Search Results (172)

In the process of the work of a coal power station is formed ash and slag, which, along with process water, are deposited in the dumps. Coal ash waste dumps significantly degrade the surrounding environment due to their unprotected surfaces, which are highly susceptible to wind and water erosion. This results in the dispersion of contaminants into adjacent ecosystems. Pollutants migrate into terrestrial and aquatic systems, compromising soil quality and water resources, and posing documented risks to the environment and human health. Primary succession on the coal ash dumps of the Apatity thermal power plant (Murmansk Region, NW Russia) was initiated by cyanobacterial colonization. We studied cyanobacterial communities inhabiting three spoil sites that varied in time since decommissioning. These sites are characterized by exceptionally high concentrations of calcium and magnesium oxides—levels approximately double those found in the region’s natural soils. A total of 18 cyanobacterial taxa were identified in disposal sites. Morphological analysis of visible surface crusts revealed 16 distinct species. Furthermore, 24 cyanobacterial strains representing 11 species were successfully isolated into unialgal culture and tested with a molecular genetic approach to confirm their identification from 16S rRNA. Three species were determined with molecular evidence. Cyanobacterial colonization of coal fly ash disposal sites begins immediately after deposition. Primary communities initially exhibit low species diversity (four taxa) and do not form a continuous ground cover in the early years. However, as succession progresses—illustrated by observations from a 30-year-old deposit—spontaneous surface revegetation occurs, accompanied by a marked increase in cyanobacterial diversity, reaching 12 species. Full article

Anthropogenic revegetation allows effective and timely soil development in mine restoration areas. The evaluation of soil quality is one of the most important criteria for measuring reclamation effectiveness, providing scientific reference for the subsequent management of ecological restoration projects. The aim of this research was to further investigate the influence of revegetation on mine-reclaimed soils in a semi-arid region. Thus, a coal-gangue dump within the afforestation chronosequence of 1 and 19 years in Shanxi Province, China, was selected as the study area. We assessed the physicochemical properties and nutrient stock of topsoils under four revegetation species, i.e., Pinus tabuliformis (PT), Medicago sativa (MS), Styphnolobium japonicum (SJ), and Robinia pseudoacacia ‘Idaho’ (RP). A two-way ANOVA revealed that reclamation age significantly affected SOC, TN, EC, moisture, and BD (p < 0.05), while the interaction effects of revegetation type and age were also significant for TN and moisture. In addition, SOC and TN stocks at 0–30 cm topsoil at the RP site performed the best among 19-year reclaimed sites, with an accumulation of 62.09 t ha⁻¹ and 4.23 t ha⁻¹, respectively. After one year of restoration, the MS site showed the highest level of SOC and TN accumulation, which increased by 186.8% and 88.5%, respectively, compared to bare soil in the 0–30 cm interval, but exhibited declining stocks during the 19-year restoration, possibly due to species invasion and water stress. In addition, an integrated soil quality index (ISQI) and the partial least squares structural equation model (PLS-SEM) were used to estimate comprehensive soil quality along with the interrelationship among influencing factors. The reclaimed sites with an ISQI value > 0 were 19-RP (3.906) and 19-SJ (0.165). In conclusion, the restoration effect of the PR site after 19 years of remediation was the most pronounced, with soil quality approaching that of the undisturbed site, especially in terms of soil carbon and nitrogen accumulation. These findings clearly revealed the soil dynamics after afforestation, further providing a scientific basis for choosing mining reclamation species in the semi-arid regions. Full article

Coal gangue, a primary byproduct of coal mining, causes significant environmental harm due to its improper utilization. This research proposes integrating microalgae with coal gangue-derived ecological products to improve soil conditions in ecologically vulnerable coal-mining regions. A field-scale experiment at the Jintong Coal Mine tested soils amended with varying proportions of a coal gangue ecological matrix (0%, 10%, 30%, and 50%), with and without microalgae inoculation. The results demonstrated that coal gangue addition caused undesirable soil pH decreases (11.30~42.20%) while increasing total dissolved solids (506.88~524.93%) and organic matter (8.51~46.81%). These effects were mitigated by the presence of microalgae. Microalgae play a role in regulating soil nutrient profiles, enhancing enzymatic activities, and modulating the microbial community structure. For example, they restored catalase activity under the stress imposed by coal gangue and stimulated urease activity at higher coal gangue proportions. Plant growth trials revealed that adding 30% coal gangue or combining coal gangue with microalgae significantly promoted the growth of Medicago sativa L. In summary, coupling the coal gangue ecological matrix with microalgae effectively enhances soil quality. Maintaining the coal gangue addition at 30% or less in conjunction with microalgae application represents an optimal approach for soil improvement in mining areas. Full article

