Coal Mine Spoil Research Articles

Monitoring the aerosol solids deposited in snow in the area affected by the technological road of the Gorlov anthracite mining pit (Novosibirsk region, Russia)

The aim of the study. To monitor and assess the chemical composition of the solid aerosols deposited in the snow in the area affected by the technological road of the Gorlov anthracite mining site. Location and time of the study. The study was conducted in the Iskitim district of the Novosibirsk region (54.58o N, 83.57o E) in 2018–2020. Methodology. The content of total solids in snow was measured by gravimetric method after filtering the melted snow sample through the filter with 0.22 µm mesh size. Micromorphology of the solids was studied by using scanning electron microscope Hitachi TM-3000 (Japan) with attached EDS detector console Bruker Quantax 70 for the element analysis of the surface. The carbon content, С/Н and C/N ratios were determined by dry combustion using the СHN-analyzer (Perkin Elmer 2400 Series II, USA). The content and composition of polycyclic aromatic hydrocarbons (PAH) were determined by gas chromatography using Agilent Technologies АТ 6890N with AT 5975N mass-selective detector and AT 7683B autosampler. Main results. The article presents the results of the three-years long study of the solids accumulated in snow along the technological road in the north of the Gorlov anthracite basin. The influence of the automobile road used for the anthracite transportation was shown to reach as far as 2000 m in all directions. The snow cover was found to accumulate from 1.4 to 1131.6 g/m2 of deposited aerosol solids. Those solids were mostly represented by coal particles, the carbon content ranging 26.5–64.1% and increasing with the distance from the road. The aerosol solids, accumulated in snow, were found to contain significant amounts of PAH, including the carcinogenic ones. In the snow samples collected at 25–2000 m off the road, carcinogenic PAH content was found to be 9–13000 times higher than at the control site remoted from the road. Conclusion. The presented study helped to elucidate the factors, contributing to decreasing the spread of the anthracite solids during automobile transportation. Such spread can be attained by a) establishing wide multi-storeyed forested protective belts along technological automobile roads; b) compulsory covering of the loads in the coal-transporting vehicles; c) decreasing the speed limit of the vehicles; and d) taking into consideration a wind rose while projecting locations new automobile roads and coal mining spoils.

Comparative assessment of the use of humic substances derived from brown coals for technogenic landscapes reclamation

The objective of the study. To identify the prospects for the use of humic preparations for the restoration of disturbed coal-mining areas, by assessing the relationship between their biological activity and the structural-group composition. Location and time of the study. The study was carried out in the Novokuznetsk district of the Kemerovo region (N 54.14o N and E 87.10o E) in 2020. Methodology. The study of the structure-group composition of humic preparations was carried out by the 13C NMR spectroscopy. Evaluation of the effect of humic preparations was performed in a series of plot experiments setup in the reclaimed and non-reclaimed areas of the coal mining spoils. The properties of the soils substrates of the technogenic landscapes were determined by traditional soil methods. The effect of the preparations was assessed by the dry phytomass production and pod yields of Vícia villósa vetch, as well as the phytomass production of the Avéna satíva + Vícia villósa mixture. Statistical analysis of the data was carried out by the principal components analysis. Main results: Comparison of humic preparations obtained from brown coals of the Tisulsky (Kansk-Achinsky basin) and Tyulgansky (South Ural basin) deposits showed that, in general, all preparations positively affected phytomass production and pod yeild. However, in different conditions of technogenic landscapes and in relation to different plant species, the effect could manifest itself in different directions. A stable positive effect from pre-sowing seed treatment was achieved only with substrates depleted in natural humic substances (humus and peat), and with optimal moisture. Under such conditions, the greatest influence was exerted by preparations obtained from brown coals of the Tisulsky deposit of the Kansk-Achinsky basin, and their naturally oxidized form, which are characterized by a high proportion of oxygen-containing aliphatic (CO-Alk-O), as well as aromatic (СAr) groups. At the same time, under moisture deficit, the indicated chemical properties negatively affected the yield. In stony areas of technogenic landscapes, a positive effect was manifested only by preparations with a maximum proportion of aromatic hydroxide-containing groups (СAr-ОН). Enrichment of humic preparations with microelements (Zn and Cu) did not result in either positive or negative consequences. Conclusion. The use of humic preparations obtained from brown coals for restoring technogenic landscapes is justified only in areas composed of loamy rocks with a low content of humic substances of humus and peat. The noted multidirectional action of humates, which manifests itself depending on their structural and group composition, properties of substrates and plant species used at the biological stage of reclamation, indicates that using the same standardized preparations for the reclamation of various technogenic objects may not be reasonable.

