The content and profile distribution of ¹³⁷Cs in iron-illuvial dwarf and shallow-podzolic podzols (Albic Podzols) under bilberry-lichen and green-lichen-bilberry pine forests in the located near the Kola Nuclear Power Plant have been analyzed. The pollution density (reserve) of ¹³⁷Cs in the root-inhabited layer (0–30 cm) in the studied soils was significantly lower than the established control level of 37 000 Bq/m² and amounts to 530–2459 Bq/m². A significant part of ¹³⁷Cs (60 to 90%) was concentrated in mineral horizons. It has been shown that the pollution density of ¹³⁷Cs in the observation zone of a nuclear power plant was mainly due to global fallout. The greatest influence on ¹³⁷Cs accumulation in the studied soils was exerted by the organic matter reserve.

This study presents the first comprehensive examination of ¹³⁷Cs behavior in northern taiga ecosystems of the Kola Peninsula, a previously understudied region regarding radionuclide mobility. The background radioactive contamination of these ecosystems stems from global fallout and differs from more extensively studied contaminated areas. Twelve monitoring sites at varying distances from the Kola nuclear power plant were established to assess ¹³⁷Cs accumulation in dominant plant species across three forest tiers. Gamma-spectrometric measurements revealed high mobility of ¹³⁷Cs with specific activity ranging within 4.7–34.5 Bq/kg in trees, 8.4–164.8 Bq/kg in shrubs, and 15.0–94.5 Bq/kg in mosses. Notably, Ericaceae family plants demonstrated the highest accumulation capacity. ¹³⁷Cs concentrations were significantly higher at the background site (30 km from the power plant) than in the sanitary protection zone, indicating no detectable influence from the nuclear facility. Strong correlations (up to |rs| = 0.93) between bioaccumulation indicators and soil properties were found—particularly with potassium content, exchangeable cation concentration, and organic matter content—suggesting that soil characteristics primarily determine ¹³⁷Cs mobility. These findings highlight the potential risk of ¹³⁷Cs movement through food chains in northern taiga ecosystems, with bioaccumulation coefficients exceeding those of central Russian landscapes and being comparable to those of Scandinavian taiga ecosystems.

Radionuclide contamination of surface water bodies poses a significant environmental challenge, particularly for low-productivity dystrophic systems where natural self-purification capacity is limited. This study aimed to assess the potential of phytoplankton and bottom sediments as biogeochemical barriers for radionuclides. Laboratory modeling of ⁹⁰Sr, ²³³U, ²³⁹Pu, and ²⁴¹Am accumulation was conducted using samples of Lake Dryazlo (Tver Oblast) water and bottom sediments as a representative dystrophic model system. Sorption onto phytoplankton biomass over a single growing season was estimated at 1.89 × 10⁴, 5.41 × 10⁴, 6.64 × 10⁴, and 4.04 × 10⁴ Bq g⁻¹ dry biomass for ⁹⁰Sr, ²³³U, ²³⁹Pu, and ²⁴¹Am, respectively. Actinide immobilization in bottom sediments depended on mineral composition and microbial community activity. Ammophos addition increased radionuclide removal from the liquid phase by 2–5-fold through enhanced phytoplankton productivity, and promoted actinide fixation via phosphate mineral phase formation and stimulation of anaerobic sulfur- and iron-cycling bacteria. These results demonstrate a viable biogeochemical barrier approach applicable to the decommissioning of radioactive waste storage ponds and remediation of radionuclide-contaminated water bodies.

The paper presents data obtained by studying the modes of ¹³⁷Cs, ⁹⁰Sr, ^239,240Pu, and ²³⁷Np occurrence in different genetic horizons of Albic podzols in the area of the Kola nuclear power plant (KoNPP). The data were obtained by artificially introducing solutions of the isotopes into dry soil samples. Comparison of the results with literature data on the distribution of these radionuclides in soils elsewhere around Russia showed that the radionuclides are much more mobile in northern Albic podzols than in soils studied elsewhere in Russia: the total amounts passing into water-soluble and exchangeable forms are up to 33% ¹³⁷Cs, up to 82% ⁹⁰Sr, up to 39% ^{239, 240}Pu, and up to 69% ²³⁷Np.

The accumulation of ¹³⁷Cs and its stratification in Cladonia lichens growing in the area of Kola nuclear power plant have been studied. For this purpose, samples of reindeer lichens were selected at 12 test sites in the sanitary protection zone of the station, in the observation zone, and in the background area. The specific activities of ¹³⁷Cs in the samples were determined using a scintillation gamma spectrometer. The weighted average specific activities of ¹³⁷Cs in Cladonia lichens were 22.3–104.8 Bq/kg, while most of the radiocaesium was concentrated in the upper layers of the lichen. Statistical data processing using a single-sample t-test, Spearman’s coefficient, and cluster analysis indicated the dominant role of global fallout in the ¹³⁷Cs input into the lichens, while the possible impact of the Kola nuclear power plant on this process is limited to the sanitary protection zone.