Lead Isotope Systematics in Groundwater: Implications for Source Tracing in Different Aquifer Types

We report Pb isotope measurements for 23 groundwater samples collected at different sites in France located from various types of aquifers (alluvial, sedimentary, karst, sand, volcanic and crystalline lithologies). We have measured the range of Pb isotopic variations in these groundwater samplesin order to test the usefulness of Pb isotopes as a tool for tracing Pb sources in aquifer systems. In these groundwater samples, Pb isotopic ratios ranged from 17.33 to 18.56, from 15.45 to 16.11 and from 37.06 to 40.35, respectively for 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, whereas the Pb concentrations were between 0.023 and 0.160 μg/L, and below the 10 μg/L maximum allowable concentration of Pb in drinking water. Lead isotope ratios of the study groundwater display very large variations, in particular for the sedimentary aquifers. The Pb isotopic variations werenot related to lead concentrations nor to the type of aquifers. The data indicate that Pb in groundwater is typically originatedfrom the mixing of natural and anthropogenicsources.