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At least 325 records · Page 18Linked to original sources
USGS2009

Compression-cuticle relationship of seed ferns: Insights from liquid-solid states FTIR (Late Palaeozoic-Early Mesozoic, Canada-Spain-Argentina)

Cuticles have been macerated from suitably preserved compressed fossil foliage by Schulze's process for the past 150 years, whereas the physical-biochemical relationship between the "coalified layer" with preserved cuticle as a unit has hardly been investigated, although they provide complementary information. This relationship is conceptualized by an analogue model of the anatomy of an extant leaf: "vitrinite (mesophyll) + cuticle (biomacropolymer) = compression". Alkaline solutions from Schulze's process as a proxy for the vitrinite, are studied by means of liquid-solid states Fourier transform infrared spectroscopy (FTIR). In addition, cuticle-free coalified layers and fossilized cuticles of seed ferns mainly from Canada, Spain and Argentina of Late Pennsylvanian-Late Triassic age are included in the study sample. Infrared data of cuticle and alkaline solutions differ which is primarily contingent on the mesophyll +biomacropolymer characteristics. The compression records two pathways of organic matter transformation. One is the vitrinized component that reflects the diagenetic-post-diagenetic coalification history parallel with the evolution of the associated coal seam. The other is the cuticle that reflects the sum-total of evolutionary pathway of the biomacropolymer, its monomeric, or polymeric fragmentation, though factors promoting preservation include entombing clay minerals and lower pH conditions. Caution is advised when interpreting liquid-state-based FTIR data, as some IR signals may have resulted from the interaction of Schulze's process with the cuticular biochemistry. A biochemical-study course for taphonomy is suggested, as fossilized cuticles, cuticle-free coalified layers, and compressions are responses to shared physicogeochemical factors. ?? 2009 Elsevier B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2009

Mercury and trace element contents of Donbas coals and associated mine water in the vicinity of Donetsk, Ukraine

Mercury-rich coals in the Donets Basin (Donbas region) of Ukraine were sampled in active underground mines to assess the levels of potentially harmful elements and the potential for dispersion of metals through use of this coal. For 29 samples representing c 11 to m 3 Carboniferous coals, mercury contents range from 0.02 to 3.5 ppm (whole-coal dry basis). Mercury is well correlated with pyritic sulfur (0.01 to 3.2 wt.%), with an r 2 of 0.614 (one outlier excluded). Sulfides in these samples show enrichment of minor constituents in late-stage pyrite formed as a result of interaction of coal with hydrothermal fluids. Mine water sampled at depth and at surface collection points does not show enrichment of trace metals at harmful levels, indicating pyrite stability at subsurface conditions. Four samples of coal exposed in the defunct open-cast Nikitovka mercury mines in Gorlovka have extreme mercury contents of 12.8 to 25.5 ppm. This coal was formerly produced as a byproduct of extracting sandstone-hosted cinnabar ore. Access to these workings is unrestricted and small amounts of extreme mercury-rich coal are collected for domestic use, posing a limited human health hazard. More widespread hazards are posed by the abandoned Nikitovka mercury processing plant, the extensive mercury mine tailings, and mercury enrichment of soils extending into residential areas of Gorlovka.

Donbas mines↗
USGS2009

Effects of coal storage in air on physical and chemical properties of coal and on gas adsorption

This paper investigates changes in the high-volatile bituminous Lower Block Coal Member from Indiana owing to moisture availability and oxidation in air at ambient pressure and temperature over storage time. Specifically, it investigates changes in chemistry, in surface area, and pore structure, as well as changes in methane and carbon dioxide adsorption capacities. Our results document that the methane adsorption capacity increased by 40%, whereas CO 2 adsorption capacity increased by 18% during a 13-month time period. These changes in adsorption are accompanied by changes in chemistry and surface area of the coal. The observed changes in adsorption capacity indicate that special care must be taken when collecting samples and preserving coals until adsorption characteristics are measured in the laboratory. High-pressure isotherms from partially dried coal samples would likely cause overestimation of gas adsorption capacities, lead to a miscalculation of coal-bed methane prospects, and provide deceptively optimistic prognoses for recovery of coal-bed methane or capture of anthropogenic CO 2 . ?? 2009 Elsevier B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2009

