Coal Spoil Research Articles

Influence of reclamation techniques and vegetation types on water retention in hard coal spoil heaps

AbstractThis study examines the relationship between the reclamation method (with topsoil and with bare rock), individual species, and land cover (woodland, grassland, and forbsland) on micro‐climate and retention properties, that is, volumetric water content (vwc) and water storage capacity (S). The large overburden dump “Sośnica” in Upper Silesia served as a research site, which makes it possible to investigate the planned experimental variants with relatively homogeneous properties of the deposited rock. The study uses statistical analysis and multilinear regressions to investigate the correlation between reclamation method, species, and land cover with parameters such as atmospheric temperature, relative humidity, vwc, soil temperature (st), and S. The experiments were carried out both in the field and in the laboratory. The results of this study indicate that the parameters related to retention properties were higher in the recultivated areas than in the areas left to natural succession. “S” was significantly higher in grassland and forbsland (15.67–16.52%) than in control plots where 10.23% was found, and in areas where an additional soil layer was applied (14.72%). Maximum vwc (22.17%) was on plots with topsoil than on bare rock (14.89%). Vwc were highest in the areas designated as grassland (28.54%), in comparison with woodlands and forblands (the control without vegetation cover had the worst thermal and retention properties). This study sheds light on the effects of reclamation method, species, and land cover on various parameters and helps to understand the importance of appropriate reclamation techniques for soil and water conservation. Further research on the impacts of reclamation techniques and land cover on micro‐climatic conditions in diverse post‐mining landscapes is crucial for developing globally applicable restoration strategies that promote ecological resilience.

Nutrient uptake efficiency and stoichiometry for different plant functional groups on spoil heap after hard coal mining in Upper Silesia, Poland

Various plant functional groups (PFGs) used in the reclamation of post-mining heaps may differ in their nutrient uptake efficiency and thus in their effect on the ecosystem development. The effect of PFGs may be additionally modified by the applied reclamation measures such as e.g. topsoiling. In this study we compared the nutrient uptake efficiencies and plant stoichiometry for two PFGs (grasses and forbs) growing on the sites reclaimed by applying topsoil (TS) and unreclaimed sites on carboniferous bare rock (BR) in hard coal spoil heap in Upper Silesia (southern Poland). Basic soil parameters, including pH, texture, soil organic carbon, and nutrients (N, P, K, Ca, and Mg), were measured, and the aboveground plant biomass and nutrient content in plant tissue were determined. Forbs were characterized by a larger biomass and higher nutrient concentrations (except for P) than grasses. The TS treatment supported higher concentrations of N and P in plant tissues but not to the level ensuring more significant primary biomass production. The nutrient concentration and elemental stoichiometry in plant tissue indicated that N was the primary limiting element. However, the major growth limitation for N-fixing forbs was from P. Forbs were much more efficient in nutrient uptake than grasses, independent of the reclamation treatment. Therefore, they stimulate nutrient cycling in the restored ecosystems more than grasses.

Geotechnical characterisation of coal spoil piles using high-resolution optical and multispectral data: A machine learning approach

Geotechnical characterisation of spoil piles has traditionally relied on the expertise of field specialists, which can be both hazardous and time-consuming. Although unmanned aerial vehicles (UAV) show promise as a remote sensing tool in various applications; accurately segmenting and classifying very high-resolution remote sensing images of heterogeneous terrains, such as mining spoil piles with irregular morphologies, presents significant challenges. The proposed method adopts a robust approach that combines morphology-based segmentation, as well as spectral, textural, structural, and statistical feature extraction techniques to overcome the difficulties associated with spoil pile characterisation. Additionally, it incorporates minimum redundancy maximum relevance (mRMR) based feature selection and machine learning-based classification. This automated characterisation will serve as a proactive tool for dump stability assessment, providing crucial data for improved stability models and contributing to a greener and more responsible mining industry .

How applied reclamation treatments and vegetation type affect on soil fauna in a novel ecosystem developed on a spoil heap of carboniferous rocks

