Size and time-resolved roadside enrichment of atmospheric particulate pollutants

Abstract

Abstract. Size and time-resolved roadside enrichments of atmospheric particulate pollutants in PM 10 were detected and quantified in a Mediterranean urban environment (Barcelona, Spain). Simultaneous data from one urban background (UB), one traffic (T) and one heavy traffic (HT) location were analysed, and roadside PM 10 enrichments (RE) in a number of elements arising from vehicular emissions were calculated. Tracers of primary traffic emissions (EC, Fe, Ba, Cu, Sb, Cr, Sn) showed the largest REs (>70%). Other traffic tracers (Zr, Cd) showed lower but still consistent REs (25-40%), similar to those obtained for mineral matter resulting from road dust resuspension (Ca, La, Ce, Ti, Ga, Sr, 30-40%). The sum of primary and secondary organic carbon showed a RE of 41%, with contributions of secondary OC (SOC) to total OC ranging from 46% at the HT site, 63% at the T site, and 78% in the UB. Finally, other trace elements (As, Co, Bi) showed unexpected but consistent roadside enrichments (23% up to 69%), suggesting a link to traffic emissions even though the emission process is unclear.Hourly-resolved PM speciation data proved to be a highly resourceful tool to determine the source origin of atmospheric pollutants in urban environments. At the HT site, up to 62% of fine Mn was attributable to industrial plumes, whereas coarse Mn levels were mainly attributed to traffic. Similarly, even though Zn showed on average no roadside enrichment and thus was classified as industrial, the hourlyresolved data proved that at least 15% of coarse Zn may be attributed to road traffic emissions. In addition, our results indicate that secondary nitrate formation occurs within the Correspondence to: F. Amato (fulvio.amato@idaea.csic.es) city-scale, even in the absence of long atmospheric residence times or long-range atmospheric transport processes. Characteristic tracer ratios of road traffic emissions were identified: Cu/Sb = 6.8-8.0, Cu/Sn = 4.7-5.4 and Sn/Sb = 1.5.

Variations in time and space of trace metal aerosol concentrations in urban areas and their surroundings

“…Such events usually occurred at only one or the other of the monitoring sites at a given time, although in the case of Zn or Pb, transient peaks of these metals during the winter campaign were occasionally registered simultaneously at both 12 h filters in BCN and MSY. These transient peaks being so short in time (hours) seem to be related to specific sources, thus V-Ni and Zn-Pb are proven tracers of fuel oil combustion and industrial emissions respectively (Amato et al, 2011), whereas in the case of Mn-Cu this association is not typical of a single source and it is probably more related to mixtures of traffic and industrial emissions. These metal associations are in agreement with the PCA results (Table 4) for the finer PM fractions in both sites and also with the PMF results from studies on previous BCN continuous measurements (Pérez, 2010) identifying trace metals in mineral matter (Li, Ti, Rb, Sr, La, Ce), road traffic (Cu, Cr, Sn, Sb), industrial emissions (Pb, Zn, Cd, As, Mn) and fuel oil combustion (V, Ni) factors.…”

“…6f). Their presence in the ambient urban atmosphere is attributed partly to resuspension processes such as traffic movement but especially to ubiquitous construction activity that was taking place during the campaign (Amato et al, 2011;Reche et al, 2011). Pearson correlation coefficients among trace metals, for each of the considered PM fractions hourly measured at BCN, show values >0.7 in PM 2.5−10 and PM 1−2.5 fractions for mineral (Ti, Rb, Sr), industrial (Cr, Mn, Ni) and road dust components (Cu, Sn, Sb, Co), whereas in the PM 0.1−1 samples the coefficient is only that high for elements related to anthropogenic sources such as V-Ni, Cr-Sn, Mn-Zn-Pb, Cu-Sb.…”

Characterization of Fine Particulate Matter Emitted from the Resuspension of Road and Pavement Dust in the Metropolitan Area of São Paulo, Brazil

“…The objective is to distinguish, within the PM 2.5 fraction, between the metals and black carbon that originate from the exhaust process and those that originate from the resuspension of dust from paved roads. The same approach was applied by [16], who presented an analysis of the enrichment factors of atmospheric particulate pollutants at the roadside, calculating the contribution that each different source made to the total particle concentration.…”

Particulate Matter from the Road Surface Abrasion as a Problem of Non-Exhaust Emission Control

“…The ambient concentration of PM-bound elements in the areas affected by road-traffic emissions also depends on the traffic intensity, the vehicle-fleet characteristics car type and speed, the type of road surface, the road-cleaning intensity, and the concentration of PM components in the so-called urban background [70][71][72][73]. Given that, it is easy to imagine the difficulty in quantitatively dividing PM-bound elements, located in urban sites that are influenced by traffic emissions, into specific source groups.…”