Coal Mine Spoil Research Articles

Phenology of selected exotic plant species on coal mine spoil land

Phenology of selected exotic plant species on coal mine spoil land

Selection of appropriate host plants used in trap culture of arbuscular mycorrhizal fungi.

Arbuscular mycorrhizal (AM) fungi in coalmine spoil, island forest and saline soils were enriched in pot culture with maize (Zea mays L.), tobacco (Nicotiana tabacum L.), white clover (Trifolium repens Linn.) and silverweed cinquefoil (Potentilla anserina L.). Based on spores, there were more species of AM fungi in the coalmine spoil (15 species, 3 genera), than in the forest soil (11 species, 4 genera) and the saline soil (5 species, 2 genera). In the trap cultures, the total of 28 species in Acaulospora, Gigaspora, Glomus, and Sclerocystis detected in the original soils were all recovered with at least one of the four trap plants. The highest spore and species numbers were recovered in trap cultures of T. repens inoculated with coalmine spoil. Glomus constrictum and Glomus multicaule were the dominant species associated with N. tabacum grown in saline soil and forest soil. The dominant species of AM fungi on the four hosts was Acaulospora mellea, which had over 90% of the spore incidence in pot trap culture in coalmine spoil. It is suggested that there be selectivity between host plants and AM fungi. The number of species of AM fungi detected was influenced by host plants under certain conditions and white clover was generally the optimal host plant to detect diversity of AM fungi.

Leaching of coal-mine tips (Nord-Pas-de-Calais coal basin, France) and sulphate transfer to the chalk aquifer: example of acid mine drainage in a buffered environment

In northern France, the weathering and oxidation of pyrite-containing coal mine spoils can lead to sulphate enrichment of the underlying chalk aquifer. Two sites have been studied: in a free water-table zone and in a confined-aquifer zone. Solid-fraction analyses have shown a release of carbon and sulphur from the waste dump surfaces. The groundwater isotopic analysis (notably 34S) showed the existence of two sulphate sources (mine spoils and gypsum contained in Cenozoic formations). This study also saw evidence of bacterial sulphate reduction in the confined zone as a result of the release of carbon from mine spoils. The effects of acid mine drainage were the presence of secondary minerals as small jarosite dots (cm) present at depth, gypsum or ferrihydrite present on the bottom of temporary ponds, and an increase in sulphate content of groundwaters sampled downstream of the waste dumps. This acid mine drainage is buffered during its infiltration into the chalk aquifer. This is evidenced by the increase in magnesium, calcium, bicarbonate or strontium, resulting of carbonate digestion downstream of the sites. No significant leaching of metals, even those associated with the sulphide fraction, was seen at the two studied sites.

Influence of flyash application on micronutrient availability and uptake by Sudan grass and oats grown on coal mine spoils

Influence of flyash application on micronutrient availability and uptake by Sudan grass and oats grown on coal mine spoils

Efeito da compactação e CaCO3 na oxidação da pirita em estéril de mineração de carvão

A drenagem ácida, provocada pela oxidação de sulfetos, é um problema ambiental capaz de comprometer a qualidade dos solos e recursos hídricos. Tal impacto pode ocorrer em vários ambientes, estando relacionado principalmente com a mineração de carvão. O presente trabalho foi realizado para estudar a cinética de oxidação da pirita, em estéril de mineração do carvão de Candiota - RS, sob diferentes condições de acesso do O2 atmosférico e pH. O estudo buscou avaliar a possibilidade de ajustar a taxa de dissolução do carbonato à taxa de oxidação dos sulfetos, dificultando o contato do ar atmosférico com os sulfetos presentes no estéril. As unidades experimentais constaram de frascos de lixiviação que continham 100g do estéril e doses crescentes de CaCO3, tendo sido o material submetido a diferentes níveis de compactação. Os tratamentos foram dispostos em delineamento inteiramente casualizado, fatorial4x4 (quatro doses de CaCO3 e quatro níveis de compactação), com três repetições. Os frascos que continham o material foram, então, submetidos a lixiviações periódicas com 50mL de água destilada, a cada duas semanas, por um período de oito meses. Nas soluções lixiviadas, foram determinados o pH e os teores de S e Fe. Verificou-se que o uso de carbonato e a compactação interferiram na cinética de oxidação dos sulfetos presentes no estéril. O aumento da compactação favoreceu a dissolução do carbonato, aumentando o pH, ao mesmo tempo que retardou a oxidação dos sulfetos, com diminuição dos teores de sulfato e ferro nas águas de drenagem.

