Ecological monitoring of territories of liquidated mines of the Arctic zone of Russia

Khudyakova Elena Viktorovna Doctor of Economics Professor; Department of Applied Informatics; Russian State Agrarian University - Moscow Timiryazev Agricultural Academy 49 Timiryazevskaya str., Moscow, 127434, Russia evhudyakova@rgau-msha.ru Stupin Oleg Gennad'evich Graduate student; Department of Digital Management Technologies; Siberian Federal University 660041, Russia, Krasnoyarsk Territory, Krasnoyarsk, Oktyabrsky district, Svobodny Prospekt, 79 ipdme@mail.ru Other publications by this author     Stepantsevich Marina Nikolaevna PhD in Economics Associate Professor; Department of Applied Informatics; Russian State Agrarian University - Moscow Timiryazev Agricultural Academy 49 Timiryazevskaya str., Moscow, 127434, Russia stepancevich@rgau-msha.ru

Kukartsev Vladislav Viktorovich PhD in Technical Science Associate Professor; Department of Applied Informatics; Russian State Agrarian University - Moscow Timiryazev Agricultural Academy 49 Timiryazevskaya str., Moscow, 127434, Russia vlad_saa_2000@mail.ru

1. Introduction

In today's world, where economic growth is often put at the forefront, the problem of the impact of industrial activity on the environment is becoming particularly acute. Globally, we are witnessing the depletion of natural resources, pollution of the atmosphere, water bodies and soils, which leads to a violation of the ecological balance and endangers the health of the population and the sustainable development of entire regions. These problems are particularly relevant in the Arctic zone, characterized by fragile ecosystems and slow recovery rates ^{[1, 2]}. Arctic pollution caused by industrial activities, including mining, poses a serious threat to the unique flora and fauna, as well as to the traditional way of life of indigenous peoples.

Coal mining is one of the most difficult and environmentally hazardous areas of industrial activity. The coal industry has a multifaceted negative impact on the environment, including pollution of water resources by mine waters, emissions of pollutants into the atmosphere, land disturbance and the formation of landfills ^[3-5]. The restructuring of the coal industry, carried out in Russia since the 1990s, led to the closure of many mines, which, on the one hand, reduced the environmental burden, but on the other hand, created new environmental problems associated with flooding of mine workings, the release of mine waters to the surface, the formation of sinkholes and the release of dangerous gases ^{[6, 7]}.

Solving these problems requires an integrated approach that includes various methods and strategies. One of the possible ways is to carry out reclamation of disturbed lands, which allows restoring soil fertility and returning them to economic circulation. However, reclamation is an expensive process that requires significant financial investments and a long time ^[8-10]. Another option is to introduce modern technologies for mine water treatment, which reduces the concentration of pollutants and prevents contamination of water bodies. But even here there are difficulties associated with the need to develop and implement effective and economically feasible technologies. An alternative approach is to create systems for monitoring and controlling the state of the environment in the territories of closed mines, which allows timely detection and prevention of negative consequences ^[11-14]. The disadvantage of this approach is its reactive nature, that is, monitoring only allows you to identify the problem, but does not eliminate its root cause.

In the context of the Arctic zone and, in particular, the Pechora coal basin, the problem of the environmental consequences of mine closures is of particular importance. The Pechora coal basin, located in harsh climatic conditions, is an important source of coal for the region's economy. However, coal mining in this region is fraught with serious environmental risks, exacerbated by the fragility of Arctic ecosystems. In conditions of permafrost and a short growing season, restoration of disturbed lands and water bodies is a particularly difficult task ^[15-17]. In addition, Arctic pollution has global consequences, as pollutants can spread over long distances and have a negative impact on human health and ecosystems around the world.

In this regard, the direction of solving the problem related to the organization of comprehensive monitoring of the state of the environment in the territories of closed mines is particularly relevant and important. Monitoring allows not only to identify and prevent negative environmental consequences, but also to develop effective measures to localize and eliminate pollution. The collected data can be used to make informed management decisions in the field of nature management and environmental protection. In addition, monitoring is an important tool for informing the public about the state of the environment and the risks associated with industrial activities ^[18-20].

The purpose of this study is to develop proposals and measures for planning restoration work to localize the negative environmental consequences of mine liquidation and ensure the safe functioning of the population of the mining territories of the Pechora coal basin located in the Arctic zone of Russia. This goal is achieved by analyzing environmental monitoring data, identifying the main sources of pollution and developing recommendations for their elimination.