Colloidal metal transport in soils developing on historic coal mine spoil

Chemical weathering of pyrite via oxidative dissolution is well-known for generating Fe(III)-bearing colloids at acid mine drainage (AMD) sites; however, the potential for physical weathering of pyrite-bearing materials and subsequent release and transport of colloidal pyrite and associated trace metals has not been studied. Here, we monitored the colloidal metal transport in soil developing on abandoned coal mine spoil with a history of AMD generation to systematically study the contribution of colloids to base and trace metal transport and determine the elemental and mineralogical composition of colloids. We collected soil pore water using lysimeters with a pore size of approximately 1.3 μm and centrifugation was used to separate the colloids from aqueous fractions. Metal concentrations of Na, Ca, Mg, K, Si, Al, Mn, Fe, Cu, and Zn were analyzed. Our results show only 14% of the total Al and Cu were present in colloidal fractions whereas 23%, 43%, and 54% of Fe, Mn, and Zn were transported in the colloidal phase, respectively. In contrast, all base metals were primarily present in the aqueous concentration with a small fraction (<10%) present in the colloidal phase. The colloidal fractions of the base metals were inferred to be associated with the concentration of clay colloids. The release of colloids exhibited possible sensitivity toward weather conditions such as alternating high temperatures and rainfall during summer (May–July) compared to fall (August–November). The morphology, elemental, and mineral composition of colloids were determined by a scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD). Colloids were dominated by phyllosilicates (biotite, muscovite, and kaolinite) with minor quartz and feldspars. Other minerals phases identified in colloidal fractions were hematite, goethite, arsenopyrite, and chalcopyrite. Colloids consisting of Fe, S, and O with structures resembling framboidal pyrite were identified, which is consistent with the non-silicates minerals identified by XRD. Our study suggests that the physical weathering of pyrite in the mine spoil can generate colloidal pyrite, which is mobilized and transported by soil pore water. Our results also indicate that these pyritic colloids are associated with toxic trace metals including Cu, Mn, and Zn. Colloid mobilization is also impacted by changes in temperature and precipitation, where clay mobilization afer rain events is favored. Further, sudden spikes in aqueous and/or colloidal concentrations may be the result of local heterogeneity within soils developing on mine spoil, indicating that further field-based work is necessary to better characterize pore-scale processes that control aqueous and colloid transport at similar sites to have a better understanding of potential contaminant transport from mine spoil systems.

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.

The Assesment of Physical Variables of the Soil Quality Index in the Coal Mine Spoil Depends

The Assesment of Physical Variables of the Soil Quality Index in the Coal Mine Spoil Depends

Resources and specificity of reclamation at the coal mining spoils

The article analyses Khakassia environmental conditions with the aim to estimate their resources and role in the efficient reclamation of coal mining spoils. The availability of potentially fertile soil substrate as a resource for large-scale reclamation was evaluated by the thickness of the quaternary clay and loamy bedrock layers, taking into account the amount of the substrate needed for reclamation. The availability of resources of the potentially fertile soil substrate was carried out by taking into account the thickness and soil bulk density of the humus horizon of the most fertile soils of the region, and considering the obtained estimayes within the framework of the methodical rules and normative regulations for optimal reclamation. The availability of hydrothermal resources was estimated by active temperature sums and hydrothermal coefficient. Overall the distribution of reclamation resources was found to be very uneven throughout the region. In the south of Khakassia with its large areas occupied by technogenic landscapes the reclamation resources were concluded to be in deficit, insufficient for carrying out the reclamation according with the optimal protocols. Such lack of resources is indirectly confirmed by prevailing areas occupied by self-revegetating coal mining spoils. The article also describes some successful reclamation examples where specific local environmental conditions were used in such a way as to decrease the effect of deficient resources, thus increasing the efficacy of the self-restoration of technogenic landscapes.