The Tiptop coal-mine fire, Kentucky: Preliminary investigation of the measurement of mercury and other hazardous gases from coal-fire gas vents

The Tiptop underground coal-mine fire in the Skyline coalbed of the Middle Pennsylvanian Breathitt Formation was investigated in rural northern Breathitt County, Kentucky, in May 2008 and January 2009, for the purpose of determining the concentrations of carbon dioxide (CO2), carbon monoxide (CO), and mercury (Hg) in the vent and for measuring gas-vent temperatures. At the time of our visits, concentrations of CO2 peaked at 2.0% and > 6.0% (v/v) and CO at 600 ppm and > 700 ppm during field analysis in May 2008 and January 2009, respectively. For comparison, these concentrations exceed the U.S. Occupational Safety & Health Administration (OSHA) eight-hour safe exposure limits (0.5% CO2 and 50 ppm CO), although the site is not currently mined. Mercury, as Hg0, in excess of 500 and 2100 μg/m3, in May and January, respectively, in the field, also exceeded the OSHA eight-hour exposure limit (50 μg/m3). Carbonyl sulfide, dimethyl sulfide, carbon disulfide, and a suite of organic compounds were determined at two vents for the first sampling event. All gases are diluted by air as they exit and migrate away from a gas vent, but temperature inversions and other meteorological conditions could lead to unhealthy concentrations in the nearby towns. Variation in gas temperatures, nearly 300 °C during the January visit to the fire versus < 50 °C in May, demonstrates the large temporal variability in fire intensity at the Tiptop mine. These preliminary results suggest that emissions from coal fires may be important, but additional data are required that address the reasons for significant variations in the composition, flow, and temperature of vent gases.

Kentucky↗
USGS2009

Notes on the origin of inertinite macerals in coals: Observations on the importance of fungi in the origin of macrinite

Macrinite is a, generally, rare inertinite maceral, often incorporating remnants and fragments of other macerals, including vitrinite, liptinite, and other inertinite. The associated inertinites include multiple forms of funginite. Funginite is also commonly found in association with vitrinite of slightly elevated reflectance and with degraded varieties of vitrinite. Together with the highly degraded macrinite, the latter two associations are here inferred to be part of a continuum of fungal and microbial degradation of peat. In any case, the origin of some macrinite is potentially distinct from that of inertinite generated by fire. ?? 2009 Elsevier B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2010

Geochemistry of trace elements in coals from the Zhuji Mine, Huainan Coalfield, Anhui, China

The abundances of nine major elements and thirty-eight trace elements in 520 samples of low sulfur coals from the Zhuji Mine, Huainan Coalfield, Anhui, China, were determined. Samples were mainly collected from 10 minable coal seams of 29 boreholes during exploration. The B content in coals shows that the influence of brackish water decreased toward the top of coal seams; marine transgression and regression occurred frequently in the Lower Shihezi Formation. A wide range of elemental abundances is found. Weighted means of Na, K, Fe, P, Be, B, Co, Ni, Cr, Se, Sb, Ba, and Bi abundances in Zhuji coals are higher, and the remainder elements are either lower or equal to the average values of elements in coals of northern China. Compared to the Chinese coals, the Zhuji coals are higher in Na, K, Be, B, Cr, Co, Se, Sn, Sb, and Bi, but lower in Ti, P, Li, V and Zn. The Zhuji coals are lower only in S, P, V and Zn than average U.S. and world coals. Potassium, Mg, Ca, Mn, Sr, As, Se, Sb and light rare earth elements (LREE) had a tendency to be enriched in thicker coal seams, whereas Fe, Ti, P, V, Co, Ni, Y, Mo, Pb and heavy rare earth elements (HREE) were inclined to concentrate in thinner coal seams. The enrichment of some elements in the Shanxi or Upper Shihezi Formations is related to their depositional environments. The elements are classified into three groups based on their stratigraphic distributions from coal seams 3 to 11-2, and the characteristics of each group are discussed. Lateral distributions of selected elements are also investigated. The correlation coefficients of elemental abundances with ash content show that the elements may be classified into four groups related to modes of occurrence of these elements. ?? 2009 Elsevier B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2010

