Urban Sediment Cascade as Geochemical Archive: Tracking Industrial Impact and Pollution in Urban Environment

Urban surface deposited sediments are important reservoirs of pollutants, yet their relationships with other environmental media and their value for distinguishing legacy contamination from current anthropogenic inputs remain insufficiently understood. This study examines the urban sediment cascade across eight industrial cities in Sverdlovsk Oblast, Russia. The study combines geochemical data for urban soils from regional monitoring with analyses of urban surface deposited sediments, their fine fraction (<0.1 mm), and snow cover. Concentrations of Mg, Mn, Ni, Cu, Zn, Cd, Sb, and Pb in the sediment cascade strata were considered. An initial geochemical baseline was reconstructed using principal component analysis and non-parametric Kernel density estimation. Pollution was assessed using geochemically justified element-specific pollution index and an integrated toxicity-weighted pollution index. The multi-strata profiling and analysis of eco-geochemical spectra successfully isolated key trajectories of technogenic transformation, including post-industrial legacy, continuous metallurgical complexes pressure, mining impacts, and climate-dependent transboundary transit. The toxicity-weighted pollution assessment classified 54% of sampling sites as heavily or severely polluted. The developed approach provides a universally scalable methodology for multi-temporal environmental monitoring within industrial and post-industrial urban areas.