tyle="MARGIN: 0cm 0cm 0pt" class=MsoNormal>The platinum-group elements (PGEs) (mostly, tyle="mso-spacerun: yes"> Pt, tyle="mso-spacerun: yes"> Pd and Rh) have been used as automobile catalytic converters in automobile industry, tyle="mso-spacerun: yes"> the emission of PGEs has led to the concentration of PGE in road dusts and roadside soils in urban areas that are well above natural background levels. Reported in this paper is the evaluation of contamination of all the PGEs and Au recorded in road dusts and roadside soils from the four major cities: t1 ns = "urn:schemas-microsoft-com:office:smarttags" />t1:City w:st="on">Beijingt1:City>, Shenzhen, t1:City w:st="on">Guangzhout1:City> and t1:City w:st="on">Guiyangt1:City> in t1:place w:st="on">t1:country-region w:st="on">Chinat1:country-region>t1:place>. tyle="mso-spacerun: yes"> The results show that there are clearly positive correlations between Pt and Pd, Pt and Rh and Pd and Rh for all the samples, indicating that the compositions of automobile catalyst are Pt, Pd and Rh. The concentrations of Ir, Ru and Os in all the samples are higher than the background values of uncontaminated soil. Dust samples with higher Os contents have lower 187Os/188Os ratios, suggesting that Ir, Ru and Os come also from automobile catalytic converters, and may be present as impurities of the automobile catalysts. t;urn:schemas-microsoft-com:office:office" />
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