Ways of soil development on stony substrate from hard coal mining spoil

Ways of soil development on stony substrate from hard coal mining spoil

Soil organic matter and microbiological development of technosols in the South Wales Coalfield

Degraded land (formerly ‘reclaimed’) after surface-coal-mining is a serious problem in South Wales. This project uses forestation to foster soil development on opencast coal-mine spoil technosols. It compares records of humification and the soil microbiological system (microcoenosis) using paired data from the same plantings in 1998 and 2018. Statistical analysis finds no significant difference between samples collected under trees planted by the pit-planting versus trench planting method or trees planted using organic or mineral fertilizer. However, there are strong significant differences in both soil organic matter and microflora components and significant correlations with time since tree planting. Most components of the soil organic carbon (TOC) and the microflora increase, often significantly. However, compared to 2018, 1998 samples contain significantly greater maximum levels of Insoluble Carbon while the microflora had significantly more Ammonifying bacteria. Decreases in Insoluble Carbon explain the relatively small increase in TOC between 1998 and 2018. The % extracted with 0.1 N H2SO4 is significantly larger in 2018, suggesting active weathering. Similarly, both the maxima and minima of total Humic and Fulvic acids content, extracted with 0.1 M Na4P2O7 + 0.1 M NaOH, are significantly greater in 2018. Total microflora shows significant positive correlations with time-since-tree-planting as do the proportions of bacilli and actinomycetes but the correlation with ammonifying bacteria is negative. In 1998, the microflora was dominated by non-spore-forming bacteria while, in 2018, bacilli and actinomycetes prevail; both are involved in the transformation of complex organic compounds and humification. This indicates active transformation of more complex organic compounds and advancing humification. In sum, forestation of these degraded, formerly reclaimed, opencast coal-mine spoils has resulted in a massive increase in both the size and functioning of the soil organic system.

Genotype and soil substrate effects on the wood quality of poplar grown in a reclaimed lignite-mining area

An understanding of the structural organisation and chemistry of the cell walls in woody tissues is crucial from the perspective of plant mechanical strength, water transportability, as well as subsequent commercial utilisation of the wood. Poplar trees (Populus sp.), grown on two reclamation substrates (“Humus” and “Sand”) under the extreme soil conditions of an external coal mining spoil heap of the lignite mine in Bełchatów (Central Poland), were examined. Conventional parameters - tree-ring width (TRW) and wood density (WD) resolved annually (years 2008–2017) were corroborated by a novel approach of Raman spectroscopic analysis. Annually resolved Raman spectroscopic data representing the lignin-to-cellulose ratio (Li/Ce) enabled to estimate trends of lignification. The above traits were obtained for the three poplar genotypes: H-275, Grandis, and Androscoggin to assess the suitability of their plantation on the reclaimed heap.Our results show a significant effect of genotype on TRW, WD, and the Raman Li/Ce, while the effect of the soil substrate was less pronounced. The highest Li/Ce was identified in the H-275 genotype grown on a substrate with hummus. H-275 also showed higher TRW values compared to the other genotypes. WD was significantly higher in Grandis and Androscoggin genotypes grown on the “Sand” substrate. Associations between tree-ring parameters and climatic variables (temperature and precipitation) were mostly low and not statistically significant. Our findings from individual tree rings indicate that the genotype is the crucial factor influencing the lignification of poplar trees grown on post-mining lands.

How High Is the Recreation Value of Successional Forests Growing Spontaneously on Coal Mine Spoil Heaps?