The restoration of soil fauna on a spoil heap is a strong indicator of successful reclamation. The studies were conducted on two types of materials: bare rock (BR) and BR with topsoil (TS) which were applied during coal spoil reclamation and three vegetation types. Four variants investigated included natural forest succession on BR (Succession_BR) and TS (Succession_TS), afforestation (Reclamation_TS) and afforestation with Robinia pseudoacacia (Robinia_TS). Soil pH, soil organic carbon (SOC) and total nitrogen (TN) content, and soil texture were measured in 0–10 cm layers. Earthworms were collected using hand sorting method, and enchytraeids were collected using wet extraction with the heating method.The investigated soil had varying pH values from 5.3 in a BR to 7.2 in Robinia_TS. The highest content of SOC and TN were in Successinon_BR, and the lowest was in Succession_TS. Enchytraeids density was in the following increasing order: 275, 2982, 3001 and 4548 ind m−2 for Succession_BR, Robinia_TS, Succession_TS and Reclamation_TS, respectively. Earthworm density ranged from 0 ind. m−2 in the Succession_BR through 116 ind m−2 and 120 ind m−2 in Reclamation_TS and Succession_TS, respectively up to 162 ind m−2 in the Robinia_TS.The reclamation treatment was a major driver for soil fauna development while vegetation type was of secondary importance. Investigated soil fauna was positively related to pH value and clay content. The most stimulating variant for the development of earthworms and enchytraeids was the application of reclamation with various tree species and the planting of Robinia pseudoacacia on the topsoil.

Spoil characterisation using UAV-based optical remote sensing in coal mine dumps

The structural integrity of mine dumps is crucial for mining operations to avoid adverse impacts on the triple bottom-line. Routine temporal assessments of coal mine dumps are a compliant requirement to ensure design reconciliation as spoil offloading continues over time. Generally, the conventional in-situ coal spoil characterisation is inefficient, laborious, hazardous, and prone to experts' observation biases. To this end, this study explores a novel approach to develop automated coal spoil characterisation using unmanned aerial vehicle (UAV) based optical remote sensing. The textural and spectral properties of the high-resolution UAV images were utilised to derive lithology and geotechnical parameters (i.e., fabric structure and relative density/consistency) in the proposed workflow. The raw images were converted to an orthomosaic using structure from motion aided processing. Then, structural descriptors were computed per pixel to enhance feature modalities of the spoil materials. Finally, machine learning algorithms were employed with ground truth from experts as training and testing data to characterise spoil rapidly with minimal human intervention. The characterisation accuracies achieved from the proposed approach manifest a digital solution to address the limitations in the conventional characterisation approach.

Thermal signatures of relict coal spoil, waste and tailing dumps

ABSTRACT As relict features of coal mines, carbonaceous spoil, waste and tailing dumps remain susceptible to coal oxidation and thermal decomposition, together with spontaneous combustion. Modern methods for monitoring surface thermal signatures regularly include the use of UAV’s, equipped with suitably sensitive infrared cameras. Detection of sub-surface thermal anomalism includes Vegetation Index Monitoring and/or the use of in-ground probes. Research across thermally active tailings offers insights into how best apply these two techniques, and increasingly the required scheduling of UAV surveys.

Changes in microbial community structure during the biooxidation of iron and inorganic/organic sulfur provide prediction of acid mine drainage from coal spoil

To thoroughly investigate the formation mechanism of acid mine drainage (AMD) from coal mine spoil, this study conducted microbial shake flask experiments on gangue possessing inorganic and organic sulfur to predict the future generation of AMD. The results revealed that microbial-mediated sulfur oxidation effectively lowered the pH of leachate and increased metal ion and sulfate concentrations. The oxidation of pyrite sulfur and thiophene sulfur contributed to 70 % and 30 % of the total acid production, respectively, highlighting the importance of both processes in coal mine acidification. The abundance and diversity of the microbial community increased, with “new” iron and sulfur oxidizing bacterial species during acidification, with “new” iron and sulfur oxidizing bacterial species, such as Sulfobacillus sp. and Acidibacillus sp., emerging and constituting approximately one-third of the bacterial population. These bacteria survived desiccation and proliferated faster than A. ferrooxidans YQ-N3 when conditions favored growth.

Comparison of rehabilitation treatments on mechanically reconstructed soils following strip coal mining activities: effects on soil properties

A rainfed rehabilitation trial on mechanically reconstructed soil, following strip coal mining, was laid out in the Mpumalanga Province of South Africa. It was used to evaluate seven rehabilitation treatments with four different depths of topsoil on coal spoil over three experimental seasons. A strip plot design was used to apply the treatments. The test crop was a grass mixture comprising of annual and perennial species. Trial measurements included soil physical, chemical and microbiological measurements, as well as growth and composition of the grass stand. Monthly rainfall was very variable with annual totals below the long-term values. Statistical significance was proved for most measurements. Relatively high soil bulk densities, stratified with depth, were measured, indicating undesirable soil compaction. Infiltration rates increased while soil strength decreased dramatically with increased topsoil thickness. A reciprocal interaction of profile water content and biomass yield was observed with water content decreasing as biomass yield increased. A large variation in soil chemical properties was observed as a function of the treatments. This study highlights the fact that the monitoring of soil and plant properties should be a prerequisite in any rehabilitation study. Similar trials on different soils and in different rainfall regions should be considered to expand our knowledge of the impacts of different soil treatments in a range of ecosystems.