Coal mines play an important role in the global energy supply. Monitoring the displacement of open-pit mines is crucial to preventing geological disasters, such as landslides and surface displacement, caused by high-intensity mining activities. In recent years, multi-temporal Synthetic Aperture Radar Interferometry (InSAR) technology has advanced and become widely used for monitoring the displacement of open-pit mines. However, the scattering characteristics of surfaces in open-pit mining areas are unstable, resulting in few coherence points with uneven distribution. Small BAseline Subset InSAR (SABS-InSAR) technology struggles to extract high-density points and fails to capture the overall displacement trend of the monitoring area. To address these challenges, this study focused on the Shengli West No. 2 open-pit coal mine in eastern Inner Mongolia, China, using 201 Sentinel-1 images collected from 20 May 2017 to 13 April 2024. We applied both SBAS-InSAR and distributed scatterer InSAR (DS-InSAR) methods to investigate the surface displacement and long-term behavior of the open-pit coal mine over the past seven years. The relationship between this displacement and mining activities was analyzed. The results indicate significant land subsidence was observed in reclaimed areas, with rates exceeding 281.2 mm/y. The compaction process of waste materials was the main contributor to land subsidence. Land uplift or horizontal displacement was observed over the areas near the active working parts of the mines. Compared to SBAS-InSAR, DS-InSAR was shown to more effectively capture the spatiotemporal distribution of surface displacement in open-pit coal mines, offering more intuitive, comprehensive, and high-precision monitoring of open-pit coal mines. Full article

The process of anthropogenic pedogenesis has necessarily become an important aspect of the study of today’s soils. The sustainable reclamation or remediation of soils degraded by industrial or mining activities is currently of great interest worldwide. In this field, the study of thin soil sections can provide relevant answers, particularly to questions concerning the evolution of these soils under the impact of reclamation practices. Here, we describe an experiment to reclaim former rare earth element mining sites in China using organic soil amendments and plantations of a local fiber plant, Boehmeria nivea. Two years after the start of the experiment, a study of soil structure, considered as an indicator of soil biofunctioning, was carried out on the different plots, supplemented by monitoring of physico-chemical properties. Morphological (light microscopy) and analytical (SEM-EDX, µ-XRF) characterization of thin sections allowed us to pinpoint some pedological processes as aggregation with particular reference to the contribution of biological factors and mineral species, highlighting the impact of the practices implemented. Using a soil micromorphology approach enabled us to track the rapid evolution of the early stages of pedogenesis of these Technosols and to provide insight into the potential for reclamation of these mined sites in the future. Full article

This study was conducted at a fixed monitoring site in the southern dump of the large-scale Antaibao open-pit coal mine of China Coal Pingshuo, using long-term monitoring methods. Based on data from 2019 and 2024 in the reclaimed area of the Pingshuo open-pit coal mine, all seedlings and saplings within the Robinia pseudoacacia L. + Ulmus pumila L. + Ailanthus altissima (Mill.) Swingle mixed forests were studied to analyze changes in their abundance and the driving factors influencing their survival rates from 2019 to 2024. The main conclusions are as follows: (1) The species composition of seedlings and saplings remained unchanged but the number of seedlings increased significantly. The majority of newly recruited seedlings were U. pumila., accounting for 92.22% of the total new seedlings, whereas R. pseudoacacia had the highest mortality rate among seedlings. The distribution patterns of seedling-to-sapling transition, sapling-to-tree transition, and seedling–sapling mortality were generally consistent with the overall distribution of seedlings and saplings at the community level. (2) At both the community and species levels, the optimal models for seedling and sapling survival were the height model and the biological factor model. Overall, survival rates of both seedlings and saplings showed a significant positive correlation with height. (3) The biological factors affecting the survival of U. pumila saplings were the basal area (BA) at breast height and the number of conspecific adult trees. The former was significantly negatively correlated with U. pumila seedling survival, while the latter was positively correlated. For R. pseudoacacia seedlings, the key biological factors were the number of heterospecific adult trees and the number of heterospecific seedlings. The former was significantly negatively correlated with survival, whereas the latter was significantly positively correlated. The primary factor influencing sapling survival was sapling height, which showed a significant positive correlation. Full article