Organic petrology of subbituminous carbonaceous shale samples from Chalāw, Kabul Province, Afghanistan: Considerations for paleoenvironment and energy resource potential

Neogene (?) subbituminous carbonaceous shale deposits from Chalāw, Afghanistan, were investigated through organic petrology techniques and standard coal analyses to determine paleoenvironment and potential for resource utilization. The Chalāw deposit, approximately 30 km southeast of Kabul, currently is exploited for brick making and domestic heating and cooking. Three multiple-bench channel samples of the mined bed at Chalāw were collected and evaluated. The presence of significant huminite (ranging from 0.2 to 59.0 vol.%, mineral-inclusive basis) is suggestive of a terrestrial lignin-rich precursor plant material. Measured reflectance values of 0.38–0.55% indicate subbituminous rank. This rank suggests burial depths of approximately 1500 m and maximum temperatures of approximately 50 °C. Structured liptinite macerals generally are absent except for some fluorescing morphologies interpreted to be poorly-preserved root cork suberinite. Sponge spicule bioliths including gemmoscleres and megascleres are common. These petrographic observations, in addition to high mineral matter content (33 to > 95 vol.%), medium to high sulfur content (2.1–11.5 wt.%, dry basis; db), and the presence of common gastropod? shell fragments and an aragonite-needle chalk bed are consistent with, but not directly indicative of, a marginal marine or estuarine mangrove depositional environment. However, additional data are necessary to confirm this hypothesis and deposition in a freshwater environment cannot be ruled out at this time. Commercial-scale development and utilization of the Chalāw deposit as a thermal fuel resource may be possible using a fluidized bed combustion system which could accept the low-quality mine product currently produced. Samples examined herein contain high-ash yield (45–90 wt.%, db), high total moisture content (17–39 wt.%), low calorific value (980–6860 Btu/lb, m,mmf), and have poor agglomerating properties (FSI = 0), consistent with fuels utilized in fluidized bed combustors. However, delineation of the extent of the deposit through field investigation will be necessary to make a quantified resource estimate for mine planning.

Kabul Province↗
USGS2010

Cyclic changes in Pennsylvanian paleoclimate and effects on floristic dynamics in tropical Pangaea

Wetland floras narrowly define perceptions of Pennsylvanian tropical ecosystems, the so-called Coal Age. Such wetlands reflect humid to perhumid climate, leading to characterizations of Pennsylvanian tropics as everwet, swampy. These views are biased by the high preservation potential of wetlands. Sedimentation patterns, paleosols, and fossil floras indicate the presence of vegetation tolerant of subhumid to dry-subhumid, perhaps semi-arid climate in basins between peat formation times. Understanding the significance of this seasonally-dry vegetation has suffered from conceptual and terminological confusion. A clearer view has emerged as models for framing the data have improved. Basinal floras typical of seasonally-dry conditions, relatively low soil moisture regimes, are well documented but mainly from isolated deposits. Some of the earliest, dominated by primitive pteridosperms ("Fl??zfern" floras), occur in clastic rocks between European Early Pennsylvanian coal beds. Later Early Pennsylvanian, fern-cordaitalean vegetation, different from coal floras, is preserved in marine goniatite bullions. Conifers are first suggested by late Mississippian Potoniesporites pollen. About the same time, in North America, broadleaf foliage, Lesleya and Megalopteris occur in basin-margin settings, on drought-prone limestone substrates. The best known, xeromorphic floras found between coal beds appear in the Middle through Late Pennsylvanian, containing conifers, cordaitaleans, and pteridosperms. The Middle Pennsylvanian appearances of this flora are mainly allochthonous, though parautochthonous occurrences have been reported. Parautochthonous assemblages are mostly Late Pennsylvanian. The conifer flora became dominant in western and central Pangaean equatorial lowlands in earliest Permian. Location of the humid-perhumid wetland flora during periods of relative dryness, though rarely discussed, is as, or more, perplexing than the spatial location of seasonally-dry floras through time - wetland plants had few migratory options and possibly survived in small refugia, within and outside of basins. Coupled oscillations in climate, sea level, and vegetation were driven most likely by glacial-interglacial fluctuations, perhaps controlled by orbital cyclicity. ?? 2010.