Chemical and sanitary assessment of coal spoil heaps in the south of the Kuznetsk Basin

Due to the large amount of pollution at coal spoil heaps, soil reclamation is slow and requires development and use of microbial preparations, selected based on assessments of the biochemical parameters of soil and the extent of its contamination. The material for this study was mine soils sampled in three different zones (Ka, Kb, Kc) of the Korchakol coal spoil heap. The studied sanitary and chemical indicators did not exceed the approximate permissible concentrations (APC) / maximum allowable concentrations (MAC), except for oil products (in the Ka, Kb, Kc zones, the excess averaged 2.2, 1.4, 1.2 times, respectively). The study found a direct correlation between the zinc content and the enzymatic activity of polyphenol oxidase, the level of Ni and peroxidase, as well as an inverse correlation between the As and Cu concentrations with invertase and nitrite reductase, respectively. The index of bacteria of the Escherichia coli group (coliform bacteria) in different zones exceeded the standard values by 61 and 171 times. Even though the sanitary indicators studied do not exceed permissible levels, they can slow down growth and development of plants. Thus, successful reclamation of mine soils requires introduction of biological preparations based on microorganisms that biotransform heavy metals and rhizobacteria.

Efficiency of Vegetative Reclamation of Coal Spoil Heaps

Efficiency of Vegetative Reclamation of Coal Spoil Heaps

Reclaiming Open Coal Spoils by Mixed Woodland: Varteg (Wales), 10 Year Results

Many reclaimed opencast coal-lands in Wales are now seriously degraded. This study explores the 10-year growth of native trees planted on compacted coal spoil. It compares the relative benefits of planting with spent mushroom compost (SMC) or well-rotted farmyard manure (FYM), both with and without supplementary fertilizer. Four main tree species—Common Alder, Oak, Scots Pine and Silver Birch—are considered. The survival of SMC-planted trees (77%) was significantly higher than for FYM-planted (72%). In Year 10, SMC-planted trees were significantly taller than those planted with FYM (4.75 vs. 4.57 m, respectively). Similarly, basal diameter (measured above the root collar) was larger among the SMC-planted trees. Discriminant analysis showed that the key discriminating variable between SMC-planted and FYM-planted trees was the type of fertilizer applied during planting. Adding slow-release fertilizer (SRF) and SRF plus superphosphate (SRF + P2O5) was beneficial to FYM-planted trees. Fertilizer supplements often favor the growth of FYM-planted trees in the early years, but later SMC-planted trees take the lead. The only species that benefited long term from FYM or fertilizer supplements was Alder. Overall, SMC-planted trees perform better than FYM-planted trees, but some of the difference can be mitigated by supplementary fertilization. Overall, SMC-planted trees perform better than FYM-planted trees.

The role of plants and soil properties in the enzyme activities of substrates on hard coal mine spoil heaps

Knowledge about biotic (plant species diversity, biomass) and/or abiotic (physicochemical substrate parameters) factors that determine enzyme activity and functional diversity of the substrate on hard coal spoil heaps is limited. Spontaneously developed vegetation patches dominated by herbaceous species commonly occurring on these spoil heaps: grasses (Poa compressa, Calamagrostis epigejos) and forbs (Daucus carota, Tussilago farfara), were examined. The activity of dehydrogenase and alkaline phosphatase was twice as high in plots dominated by grass species compared with those dominated by forbs. Significant positive correlations were found between the activity of dehydrogenase and alkaline phosphatase with pH, available P, soil moisture, and water holding capacity and negative correlations between the activity of urease and soil organic carbon. Strong positive correlations were found between values for Shannon–Wiener diversity index, evenness, species richness and soil functional diversity in plots dominated by grasses. We found that the soil physicochemical parameters had a greater impact on enzyme activity of the substrate than plant biomass and species diversity. However, grasses, through their extensive root system, more effectively increased enzyme activity and health of the substrate than other herbaceous species, and as they stabilize the substrate and form dense plant cover, they can be recommended for reclamation purposes.

