Vasilii A. Efimov

Современное содержание фтора в водах реки Оби

Permafrost regions are under particular pressure from climate change resulting in widespread landscape changes, which impact also freshwater chemistry. We investigated a snapshot of hydrochemistry in various freshwater environments in the lower Kolyma river basin (North‐East Siberia, continuous permafrost zone) to explore the mobility of metals, metalloids and non‐metals resulting from permafrost thaw. Particular attention was focused on heavy metals as contaminants potentially released from the secondary source in the permafrozen Yedoma complex. Permafrost creeks represented the Mg‐Ca‐Na‐HCO₃‐Cl‐SO₄ ionic water type (with mineralisation in the range 600–800 mg L⁻¹), while permafrost ice and thermokarst lake waters were the HCO₃‐Ca‐Mg type. Multiple heavy metals (As, Cu, Co, Mn and Ni) showed much higher dissolved phase concentrations in permafrost creeks and ice than in Kolyma and its tributaries, and only in the permafrost samples and one Kolyma tributary we have detected dissolved Ti. In thermokarst lakes, several metal and metalloid dissolved concentrations increased with water depth (Fe, Mn, Ni and Zn – in both lakes; Al, Cu, K, Sb, Sr and Pb in either lake), reaching 1370 μg L⁻¹ Cu, 4610 μg L⁻¹ Mn, and 687 μg L⁻¹ Zn in the bottom water layers. Permafrost‐related waters were also enriched in dissolved phosphorus (up to 512 μg L⁻¹ in Yedoma‐fed creeks). The impact of permafrost thaw on river and lake water chemistry is a complex problem which needs to be considered both in the context of legacy permafrost shrinkage and the interference of the deepening active layer with newly deposited anthropogenic contaminants.

Permafrost environment will undergo significant changes during the 21st century related to the forecasted climate warming, therefore, we may expect that rising temperatures will cause enhanced re-mobilization of deposited compounds from sinks in soils and permafrost. By analysing persistent organic pollutants (POPs) concentrations in surface waters we attempt to answer the question if permafrost is a secondary source of POPs stored in it. One of the most common organic pollutant groups worldwide, the polycyclic aromatic hydrocarbons (PAHs), occurred also in Russian periglacial soils, sediments and water, and their further research is of interest due to them causing adverse effects in animal health. PAHs concentrations range from several to several thousand ng·g–1, reflecting a spatial variability related to supply from both anthropogenic and natural sources (e.g., Abakumov et al., 2015; Elmquist  et al., 2007; Gabov et al., 2019).Preliminary research on the possibile release of POPs into water has been conducted in July 2021 near the North-East Science Station (the lower Kolyma basin) (within the scope of PollAct project). Water samples (28 pcs) were collected from the Kolyma river, its tributaries and thermokarst lakes. The results of laboratory analysis (PAHs, PCBs, metals) are tested to find potential sources of contaminants (natural vs anthropogenic), and verify the possibility of their remobilisation from permafrost during thaw season. The study will be continued in 2022-2025 through the PER2Water project.AcknowledgmentThis research was funded by INTERACT, H2020-EU.1.4.1.2., grant number 730938; project: PollAct. This research was funded also in part by National Science Centre, Poland, grant number 2021/41/B/ST10/02947, PER2Water project.ReferencesAbakumov E.V., Tomashunas V.M., Lodygin E.D., Gabov D.N., Sokolov V.T., Krylenkov V.A., Kirtsideli I.Yu., 2015. Polycyclic aromatic hydrocarbons in insular and coastal soils of the Russian Arctic. Eurasian Soil Sc. 48, 1300–1305.Elmquist M., Zencak Z.,Gustafsson Ö., 2007. A 700 Year Sediment Record of Black Carbon and Polycyclic Aromatic Hydrocarbons near the EMEP Air Monitoring Station in Aspvreten, Sweden. Environ. Sci. Technol. 41(20), 6926–6932.Gabov D.N., Yakovleva Y.V., Vasilevich R.S., Kuznetsov O.L., Beznosikov V.A., 2019. Polycyclic Aromatic Hydrocarbons in Peat Mounds of the Permafrost Zone. Eurasian Soil Sc. 52(9), 1038–1050.