Research highlights: Recreation value increases with the age of replanted as well as successional forests. Successional forests are not systematically less valuable for recreation than replanted forests. Succession may be used as a viable and low-cost reclamation practice of spoil heaps. Background and objectives: Afforestation has been a popular practice in post-mining land reclamation in the Czech Republic. To expand the current evidence on the recreation values of reclaimed forests, we conducted a valuation study for most typical reclaimed forests, as well as for successional forests spontaneously growing on surface coal mine deposit heaps. Using two distinct measurement methods, we also explore whether the estimated recreation value of forests is robust. Materials and Methods: An online survey was conducted in 2016 on a sample of residents living in the vicinity of coal mine deposit heaps, residents of the adjacent region of Karlovy Vary, and a control population from the central Bohemian region. Participants evaluated visual representations of forest stands typical for reclamation and succession, along with commercial spruce forest as a reference type. In the direct measurement, we measured the attractiveness of a respective forest for a walk using a 5-point scale. In the indirect measurement, a hypothetical choice between two forests for a walk was elicited in a discrete choice experiment. Results: Both direct and indirect measurements provide similar results. All reclaimed forests have a lower recreation value than the reference spruce forest. Successional forests are not systematically less valuable for recreation than replanted forests and the recreation value of both types increases with their age. The age, gender, and education of the participants did not affect the recreation value of a forest. Conclusions: We demonstrate that succession may be used as a viable and low-cost reclamation practice of spoil heaps emerging as a by-product of open-cast coal mining. With recreation as only one of many forest uses, our findings need to be interpreted vis-à-vis the objectives and expected results for individual sites and their habitat conditions.

Rehabilitating open-cut coal mine spoil for a pasture system in south east Queensland, Australia: Abiotic soil properties compared with unmined land through time

Rehabilitation of mined land intends to support food and biomass production, with open cut mines required to return the land to a safe, stable and productive state in Queensland, Australia. The aim of this investigation was to assess the potential for soil that was previously farmed, then mined and rehabilitated to support pasture for commercial cattle production. The study was focussed on abiotic properties of the rehabilitated soils, in comparison to properties of a range of unmined soil profiles supporting pastures within the immediate vicinity. Three hypotheses were tested: 1) the abiotic properties of rehabilitated soils would fall within the range of those from nearby unmined soils; 2) that rehabilitated soils would support viable pasture production; and 3) that the mine-spoil would restrict root function. The mine was situated near Acland, Queensland, with rehabilitated land sown to pasture 1, 3 and 6 years prior to the initiation of the study in 2013. The investigation followed these rehabilitated sites, in comparison to a Control site, and 18 proximal unmined sites, through a five year period. All sites were used to support cattle grazing, with soil nutrients, structural condition and pasture growth (8 sites) monitored. Evidence from pasture production and root exploration obtained through soil pit investigations demonstrated that the mine spoil was capable of supporting root growth beyond the replaced soil layer. There were few differences between the Control and rehabilitated sites with regard to benefits or constraints to pasture production, with exception that two rehabilitated sites had simillar or higher plant-available phosphorus and nitrogen. It was concluded that: 1) abiotic properties of rehabilitated soils fell within the range of unmined soils; 2) viable pasture production was achieved from the rehabilitated sites; and 3) both the replaced soil layer and the mine spoil supported root exploration and pasture production.

Agricultural populations of Festuca pratensis (Poaceae) on the coal mining spoils in the forest-steppe of the Kuznetsk Basin, Russia

The study of meadow fescue agropopulations was conducted in the agricultural phytocoenoses, established on the leveled coal mining spoils in the forest-steppe zone of the Kuznetsk Basin mining region in Russia. In agrophytocoenoses the fescue is not a dominant species, as in the natural meadows of herbs and fescue, which occupied the area prior to spoiling. However, the presence of the meadow fescue in the newly established plant communities resulted in increasing their biological diversity and improving the forage quality. The species was shown to sustain in agricultural communities on the coal mining spoils for more than 25 years, whereas when sown on the zonal soils it maintains it presence for 4-6 years. The ontogenetic groups of the plant in all communities were found to be dominated by virginile, young and mid-aged generative specimen. By the 25th year of agricultural phytocoenoses development the vitality of the agropopulations decreased on the coal mining spoils, composed of both Quaternary and Permian sediments. The study showed for the first time that meadow fescue is a species with good potential to restore vegetation cover in the areas disturbed by the open coal mining.

Biochar for sustainable soil management

Biochar for sustainable soil management

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.