Aboveground Vegetation, Seed Bank and Soil Analysis of a 31-year-old Forest Restoration on Coal Mine Spoil in Southeastern Ohio

A 31-y-old forest restoration on coal mine spoil was studied to assess soil chemical composition, percent change in tree density and percent similarity of the seed bank and ground-story vegetation. Seed bank and soil chemistry results were compared to an adjacent unvegetated spoil bank. Of fifteen tree species planted on a barren, coal, spoil bank in 1966, four increased in density (indicating recruitment since 1966), seven decreased in density to 50% and four decreased in density >50% after 31 y. Nine volunteer tree species were recorded on the reforested site since the plantings in 1966. March and July soil collections in 1997 contained seeds of 18 species each, 13 in both collections. Most of the species found in the seed bank were shade-intolerant. No significant difference was found for total seed density between the March (4257 ± 490 seeds/m2) and July (3589 ± 365 seeds/m2) seed banks. Percent similarity between the seed bank and ground-story vegetation from the March and July seed collections was 9.8% and 8.2%, respectively. No seeds were found in soil collections from the adjacent unvegetated spoil bank. Soil pH and ionic content between the reforested study area and the unvegetated spoil bank differed significantly. We believe that the 1966 plantings have provided a habitat for other species to establish by reducing erosion and improving edaphic conditions.

Hydrogeological and geochemical interactions of adjoining mercury and coal mine spoil heaps in the Morgao catchment (Mieres, NW Spain)

Abstract Asturias, NW Spain, has a long coal and metal mining tradition including mining for mercury, which was intermittently exploited from Roman times up to 1974. In the valley of the Morgao Stream, there is a spoil heap from the Los Rueldos mercury mine immediately uphill from another one from the Morgao coal washery, both situated less than 3 km away from the town of Mieres (30,000 inhabitants). At the Los Rueldos site, arsenic is abundant in the form of As-rich pyrite. Total arsenic concentrations in representative samples from the spoil heap range from 4746 to 62 196 mg kg −1 . Readily leachable Pb and Zn are respectively present at average concentrations of 3680 and 45 mg kg −1 . Leachate from this spoil heap drains on to the El Batán coal spoil heap, together with acid drainage from old underground workings of the Los Rueldos Mine, which has very low pH (2.5), with up to 2900 mg 1 −1 SO 4 , and between 5.3 and 8.3 mg 1 −1 As. The total flow of polluted water from the Los Rueldos site that flows into the Morgao Stream is estimated to average 3200 m 3 year −1 (corresponding to only 1% of the total flow from the Morgao drainage basin). Analysis of the Morgao Stream downstream of both spoil heaps clearly shows the results of the dilution effects, with the As content being lowered by more than 95%.

Mobility of heavy metals associated with the natural weathering of coal mine spoils

Knowledge of chemical mobility of heavy metals is fundamental to understanding their toxicity, bioavailability, and geochemical behavior. In this paper, two different methods, i.e. mineralogical means and sequential extractions, were employed to analyze the total contents, existing states, and chemical forms of heavy metals in coal mine spoils. The results demonstrate that the mobility of heavy metals in coal mine spoils depends not only on their existing states and the stability of their host minerals but also on the properties of the coal mine spoils. In the process of coal mine spoils–water interaction, sulfides that contain heavy metals first break down and release metals, which are then adsorbed and complexed by the iron oxyhydroxide colloid resulting from pyrite oxidization and organic matter. During the natural weathering of coal mine spoils, only a small fraction of these metals are released to the environment, and most of them still remains in the residual material

