Tracing geogenic and anthropogenic sources in urban dusts: Insights from lead isotopes

R. Del Rio-Salas, J. Ruiz, M. De la O-Villanueva, M. Valencia-Moreno, V. Moreno-Rodríguez, A. Gómez-Alvarez, T. Grijalva, H. Mendivil, F. Paz-Moreno, D. Meza-Figueroa*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

53 Scopus citations

Abstract

Tracing the source of metals in the environment is critical to understanding their pollution level and fate. Geologic materials are an important source of airborne particulate matter, but the contribution of contaminated soil to concentrations of Pb in airborne dust is not yet widely documented. To examine the potential significance of this mechanism, surface soil samples were collected, as well as wind-transported dust trapped at 1 and 2 m height at seven different locations including residential, industrial, high-traffic and rural sites. Samples of dust deposited on roofs from 24 schools were also obtained and analyzed for Pb isotope ratios.Spatial distribution of Pb of airborne and sedimented dust suggests a process dominated by re-suspension/sedimentation, which was controlled by erosion, traffic and topography of the urban area. Anthropogenic lead input in the city grades outward the urban zone toward geogenic values. Our results shows that Pb-isotopic signatures of leaded gasoline are imprinted in dust sedimented on roofs. Considering that leaded-gasoline has not been in use in Mexico since two decades ago, this signature shows not only a Pb-legacy in soil, but also a re-suspension process affecting air column below 3 m in height. The combination of the 207Pb/ 206Pb data of the surrounding rocks and urban dust, reveal three well-defined zones with remarkable anthropogenic influence, which correspond to the oldest urban sectors. This work highlights the importance of spatial characterization of metals in particles suspended below a height of 3 m of the airborne column, a fact that should be considered to identify exposure paths to humans and the potential risks. Lead isotope signatures allowed the identification of geogenic and anthropogenic emission sources for dust, a matter that deserves consideration in the efforts to control airborne metal emissions.

Original languageEnglish
Pages (from-to)202-210
Number of pages9
JournalAtmospheric Environment
Volume60
DOIs
StatePublished - Dec 2012

Bibliographical note

Funding Information:
This project was supported by the Mexican Office of Public Education (SEP) and the University of Sonora through the Research and Graduate Studies Office (Grant PICA 05/DCEN05 and PIFI 3.1 ). Lead isotope analyses were done at the Department of Geosciences of the University of Arizona. The authors gratefully acknowledge John Chesley and Mark Baker for the kindly assistance during sample preparation and lead isotope analysis. Authors deeply acknowledged two anonymous reviewers for their constructive suggestions.

Keywords

  • Airborne dust
  • BSNE
  • Lead isotopes
  • México
  • Soil resuspension

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