Revegetation intervention of drought-prone coal-mined spoils using Caragana korshinskii under variable water and nitrogen-phosphorus resources

Coal-mine spoils are typically drought-prone and deficient in essential nutrients thus creating conditions, which significantly limit plant growth and development. Here, we searched for suitable combinations of key resources [water (W) and fertilizers (nitrogen, N and phosphorus, P)] to improve physiological and biochemical adaptations of Caragana korshinskii to coal-mined spoils. We observed that under low W and N-P resource availability, C. korshinskii displayed poor growth performance in coal-degraded spoils. Negative growth of C. korshinskii was associated with reduced photosynthetic rate, decreased water status and increased contents of reactive oxygen species (ROS) and malondialdehyde. Low resource availability to C. korshinskii resulted in enhanced levels of compatible solutes, including proline and soluble sugars that contributed to osmotic adjustment, and also increased activities of superoxide dismutase, peroxidase, catalase and ascorbate peroxidase, which ultimately conferred enhanced oxidative stress protection. Moderate-to-high W and N-P doses greatly enhanced C. korshinskii performance in coal-spoils by improving photosynthesis traits, water status and growth-related attributes. Increasing supply of W and N-P also helped C. korshinskii to reduce oxidative stress, as evidenced by low accumulation of ROS and malondialdehyde, and lower induction of antioxidant enzyme activities. The addition of N and P also improved drought resistance of C. korshinskii. Overall, we found that optimum growth of C. korshinskii in coal-mined spoils was achieved under W additions corresponding to 68% of field capacity (1.85 mmd1), N and P at 52.0 and 37.0 mg kg1 soil, respectively. These findings suggest that under appropriate W, N and P doses, C. korshinskii has greater potential to grow and persist in coal-mined spoils and could thus be used for revegetation interventions in drought-prone areas in north-western China, and perhaps across other coal-degraded areas worldwide.

Ameliorative effect of Lantana camara biochar on coal mine spoil and growth of maize (Zea mays)

AbstractThe aftermath of surface mining is a wasteland deprived of vegetation, soil structure and biodiversity. The unearthed overburden material is nutrient deprived and can only support the growth of invasive weeds such as Lantana camera which often cause allelopathy. The aim of the study is to prepare biochar from these noxious weeds and use it as an amendment for the mine spoil reclamation. Lantana biochar (LB) was prepared and applied to mine spoil, and Zea mays L. growth on biochar amended mine spoil was monitored for three months. Biochar application in a coal mine spoil using LB is comparatively de novo approach for reclamation practitioners. LB was prepared at varying temperature (250, 350 and 450℃) and residence times (30, 45 and 60 min) and characterized. After characterization, the most recalcitrant biochar at 450℃ for 60 min was chosen for application for the study. A pot trial was conducted to study the effect of LB at 0, 5, 10, 20 and 30 g kg−1 dosage on the yield of Zea mays and mine spoil properties. Significant ameliorative effects were observed with increase in organic carbon content (2.9 times), cation exchange capacity (2 times), water holding capacity (0.13 times) and decrease in bulk density (0.5 times) in the mine spoil. The seedling vigour index and germination also increased significantly (p &lt; .05) at 30 g kg−1 biochar treatment compared to control. The study concluded that LB has the potential to remediate coal mine spoils and promote re‐vegetation in degraded land.

Formation of secondary mineral coatings and the persistence of reduced metal-bearing phases in soils developing on historic coal mine spoil