Comparative Growth Behaviour and Leaf Nutrient Status of Native Trees Planted on Mine Spoil With and Without Nutrient Amendment

The effect of nutrient amendment on growth of nine indigenous tree species planted on coal mine spoil was studied. Greater growth in fertilized plots was accompanied by greater foliar N and P concentrations in all species. The response to fertilization varied among species and was greater in non-leguminous than in leguminous species. Furthermore, leguminous species exhibited higher growth rates compared to non-leguminous species. The log-transformed height-diameter relationships were significant for all tree species and treatments. Acacia catechu, Dalbergia sissoo, Gmelina arborea and Azadirachta indica fitted the elastic similarity model of tree growth; whereas Pongamia pinnata and Phyllanthus emblica followed the constant stress model. Tectona grandis was the only species which fitted the geometric similarity model. In Albizia lebbeck and Terminalia bellirica, the b -values (the gradients of the log-transformed height to diameter relationships) were considerably lower (<0.5), and these two species did not fit any model of tree growth. In several cases, the b -values were considerably influenced by nutrient amendment. The log-transformed crown mass and trunk mass relationships were significant for all treatments and species. The slope of the crown mass:trunk mass relationship was near unity in A. indica, D. sissoo, G. arborea, P. emblica, P. pinnata, T. grandis, and T. bellirica. However, in A. catechu and A. lebbeck, this slope was well below unity suggesting a greater allocation to non-photosynthetic tissue. Fertilizer amendment resulted in a heavier crown relative to trunk in A. indica, T. grandis and T. bellirica.

Spatial distributions of lignite mine spoil properties for simulating 2-D variably saturated flow and transport

In open–cast brown coal mine spoils, the effect of heterogeneity on water flow and solute transport is largely unknown. The objective of this study is to analyze the effects of differently generated hydraulic property distributions on transport processes in mine spoil heaps originating from open–cast lignite mining. Spatial distributions of hydraulic properties are generated with two different approaches. A deterministic approach is based on the description of mixing, segregation, and compaction during dumping. Using information on the mining and dumping technology along with geological properties of overburden sediments, we generate spatial distributions of the spoil bulk density and texture for a representative 2-D-vertical cross-section of 22 m depth and 29 m width. Water retention is calculated with the Arya and Paris approach and hydraulic conductivity with the Kozeny–Carman equation. The second approach uses direct geostatistical simulation of relative hydraulic conductivity. Water flow and solute transport is simulated with the numerical finite element code SWMS_2 D. The deterministic approach leads to a two-peaked concentration front with tailing. A significant fraction of the solutes is transported faster as compared with a homogeneous profile. Both approaches induce a spreading of the concentration front. Utilizing available information on the dumping technology and on the overburden geology may help to improve predictions of water flow and solute transport in spoil heaps.

Associations of dominant plant species with arbuscular mycorrhizal fungi during vegetation development on coal mine spoil banks

Among plants colonizing mine spoil banks in Northern Bohemia the first colonizers, mainly ruderal annuals fromChenopodiaceae andBrassicaceae were found not to be associated with arbuscular mycorrhizal fungi (AMF). These species cultivated in pots with soil from four sites in different succession stages of the spoil bank did not respond to the presence of native or non-native AMF. All grass species studied (Elytrigia repens, Calamagrostis epigejos andArrhenatherum elatius) were found moderately colonized in the field and they seemed to be facultative mycotrophs, because their response to mycorrhiza in the experiment was negligible.Carduus acanthoides was found to be highly colonized in the field, however, it did not show growth response to AMF in the pot experiment. The AMF native in four sites on the spoil banks showed high infectivity but low effectiveness in association with colonizing plants compared to the non-native isolateG. fistulosum BEG23. In general, dependence on AMF in the cultivation experiment was rather low, regardless of the fact that plants were found to be associated with AMF either in the field or in pots. Occurrence and effectiveness of mycorrhizal associations might relate primarily to the mycotrophic status of each plant species rather than to the age of the spoil bank sites studied.

