Lead isotopes as tracers of anthropogenic pollution in urban topsoils of Mexico City

A survey was performed to trace the main source of anthropogenic Pb pollution in Mexico City through Pb isotopic signatures ( 208Pb/ 204Pb, 206Pb/ 204Pb, 206Pb/ 207Pb, and 208Pb/ 207Pb) from 103 urban topsoil (0–5 cm) samples. Those were collected in the metropolitan area of Mexico City and compared with isotopic compositions of leaded gasoline (LG), domestic Pb ores (DLO) and parent rock (PR). The isotope ratios (IRs) of Pb were determined by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) and total Pb concentration analyzed by wavelength dispersive X-ray fluorescence (WDXRF). The range of Pb concentrations levels in urban topsoil samples was 15–473 mg/kg. The IR values obtained for these samples were 37.965–39.718 ( 208Pb/ 204Pb), 18.375–19.204 ( 206Pb/ 204Pb), 1.177–1.218 ( 206Pb/ 207Pb) and 2.443–2.496 ( 208Pb/ 207Pb). Analyzed topsoil samples with low Pb content (