Soil reclamation is essential for restoring the ecological environment in coal mining subsidence areas, with reclaimed soil quality serving as a key indicator of success. Traditional evaluation methods often rely on subjective judgment, leading to potential biases. This study proposes an approach combining cluster analysis (CA), correlation degree analysis (CDA), principal component analysis (PCA), and membership function (MF) to evaluate soil reclamation quality in the Ezhuang subsidence area, Shandong Province, China. A minimum dataset (MDS) was established, including seven indicators: exchangeable magnesium, total nitrogen, available copper, available manganese, zinc, free iron, and available silicon. Soil quality indices (SQIs) were calculated using membership functions, revealing moderate soil quality across the reclamation area, with significant spatial variations. The northeastern section exhibited relatively good soil quality, while the northwestern and southeastern sections were poorer. Key factors influencing soil quality included variations in organic matter, exchangeable magnesium, and available copper. The accuracy of the CA-CDA-PCA-MF method was validated, with a coefficient of determination (R²) of 0.877 and a coefficient of deviation (CV) of 0.053, demonstrating its reliability. This method provides a robust tool for evaluating and improving soil restoration in mining areas, with potential applications in similar reclamation projects. Full article

Reclaiming land after mining activities and ensuring environmental protection are mandatory aspects of the decommissioning process for mining sites. Groundwater assessments, particularly those evaluating vulnerability to contamination using the DRASTIC rank method, are critical tools for guiding and controlling reclamation efforts. By analysing changes in hydrogeological and environmental factors, as well as parameter classes through sensitivity analyses, the DRASTIC method can be optimised to predict the effects of reclamation. Results indicate that reclamation typically decreases groundwater vulnerability, as evidenced by a shallower water table, reduced recharge volume, groundwater flow within new waste rock formations, changes in soil types, lower slopes, and reduced conductivity. Vulnerability changes during reclamation vary spatially, including both decreases and localised increases. Reclamation planning should prioritise groundwater vulnerability assessments to ensure effective land use and environmental protection. Modifications to groundwater-monitoring networks, especially in areas prone to flooding and significant surface changes, are also essential for comprehensive reclamation management. Full article

Soil organic carbon (SOC) is essential for maintaining ecosystem health, and its depletion is widely recognized as a key indicator of soil degradation. Activities such as mining and wildfire disturbances significantly intensify soil degradation, leading to quantitative and qualitative declines in SOC. Accurate SOC monitoring is critical, yet traditional methods are often costly and time-intensive. Advances in technologies like Unmanned Aerial Vehicles (UAVs) and satellite remote sensing (SRS) now offer efficient and scalable alternatives. Combining UAV and satellite data through machine learning (ML) techniques can improve the accuracy and spatial resolution of SOC monitoring, facilitating better soil management strategies. In this context, this study proposes a methodology that integrates geochemical data (SOC) with UAV-derived information, upscaling the UAV data to satellite platforms (GEOSAT-2 and SENTINEL-2) using ML techniques, specifically random forest (RF) algorithms. The research was conducted in two distinct environments: a reclaimed open-pit coal mine, representing a severely degraded ecosystem, and a high-altitude region prone to recurrent wildfires, both characterized by extreme environmental conditions and diverse soil properties. These scenarios provide valuable opportunities to evaluate the effects of soil degradation on SOC quality and to assess the effectiveness of advanced monitoring approaches. The RF algorithm, optimized with cross-validation (CV) techniques, consistently outperformed other models. The highest performance was achieved during the UAV-to-SENTINEL-2 upscaling, with an R² of 0.761 and an rRMSE of 8.6%. Cross-validation mitigated overfitting and enhanced the robustness and generalizability of the models. UAV data offered high-resolution insights for localized SOC assessments, while SENTINEL-2 imagery enabled broader-scale evaluations, albeit with a smoothing effect. These findings underscore the potential of integrating UAV and satellite data with ML approaches, providing a cost-effective and scalable framework for SOC monitoring, soil management, and climate change mitigation efforts. Full article