Acid mine drainage (AMD) from historic and abandoned coal mine spoil represents a potential long-term source of contaminants to surface and groundwater. Determining the risk associated within AMD generation and metal(loid) transport from coal mine spoil is complicated by the heterogeneous natural of spoil heaps and mineralogical and hydro(bio)geochemical factors that may limit or promote metal(loid) transport. The current work aims to determine if primary, reduced phases such as pyrite continue to persist in abandoned and historic coal mine spoil. This objective was accomplished through characterization soils undergoing active weathering while developing on coal mine spoil in Appalachian Ohio to determine the factors that might limit oxidative dissolution. Soils in the Huff Run Watershed (Ohio, USA) were sampled at 0–10 cm, 30–40 cm, 70–80 cm, and 110–120 cm depth. X-ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), and synchrotron-based X-ray Microprobe (XMP) analyses were used to determine the speciation and distribution of metal(loid)s and the minerals they are associated with. The XMP analyses included micro-focused XRD (μ-XRD), X-ray Fluorescence (μ-XRF) element and redox state mapping, and X-ray absorption Near Edge Structure (μ-XANES) Spectroscopy. Soil mineralogy was dominated by quartz, muscovite, kaolinite, and feldspar, with minor amounts of chlorite and other phases including pyrite, arsenopyrite, realgar, orpiment, hematite, and goethite. Soils from all depths contained metal(loid)-sulfide particles with secondary mineral surface coatings, often in physically complex and heterogeneous aggregates that were composed of clay minerals and secondary Fe(III)-(oxy)hydroxides. These assemblages were typically 10–20 μm in diameter, with an individual pyrite particle core grain size ranging from 0.5 to 10 μm, and secondary mineral surface coatings ranging in thickness from undetectable to 1 μm. Within these aggregates, S and As were present as: (1) small (<20 μm) phases that were spatially correlated with Fe and other trace metal(loids) (Cu, Se, and Zn) and identified as metal(loid)-sulfide minerals; and (2) As(III), As(VI), and S(VI) associated with secondary Fe(III)-(oxy)hydroxides. Intermediate S oxidation state was also observed to be associated with remnant coal and organic matter. These results indicate that pyrite and other metal(loid) sulfides are present in soils developing on historic coal mine spoil after several decades since waste emplacement. The persistence of the μm-scale pyrite grains is likely the result of the formation of the secondary mineral surface coatings which can limit complete oxidative dissolution. These phases also play a role in re-sequestration of metal(loid)s release from sulfide mineral weathering. This work highlights the importance for considering AMD generation from non-point sources, and the potential for long-term ecosystem impairment.

Intra- and Interspecific Interactions among Pioneer Trees Affect Forest-Biomass Carbon Accumulation in a Nutrient-Deficient Reclaimed Coal Mine Spoil

Pioneer trees play a key role in the recovery of a reclaimed ecosystem that is nutrient-deficient in the initial stage of reclamation. Clarifying the growth of pioneer trees and their response to intra- or interspecific competition is of great importance to help stewards manage reclaimed forest. Nevertheless, such documents are lacking. We utilized forestry inventory data from a R. pseudoacacia and P. tabuliformis mixed forest plot with an area of 8000 m2 to find out the effect of trees interaction on their growth (indicated by the amount of biomass carbon per stem) in a nutrient-lacking reclaimed ecosystem 17 years after reclamation in Pingshuo opencast coal mine, Shanxi Province, China. In total, 2133 tree individuals were measured and tagged; the kriging interpolation method was applied to map spatial variation of forest-biomass carbon (C). Univariate and bivariate mark correlation functions were employed to examine the effect of intra- and interspecific interactions on tree’s biomass C accumulation. The results showed that tree biomass C was 27.84 Mg ha−1 in the forest. C class structure of planted R. pseudoacacia followed inversed J-shaped distribution and seeded-in R. pseudoacacia and Ulmus pumila (a spontaneous species) had L-shaped distribution. P. tabuliformis, however, followed a nearly normal distribution. Patchy distribution was observed with regard to C spatial arrangement of all tree species. In terms of the intraspecific correlation of biomass C, no significant competitive or facilitative interactions (GoF p ≥ 0.05) was observed among conspecific trees of seeded-in R. pseudoacacia and P. tabuliformis. In contrast, significant negative interactions (GoF p &lt; 0.05) or repulsion correlations between biomass C of planted R. pseudoacacia individuals and U. pumila individuals were found at the scale of 1–2 and 0–8.5 m, respectively. In term of the interspecfic spatial correlation of biomass C, a significant positive interaction between the heterospecific individuals of planted R. pseudoacacia and seeded-in R. pseudoacacia was observed at the scale of 2.5–4 and 12.5–15 m. Similarly, seeded-in R. pseudoacacia and U. pumila were found to be attracted by P. tabuliformis at 7–9 and 0–2 m, respectively. Conversely, significant departure effect was observed at the scale of 1–3 m between the biomass C of U. pumila and planted R. pseudoacacia and 4.5–5.5 m between the biomass C of U. pumila and seeded-in R. pseudoacacia. Consequently, R. pseudoacacia and P. tabuliformis could coexist for a long term and P. tabuliformis was a species that facilitated the accumulation of C of other tree species. Overall, complex intra- and interspecific interactions in nutrient-limit reclamation ecosystem affected biomass C accumulation. R. pseudoacacia–P. tabuliformis mixed forest could be an efficient reclamation pattern to restore biomass C in the Loess Plateau area.

