Lake sediments are used as indicators of the condition of water bodies and the changes that have recently occurred in them and in their catchments. This work for the first time detailed examined two small lakes in Northwestern Russia (Arctic). Sediment cores were collected from the center of each lake and separated into 1 cm layers. An ICP-mass spectrometer was used to determine the chemical composition. It was found that both lakes have sediments containing organic matter (up to 61

The paper assesses the chemical transformation of surface waters in the southeastern part of the Khibiny Mountainous Massif after launching the Oleniy Ruchey apatite–nepheline ore deposit in 2012. The influence of the Oleniy Ruchey Mine was reflected in an increase in water mineralization (by an order of magnitude) and in a change in the basic ion ratios in water objects receiving runoff from mines, rock, and tailing dumps compared to the watercourses unaffected by the mining enterprise’s activities. Natural hydrocarbonate–sodium water with a mineralization of 10 mg/L was transformed into the nitrate–sodium or sulfate–calcium water. The content of nitrogen group compounds in the Lake Komarinoe water, which receives wastewater from the tailing dumps over the ten-year history of the mining and processing plant, has increased by two orders of magnitude, and the nitrate became basic ion. The concentrations of other basic ions and mineralization in this lake increased by an order of magnitude, as the content of trace elements (Sr, F, Mo), which belong to the main rock-forming minerals of apatite–nepheline deposits. Compared to the background water bodies, the mine wastewaters have the elevated mineralization (up to 260 mg/L), pH value (up to 10), and a modified chemical composition. They are characterized by a hydrocarbonate–sodium composition with a large proportion of nitrates and sulfates. Mine wastewaters have elevated contents of nutrient compounds, organic matter, and some trace elements (Al, Fe, Sr, Cu, Mn, Zn, and Cr). It has been established that the geochemical modifications in the quality of surface water are locally developed, being typical of water bodies receiving wastewater from a mining enterprise, in contrast to metallurgical plants, the atmospheric emissions of which caused pollution over tens and hundreds km.

The chemical composition of the snow cover in the area of industrial development of the apatite–nepheline deposit is analyzed to estimate the ecological and geochemical environmental impact of the mining enterprise. It has been established that the snow of the studied area of the Khibiny is enriched in Cl– and Na+ ions (on average 38 and 41 µeq/L), and relations between basic ions (Cl– and Na+ Ca2+ K+ = Mg2+) and mineralization value (from 1.7 to 6.4 mg/L) are typical for precipitates in the coastal regions of the northern European Russia. The average content of total nitrogen and phosphorus in the snow of the impact zone is 495 and 26 μg/L, respectively, which is 3 and 5 times higher than in the background zone. This is explained by their influx into the atmosphere with dust emissions from the mining enterprise. The content of organic matter (CODMn and TOC 5.5 and 5.8 mg/L) in the snow of the impact zone is about two times higher than in the snow of the background zone and in the water of the Khibiny water bodies. Probably, the elevated content of organic matter in the snow is associated with the supply of organic substances-reagents from the tailing dump, which are used to obtain apatite concentrate, as well as the intensive growth of unicellular green algae Chlamydomonas nivalis (Bauer) Wille under conditions of an increased content of nutrients and long daylight hours. The concentrations of a number of heavy metals (Zn, Mn, Cu, Cr, Pb, Cd) in the snow of the impact zone exceed their contents in the water of water body of the impact zone (13.4, 5.4, 3.8, 0.8, 0.65, 0.035 μg/L, respectively). These metals enter the snow as a part of dust emissions from the mine, and as polluted air masses from the industrial regions of Eurasia.

The chemical composition and seasonal dynamics of the water in Murmansk urban lakes (Murmansk region, Russia) under the anthropogenic load of varying intensity was analysed. The studies were conducted in the period from 2018 to 2020. The chemical composition of the water in the studied lakes differed significantly from that of the lakes located in the background territories of the region. High values of pH and mineralization, increased concentrations of major ions and elevated content of nitrogen and phosphorus compounds were recorded in the surface waters. The nutrient concentrations were subject to noticeable seasonal fluctuations, mainly due to their consumption by phytoplankton, as well as to the changes in the ratios of surface and underground runoff. Lake Ledovoe (the central part of Murmansk) was the most polluted among the studied lakes, and Lake Bolshoe (used for drinking supply of the city) was the least polluted. Assessing the trophic status of the Murmansk lakes showed that the studied lakes are mostly mesotrophic, except for Lake Bolshoe (oligotrophic) and Lake Ledovoe (hypertrophic). In most of the lakes, phosphorus was the limiting factor for the growth and development of phytoplankton. The data obtained can be useful for understanding the fundamental processes of water composition transformation in the urbanized territories of the Arctic regions of the world and for making managerial (practical) decisions to create a comfortable urban environment in the North of Russia.

