PM10 and PM2.5 chemical source profiles of road dust over China: Composition, spatio-temporal distribution, and source apportionment

The composition, spatio-temporal distribution, and source identification of PM2.5 and PM10 road dust in cities across China were studied. The dominant composition was based on OC, Si, EC, Ca2+, SO42−, K, Al, Mg, Ca, and Fe with a decreasing sequence of elements > total carbon > ions. The correlation coefficient between PM2.5 and PM10 was 0.95 and the coefficient of divergence (COD) was 0.19, indicating that the profiles of the two-particle sizes were similar. The non-parametric test determined that there was no statistically significant difference in the source profiles of road dust in terms of interannual variations. Considerable discrepancies (the COD values all >0.20) demonstrated that the dust profiles in different seasons were different, while they were similar for different road types. Cluster analysis (CA) was conducted to examine the differences between the chemical profiles among the study cities. The chemical composition of road dust PM2.5 and PM10 could be placed into five and six clusters, respectively, with the COD proving an absence of similarity among the different clusters. Principal component analysis (PCA) revealed that there were five principal factors affecting the accumulation of road dust: dust source, vehicular traffic, coal burning, industrial activities, and secondary particle formation.