Vegetation- and Environmental Changes on Non-Reclaimed Spoil Heaps in Southern Poland.

The study focused on the changes in vegetation and soils on an undeveloped area of coal mine spoil heaps. The process of vegetation changes was evaluated on the basis of historical cartographic materials and fieldwork. Changes of vegetation in nearly 200 years are presented herein. The main purpose of this study is to present an analysis of spatio-temporal changes in vegetation and their influence on soil features. The diversity of ecological species in terms of habitat requirements, tendency of hornbeam communities formation, and the relationship between forest communities and soil features was found. The basic soil properties were examined under selected plant communities (pH, Corg, Nt), available forms of elements (P, K, Mg), and as plant nutrients and heavy metal occurrence (Fe, Zn, Mn, Co, Cd, Pb, Sr, Cr, Cu). The soil organic carbon (Corg) content varied from 3.17 ± 0.007% to 17.7 ± 0.21% and significant differences were observed between sites. The highest total nitrogen (Nt) content was recorded in the soils of the sites that were represented by Populus-Betula stands (0.60 ± 0.01%). Soil acidity (pH) varied greatly, ranging from acidic (pH = 4.1) to weakly acidic (pH = 5.9). The highest value for Mgavail (205.43 ± 0.5 mg·kg−1) was noted in the soils under Calamagrostis epegijos (L.) Roth community and for Pavail (184.07 ± 3.77) and Kavail (346.19 ± 2.92 mg·kg−1) under the Quercus-Pinus stand. On all sites, Zn was a dominant element and its concentration ranged from 526.1 to 1060.4 mg·kg−1. Obtained results show how important it is to study the issue of vegetation changes and the formation of the landscape within an industrial city. The described results are important for the management of urban greening issues. Human influence on the disintegration and development of the natural environment is clearly visible. Due to the diversity of former mining areas and their time of creation, the studied area is one of the most important experimental areas for the determination link between vegetation and soil.

Optimal water and fertilizer applications improve growth of Tamarix chinensis in a coal mine degraded area under arid conditions.

Coal-mined areas are often associated with hostile environmental conditions where the scarcity of water and key nutrient resources negatively affect plant growth and development. In this study we specifically addressed how different combinations of water (W), nitrogen (N) and phosphorus (P) might affect morpho-physiological and biochemical attributes of a native shrub species, Tamarix chinensis, grown on coal mine spoils. Our results show that under greenhouse conditions the application of moderate-to-high doses of W, N and P considerably improved growth-associated parameters (i.e. plant height, stem diameter, dry weight), as well as gas-exchange parameters, photosynthetic pigment contents and leaf water status of T. chinensis. Under field conditions high W and low N, P doses led to significant increases in plant growth-associated traits, gas-exchange parameters and leaf water status. Plant growth was generally higher under greenhouse conditions mainly because seedlings faced multiple stress when growing under field conditions. Low W-regime, regardless of N-P additions, improved osmotic adjustments in leaf tissues and also boosted the activity of several antioxidant enzymes to reduce the oxidative stress associated with W scarcity under greenhouse conditions. Importantly, our study shows how maximum growth performance of T. chinensis under field conditions was achieved at W, N and P doses of 150 mm year-1 , 80 kg ha-1 and 40 kg ha-1 , respectively. Our findings suggest that achieving optimal rates of W, N and P application is crucial for promoting the ecological restoration of coal-mined areas with T. chinensis under arid environmental conditions.