2. Methodology and methods of research

As part of the presented work on integrated environmental monitoring in the territories of closed coal enterprises, a multi-year experimental research plan was implemented aimed at assessing the environmental consequences of mine liquidation and developing proposals for their localization. The main emphasis was placed on the study of hydrogeological, gas-geochemical and geodynamic processes occurring in the mining branches of the closed mines of the Pechora coal basin.

Hydrogeological monitoring included systematic measurements of the level of flooding of man-made horizons by mine waters, assessment of flooding and pollution of territories, as well as analysis of the quality of mine, groundwater and surface waters. Portable water quality analyzers such as the YSI ProDSS multiparameter probe were used to determine the chemical composition of water samples. The data obtained were used to assess the degree of contamination of water bodies with heavy metals, sulfates and other pollutants typical of mine waters. In addition, for a more detailed analysis of water samples from wells and surface reservoirs, the PerkinElmer AAnalyst 800 atomic absorption spectrometer was used in laboratory conditions, which allows determining the concentration of various elements with high accuracy.

Gas monitoring was aimed at controlling the release of harmful and dangerous gases, such as methane and carbon dioxide, to the Earth's surface, especially in residential facilities and in areas dangerous for gas release. For these purposes, portable gas analyzers MSA Altair 5X were used, capable of simultaneously measuring the concentration of several gases. Within the framework of geodynamic monitoring, observations of deformations of the Earth's surface at life support and vital activity facilities were carried out. Remote sensing methods were used to identify failures and insulation defects in previously eliminated workings, in particular, aerial photography using DJI Phantom 4 Pro unmanned aerial vehicles equipped with high-resolution cameras. The methane and carbon dioxide concentrations were measured using an MSA Altair 5X gas analyzer.

3. The results of the study

The long-term studies of the ecological condition of the territories of the liquidated coal mines of the Pechora coal basin carried out within the framework of comprehensive monitoring made it possible to form a detailed picture of the anthropogenic impact on the environment and identify the most acute environmental problems. The experimental work, which included systematic field observations, sampling and laboratory analyses, was aimed at assessing the hydrogeological, gas-geochemical and geodynamic conditions, as well as the state of the soil cover in the zones of influence of former coal mining enterprises.

Fig. 1. Location of the Pechora coal basin on the map of Russia

At the first stage, Earth remote sensing data was used to determine the boundaries of the areas most affected by man-made impacts. The analysis of Sentinel-2 and Landsat 8 satellite images processed using classification and decryption algorithms revealed areas of disturbed land with a total area of about 5,300 hectares, characterized by the absence of vegetation, the presence of erosion processes and signs of pollution. Special attention was paid to identifying potential sites of sinkholes and subsidence of the Earth's surface, for which the methods of radar image interferometry (InSAR) were used.

At the second stage, based on the analysis of remote sensing data and the results of a preliminary survey of the territories, a network of monitoring points was formed, including 120 water sampling points, 80 soil sampling points and 50 points for measuring the concentration of gases in the surface layer of the atmosphere. Water sampling was carried out from mine shafts, lakes, rivers and streams located near the liquidated mines, as well as from observation wells designed to monitor the level and quality of groundwater. Portable Grundfos MP 1 pumps and bathometric samplers were used for sampling. Soil samples were taken from various depths (0-20 cm, 20-50 cm, 50-100 cm) in areas of disturbed lands, rock dumps, industrial sites and agricultural lands. Air sampling was carried out using GilAir Plus aspiration units and activated carbon samplers to determine the concentration of organic pollutants.

At the third stage, the selected samples were subjected to laboratory analysis using modern analytical equipment. The content of petroleum products in water and soil was determined by gas chromatography with mass spectrometric detection on an Agilent 7890B/5977A chromatograph. Concentrations of gaseous pollutants in the air were determined using Testo 350 and Dräger X-am 5000 gas analyzers.

The results of long-term hydrogeological monitoring indicate an increasing environmental and man-made impact on the territory of the liquidated coal mines of the Pechora coal basin. The most significant changes are recorded in the form of intensive flooding of mine workings, changes in the chemical composition of mine and groundwater, degradation of the landscape and emissions of greenhouse gases and explosive gases. The average annual rate of rise in the mine water level for the period from 2010 to 2024 ranged from 0.5 to 1.5 meters per year, while in the last three years there has been an acceleration in the rate of rise to 1.7 m/year in some areas, due to a decrease in the efficiency of natural and artificial drainage. In particular, on the territory of the Intinskaya mine, which was closed in 1998, the mine water level rose by a total of 31.5 meters over the period 1999-2024, reducing the distance to the surface to a critical 3 meters. This confirms the high level of flooding, which poses a threat to infrastructure, the environment and the public.

