RESUMO
An assessment of uranium contents and distribution in drinking water limescale has been conducted in the Republic of Bashkortostan (RB), Russia. A total of 515 limescale samples from 262 settlements of the RB were analyzed. The spread of U concentration values in limescale samples ranged from 0.01 to 61.0 µg/g. Elevated U concentrations in the West of the RB corresponded with the horsts of the granite-gneiss crystalline basement of the South-Tatar Dome and their Eastern slopes, the areas with the Lower Permian red beds and the oil and gas fields. The U migration from the granite-gneiss basement is attributed to the tectonic factor and hydrocarbons movement. Elevated concentrations of U within the South of the RB are associated primarily with the deposits of the Southern Ural brown coal basin. The Bashkir Trans-Urals anomalies are mainly associated with Lower Paleozoic eclogite complex, Devonian and Carboniferous volcanic-sedimentary, carbonate, intrusive formations, as well as the Jurassic cover of terrigenous marine sediments. The negative anomalies of the spatial distribution of U are located in the area of the Ufimian Plateau mainly composed of limestone.