The chemical composition of sediments from the Arctic mountain Lake Bolshoy Vudjavr, situated in the western part of the Russian Arctic zone, was studied. The lake has been under intense anthropogenic load for more than 90 years since the development of the richest apatite–nepheline deposits in the world started. A 27 cm thick sediment core was sampled in the central part of the lake at the maximum depth of 37.4 m. The concentrations of more than 50 elements were analyzed by the mass spectral method, ICP-MS. The lake sedimentation rate established from the change in the content of the radioactive isotope 210Pb was 2.3 mm/yr. The effluent from apatite–nepheline production and atmospheric fallout enrich the sediments of Lake Bolshoy Vudjavr with alkali and alkaline earth metals, N, P, Mn, Fe, Al compounds, rare earth elements, and trace elements (Sb, Cu, Zn, Pb, Bi, Nb, Ta, Th). Analysis of the forms of elements in the lake sediments showed that the studied elements are mainly found in stable fractions—mineral, acid-soluble, and associated with organic matter. The pollution of the sediments of Lake Bolshoy Vudjavr was assessed by the integral index PLI (Pollution Load Index) and CF (contamination factor). The PLI value sharply increased after the “Apatite” Plant had been launched and a large amount of wastewater from the mines had been released into the lake. The highest PLI values were detected in the sediment layers accumulated during the period 1990s–2000s. Sb (18.2), P (10.3), Sr (7.8), and La (6.0) have the maximum CF values among all the studied elements.

The article presents the first data on the study of a wide range of chemical elements in the water and sediments of small lakes located in the Arctic Zone of Russia. Among the selected objects are two lakes located in the urbanized areas. As a result, the sediments of all lakes were classified by the ratio of the main elements and the total content of organic matter. The concentration coefficients of all elements were calculated taking into average concentrations of different elements in the continental crust and the potentially toxic elements in the sediments of the background area. Analyzing sediment cores made it possible to evaluate the historical dynamics of the behavior of some metals and metalloids (Pb, Cd, Sb, Sn, Bi, Ni, Cu) in the aquatic environment during the industrial era, both in urbanized territories and in the background regions of the Arctic. The main natural and anthropogenic factors of the formation of geochemical anomalies in the concentrations of different elements, including potentially toxic ones, in the sediments studied, were identified. In urban areas, the main sources of metals entering the lake environment are emissions of the copper–nickel, thermal power plants, coal port, and an incineration plant. For all lakes, the pollution level of objects was estimated by calculating the geo-accumulation index and pollution load index. The most polluted lakes are the lakes of urban areas of the Arctic, the lakes of the background territories are characterized by a moderate level of pollution or no pollution.

This paper presents the comprehensive evaluation of the level of accumulation of some of the most dangerous environmental pollutants (V, Co, Sn, Ni, Cr, Mn, Cd, Cu, Pb, Sb, Zn) and analyses their chemical forms in sediments of four small lakes located within Murmansk urban territory. Furthermore, the authors first studied morphology and chemical composition of industrial dust collected from the snow covering the ice of Lake Srednee. Fieldwork was carried out in April 2019. The results showed that sediments of the Murmansk urban lakes are significantly enriched in the content of the toxic metals and metalloids Cd, Pb, Sb, Zn, Cu, V, and Ni. An integrated assessment of anthropogenic impact using the pollution load index (PLI) and geoaccumulation index (Igeo) revealed a moderate to the extremely strong pollution level in recent sediment layers. The analysis of the fractions of the elements showed that they are mainly associated with stable compounds, such as primary minerals or persistent technogenic compounds (slag, matte, and dust). However, humic substances are a significant accumulative matrix for most studied elements. The share of the most mobile fractions does not exceed 30% for the vast majority of elements, even in the most polluted layers. The accumulation of the major part of pollutants can be attributed to the activities of the main industrial objects of the city (thermal power plant, coal port, transport infrastructure), and the impact of the global atmospheric transport of pollutants to the Arctic regions of Russia.

This article presents the results of the analysis and estimation of the seasonal variation of heavy metals in the water of urban lakes and the assessment of their environmental state based on the chemical data. The research covered seven lakes in Murmansk, subject to various levels of anthropogenic load. Field studies were conducted in 2019–2020. Water samples were taken both in summer and in winter/spring seasons. The most polluted lake was Lake Ledovoe, where the highest concentrations of V, Cr, Co, Ni, Cu, W, and Mn were found. Lake Yuzhnoe, which is characterized by the lowest concentrations of studied heavy metals, was the least subject to anthropogenic load. In total, V, Ni, Zn, Fe, and Mn were above the background levels in the lakes of Murmansk. The analysis of the seasonal variation showed that the highest concentrations of heavy metals were found in winter/spring season and reached their maximum during the period of melt water intake from the catchment area. The research showed the impact of the urban environment on the chemical composition of the Murmansk lakes.