International Journal of Coal Geology↗
USGS2010

A high-pyrite semianthracite of Late Permian age in the Songzao Coalfield, southwestern China: Mineralogical and geochemical relations with underlying mafic tuffs

The No. 12 Coal (Late Permian) in the Songzao Coalfield, Chongqing, southwestern China, is characteristically high in pyrite and some trace elements. It is uniquely deposited directly above mafic tuff beds. Samples of coal and tuffs have been studied for their mineralogy and geochemistry using inductively coupled plasma-mass spectrometry, X-ray fluorescence, plasma low-temperature ashing plus powder X-ray diffraction, and scanning electron microscopy equipped with energy-dispersive X-ray analysis.The results show that the minerals of the No. 12 Coal are mainly composed of pyrite, clay minerals (kaolinite, chamosite, and illite), ankerite, calcite, and trace amounts of quartz and boehmite. Kaolinite and boehmite were mainly derived from sediment source region of mafic tuffs. Chamosite was formed by the reaction of kaolinite with Fe-Mg-rich fluids during early diagenesis. The high pyrite (Sp,d=8.83%) in the coal was related to marine transgression over peat deposits and abundant Fe derived from the underlying mafic tuff bed. Ankerite and calcite were precipitated from epigenetic fluids.Chemical compositions of incompatible elements indicate that the tuffs were derived from enriched mantle and the source magmas had an alkali-basalt character. Compared to other coals from the Songzao Coalfield and common Chinese coals, the No. 12 Coal has a lower SiO2/Al2O3 (1.13) but a higher Al2O3/Na2O (80.1) value and is significantly enriched in trace elements including Sc (13.5??g/g), V (121??g/g), Cr (33.6??g/g), Co (27.2??g/g), Ni (83.5??g/g), Cu (48.5??g/g), Ga (17.3??g/g), Y (68.3??g/g), Zr (444??g/g), Nb (23.8??g/g), and REE (392??g/g on average). Above mineralogical compositions, as well as similar ratios of selected elements (e.g., SiO2/Al2O3 and Al2O3/Na2O) and similar distribution patterns of incompatible elements (e.g., the mantle-normalized diagram for incompatible elements and chondrite-normalized diagram for rare earth elements) of coal and tuff, indicated that enriched trace elements above were largely derived from mafic tuffs, in addition to a minor amount from the Kandian Oldland. ?? 2010 Elsevier B.V.

International Journal of Coal Geology↗
USGS2010

Coal lithotypes before and after saturation with CO2; insights from micro- and mesoporosity, fluidity, and functional group distribution

Four lithotypes, vitrain, bright clarain, clarain, and fusain, were hand-picked from the core of the Pennsylvanian Springfield Coal Member (Petersburg Formation) in Illinois. These lithotypes were analyzed petrographically and for meso- and micropore characteristics, functional group distribution using FTIR techniques, and fluidity. High-pressure CO2 adsorption isotherm analyses of these lithotypes were performed and, subsequently, all samples were reanalyzed in order to investigate the effects of CO2. After the high-pressure adsorption isotherm analysis was conducted and the samples were reanalyzed, there was a decrease in BET surface area for vitrain from 31.5m2/g in the original sample to 28.5m2/g, as determined by low-pressure nitrogen adsorption. Bright clarain and clarain recorded a minimal decrease in BET surface area, whereas for fusain there was an increase from 6.6m2/g to 7.9m2/g. Using low-pressure CO2 adsorption techniques, a small decrease in the quantity of the adsorbed CO2 is recorded for vitrain and bright clarain, no difference is observed for clarain, and there is an increase in the quantity of the adsorbed CO2 for fusain. Comparison of the FTIR spectra before and after CO2 injection for all lithotypes showed no differences with respect to functional group distribution, testifying against chemical nature of CO2 adsorption. Gieseler plastometry shows that: 1) softening temperature is higher for the post-CO2 sample (389.5??C vs. 386??C); 2) solidification temperature is lower for the post-CO2 sample (443.5??C vs. 451??C); and 3) the maximum fluidity is significantly lower for the post-CO2 sample (4 ddpm vs. 14 ddpm). ?? 2010 Elsevier B.V.