Litterfall, litter decomposition and nutrient release in five exotic plant species planted on coal mine spoils

Summary Litterfall, leaf litter decomposition and nutrient dynamics (N, P, K and Ca) were studied for four years in old plantations of five exotic plant species namely Acacia auriculiformis, Cassia siamea, Casuarina equisetifolia, Eucalyptus hybrid and Gravelia pteridifolia growing on coal mine spoil. Maximum litterfall on mine spoil was found during cooler and drier seasons than in to the hotter and moist. Total litterfall was maximum for G. pteridifolia and minimum for C. siamea . Litter of different plant species showed variations in their decomposition. The mean relative decomposition rate was maximum in the rainy season and minimum during summer. The concentrations of N and P increased, whereas K and Ca decreased in decomposing litter with increasing retrieval days. Mass loss was negatively correlated with N and P concentrations, whereas the same was positively correlated with K and Ca. Maximum litter decomposition rate was recorded for C. siamea , whereas G. pteridifolia showed the slowest decomposition rate. The plant species A. auriculiformis, E. hybrid and C. equisetifolia were found to be most suitable for planting on mine spoils as these have led to the most balanced nutrient cycling with both moderate litter deposition and decomposition rates.

Sources of salinity near a coal mine spoil pile, north-central Colorado.

A small (1 km2) salt-affected stream drainage on the High Plains north of Denver, Colorado was sampled to determine the near-surface dispersion of soluble salts and metals from low-sulfur coal mining waste (spoil). Surface waters collected along the 0.8-km stream reach, and aqueous leachates of spoil and naturally saline local soil, were analyzed for chemical constituents and sulfur isotopes. In this semiarid setting with abundant carbonate-bearing surficial sediments, the limited, mildly acidic drainage from the spoil pile is quickly neutralized, restricting the mobility of many elements. However, some spoil-derived constituents were clearly traceable within the upper 0.4 km of the stream reach. Spoil leachates and surface water near the spoil pile have distinctive compositions of major anions and cations, and elevated levels of dissolved nitrate compared with downstream waters. Spoil-derived sulfate was traceable because it has generally positive values of delta34S that contrasted with generally negative values of delta34S in soil leachates and evaporite salts from the surrounding area. Spatial-chemical sampling of surface water showed an abrupt increase in dissolved U, Se, B, Li, and Mn in the lower 0.4 km of the stream reach where shallow ground water from surrounding irrigated fields contributed to surface flow. The downstream evolution of surface water chemistry and sulfur isotopic composition is consistent with mixing between spoil-affected upstream water and irrigation-return water. The methods described should be applicable at other sites in similar settings where the environmental effect of low-sulfur coal mining waste must be assessed and where access to samples of shallow ground water is limited.

Microflora of technogenous wastes characterised by fatty acid profiling

Fatty acid methyl ester (FAME) profiles obtained directly in situ have been used to estimate microbial community structure in different technogenous wastes. The effect of nutrients added, simulating the effect of plant-derived exudates on the indigenous microflora in the heaps during the reclamation process, was also studied in microcosms. The wastes such as coal-mine spoil, non-ferrous metallurgical slag and coal fly-ash were characterised by a poorly developed microflora as compared to a typical sandy loam soil. However, the most similar to the soil was the community structure in the coalmine spoil. The high content of 18: 2w6,9 found in the metallurgical slag indicated the domination of fungi in this waste. In contrast, representatives of the Cytophaga-Flavobacterium group dominated the coal fly-ash, for which 16:1ω5e was used as the marker acid. The waste amendment resulted in changes of FAME profiles obtained. However, the changes were sitespecific, indicating response of particular microbial groups to the added nutrients.

