measured in Bagnolo Mella (~80,000 – 180,000 µg/g) were several fold higher than the highest level reported from Witibank (20,000 µg/g). Notably, that study also reported a significant inverse relationship between dust Mn levels and distance from the steel plant, as we observed in Bagnolo Mella.…”

Assessment of Heavy Metals Contamination in Near-Surface Dust

“…The NIPI of the seven metals for each sampling site was defined as follows [33]: (2) ...where PI imax is the maximum PI value of each heavy metal and PI iave is the average PI value of each heavy metal. The NIPI was classified as: non-pollution (NIPI≤0.7), warning line of pollution (0.7<NIPI≤1), low level of pollution (1<NIPI≤2), moderate level of pollution (2<NIPI≤3), and high level of pollution (NIPI>3) [33].…”

“…Several categories of contaminates, such as heavy metals [1,2] and polycyclic aromatic hydrocarbons (PAHs) [3], etc., are continuously emitted into the terrestrial environment, thus posing a great threat to human health [3][4][5]. Nowadays, more and more people dwell in urban areas.…”

“…Meanwhile, compared with urban soils, urban dusts, as a special type of environmental medium, have been reported in many countries to contain toxic organic and inorganic pollutants, especially high levels of trace metals [1][2][3][4][6][7][8][9][10][11]. These metals can remain in urban environments for a long time or be re-suspended into the atmosphere and thus pose a potential threat to local ecosystems and public health.…”

Pediatric anxiety and/or depression problems : associations with PM10, fly ash, and metal exposure.

“…Coal combustion generates a byproduct, commonly known as coal ash, which consists of small particles that contain polycyclic aromatic hydrocarbons; naturally occurring radioactive materials; and a variety of heavy metals including aluminum, arsenic, iron, lead, mercury, and copper (7)(8)(9)(10)(11)(12)(13). In 2014, the United States alone produced 130 million short tons of coal ash -a marked increase from the previous two years (14).…”