International Journal of Coal Geology↗
USGS2010

Phytochemistry of the fossilized-cuticle frond Macroneuropteris macrophylla (Pennsylvanian seed fern, Canada)

In Canada's Sydney Coalfield, specimens of the extinct Carboniferous seed fern Macroneuropteris macrophylla (Brongniart) invariably show preservation stages intermediate between compression and fossilized-cuticle, even concerning a single pinnule. In this interdisciplinary approach, we study a ca. 300 to 350 mm long fossilized-cuticle-preserved frond section of M. macrophylla (Brongniart) that represents about one third of the length of a frond that was originally 1 m long. Size and preservation allow us to study the phytochemistry of the cuticle biomacropolymers over the length of the frond to assess what impact, if any, results would have on Carboniferous palaeophytochemotaxonomy. For comparison, the phytochemistry of compressions with their extracted cuticles from the same species and the same sample locality is also investigated. We use solid- and liquid-state, semi-quantitative Fourier transform infrared spectroscopy (FTIR) for the chemical characterization of the frond.Based on our results, we infer an essentially uniform phytochemistry over the fossilized-cuticle frond, suggesting that only a single pinnule needs to be analyzed to get an overall phytochemical picture of the frond, which has been our long-time working hypothesis. We distinguish between phytochemistry and cutinization. The latter is much less pronounced above than below the frond dichotomy, and we suggest a palaeoecological cause, rather than differing pathways of organic matter transformation. Moreover, cuticles below and above the frond dichotomy have essentially the same epidermal pattern, but those from below have features that may have been an adaptation to prevent stomatal flooding during the tropical, rainy season.This study suggests that chemically the fossilized-cuticle is more similar to the compression than to the cuticle obtained from that compression of the same species which invites reevaluation of the classical compression concept. ?? 2010 Elsevier B.V.

International Journal of Coal Geology↗
USGS2010

Depositional setting, petrology and chemistry of Permian coals from the Paraná Basin: 2. South Santa Catarina Coalfield, Brazil

In Brazil economically important coal deposits occur in the southern part of the Paraná Basin, where coal seams occur in the Permian Rio Bonito Formation, with major coal development in the states of Rio Grande de Sul and Santa Catarina. The current paper presents results on sequence stratigraphic interpretation of the coal-bearing strata , and petrological and geochemical coal seam characterization from the South Santa Catarina Coalfield, Paraná Basin. In terms of sequence stratigraphic interpretation the precursor mires of the Santa Catarina coal seams formed in an estuarine-barrier shoreface depositional environment , with major peat accumulation in a high stand systems tract (Pre-Bonito and Bonito seams), a lowstand systems tract (Ponta Alta seam, seam A, seam B) and a transgressive systems tract (Irapuá, Barro Branco and Treviso seams). Seam thicknesses range from 1.70 to 2.39 m, but high proportions of impure coal (coaly shale and shaley coal), carbonaceous shale and partings reduce the net coal thickness significantly. Coal lithoypes are variable, with banded coal predominant in the Barro Branco seam, and banded dull and dull coal predominantly in Bonito and Irapuá seams, respectively. Results from petrographic analyses indicate a vitrinite reflectance range from 0.76 to 1.63 %Rrandom (HVB A to LVB coal). Maceral group distribution varies significantly, with the Barro Branco seam having the highest vitrinite content (mean 67.5 vol%), whereas the Irapuá seam has the highest inertinite content (33.8 vol%). Liptinite mean values range from 7.8 vol% (Barro Branco seam) to 22.5 vol% (Irapuá seam). Results from proximate analyses indicate for the three seams high ash yields (50.2 – 64.2 wt.%). Considering the International Classification of in-Seam Coals, all samples are in fact classified as carbonaceous rocks (> 50 wt.% ash). Sulfur contents range from 3.4 to 7.7 wt.%, of which the major part occurs as pyritic sulfur. Results of X-ray diffraction indicate the predominance of quartz and kaolinite (also pyrite). Gypsum , gibbsite , jarosite and calcite were also identified in some samples. Feldspar was noted but is rare. The major element distribution in the three seams (coal basis) is dominated by SiO 2 (31.3 wt.%, mean value), Al 2 O 3 (14.5 wt.%, mean value) and Fe 2 O 3 (6.9 wt.%, mean value). Considering the concentrations of trace elements that are of potential environmental hazards the Barro Branco, Bonito and Irapuá seams (coal base) are significantly enriched in Co (15.7 ppm), Cr (54.5 ppm), Li (59.3 ppm), Mn (150.4 ppm), Pb (58.0 ppm) and V (99.6 ppm), when compared to average trace elements contents reported for U. S. coals. Hierarchical cluster analysis identified, based on similarity levels, three groups of major elements and seven groups of trace elements. Applying discriminant analyses using trace and major element distribution, it could be demonstrated that the three seams from Santa Catarina show distinct populations in the discriminant analyses plots, and also differ from the coals of Rio Grande do Sul analyzed in a previous study.