Chemical and analytical studies conducted in 2023-2024 showed a further deterioration in the quality of mine waters. Mineralization reached values from 3,200 to 5,600 mg/l. The pH values remain low and range from 2.5 to 4.3, indicating increased acid drainage, especially in areas with a high content of pyrite-containing rocks. According to laboratory tests, the average iron concentration was 42 mg/l, with peak values up to 81 mg/l, which is 60% higher than the values recorded in the early 2010s. The concentration of manganese ranged from 9-19 mg/l, and the zinc content ranged from 3.5 to 8.2 mg/l. An increase in sulfate concentrations was recorded, in some areas (for example, near the depleted formations at the Yuzhnaya Vorgashorka site) — up to 5,100 mg/l, which is 25-30 times higher than the maximum permissible concentrations for water bodies of fishery importance (Table 1). This indicates the continued flow of acid mine waters into aquifers and the need for urgent remediation and water treatment measures.

Table 1. Dynamics of pollutant concentrations in the mine waters of the Pechora coal basin (2012-2024)

Fig. 2. Mouth of the Vorgashorka River on the territory of the Pechora coal basin

A comparative analysis of samples taken from the Vorgashorka River in 2012, 2018, and 2023 shows a steady downward trend in surface water quality. In 2023, the average iron concentration was 7.2 mg/l (MPC — 0.3 mg/l), which is 24 times higher than the standard. The concentration of manganese reached 3.4 mg/l (maximum concentration of 0.1 mg/l), and of sulfates — 2,900 mg/l with maximum concentration of no more than 100 mg/l. Sampling in the area of Promyshlennyj settlement and the Kapitonovka River catchment area in 2022 confirmed the presence of heavy metals even during periods of high water content, which indicates the persistent nature of pollution. Similar results were obtained in groundwater samples taken within a radius of 2-3 kilometers from the liquidated mines: iron — up to 14 mg/l, manganese — up to 5.8 mg/l, sulfates — up to 1750 mg/l. In some areas near the old pits, local contamination with copper (up to 1.2 mg/l) and lead (up to 0.4 mg/l) was noted, which had not previously been recorded on a regular basis.

Gas monitoring of closed mine areas also demonstrates the increasing environmental risks. According to the measurement results from 2022-2024, the average methane concentration near the ventilation shafts of the Zapolyarnaya and Severnaya mines was 3.1% vol., with maximum values up to 9.4%, which creates a constant threat of explosion. In the area of the Kapitalnaya mine dumps, where long-lasting smoldering areas are recorded, the concentration of co₂ in the surface air layer ranged from 0.7% to 1.6%, which is 2-3 times higher than the maximum permissible concentration (MPC) in residential areas (0.5%). New cases of methane penetration into the basements of residential buildings were registered in the villages of Vostochny and Severny in 2023, where the methane level reached 1.4%, exceeding the safe threshold by almost three times. This confirms the need for constant monitoring of the gas regime and ventilation of the mine cavities, even after their conservation.

Geodynamic monitoring data over the past 15 years demonstrate an increase in the processes of deformation of the Earth's surface. From 2010 to 2024, more than 55 failures of various scales were recorded in the Pechora Basin, including 16 cases that occurred over the past three years (Fig. 3-6). The diameter of the sinkholes ranged from 2 to 38 meters, and the depth from 1.5 to 19 meters. The largest of them was registered in 2023 in the area of the Yuzhnaya Vorgashorka mine, with a diameter of 42 meters and a depth of 21 meters. There is also an increase in the number of subsidence zones — in 2022, their area reached 1.7 km2, compared with 1.1 km2 in 2015 (Table 2). GPR studies have confirmed the presence of subsurface voids in previously unexplored areas. The activation of landslide processes was observed in the area of the left bank of the Usa River, where in 2024 there was a displacement of the soil to a depth of 1.3 m in an area of about 120 meters.

