Geochemical Characterization and Provenance of Urban Stream Sediments Draining into the Keban Dam Lake, Türkiye: Implications for Environmental Monitoring and Sustainability

This study presents a comprehensive geochemical and isotopic investigation of urban stream sediments draining into the Keban Dam Lake in Eastern Türkiye. A total of 15 sediment samples were collected along a ~35 km transect, spanning rural-to-urban transition zones. PAAS-normalised REE patterns revealed coherent light REE behaviour and positive Eu anomalies (Eu/Eu* = 1.57–2.01), except sample K8 (Eu/Eu* = 0.91), indicating contributions from plagioclase-bearing lithologies. Enrichment Factor (EF) calculations based on scandium normalisation showed notable enrichment in Li, Zr, Nb, and REEs, reflecting felsic source rocks and mineralogical sorting. Multivariate statistical analyses (PCA and HCA) revealed distinct groupings of elements associated with lithogenic sources (Be, Sc, and Y) and anthropogenic inputs (Li, Sn, and Rb). Spatial clustering of samples into rural, transitional, and urban zones supported this differentiation, suggesting increasing anthropogenic influence downstream. Sr isotopic data ( 87 Sr/ 86 Sr = 0.7045–0.7057) and Pb isotope ratios ( 206 Pb/ 204 Pb = 18.914–18.947) suggest dominantly geogenic control, with slightly more radiogenic signatures in urban sediments. These integrated geochemical and isotopic results provide the provenance model for the Keban catchment, highlighting how natural lithological sources and urbanisation jointly shape sediment composition and metal distribution. The findings also provide a useful geochemical baseline for environmental monitoring, sediment quality assessment, and sustainable watershed management in the Keban Dam Lake basin.