Biogenic Factors of Formation of Geochemical Uranium Anomalies near the Sludge Storage of the Novosibirsk Chemical Concentrate Plant

Abstract

This paper presents evidence on the possible impact of aerobic and anaerobic microbiological processes on uranium migration in upper aquifers polluted by sulfates and nitrates at the Novosibirsk chemical concentrate plant (PAO NCCP). Uranium can be immobilized in local areas with high contents of organic substances, and the most important microbiological process is a decrease in redox potential owing to aerobic respiration, which can be followed under anaerobic conditions by redox-dependent uranium reduction in areas with negative Eh values. Moreover, in the presence of sufficient amounts of sulfate ions, further anaerobic processes of microbial sulfate and iron reduction result in the formation of iron sulfide, which serves as an antioxidant buffer in the case of oxygen infiltration into the sediment and transforms to molecular sulfur or sulfate preventing uranium oxidation.