Table 2. Geodynamic risks: registered sinkholes in the Pechora coal basin (2010-2024)

Thus, the environmental situation in the area of the closed mines of the Pechora coal basin continues to deteriorate. Objective data from long-term observations indicate a steady increase in the mineral and gas load on the ecosystem of the region. Of particular concern is the increased acid drainage, the spread of toxic elements, as well as the increasing geomechanical risks. In the context of progressive climate change and melting of permafrost in the Arctic zone, the problem of degradation of underground infrastructure is becoming systemic and requires the development of comprehensive programs for wastewater disposal, degassing, remediation and monitoring. It is recommended to expand observation programs using remote sensing, geophysical methods, and AI systems for predicting sinkholes and gas emissions.

Fig. 3. Sinkholes and subsidence of soil in the territory of the closed mine of the Pechora coal basin

Fig. 4. Sinkhole on the territory of the closed mine of the Pechora coal basin

Fig. 5. Sinkhole in the Yun-Yaga mine

Fig. 6. The sinkhole on the outskirts of Vorkuta

An analysis of the ecological state of the soil cover in the territories of the liquidated coal mines of the Pechora coal basin in the Arctic zone of Russia showed the presence of significant contamination with both heavy metals and petroleum products. According to long-term monitoring observations conducted in 2020-2024 within the framework of the federal program "Clean Arctic", the average concentration of iron in soils in areas occupied by landfills reaches 2500 mg/kg with maximum values up to 5500 mg/kg, which exceeds the maximum permissible concentrations (MPC) by 3-7 times. The concentration of manganese averages 500 mg/kg (maximum - 1200 mg/kg), and the zinc content is 200 mg/kg (maximum — 450 mg/kg), which is also significantly higher than the regional background values (Table 3).

Table 3. Comparative characteristics of soil pollution in coal basins of Russia (2022)

The content of petroleum products in soils in industrial and adjacent territories reaches an average of 5,000 mg/kg, and in some areas pollution levels of up to 12,000 mg/kg were observed, which is almost 12 times higher than sanitary standards for soils in populated areas. According to Roshydromet and the Institute of Industrial Ecology of the North (IPPES of the KSC RAS), over the period 2021-2023, there was a further deterioration in the quality of soil cover, especially in conditions of active permafrost melting, which contributes to deeper penetration of pollutants into the subsurface horizons. This makes the territories completely unsuitable for agricultural use and requires large-scale measures for technical and biological reclamation.

When comparing with similar studies conducted in the Kuznetsk and Donetsk basins, it was revealed that the nature of soil pollution and the level of accumulation of toxicants in the Pechora basin are comparable to the most affected coal-producing regions. However, in the conditions of the Russian Arctic zone, the environmental consequences become particularly acute due to extreme climatic vulnerability, slow biochemical processes of self-purification and the limited ability of natural ecosystems to recover. According to observations in recent years, the average rate of decomposition of petroleum products in Arctic soils is no more than 1-3% per year, which is 5-6 times lower than in the temperate zone ^[18-20].

As a result of the analysis of archival materials, Sentinel-2 and Landsat-9 satellite survey data, as well as field research in 2023-2024, the total area of disturbed and polluted lands in the Pechora coal basin is estimated at 7,200 hectares. Of these, more than 80% are man-made landscapes where soils have lost their structure, biological activity, and water-physical properties. As of 2024, the volume of polluted mine waters to be treated has increased to 54 million cubic meters due to an increase in groundwater levels after the closure of workings.

Of particular concern are annual methane emissions, estimated in 2022-2024 at 10.2–10.7 thousand tons, which is about 0.3% of all anthropogenic methane emissions in Russia. According to the International Energy Agency (IEA, 2023), this has a noticeable impact on the climate of the region, contributing to further melting of ice and the destruction of cryogenic textures. Modeling the spread of methane fluids in bottomhole zones shows a significant potential for their utilization — up to 70% with the introduction of degassing systems with gas capture and reuse.

To eliminate the identified environmental risks, it is proposed to implement a comprehensive rehabilitation program based on the principles of best available technologies (BAT). One of the key areas is the construction of a new generation of wastewater treatment plants using multi-stage filtration, reverse osmosis and bioremediation methods. Such stations, successfully tested in Norilsk and Vorkuta in 2022-2023, can reduce the iron content in mine waters to 0.3 mg/l, manganese to 0.05 mg/l, and petroleum products to 0.1 mg/l, which meets drinking water quality standards (SanPiN 1.2.3685-21).

The second most important element of ecological restoration is phytoremediation using frost-resistant herbaceous and shrubby forms (in particular, Deschampsia caespitosa, Salix lanata, Festuca rubra) adapted to soils with a high level of toxicity. Experiments conducted in 2022 at the experimental landfills in Inta showed that the use of phytoremediation in combination with organomineral fertilizers can increase the humus content by 25%, and the penetrating root system helps reduce oil pollution by 40% over 3 growing seasons.

