Lead Isotopes Combined with Geochemical Baseline in Sediments: A Novel Tool to Trace Anthropogenic Pb Sources

Traditional Pb isotopic identification only based on total Pb concentration and Pb isotopic ratios, resulted in difficulty for tracing Pb sources in the complex environmental medium, especially for sediment. Herein, a novel approach combining with regional geochemical baseline (RGB) and Pb isotopic ratios are used to directly trace anthropogenic Pb sources and calculate Pb source appointments in sediment. In this study, total Pb concentrations and isotopic ratios were analyzed for a 7-m long sediment core (92 sediment samples) collected from a reservoir. RGB of Pb was used to calculate anthropogenic Pb concentrations (R_d), their contributions (C_Rd) and screen the sediments influenced by anthropogenic activities. Among those sediments influenced by anthropogenic activities, a positive correlation was found between ²⁰⁶Pb/²⁰⁷Pb ratios and R_d, indicating there were two anthropogenic Pb sources in sediment. Further source identification using ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb indicated that these two anthropogenic Pb sources originated from coal consumption and aerosol input. Finally, C_Rd and Pb isotopic ratios were used to calculate these two Pb source appointments (1.13% for coal consumption and 7.53% for aerosol input). This study demonstrated that source identification using RGB and Pb isotopes could be a novel attempt for identifying anthropogenic Pb sources in sediment.