Santa Catarina↗
USGS2011

Notes on the origin of inertinite macerals in coals: Funginite associations with cutinite and suberinite

The association of fungus with plant leaves and roots is ubiquitous. While many of these occurrences are considered to be pathogenic, mycorrhizzal fungal associations with roots are essential for plant growth. Despite the common knowledge of such relationships in plant science, with a few exceptions, the fungus/leaf/root/stem association as the macerals funginite, cutinite, and suberinite in coals has not been extensively studied. In this work, examples of funginite associations with cutinite and suberinite are discussed. ?? 2010 Elsevier B.V.

International Journal of Coal Geology↗
USGS2011

Splint coals of the Central Appalachians: Petrographic and geochemical facies of the Peach Orchard No. 3 split coal bed, southern Magoffin County, Kentucky

The Bolsovian (Middle Pennsylvanian) Peach Orchard coal bed is one of the splint coals of the Central Appalachians. Splint coal is a name for the dull, inertinite-rich lithologies typical of coals of the region. The No. 3 Split was sampled at five locations in Magoffin County, Kentucky and analyzed for petrography and major and minor elements. The No. 3 Split coals contain semifusinite-rich lithologies, up to 48% (mineral-free basis) in one case. The nature of the semifusinite varies with position in the coal bed, containing more mineral matter of detrital origin in the uppermost durain. The maceral assemblage of these terminal durains is dominated by detrital fusinite and semifusinite, suggesting reworking of the maceral assemblage coincident with the deposition of the detrital minerals. However, a durain in the middle of the coal bed, while lithologically similar to the uppermost durains, has a degraded, macrinite-rich, texture. The inertinite macerals in the middle durain have less distinct edges than semifusinites in the uppermost terminal durains, suggesting degradation as a possible path to inertinite formation. The uppermost durain has higher ash and semifusinite contents at the eastern sites than at the western sites. The difference in the microscopic petrology indicates that megascopic petrology alone can be a deceptive indicator of depositional environments and that close attention must be paid to the individual macerals and their implications for the depositional setting, especially within the inertinite group.

International Journal of Coal Geology↗
USGS2011

Notes on the origin of inertinite macerals in coal: Evidence for fungal and arthropod transformations of degraded macerals

The role of fungus in the formation of coal macerals, both as a primary contributor in the form of a fungus fossil/maceral funginite, and in their role in degrading wood, thus producing degraded maceral forms, has been established. Fungus, in the course of breaking down the lignin and cellulose in wood, make the wood more digestible for grazers, such as arthropods. In turn, the remnants of the digested wood and anything else eaten but not completely digested are excreted and can be preserved intact; eaten by other fauna with a repeat of the cycle; or colonized by bacteria and/or coprophilous fungi with or without subsequent preservation. Ultimately, the coprolites can be preserved as a form of macrinite.

