Identifying sources of Pb pollution in urban soils by means of MC-ICP-MS and TOF-SIMS
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Lead pollution was evaluated in 17 urban soils from parks and gardens in the city of Vigo (NW Spain). The Pb isotope ratios (207Pb/206Pb, 208Pb/204Pb, 206Pb/204Pb and 208Pb/206Pb) were determined after being measured by MC-ICP-MS. The association of the isotopes (204Pb, 206Pb, 207Pb and 208Pb) with the different components of the soil was studied using TOF-SIMS. The isotopic ranges obtained for the samples were between 1.116 and 1.203 (206Pb/207Pb), 2.044–2.143 (208Pb/206Pb), 37.206–38.608 (208Pb/204Pb), 15.5482–15.6569 (207Pb/204Pb) and 17.357–18.826 (206Pb/204Pb). The application of the three-end-member model indicates that the Pb derived from petrol is the main source of Pb in the soils (43.51 % on average), followed by natural or geogenic Pb (39.12 %) and industrial emissions (17.37 %). The emissions derived from coal combustion do not appear to influence the content of Pb in the soil. TOF-SIMS images show that the Pb mainly interacts with organic matter. This technique contributes to the understanding of the association of anthropogenic Pb with the components of the soil, as well as the particle size of these associations, thus allowing the possible sources of Pb to be identified.
KeywordsLead stable isotope Urban soils TOF-SIMS MC-ICP-MS Three-end-member model Roadside soils
We would like to thank the Xunta de Galicia for financing the project EM2013/018. Vega, F.A. and Arenas-Lago, D. thank the Ministry of Science and Innovation and the Universidade of Vigo for the Ramón and Cajal grant and for the FPI-MICINN, respectively. We thank Li, H. for his help with the application of the three-end-member model and the Council of Vigo (Spain) for their help with the sample collection.
Conflict of interest
The authors declare that they have no conflict of interests.
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