Source characterisation of road dust based on chemical and mineralogical composition

Abstract

Road dust contain potentially toxic pollutants originating from a range of anthropogenic sources common to urban land uses and soil inputs from surrounding areas. The research study analysed the mineralogy and morphology of dust samples from road surfaces from different land uses and background soil samples to characterise the relative source contributions to road dust. The road dust consist primarily of soil derived minerals (60%) with quartz averaging 40-50% and remainder being clay forming minerals of albite, microcline, chlorite and muscovite originating from surrounding soils. About 2% was organic matter primarily originating from plant matter. Potentially toxic pollutants represented about 30% of the build-up. These pollutants consist of brake and tire wear, combustion emissions and fly ash from asphalt. Heavy metals such as Zn, Cu, Pb, Ni, Cr and Cd primarily originate from vehicular traffic while Fe, Al and Mn primarily originate from surrounding soils. The research study confirmed the significant contribution of vehicular traffic to dust deposited on urban road surfaces.

The sources, impact and management of car park runoff pollution: A review

“…There is no obvious explanation for these large variations although it is accepted that differing metal concentrations will occur in these environments due to factors such as traffic density, weather conditions and neighbouring land-use activities. However, the metal concentrations reported by Gunawardana et al (2012) do appear to be more consistent with other comparable studies (e.g. Wei and Yang, 2012) and with the levels to be expected given the identified metal contents of the source contributions.…”

“…In a separate review, Sorme (2003) The concentrations of a range of metals reported in road dusts from a supermarket car park and from urban areas with similar characteristics to car parks are presented in Table 2. The studies were conducted in the same geographical region but represent diverse ranges of metal concentrations deriving from similar land-use types with the results reported by Herngren et al (2006) being two to three orders of magnitude lower than those of Gunawardana et al (2012). There is no obvious explanation for these large variations although it is accepted that differing metal concentrations will occur in these environments due to factors such as traffic density, weather conditions and neighbouring land-use activities.…”

“…For example, a residential area with a surface texture depth of 0.76-0.92 mm produced an average solids loading of 0.81-1.79 g m -2 which increased to 1.75-2.22 g m -2 for a commercial area with a surface texture depth of 0.63-1.11 mm (Gunawardana et al, 2012). These values are considerably lower than the model predictions for TS obtained by Chen and Adams (2006) (Table S1) which are more compatible with the surface loading values reported by Carraz et al (2006) for urban roads (7.3 to 740 g m -2 ) and by Vaze and Chiew (2002) for a series of car parking bays (5-70 g m -2 ).…”

“…lighting, barriers and signage), general litter, accidental spills and erosion of soils from surrounding areas via both direct and indirect deposition routes. Traffic has been identified as an important contributor of particulate materials in urban areas with specific sources including the wear and tear of car bodies and engines, abrasion of brakes and tyres, exhaust emissions, friction-assisted break-up of paving and road materials and de-icing/anti-skid materials (Gunawardana et al, 2012;Herngren et al, 2006;Sorme, 2003;Thorpe and Harrison, 2008;Westerlund, 2005). Thorpe and Harrison (2008) distinguished between particulate matter emitted from exhaust emissions and that derived from non-exhaust emissions and concluded that they contributed similar loads to local traffic related emissions.…”

Chemical and Mineralogy Characteristics of Dust Collected Near the Phosphate Mining Basin of Gafsa (South-Western of Tunisia)

“…The ranges obtained are comparable though lower those presented by Chandima Gunawardana et al which range from 1.40 to 5.88 ppm [23]. Cr and Mn exhibit levels varying from 71 to 277 ppm and from 30 to 177 ppm respectively.…”