Biogeochemical Controls on the Potential for Long-Term Contaminant Leaching from Soils Developing on Historic Coal Mine Spoil

Coal mine spoil is widespread in US coal mining regions, and the potential long-term leaching of toxic metal(loid)s is a significant and underappreciated issue. This study aimed to determine the flux of contaminants from historic mine coal spoil at a field site located in Appalachian Ohio (USA) and link pore water composition and solid-phase composition to the weathering reaction stages within the soils. The overall mineralogical and microbial community composition indicates that despite very different soil formation pathways, soils developing on historic coal mine spoil and an undisturbed soil are currently dominated by similar mineral weathering reactions. Both soils contained pyrite coated with clays and secondary oxide minerals. However, mine spoil soil contained abundant residual coal, with abundant Fe- and Mn- (oxy)hydroxides. These secondary phases likely control and mitigate trace metal (Cu, Ni, and Zn) transport from the soils. While Mn was highly mobile in Mn-enriched soils, Fe and Al mobility may be more controlled by dissolved organic carbon dynamics than mineral abundance. There is also likely an underappreciated risk of Mn transport from coal mine spoil, and that mine spoil soils could become a major source of metals if local biogeochemical conditions change.

Habitat requirements of wetland bees and wasps: several reed-associated species still rely on peaty meadows and other increasingly rare wetland habitats

Reed beds are wetland habitats with the dominance of Phragmites australis, which are inhabited by diverse communities of organisms of high conservation value, known to be good diagnostic species for conservation measures. We studied bees and wasps associated with ten reed bed types and with the galls of frit flies of the genus Lipara in hundreds of localities in central Europe between the years 2011 and 2017. Species assemblages differ among specific types of reed beds; these differences are prominent compared between the near-natural and anthropogenic sites. Species of high conservation value prefer wet meadows with flowering plants and a portion of common reed, or terrestrial reed beds near fishponds, rivers and streams. Similar species also inhabit temporary field wetlands. Reed beds in sand pits, quarries, enduro tracks, brown coal spoil heaps or power plant tailing ponds are inhabited by generalist species. Mowing, the most frequently used management tool for removing common reed, has a positive effect on species nesting in reed stalks but negative on those nesting in reed galls. It is thus necessary to implement mowing only of a part of the reed bed into the management tools and to leave some parts of the reed bed, as well as reed margins, untouched. A high number of small to large reed beds increases the biodiversity of bees, wasps and other invertebrates, and these habitats can serve as biodiversity hotspots in increasingly anthropized and agricultural landscapes.

A Preliminary Evaluation of Bamboo Tree Effect on Selected Properties of Coal Spoil Contaminated Soils of a Humid Area of Southern Nigeria

A Preliminary Evaluation of Bamboo Tree Effect on Selected Properties of Coal Spoil Contaminated Soils of a Humid Area of Southern Nigeria

Pyrolysis of Technogenic-Redeposited Coal-Bearing Rocks of Spoil Heaps

The paper presents the results of a study of epigenetic changes in technogenic-redeposited coal-bearing rocks of Irkutsk and Kuznetsk coal basin spoil heaps (Russia). Hydrocarbon products formed under high-temperature and low-temperature pyrolysis of coal-bearing rocks were studied by using a chromatography-mass spectrometer GCMS-QP2010NC Plus (made by Shimadzu Company). The average temperature of low-temperature natural pyrolysis does not exceed 120 °C, and its average speed is approximately 2 m/year. In this case, three pyrolysis zones gradually built metamorphic rock mass (from bottom to top) are clearly established: heating (focal) activated and enriched. The average temperature of high-temperature pyrolysis reaches 850 °C, and its average speed is approximately 20 m/year. Unlike low-temperature pyrolysis, high-temperature pyrolysis is accompanied by the presence of two major zones (from bottom to top): pyrogenic (focal) and enriched (coke). The chemical composition of the enriched pyrolysis zone was studied in detail. It has been established that hydrocarbon compounds in samples of the pyrolysis zone are presented by six classes: asphaltic-resinous substances; polycyclic aromatic hydrocarbons, heterocyclic compounds, organic sulphur compounds; pyrolytic hydrocarbon and heavy hydrocarbon residue. Quantitative content of hydrocarbon compounds in the analyzed samples varies from 0.35% to 41.88%.