Biomonitoring based on foliage chemistry was used to study the effects of environmental sulfur (S) pollution on forest stands. The foliage samples were collected in two forest ecosystems exposed to industrial emissions: a zinc (Zn) and lead (Pb) smelter plant in Silesia (HCM) and a reclaimed forest on the site of the former borehole S mine Jeziórko (FJSM), in the Tarnobrzeg S deposit region (southern Poland). Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth.) foliage chemistry was analyzed: S (using a TruMac CNS analyzer, Leco Corporation, Saint Joseph, MI, USA), N, P, K Ca, and Mg, and trace elements (Zn, Cd, Pb, Al, Fe, Mn, Cu) using an ICP OES ICAP 6000 spectrometer, Thermo Fisher Scientific, Waltham, MA, USA),. At the HCM site, 20 monitoring points were located in the forest at different directions and at varying distances from the smelter plant. At the FJSM site, 16 sampling points were distributed depending on vegetation type and tree species abudance. The S content in foliage was generally high at both sites. However, at the HCM site, the highest S content was found in areas close to the smelter plant (1664 mg kg⁻¹) and decreased linearly according to the direction of the dominant wind to the east (1098 mg kg⁻¹). S was correlated with Zn, Cd, and Pb (the main elements produced in the smelter plant). At the FJSM site, high S concentrations were observed in degraded soil areas (4816 mg kg⁻¹ in birch, 1563 mg kg⁻¹ in pine). These areas were hot spots that had the highest amount of S in the soil. These results indicate high biosorption of the pollutant by trees. The S concentration was also higher in birch (B) than in pine (P) foliage (regular forest: 1954 mg kg⁻¹ in B, 1272 mg kg⁻¹ in P; degraded area: 4816 mg kg⁻¹ in B, 1563 mg kg⁻¹ in P), and the differences were significant in the degraded areas. At the FJSM site, S was also correlated with Zn and, to a lesser extent, with Cd and Pb. S also influenced nutrient element supply status, in particular Mg. We confirmed that tree foliage chemistry reflects the state of the environment in highly polluted areas, so biomonitoring should be used to assessment of environmental pollution. Full article

Mining activities in arid regions of China have led to severe environmental degradation, including soil erosion, vegetation loss, and contamination of soil and water resources. These impacts are particularly pronounced in abandoned mining areas, where the cessation of mining operations has left vast landscapes unrehabilitated. In response, the Chinese government has implemented a series of legal and regulatory frameworks, such as the “Mine Environmental Protection and Restoration Program”, aimed at promoting ecological restoration in these areas. However, the unique environmental conditions of arid regions, including water scarcity, extreme temperatures, and poor soil quality, present significant challenges to restoration efforts. This review provides a comprehensive analysis of the ecological restoration of abandoned mining areas in China’s arid regions, focusing on the legal framework, restoration techniques, and evaluation systems. The restoration methods, their initiation timelines, monitoring systems, and the cost–benefit aspects of various strategies are critically reviewed alongside case studies from regions such as the Mu Us Desert and Qaidam Basin. Key strategies like phytoremediation, soil rehabilitation, and water resource management are assessed for their effectiveness, while challenges in enforcement, socioeconomic integration, and community engagement are discussed. This review concludes that while significant progress has been made, further improvements in restoration practices and evaluation systems are essential for long-term sustainability. Integration of socioeconomic indicators, community involvement, and advanced monitoring technologies are necessary for successful outcomes. Full article

Ion adsorption rare earths are an important strategic resource, but their leach mining causes post-mining wastelands and tailings to suffer from soil sanding, acidification, and heavy metal contamination. This makes natural vegetation recovery difficult, relying mainly on artificial reclamation; however, the reclaimed vegetation grows poorly due to environmental stress. Hyperspectral remote sensing technology, with its high efficiency, non-destructive nature, and wide-range monitoring capability, can accurately estimate the physiological parameters of reclaimed vegetation. This provides support for environmental regulation in mining areas. In this study, three typical types of reclaimed vegetation in the Lingbei Rare Earth Mining Area, Dingnan County, Ganzhou City, were analyzed. Hyperspectral data and the corresponding chlorophyll content were collected to compare the spectral differences between reclaimed and normal vegetation. The spectral data were processed using mathematical transformation, fractional order differentiation, discrete wavelet transform, and continuous wavelet transform. Sensitive bands were extracted, and multispectral transformed feature bands were integrated. Linear and machine learning regression models were used to estimate chlorophyll content. The effects of different spectral processing methods on chlorophyll estimation were then analyzed. The results showed that reclaimed vegetation had higher spectral reflectance than normal vegetation, with the red valley shifting towards the long-wave direction and a steeper red edge slope. Different spectral transformation methods impact the accuracy of chlorophyll content estimation. Using appropriate methods can improve estimation accuracy. Fusing multi-spectral transformation features can achieve relatively good results. Among the models, the random forest regression model provides the best performance in estimating the chlorophyll content of reclaimed vegetation. This study provides a scientific basis for rapid and accurate monitoring of reclaimed vegetation growth in rare earth mining areas, supporting environmental management and decision-making and contributing to ecological restoration. Full article