Enterprises of fuel and energy complex are the main sources of carcinogenic and mutagenic potentially toxic elements (PTEs). Their particulate and gaseous emissions, wastes, and effluents enforce migration processes of PTEs in atmosphere, soil, and then in water bodies, creating a danger to the functioning of aquatic ecosystems. Vulnerable objects include water bodies with slow water exchange, due to the accumulation of PTEs in the bottom sediments and the threat of secondary contamination. Among them it is necessary to note cooling ponds of thermal power plants (TPP). In this study, the ecological and geochemical state of components of “water-suspended sediments-bottom sediments” aquatic system is assessed on the example of the Gusinoye Lake (the Republic of Buryatia), which is used as cooling pond for the largest in the region TPP, burning brown coal from local deposits. The Gusinoye Lake is the second largest lake in Buryatia after the Baikal Lake and a valuable source of water supply, place of recreation, and fish breeding. To study the distribution of PTEs in the waters of the lake, a network of 19 monitoring stations was deployed in the summer of 2019. In contrast to the previous researches, detailed studies of the central deep-water part of the lake were carried out. As a result, data on the concentration of PTEs in the dissolved and suspended forms and also in bottom sediments was obtained. To study the balance of chemicals in the lake, its main tributaries were surveyed, as well as the drainage channel of TPP. For the first time, for the Lake Gusinoye, bulk concentrations of As, Cd, Pb, Zn, Co, Mo, Cu, Sb, Cr, V, Mn, Sr, and Ag were determined using the inductively coupled plasma mass spectrometry. The highest concentrations of dissolved PTEs in the lake water are confined to the mouths of tributaries in the northern part of the lake. Dissolved Sr, Mo, and Cu in the lake exceed maximum permissible concentrations (MPCs) for fishery. The maximum concentrations of Sr and Cu are almost 3 MPCs and that of Mo is 22 MPCs near the TPP. The suspended sediments of the Gusinoye Lake are depleted of all studied PTEs as compared to the regional clarkes (natural abundances) of the lithosphere. Mn has the highest concentrations in the suspension, and its maximum concentration was due to the surface runoff from the solid waste landfill and an abandoned coal mine. Concentrations of Cu, Zn, Sr, Mo, and Pb in bottom sediments are higher than in suspended sediments, thus indicating the accumulation of pollutants. The maximum intensity of accumulation is characteristic of the deep central basin of the lake and its eastern part, where Sr, Ag, and Mo accumulate most intensively near the coal field. The main sources of PTE pollution are concentrated in the northern and northeastern parts of the lake catchment area. Significant amount of dissolved Mo, Sr, and As enter the lake with the waters of quarries and mines of the coal fields, the solid waste landfill of the town of Gusinoozyorsk, and northern rivers-tributaries, draining the dumps of the large Zagustaj coal field.

An emerging solution in mine waste remediation is the use of biological processes, such as microbial sulfate reduction (MSR), to immobilize metals, reducing their bioavailability and buffering the pH of acid mine drainage. Apart from laboratory tests and local observations of natural MSR in, for example, single wetlands, little is known about spatiotemporal characteristics of freshwater MSR from multiple locations within entire hydrological catchments. We here applied an isotopic fractionation (δ³⁴S values in SO₄²⁻) and a Monte Carlo‐based mixing analysis scheme to detect MSR and its variation across two major mining regions (Imetjoki, Sweden and Khibiny, Russia) in the Arctic part of Europe under different seasonal conditions. Results indicate a range of catchment‐scale MSR values in the Arctic of ∼5%–20% where the low end of the range was associated with the non‐vegetated, mountainous terrain of the Khibiny catchment, having low levels of dissolved organic carbon (DOC). The high end of the range was related to vegetated conditions provided by the Imetjoki catchment that also contains wetlands, lakes, and local aquifers. These prolong hydrological residence times and support MSR hot spots reaching values of ∼40%. The present results additionally show evidence of MSR persistence over different seasons, indicating large potential, even under relatively cold conditions, of using MSR as part of nature‐based solutions to mitigate adverse impacts of (acid) mine drainage. The results call for more detailed investigations regarding potential field‐scale correlations between MSR and individual landscape and hydroclimatic characteristics, which, for example, can be supported by the isotopic fractionation and mixing scheme utilized here.

In this study, the downstream effects of pollutants spreading due to hydromorphological gradients and associated changes in sediment transport conditions along the braided-meandering and deltaic distributary reach of a large river downstream section are discussed. We demonstrate the significance of hydrodynamic control for sediment-associated metal partitioning along the river. Typically, the downward decline of the sediment and metals spreading towards Lake Baikal is observed due to buffer effects in the delta. During peak flow, the longitudinal gradients in heavy metal concentration along the distributary delta reach are neglected due to higher concentrations delivered from the upper parts of the river. In particular, significant variations of heavy metal concentrations associated with the river depth are related to sediment concentration and flow velocity profiles. Various particulate metal behavior in silt-sand delta channels and the sand–gravel Selenga main stem emphasize the importance of near-bottom exchange for particles spreading with the river flow. Using empirically derived Rouse numbers, we found quantitative relationships between the ratio of particulate metals sorting throughout depth in a single river channel and the hydrodynamic conditions of sediment transport.

The paper deals with present hydrological and hydrochemical regime of southern Khibiny rivers affected by apatite-nepheline mining activity. Changes in water quality resulting from mining activities include increase of water turbidity, concentrations of major ions and trace elements. The impact of mining area can be traced over 34 km downstream. We conclude that existing treatment system is not sufficient to mitigate pollutants loads leading to elevated concentrations of toxic substances in dissolved and suspended modes. The process substances concentration reduction is mainly represented by dilution, since the hydrochemical decrease is insignificant. Using trace elements migration phase distribution, the effect of treatment plants on elements distribution downstream was observed.