Overlooked diversity with terrestrial lifestyle in the predominantly freshwater and snow phylogroup Chloromonadinia (Volvocales, Chlorophyceae)

ABSTRACTThe phylogroup Chloromonadinia (Volvocales, Chlorophyceae) encompasses ecologically versatile green microalgae with a predominantly freshwater and snow lifestyle. Although a few species have been described from soils, the evolutionary history of terrestrial volvocalean flagellates is poorly known due to undersampling. Here we provide new insights into the phylogenetic position of terrestrial flagellates within the Chloromonadinia and investigate six unresolved strains from terrestrial and freshwater habitats in both hemispheres. The terrestrial strains differed in cell morphology, ultrastructure and lifestyle from the freshwater ones, therefore, we expected them to represent distinct evolutionary lineages (species or genera). While the terrestrial strain SAG 25.87 (Chloromonas gracillima comb. & stat. nov.) from Czech mountains clustered within the psychrotolerant core Chloromonas clade, the other terrestrial strains formed a phylogenetically separate lineage which we proposed as Ostravamonas gen. nov. The new genus differs from other closely related Chloromonadinia genera by chloroplast, eyespot, papilla and cell-wall morphology. Two terrestrial strains, CAUP G 1401 (coal spoil heap; Czechia) and SAG 12.72 (acidic soil; New Zealand), were designated as Ostravamonas chlorostellata comb. nov. and represent the first Chloromonadinia microalgae discovered in acidic terrestrial environments. Closely related ‘Chlamydomonas’ strains SAG 75.81 (ditch; France) and CCAP 11/108 (origin unknown) were reassigned to Ostravamonas meslinii comb. nov. and Ostravamonas tenuiincisa sp. nov., respectively. Our study shows that the traditional ‘Chlamydomonas’ still hides an overlooked diversity of species with a terrestrial lifestyle that are nested phylogenetically within the Chloromonadinia phylogroup.

Reagent Removal of Heavy Metals from Waters of Coal Mines and Spoil Tips of the Lviv-Volyn Industrial Mine Region

Reagent Removal of Heavy Metals from Waters of Coal Mines and Spoil Tips of the Lviv-Volyn Industrial Mine Region

Macroinvertebrate assemblages of the post-mining calcareous stream habitats: Are they similar to those inhabiting the natural calcareous springs?

Surface coal mining severely affects natural ecosystems, though it might also result in an establishment of biologically unique anthropogenic habitats. We studied spontaneously created post-mining calcareous brooks located at the brown coal spoil heap in the Sokolov coal basin (Czechia). Despite their extreme water conditions, linked most to the ionic mixture of dissolved ions (mainly SO42−, Ca2+ and Mg2+), and ferric hydroxide precipitations, we recorded unexpectedly species-rich assemblages there (150 species), including several spring fen specialists (31 species) and eight threatened red-listed species. Macroinvertebrate assemblages of post-mining calcareous habitats were compared with those reported from natural brooks draining Western Carpathians calcareous spring fens. The species richness found in the post-mining calcareous brooks was significantly lower than that of the natural calcareous spring brooks. Although we found 29% of species recorded in the two study systems in common (i.e. 80 species), species composition of their assemblages was systematically distinct. This suggests a possible role of environmental filtering in the post-mining brooks and/or dispersal limitation of some species typical for natural calcareous spring brooks (e.g. Trichodrilus strandi, Bythinella austriaca). In contrast, many macroinvertebrates, particularly those of high dispersal capacities (i.e. Odonata, Coleoptera and Diptera), can recognize post-mining calcareous brooks as surrogate habitats for the natural calcareous spring brooks.

The Potential Environmental Impact of PAHs on Soil and Water Resources in Air Deposited Coal Refuse Sites in Niangziguan Karst Catchment, Northern China.

Long-term deposition of coal spoil piles may lead to serious pollution of soil and water resources in the dumping sites and surrounding areas. Karst aquifers are highly sensitive to environmental pollution. In this study, the occurrence and release/mobilization of polycyclic aromatic hydrocarbons (PAHs) in coal waste and coal spoils fire gas mineral (CSFGM) were evaluated by field and indoor investigations at Yangquan city, one of the major coal mining districts in the karst areas of northern China. Field investigations showed that dumping of coal waste over decades has resulted in soil and water pollution via spontaneous combustion and leaching of coal spoil piles. Indoor analysis revealed that the 2-ring and 3-ring PAHs contribute to 65–80% of the total PAHs in coal spoils, with naphthalene (Nap), Chrysene (Chr), and Phenanthrene (Phe) as the dominant compounds. Based on a heating/burning simulation experiment, the production of PAHs is temperature-dependent and mainly consists of low-ring PAHs: 2-ring, 3-ring, and part of the 4-ring PAHs. The PAHs in the leachate are light-PAHs (Nap, 20.06 ng/L; Phe, 4.76 ng/L) with few heavy-PAHs. The distribution modes of PAHs in two soil profiles suggest that the precipitation caused downward movement of PAHs and higher mobility of light-PAHs.