ZHAO Zheng1,2, QI Liang2*, HUANG Xiao-wen2,3, LIU Ying-ying2,3, WAN Yi-chang2,3
(1. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;
2. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;
3. Graduate University of the Chinese Academy of Sciences, Beijing 100049, China)
Abstract: The platinum-group elements (PGEs) (mostly, Pt, Pd and Rh) have been used as automobile catalytic converters in automobile industry to transform greenhouse gases, such as carbon monoxide, nitrogen oxides (NOx) and hydrocarbons to carbon dioxide, nitrogen, and water since 1990. Although automobile catalytic converters can reduce the exhaust of greenhouse gases, 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: Beijing, Shenzhen, Guangzhou and Guiyang in China. Samples were digested with a carius tube and analyzed by isotope dilution ICP-MS, Os was separated by distillation and the other PGEs by Te-coprecipitation. PGE concentrations of all the samples have been elevated above the background values of uncontaminated soil, and higher Pt, Pd and Rh contents than the other PGEs. 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.
Key words: automobile catalyst; PGEs; road dust; roadside soil
EARTH AND ENVIRONMENT Vol. 39, No.1, Tot No.283, 2011, Page 9-18
