Material Composition and Geochemical Characteristics of Technogenic River Silts

—The paper discusses the results of many years of studying the material composition and geochemical characteristics, conditions, and processes in the formation of technogenic river silts: a new type of modern river sediments formed in riverbeds within the boundaries and zones of influence of industrial–urbanized areas. The article examines the main sources and most important characteristics of technogenic sedimentary material flowing into rivers, as well as the geochemical conditions of technogenic alluvial sedimentation, the morphology and structure of technogenic silts, the extent of their spatial distribution in riverbeds, their grain size characteristics, and mineral and chemical composition. Special attention is paid to analyzing the group composition of organic matter in river sediments and the features of its transformation in pollution zones. The study analyzes the technogenic geochemical associations that form in silts in zones of influence of various impact sources, the features of the concentration and distribution of chemical elements, heavy metal speciation, the composition of exchangeable cations in technogenic silts and natural (background) alluvium, and the composition of silt water. Possible secondary transformations of technogenic silts and their significance as a long-term source of pollution of the water mass and hydrobionts are substantiated.