In the field of reducing climate risks, it is recommended to create degassing systems with simultaneous utilization of methane through modular gas generators. According to calculations by the Ministry of Energy of the Russian Federation, the use of such installations in 30% of the mine territory will produce up to 45 GWh of electricity annually and avoid emissions of about 8000 tons of CO₂ equivalent. Combined with energy storage technologies, this will provide additional sustainability to the region's energy infrastructure. Along with technical measures, the organization of specialized landfills for thermal stabilization and burial of heavily polluted soils is required. According to the project implemented in Nenets Autonomous District in 2023-2025, such landfills can reduce the residual toxicity of soils to hazard class IV, with the subsequent use of such soils in the construction of transport infrastructure. An equally important area is the construction of a continuous environmental monitoring system, including automated monitoring stations for water, air and soil quality, with data transmission to a single regional center in real time. According to data from 2024, 17 such stations are operating in Vorkuta, Usinsk and Inta, and by 2026 their number is planned to increase to 35. This will make it possible to quickly respond to pollution and adjust rehabilitation measures.

Thus, the implementation of the proposed measures will significantly reduce the anthropogenic impact on the ecosystems of the Pechora coal basin and ensure the transition to a sustainable model of environmental management in the Arctic zone.

4. Conclusions

As a result of the environmental monitoring of the territories of the liquidated coal mines of the Pechora coal basin, located in the Arctic zone of Russia, it was possible to obtain an extensive amount of data that made it possible to characterize the current state of the environment and identify the main sources of environmental threat. The study confirmed the high degree of pollution of the components of the natural environment — water, air, soil — and also revealed active geodynamic processes that pose a danger to settlements and infrastructure facilities. The analysis and systematization of these data made it possible to develop specific practice-oriented recommendations aimed at reducing the anthropogenic burden and increasing the environmental sustainability of the region.

The data obtained in the work confirms the intensive flooding of the mine workings of the liquidated mines. The level of mine waters rises at a rate of 0.5 to 1.5 meters per year, and in some areas, such as in the area of the Intinskaya mine, an increase of 25 meters was recorded as it approached the earth's surface at a critically short distance. This is accompanied by a significant deterioration in the quality of mine and groundwater, which has a high mineralization (up to 5,000 mg/l) and a low pH (up to 2.8). Similar pollution has been recorded in surface waters. These values indicate a high level of anthropogenic transformation of the hydrosphere and the need for the immediate implementation of deep cleaning systems for mine and drainage waters.

Gas and geochemical monitoring revealed dangerous levels of methane and carbon dioxide emissions. At some observation points, the concentration of methane reaches 8.5%, and carbon dioxide — 1.5%, which creates explosion risks, especially near ventilation shafts and burning dumps. The presence of methane in the basements of residential buildings, where a value of up to 1.2% is recorded, indicates a real threat to the livelihood of the population. This requires the adoption of prompt measures for the degassing of underground workings and ventilation of residential infrastructure.

Geodynamic analysis has shown that the consequences of mine liquidation include surface deformations, the formation of sinkholes (up to 35 meters in diameter and up to 18 meters deep) and the activation of landslide processes. These phenomena are caused by decompression of the underground massif as a result of flooding and chemical leaching. Over the past 10 years, more than 30 major failures have been recorded that threaten the stability of ground facilities. This requires the creation of a system for permanent remote monitoring of the Earth's surface and the adoption of preventive measures for engineering soil stabilization.

Significant contamination of the soil cover was confirmed by sample analysis. The obtained indicators indicate complete degradation of soils, especially in areas of industrial sites and rock dumps, making them unsuitable for agricultural or other use without deep reclamation. The use of bioremediation, phytoremediation and heat treatment are promising methods for restoring soil fertility.

The quantitative estimates of the scale of environmental damage obtained in the study convincingly demonstrate the critical state of the territory: polluted lands cover an area of up to 7,000 hectares, annual methane emissions are estimated at 10,000 tons, and the volume of polluted mine waters is up to 50 million m3. This not only threatens the biotic components of ecosystems, but also directly affects the health and safety of the population. To solve the problem of pollution, the following measures can be applied: the construction of modern sewage treatment plants using reverse osmosis technology, reclamation using organic fertilizers and phytoremediation, methane utilization at power plants, the creation of a permanent monitoring system and environmental education of the population.