关键词: 铅同位素, 示踪, 城市土壤, 长春市

Abstract: An extensive survey was conducted to evaluate the potential anthropogenic sources (PAS) of Pb in the urban environment of Changchun, China, using a systematic sampling strategy of 1-3 topsoil (0-20 cm) samples composed by 3-5 sub-samples per district in the urban sites and three kinds of PAS dust samples in the urban area. X-ray fluorescence spectroscopy (XRF) and mass spectrometer (MS) were employed to analyze the Pb concentration of soils and isotopic compositions of the samples respectively. The results indicated that the mean concentration of Pb in the urban topsoils of Changchun was 44.72×10^-6, 2.35 times greater than the background value of the Changchun soils (19.06×10^-6), which shows a pollution of the topsoil in Changchun; the ²⁰⁸Pb/²⁰⁷Pb and ²⁰⁶Pb/²⁰⁷Pb ratios of the topsoils varied from 2.249 to 2.473 and from 1.158 to 1.213, respectively, which are significantly wide. The characteristics of the Pb isotopic compositions of the PAS samples differed significantly and can be used for tracing the sources of Pb in the urban environment. The results of Pb isotope tracer show that the long accumulation history of Pb from automobile exhausted deposits in a relatively confined environment over time was a key factor to the Pb pollution in the main urban area of Changchun, but effect of the current automobile exhausts was not remarkable. Coal burning by industries, such as the Second Thermo-eletric Plant, also contributed to the Pb pollution of urban area. Architectural fly ash plays a minor role in the urban topsoils contamination.

Key words: Pb isotope, tracing, urban soil, Changchun City