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Platinum group elements in airborne particles in Mexico City

Sebastien Rauch (Institutionen för bygg- och miljöteknik, Vatten Miljö Teknik) ; Bernhard Peucker-Ehrenbrink ; Luisa T. Molina ; Mario J. Molina ; Rafael Ramos ; Harold F. Hemond
Environmental Science & Technology Vol. 40 (2006), 24, p. 7554 -7560.
[Artikel, refereegranskad vetenskaplig]

Automobile exhaust catalysts using platinum group elements (PGE) have been mandatory on new cars in the Mexico City Metropolitan Area (MCMA) since 1991. Platinum, Pd, Rh, Ir, and Os concentrations and the isotopic composition of Os were determined in PM10 samples from the MCMA. Samples were prepared by isotope dilution NiS fire assay, and analysis was performed by magnetic sector ICP-MS using a single collector instrument for Pt, Pd, Rh, and Ir analysis and a multicollector instrument for Os analysis. Pt, Pd, and Rh concentrations at a downtown location (Merced) increased from 1.7 pg of Pt m-3, 2.7 (4.0) pg of Pd m-3, and 1.2 ± 0.9 pg of Rh m-3 in 1991 to 9.6 ± 1.8 pg of Pt m-3, 10.2 ± 1.8 pg of Pd m-3, and 2.8 ± 0.6 pg of Rh m-3 in 2003. Concentrations at five sites in MCMA in 2003 averaged 9.3 ± 1.9 pg of Pt m-3, 11 ± 4 pg of Pd m-3, and 3.2 ± 1.0 pg of Rh m-3. In contrast, Ir and Os concentrations and Os isotopic composition remained relatively constant and were 0.08 ± 0.04 pg of Ir m-3, 0.030 ± 0.007 pg of Os m-3, and 0.60 ± 0.04, respectively, in the MCMA in 2003. Elevated Pt, Pd, and Rh concentrations in the MCMA are attributed to automobile catalysts. A Pt-Pd-Rh concentration peak in 1993 suggests that early catalysts emitted a larger amount of PGE, possibly due to factors inherent in the technology or the use of inappropriate gasoline. Therefore, this study suggests that the current introduction of automobile catalysts in developing countries may result in elevated PGE concentrations if it is not accompanied by infrastructures and policy measures supporting their efficient use.

Nyckelord: Platinum group elements, urban atmosphere, Mexico City



Denna post skapades 2006-12-13. Senast ändrad 2017-06-28.
CPL Pubid: 24326

 

Institutioner (Chalmers)

Institutionen för bygg- och miljöteknik, Vatten Miljö Teknik (2005-2017)

Ämnesområden

Miljökemi

Chalmers infrastruktur