This paper presents the first study of five small lakes located in the city of Murmansk. Field work was carried out during 2018–2019. Water samples were collected using a bathometer, while the sediments were sampled using an Ekman grab and Limnos gravity corer. It was found that the water of the studied lakes in Murmansk belong to the sodium group of the chloride class and to the calcium group of the hydrocarbonate class. Compared to the background level, elevated pH, concentrations of the main cations of alkali and alkaline-earth metals, N compounds, total dissolved solids, and heavy metals were found in the lakes, which indicate exposure to anthropogenic impacts. The sediments of the lakes, composed of organomineral and mineral silts, also have an elevated content of heavy metals compared to the background. The most significant excessive concentrations were found for V, Ni, Sb, Pb, Co, Cr, and W. Based on the calculated pollution load index and geoaccumulation index of the sediments, the studied water bodies in Murmansk can be classified as lakes with heavy and extremely heavy pollution levels. The primary pollution sources are emissions from the Murmansk thermal power plant, coal port, road and, rail transport.

Lake Kuetsjarvi (in the lower reaches of the Pasvik River, Murmansk Region, Russia) in the border area between Russia and Norway, is one of the most polluted water reservoirs in the European Arctic. The operation of the Pechenganikel Smelter located on its shores has led to the extremely high concentrations of heavy metals observed in the waters and sediments of the lake. Long-term comprehensive studies of the ecosystem of Lake Kuetsjarvi have made it possible to identify the response of its components to the global and regional change in the environment and climate as a whole, resulting in increased water toxicity and eutrophication, reduction in the number of stenobiont species of aquatic organisms against the background of an increase in the number of eurybiontic and invasive species. Modern communities of Lake Kuetsjarvi are the result of a combination of long-term changes in the abiotic environment and biotic interactions. Heavy-metal pollution of Lake Kuetsjarvi, observed since the 1930s, has led to the formation of a community that is resistant to this type of impact and supports large populations of adapted species. Adaptations of communities to the dynamics of the environmental conditions that their members are exposed to include changes in the species composition, quantitative indicators, ratios between individual taxonomic groups, and the population structure. The development of sympatric forms that differ in the ecological niches they occupy, morphology, and life cycle strategies, including the transition to a short-cycle survival strategy, allows whitefish to remain the dominant species and maintain high population numbers. Unlike the organismal level, responses to medium-term environmental changes on the population and community level are less specific and characterized by stronger inertia.

The paper reports the results of the analysis of Pb, Sb, Cd accumulation in top core sediments from small lakes of southern Republic of Karelia. Both lakes in urban areas (Petrozavodsk, Medvezhyegorsk, Suojarvi, and Sortavala) and lakes in areas regarded as reference for southern Karelia were included in the study. Fieldwork and analytical investigations employed a common methodology in line with globally-accepted limnological practices. The concentrations of chemical elements in the lake sediments were determined by inductively coupled plasma mass spectrometry (ICP-MS). The median background concentrations of Pb, Sb, Cd in the studied sediments deposited in the preindustrial period were calculated, and the recent levels of accumulation of these metals in the industrial period were determined for the same lakes. The main factors for the formation of technogenic Pb, Sb, Cd anomalies in the top core sediments are described, and the levels of the heavy metals are compared against those in lake sediments in other parts of the world. The levels of contamination of the Karelian lakes with these metals were calculated based on the geoaccumulation index I geo . The Tessier sequential extraction procedure was employed to detect the main forms of the heavy metals in the top core sediments. Especially, the role of organic matter, which constitutes the bulk of the sediments, in binding the pollutants was assessed. Considering that Karelian lake sediments are potential sources of useful organic raw material, i.e. sapropel, some recommendations are given on the possible applications of these sediments in human activities.

The article gives an overview of the limnological research historyat INEP KSC RAS since the late 1980s. until now. The most important results of complex work are presented, including the study of the hydrochemical composition of water and bottom sediments, as well as biota (plankton, benthos and fish) of the Murmansk region lakes. The prospects for the scientific research development of are shown.

The chemical composition, including mercury, of sediments in lakes of the Murmansk Region exposed to pollution by effluents from the mining industry was studied. It was found that the highly toxic and hazardous for the lake ecosystem chalcophile Hg comes from the activities of apatite-nepheline and copper-nickel mines and mills. In the verticaldistribution of Hg in the sediments at the stations situated near the waterbodies receiving effluents from apatite-nepheline mining, there is a near-surface maximum at sedimentcore depths of 7 to 14 cm amounting to 0.6 to 2.3 μg/g, which is ten times more than the average background content (0.044 µg/g). These values were an order of magnitudehigher than the ISQG and PEL standards for Hg developed by the Canadian Council of Ministers of the Environment. The Bolshaya Imandra water area is classified as “markedlypolluted” (class III) according to the Norwegian Pollution Control Authority. Hg content in the top 1‑cm sediment layer varies widely from 0.018 to 1.000 µg/g, and the highest mercury concentrations are found in the areas receiving effluents from the apatitenepheline and copper-nickel industry.