The article reports the geochemical characterization of soils, vegetation, and groundwater of the recultivated spoils of three coal deposits. Recultivation was carried out 30-40 years ago, and then the spoils were left for selfovergrowth without any additional measures. A common pattern for all sites is the presence of carbonaceous particles, their oxidation leads to an increase in temperature in the spoil rocks. The sum of biologically active temperatures exceeds the values for natural soils of undisturbed areas. Technogenic landscapes are characterized by a smaller share of moisture-loving forest and pratal species, compared to the reference areas. Hydrogeochemical anomalies practically do not go beyond the flooded borrow excavations of spoils. Reclamation by applying a fertile soil layer provides minimization of the negative effects associated with an increase in the temperature of spoil soils and accelerates the remediation of regional plant communities.

The identification of methods for uranium immobilization is important for decision-making on remediation of contaminated areas. Here we investigate the degree of uranium binding on peat sorbents chemically modified using humic acids (HA), zero-valent iron (ZVI), and aqueous ferric chloride. The peat was sampled in the territory of the sludge storage of low-radioactive wastes. In the laboratory, the uranium adsorption on natural peat reaches the maximum values of 86% after 8 hours in comparison with the 92% after 30 min on HA modified peat and 88.8% after 2 hours on aqueous ferric chloride modified peat. The improvement of the peat sorption capacity was confirmed within the three months field experiment using HA and ZVI. The results of the sequential extraction procedure confirm the participation of both modifiers in the processes of uranium sorption.

The paper presents experimental and numerical simulation of the bioremediation in nitrate-, -sulfate-ions and uranium polluted aquifers near the Novosibirsk Chemical Concentrates Plant (NCPP) sludge storage facility. We used two HCh 4.4 (MSU) and PHREEQC 2.18 (USGS) software packages for geochemical modeling and found that the microbial consumption of oxidizers (oxygen and nitrate ions) led to a decrease in the redox potential to –400 mV. The latter plays a key role in the reduction of uranyl ions and stabilization (immobilization) of uranium in low soluble biogenic sediments containing calcium phosphates, sulfides of iron and associated heavy metals. Results of experimental and numerical simulation turned out to be consistent with the composition of mineral phase collected in situ in a discharge area of polluted aquifer.

The concentrations of radionuclides, especially anions, in water can substantially exceed local background levels in the vicinity of former and currently operating uranium enrichment plants. In this study, we present new data on environmental monitoring near the uranium sludge collector of an electrochemical plant (ECP) in Krasnoyarsk Krai, Russia. We first tracked the complex biogeochemical processes that can affect the fate and transport of U in highly nitrate-polluted ground- and surface water. We described the main mechanisms of U immobilization: (a) biogenic and abiogenic reduction (microbial nitrate reduction caused dramatically Eh decrease), (b) sorption by organic matter in peat and by microbial biofilms on a sandy rock surface, and (c) precipitation with biogenic and abiogenic phases. The intensity of the biogenic and abiogenic factors depended on the dynamics of changes in the oxidation-reduction potential (ORP)-pH conditions as well as organic- and inorganic anion concentrations with distance from the source of pollution. Anammox bacteria were found in areas with high nitrate pollution, and we believe that they played a key role in lithotrophic nitrogen consumption and primary organic production. These data can form the basis for complex groundwater remediations close to U sludge repositories and can be implemented beyond the ECP site itself.

To create predictive models for eliminating radioactive residues from anthropogenic systems, it is necessary to measure the amounts of radioactive elements in source slimes and the degree of their concentration in secondary geochemical anomalies. The slime pits of the Angara Electrolysis Chemical Plant are just such objects. In this work, the amounts of radionuclides and other elements in different types of soils are measured.