Organic accumulation and microbial action in surface coal-mine spoils, Pernik, Bulgaria

In Bulgaria, around 80% of the land disturbed by surface coal mining awaits reclamation. Top soils from the pre-mine environment are reserved for the recultivation of gently sloping agricultural benches. Steeper slopes are reclaimed through forestry. The impacts of two tree species on initial pedogenesis are examined on opencast coal-mine spoil banks near Pernik. Adjacent 30-year-old test plots have been planted for 25 years with: (l.) black pine ( Pinus nigra Arn); and (2.) black locust ( Robinia pseudoacacia L.), a third control plot remains largely unvegetated. Litter accumulation under pine is 7.68 t/ha (pH 4.86) compared to 5.53 t/ha (pH 7.07) under black locust. Beneath, an organo-mineral zone at the surface of the minespoils is 16.18 t/ha (pH 6.76) under black pine and 8.21 t/ha (pH 7.25) under black locust. The more rapid transformation of black locust litter creates more and more mobile organic substances that migrate further into the mineral profile. However, all the major components of soil organic matter are present: humic acids, fulvic acids, and unextractable organic carbon. The three sites share high levels of common carbon, which is attributable to the presence of coal as much as to pedogenesis. However, total organic carbon and humic acids are greater under the trees. Black pine supports a greater microflora, both in the litter and the organo–mineral layer beneath the litter, but a greater microflora is found in the 0–10 cm layer of the spoils under black locust. Non-sporous bacteria dominate. The spore-forming bacilli are typical of natural forest soils but their variety and numbers are much reduced. Bacillus cereus dominates the control plot and that planted to black pine. Bacillus mycoides dominates under the black locust. These results confirm the positive impacts of forestation on initial soil-forming processes in surface coalmine spoils and also that the creation of mature soils by forest fallowing is a long slow process. However, forest biological recultivation establishes the preconditions for self-sustaining natural soil development.

Potential Inhibition of Acid Formation in Pyritic Environments Using Calcium Sulfite Byproduct

Pyrite (FeS2) oxidation in coal mine spoils and coal refuse produces copious amounts of acid that can cause severe environmental damage. Prevention of acid formation by calcium sulfite (CaSO3), a flue gas desulfurization (FGD) byproduct of the scrubbing reaction used to remove sulfur dioxide from flue gases when coal is burned, was studied. First-order rate constants of CaSO3 oxidation by O2 ranged from approximately 0.0164 min-1 (initial pH 8.0, 25 °C, 21% O2) to 0.3807 min-1 (initial pH 5.0, 15 °C, 21% O2). Overall, the rate constants dramatically increased when the initial pH decreased from 6.5 to 5.0, the temperature increased from 5 to 15 °C, and the O2 content in air increased from 0.2% to 21%. When 6.4 g of CaSO3 or 10 g of CaSO3-containing FGD byproduct were mixed with 50 g of coal refuse in small columns (2.5 × 13 cm), the total acidity in the leachate water collected during 27 weeks was reduced by 45% and 64%, respectively, as compared to the untreated control. Mixing CaSO3 with coal mine spoil or coal refuse before extensive oxidation occurs reduces acid production because the CaSO3 reacts with any O2 introduced into the spoil or refuse materials before it can react with pyrite to form acid.

Effect of Nutrient Enrichment on Native Tropical Trees Planted on Singrauli Coalfields, India

AbstractGrowth performance of nine native tropical tree species planted on mine spoil under two levels of NPK treatment was studied by measuring height and diameter. Of the nine species, four were leguminous. All the tree species responded positively to NPK fertilization; however, the impact on leguminous species was little compared to non‐leguminous species. In general, the height/diameter ratio decreased from control to full‐dose NPK treatment, suggesting that nutrient enrichment influenced the resource allocation pattern such that the diameter growth was favored. The log‐transformed height‐diameter relationships were significant for the three treatments in all the tree species. The slopes (β) obtained were compared with three different models of tree growth (i.e., elastic similarity, geometric similarity, and constant stress). Acacia catechu, Dalbergia sissoo, Gmelina arborea, and Azadirachta indica fitted the elastic similarity model, whereas Pongamia pinnata and Phyllanthus emblica followed the constant stress model. Tectona grandis was the only species that followed the geometric similarity model. In Albizia lebbeck and Terminalia bellirica, the β values were considerably lower (i.e., below 0.5) and these two species did not fit any of the three models of tree growth. In several cases the β values were considerably influenced by nutrient enrichment.Key words: chemical fertilization, coal mine spoil, growth response, tree structure, tree volume, tropical tree species, height/diameter ratio.