Active vegetation restoration plays an important role in the improvement in soil organic matter (SOM), including the carbon (C), nitrogen (N) and phosphorus (P) sequestration of degraded mining ecosystems. However, there is still a lack of understanding of the key drivers of SOM pool size and dynamics in active vegetation restoration. For this study, soil was collected from five different sites (Xiaoxian, Dingyuan, Chaohu, Tongling and Dongzhi), four habitats (platforms, slopes, steps and native areas) and two soil layers (0–20 cm and 20–40 cm) in limestone mines of Anhui province to quantify the spatial distribution of SOM contents and their stoichiometric characteristics and influential factors. It was found that the top soil in Chaohu had the highest significant C, N and P contents in the ranges of 14.95–17.97, 1.74–2.21 and 0.80–1.24 g/kg, respectively. Comparing the stoichiometric ratios of the different sites revealed significant differences in C:N and N:P ratios, but C:P ratios were relatively consistent. In particular, the C:N and C:P ratios in deep soil were higher than those in top soil, whereas the N:P ratio in deep soil was lower than that in top soil, suggesting that soil N is a major limiting factor in the top soil. The SOM content did not differ significantly between the three reclaimed habitats, but was significantly higher than that in the native habitat, suggesting that mine restoration has significantly enhanced SOM accumulation. Further analysis showed that nutrient availability and enzyme activity are important factors affecting soil C, N and P content in top soil, while the relationship gradually weakens in deep soil. This was attributed to active anthropogenic management and conservation measures during the early stages of reclamation. This study shows that the ecological recovery of the mining area can be enhanced by implementing differentiated vegetation planting strategies and anthropogenic management on different habitats in the mining area. Full article

Coal mine tailings can lead to a range of environmental problems, including toxic metal contamination, soil erosion, acid mine drainage, and increased salinity. Mine spoils from coal mining activities accumulated as gob piles are difficult to reclaim due to constraints such as a steep slope, unsuitable pH, insufficient nutrient supply, metal toxicity, low water-holding capacity, and poor soil structure. We investigated the efficiency of low-cost amendments on coal gob spoils from Carthage Coal Field (CCF) in New Mexico in improving the quality of coal gob spoils. Gob spoil was incubated for 90 days with various rates of organic amendments such as biochar, compost, and a biochar–compost mix. Gob spoil quality parameters such as the pH, water-holding capacity, and total and plant-available nitrogen and phosphorus content of the gob spoil were measured over a period of 90 days. Both biochar and compost amendment led to a significant increase (40–60% for biochar and 70% for compost, p < 0.05) in water-holding capacity of the coal gob spoil. Plant-available nitrogen content increased from <200 mg N/kg to between 400 and 800 mg N/kg in the amended gob spoil. The period of incubation was a significant factor in the improvement of plant-available nitrogen content. Plant-available phosphorus content also increased; compost amendment was more effective than biochar in increasing plant-available P. This study provides crucial information about the optimum organic amendments that would help in optimizing a sustainable reclamation method for CCF. Full article

The utilization of fast-growing, economically valuable woody plants with strong stress resistance, such as poplar and willow, to revegetate severely metal-contaminated mine tailings not only offers a productive and profitable use of abandoned polluted soil resources but also facilitates the phytoremediation of these polluted soils. This study examines the diversity and functional roles of endophytic fungi naturally colonizing the roots of an artificially established Populus yunnanensis forest and the naturally reclaimed pioneer species Coriaria sinica on an abandoned tailing dam in southwest China. Culture-independent analyses revealed that the root systems of both plant species were abundantly colonized by arbuscular mycorrhizal fungi and endophytic fungi, forming rich and diverse endophytic fungal communities predominantly represented by the genera Ilyonectria, Tetracladium, Auricularia, and unclassified members of Helotiales. However, the composition of root endophytic fungal communities differed significantly between the two plant species. Using a culture-dependent approach, a total of 192 culturable endophytic fungal strains were isolated from the roots. The dominant genera included Cadophora, Cladosporium, Cyphellophora, and Paraphoma, most of which were previously identified as dark septate endophytes (DSE). Six representative DSE strains were selected for further study, and significant cadmium tolerance and various plant growth-promoting traits were observed, including the solubilization of insoluble inorganic and organic phosphorus, indole-3-acetic acid (IAA) production, and siderophore synthesis. In greenhouse experiments, inoculating two DSE strains mitigated the inhibitory effects of metal-polluted tailing soil on the growth of P. yunnanensis. This was achieved by reducing heavy metal uptake in roots and limiting metal translocation to the above-ground tissues, thereby promoting plant growth and adaptability. Our findings suggest that as plants reclaim metal-polluted tailings, root-associated endophytic fungal communities also undergo natural succession, playing a critical role in enhancing the host plant’s tolerance to stress. Therefore, these restored root-associated fungi, particularly DSE, are essential functional components of the root systems in plants used for tailing reclamation. Full article