International Journal of Coal Geology↗
USGS2011

Geochemistry of environmentally sensitive trace elements in Permian coals from the Huainan coalfield, Anhui, China

To study the geochemical characteristics of 11 environmentally sensitive trace elements in the coals of the Permian Period from the Huainan coalfield, Anhui province, China, borehole samples of 336 coals, two partings, and four roof and floor mudstones were collected from mineable coal seams. Major elements and selected trace elements were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and hydride generation atomic absorption spectrometry (HAAS). The depositional environment, abundances, distribution, and modes of occurrence of trace elements were investigated. Results show that clay and carbonate minerals are the principal inorganic constituents in the coals. A lower deltaic plain, where fluvial channel systems developed successively, was the likely depositional environment of the Permian coals in the Huainan coalfield. All major elements have wider variation ranges than those of Chinese coals except for Mg and Fe. The contents of Cr, Co, Ni, and Se are higher than their averages for Chinese coals and world coals. Vertical variations of trace elements in different formations are not significant except for B and Ba. Certain roof and partings are distinctly higher in trace elements than underlying coal bench samples. The modes of occurrence of trace elements vary in different coal seams as a result of different coal-forming environments. Vanadium, Cr, and Th are associated with aluminosilicate minerals, Ba with carbonate minerals, and Cu, Zn, As, Se, and Pb mainly with sulfide minerals.

Huainan coalfield↗
USGS2011

Chemical structures of coal lithotypes before and after CO2 adsorption as investigated by advanced solid-state 13C nuclear magnetic resonance spectroscopy

Four lithotypes (vitrain, bright clarain, clarain, and fusain) of a high volatile bituminous Springfield Coal from the Illinois Basin were characterized using advanced solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy. The NMR techniques included quantitative direct polarization/magic angle spinning (DP/MAS), cross polarization/total sideband suppression (CP/TOSS), dipolar dephasing, CH n selection, and recoupled C–H long-range dipolar dephasing techniques. The lithotypes that experienced high-pressure CO 2 adsorption isotherm analysis were also analyzed to determine possible changes in coal structure as a result of CO 2 saturation at high pressure and subsequent evacuation. The main carbon functionalities present in original vitrain, bright clarain, clarain and fusain were aromatic carbons (65.9%–86.1%), nonpolar alkyl groups (9.0%–28.9%), and aromatic C–O carbons (4.1%–9.5%). Among these lithotypes, aromaticity increased in the order of clarain, bright clarain, vitrain, and fusain, whereas the fraction of alkyl carbons decreased in the same order. Fusain was distinct from other three lithotypes in respect to its highest aromatic composition (86.1%) and remarkably small fraction of alkyl carbons (11.0%). The aromatic cluster size in fusain was larger than that in bright clarain. The lithotypes studied responded differently to high pressure CO 2 saturation. After exposure to high pressure CO 2 , vitrain and fusain showed a decrease in aromaticity but an increase in the fraction of alkyl carbons, whereas bright clarain and clarain displayed an increase in aromaticity but a decrease in the fraction of alkyl carbons. Aromatic fused-rings were larger for bright clarain but smaller for fusain in the post-CO 2 adsorption samples compared to the original lithotypes. These observations suggested chemical CO 2 –coal interactions at high pressure and the selectivity of lithotypes in response to CO 2 adsorption.

International Journal of Coal Geology↗
USGS2011

Quantifying greenhouse gas emissions from coal fires using airborne and ground-based methods

Coal fires occur in all coal-bearing regions of the world and number, conservatively, in the thousands. These fires emit a variety of compounds including greenhouse gases. However, the magnitude of the contribution of combustion gases from coal fires to the environment is highly uncertain, because adequate data and methods for assessing emissions are lacking. This study demonstrates the ability to estimate CO 2 and CH 4 emissions for the Welch Ranch coal fire, Powder River Basin, Wyoming, USA, using two independent methods: (a) heat flux calculated from aerial thermal infrared imaging (3.7–4.4 t d −1 of CO 2 equivalent emissions) and (b) direct, ground-based measurements (7.3–9.5 t d −1 of CO 2 equivalent emissions). Both approaches offer the potential for conducting inventories of coal fires to assess their gas emissions and to evaluate and prioritize fires for mitigation.

International Journal of Coal Geology↗