Potentially toxic elements in sediments of China's Shihe River: Urban-agricultural impact assessment and source...

This study investigated the pollution status of seven potentially toxic elements (PTEs) by analyzing eighteen sediment samples collected from urban and agricultural zones along an urban river in Xinyang, a major agrarian city. Results revealed that manganese (Mn), zinc (Zn), and chromium (Cr) exhibited the highest concentrations. Almost all PTEs exceeded regional background values, indicating anthropogenic contamination in the riverine system. Spatial analysis demonstrated 1.2- to 3.5-fold higher PTE concentrations in urban areas compared to agricultural zones, underscoring the predominant role of urban activities in pollution dynamics. Sequential extraction analysis identified residual fractions as the dominant phase for most PTEs, suggesting limited environmental mobility. However, Mn and cadmium (Cd) displayed elevated bioavailability through their association with non-residual fractions. The results of ecotoxicological risk methods classified Mn and Cd as priority pollutants, with urban hotspots reaching moderately to heavily contaminated status. The PCA-MLR analysis results demonstrated that sewage discharge and traffic-related sources are the primary anthropogenic contributors to PTEs contamination in the Shihe River. These findings advocating for targeted urban watershed management strategies to mitigate PTE risks in rapidly developing regions.