Litterfall, litter decomposition and nutrient release patterns in four native tree species raised on coal mine spoil at Singrauli, India

Litterfall, leaf litter decomposition and N and P release were studied in four tree species (Dalbergia sissoo, Azadirachta indica, Pongamia pinnata and Shorea robusta) planted on a mine spoil habitat. Annual litterfall varied from 1220 kg ha–1 in the S. robusta stand to 3620 kg ha–1 in the A. indica stand. The fast-growing species A. indica and D. sissoo exhibited higher litter production in comparison to the other two slow-growing species. The total N returned to the soil through litterfall ranged from 8.6 kg ha–1 year–1 in the S. robusta stand to 36.5 kg ha–1 year–1 in the D. sissoo stand. The annual percent leaf litter mass loss was distinctly greater in A. indica (73%) and D. sissoo (69%) in comparison to P. pinatta (59%) and S. robusta (47%). The mean relative decomposition rates of leaf litter material were maximum in the rainy season and minimum in summer. Rainfall and its associated variables exhibited greater control over litter docomposition than temperature. Lignin and water-soluble compounds were better predictors of annual mass loss rates accounting for 90% variability. Mass loss was positively correlated with N and P mineralization rates. Lignin was the best predictor of annual N and P mineralization rates. Nutrient release pattern differed; constant release occurred in A. indica, initial release followed by delayed immobilization and release occurred in D. sissoo and P. pinnata, and initial immobilization followed by gradual release was noticed in S. robusta. A. indica and D. sissoo, showing high litterfall and rapid litter decomposition rate, hold promise for the rehabilitation of nutrient-poor coal mine spoils. On the other hand, S. robusta with less litterfall and a slow decomposition rate may prove disadvantageous.

99/00877 Geochemical behavior of heavy metals during the natural weathering of coal mine spoil : Dang, Z. et al. Prog. Nat. Sci., 1997, 7, (6), 700–706

99/00877 Geochemical behavior of heavy metals during the natural weathering of coal mine spoil : Dang, Z. et al. Prog. Nat. Sci., 1997, 7, (6), 700–706

Soil compaction, runoff and erosion on reclaimed coal-lands (UK)

ABSTRACT Many of Britain's reclaimed coal-lands are damaged by erosion. Much accelerated runoff and erosion is caused by soil compaction that reduces the land's capacity to absorb rainwater. This study compares conditions in two types of coal-spoil, deep-mine colliery discard and surface-coal-mine overburden, and in four contexts: freshly laid spoil, old unvegetated minespoil, minespoil partly veneered by grass tufts, and ‘reclaimed’ spoils, which are defended by a dense grass turf and (ca. 100 mm) deep artificial topsoil. Bulk density testing reveals a characteristic pattern. The soil is of moderate density (< 1.3 g/cm3) in the grass root zone. However, soil densities rise to 1.8 g/cm3 and more between 30 and 50-cm depth. Particle size and stability tests confirm that minespoils contain a large proportion of water unstable primary particles, mainly mudstones and shales. These break down on wetting, flood the soil with fine particles, and help raise the soil density to levels where water infiltration and root penetration is impeded. Rainfall simulation tests on surface coalmine spoils near Blaenavon, Wales, find that poorly vegetated plots (50-90% cover) convert less rainfall to runoff, and yield a fourth as much sediment as unvegetated plots. Tests of deep coalmine spoils at the Earth Centre Reclamation Project, Doncaster, England, found that newly laid, unvegetated, recently washed and hence stabilised, coal spoils converted only 20% of rainfall to runoff. Older comparted, spoils converted 25-35% of the rainfall to runoff when unvegetated but less than 10% when mantled by thin grass turf. Soil losses for the same rain event were more than four times greater on the unvegetated sites. Finally, on both sites, plots mantled with a deep well-managed layer of applied topsoil sites absorbed most of the rainwater applied in tests. This was subsequently detected running in macropores and fissures below the applied topsoil and in the upper layers of the relatively impermeable mine-spoil subsoil.