Contamination levels and source apportionment of potentially toxic elements in size-fractionated road dust of Moscow.

The distributions of potentially toxic elements (PTEs) among PM, PM, PM, and PM fractions of the road dust were studied in the western and eastern parts of Moscow, impacted mainly by the road transport and the industrial sector, respectively. The partitioning of PTEs in road dust can provide more precise information on pollution sources and its further interpretation regarding human health risks. The concentrations of PTEs were analyzed by mass and atomic emission inductively coupled plasma spectrometry. Differences in the results between the western and eastern parts of the city were caused by the dissimilarity between traffic and industrial emissions. The source apportionment of the PTEs was carried out using absolute principal component analysis with multiple linear regressions (PCA/APCS-MLR). The contribution from anthropogenic sources was significant to PM and PM particles. In coarser fractions (PM, PM), it decreased due to the input with the wind-induced resuspension of soil and rock particles. In the eastern part of the city, the accumulation of PTEs (especially Mo, Sb, Cd, Sn, Bi, Co, and As) is the most active in PM, while in the western part, it is most pronounced in PM (especially Pb, Cu, Cr, and W) which is associated with differences in the size of particles coming from traffic and industrial sources. In the eastern part of Moscow, in comparison with the western part, the contribution from industrial sources to the accumulation of PTEs in all particle size fractions was higher by 10-30%. In the western part of Moscow, the finest particles PM and PM demonstrate the trend of rising pollution levels with the increase in road size, while in the eastern part of the city, only coarse particles PM show the same trend. In the fractions PM and PM of road dust, a significant contribution was made by anthropogenic sources; however, its role decreased in the coarse fractions-PM and especially in PM- due to the influence of roadside soils and their parent material.