Longyi Shao

Characterization of airborne individual particles collected in an urban area, a satellite city and a clean air area in Beijing, 2001

Abstract Collection campaigns for PM10 and PM2.5 have been conducted in a northwestern Beijing urban area in monthly periods over 2001, with 7 days collection per month. The samples were also collected simultaneously in a satellite city, Nankou, and a clean air area near the Ming Tombs Reservoir (MTR) over the domestic heating (March) and non-heating (July/August) periods in 2001 (both for one week). To assist the analysis, three types of ‘source’ particulate matter (PM) samples were taken. These consisted of coal combustion ash collected on top of a coke oven; dust storm particles collected during dust storm periods; and roadside PM10 collected on a major road in Beijing. Monitoring results reveal that, in the urban area, particle mass levels were higher in winter than in other seasons. The 1-week/month average PM10 mass levels were over 250 μg m −3 in winter. The particle mass levels in the satellite city were slightly lower than those at the urban site, and the lowest mass levels occurred at the MTR site. The morphology and chemical composition of individual airborne particles were determined by scanning electron microscopy, and image analysis was employed to study the number-size distributions. The number-size distributions of mineral particles showed that those in the Asia-Dust storm (ADS) collections are mostly coarser than 1 μm , while mineral particles of the non-ADS collections are predominately finer than 1 μm . The particles in the respirable ( μm ) fraction accounted for 99% of the total particles in airborne PM samples. Soot aggregates were generally the most abundant components in airborne PM samples at all three sites. The fly ash (spherical) particles at the MTR site were significantly enriched over the heating period, indicating a domestic coal-burning source.

Distribution, isotopic variation and origin of sulfur in coals in the Wuda coalfield, Inner Mongolia, China

Abstract This paper describes coal petrographic characteristics, sulfur abundance, distribution and isotopic signature in coals in the Wuda coalfield, Inner Mongolia, northern China. Petrographic studies suggest that depositional environment influences petrographic composition. The No. 9 and No. 10 coal seams, which are thought to have formed on a tidal delta plain, have high collodetrinite contents (up to 66.1%) indicating enhanced gelification and bacteria activity during coal accumulation, and also have the highest sulfur content (3.46% and 3.42%). Both organic and pyritic sulfur isotope values (−12.3‰ to 5.8‰ and −18.7‰ to 1.1‰, respectively) are variable and generally tend to be more negative in high-sulfur coals than those in low-sulfur coals in the Wuda coalfield. The negative sulfur isotope values indicate that a large portion of sulfur in the high-sulfur coals has a bacterial origin. Sulfur isotopic compositions and variations within the section were used to propose a model to explain the origin of sulfur in these coals. The presence of pyritized rod-like bacteria, cyanophytes gelatinous sheaths and degraded algae organic matter suggests that bacteria, and perhaps algae, may play an important role in the formation of these high-sulfur coals.

Geochemical and mineralogical anomalies of the late Permian coal in the Zhijin coalfield of southwest China and their volcanic origin

Abstract This paper describes the influence of volcanic ash on the concentrations and occurrences of associated elements in coal in the Zhijin Coalfield in western Guizhou Province, China. Our studies reveal that the No. 9 coal seam in the Zhijin Coalfield has very high content of Fe (4.34%), Cu (369.90 μg/g), U (49.6 μg/g), Mo (63.10 μg/g), Zn (33.97 μg/g), and Zr (841.80 μg/g). The studies have also found that elements, such as Fe and Cu, do not occur as sulfides in this coal seam, in sharp contrast to many other coal seams in China. The geochemical and mineralogical anomalies of the coal seam are attributed to synsedimentary volcanic ash. In addition to normal macerals and minerals in coal, a volcanic-influenced material (VIM) derived from volcanic ash, detrital material of terrigenous origin and organic matter was identified under polarized-light reflectance microscopy and scanning electron microscopy equipped with energy-dispersive X-ray (EDX) analyzer. The volcanic-influenced material is the main carrier of the above elements in this coal. Six types of the volcanic-influenced material (VIM-1, VIM-2, VIM-3, VIM-4, VIM-5, and VIM-6) are further distinguished on the basis of their structures and compositions. To the best of our knowledge, this is the first report that presents a detailed classification of coal components with a high content of volcanic ash.

Petrology and geochemistry of the high-sulphur coals from the Upper Permian carbonate coal measures in the Heshan Coalfield, southern China

Abstract The Heshan coals, with very high organic sulphur content, are found in the Upper Permian marine carbonate successions (Heshan Formation) in the Heshan Coalfield, central Guangxi, southern China. The petrography, mineralogy, and geochemistry of coals and non-coal partings from the Suhe and Lilan coal mines of the Heshan Coalfield have been investigated using proximate, petrographic, inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy with an energy-dispersive X-ray (SEM-EDX) techniques. The sulphur content in the coals (with ash less than 50%) ranges from 5.3% to 11.6%, of which more than 90% is organic sulphur, reflecting a strong marine water influence on the palaeomire. The high vitrinite reflectance (1.89–2.18%Romax) indicates that the coals in the Heshan Coalfield are mainly low-volatile bituminous coal. Microscopic observation has revealed that the coal is mainly composed of vitrinite and inertinite macerals with relatively low TPI and high GI values, suggesting an unusual, strongly alkaline palaeomire, with high pH. XRD analysis plus optical and scanning electron microscopy show that the minerals in these coals are mainly quartz, calcite, dolomite, kaolinite, illite, and pyrite, although marcasite, strengite, and feldspar, as well as some oxidised weathering products such as gypsum, are also present. Most trace elements in the Heshan coals are enriched with respect to their world mean, with Mo, U, and W highly enriched, more than 10 times their world means. The trace elements are believed to be associated either with organic compounds (Mo and U) or minerals such as aluminium–iron-silicates (Sc, Ge, and Bi), aluminium-silicates (Cs, Be, Th, Pb, Ga, and REE), iron-phosphates (Zn, Rb, and Zr), iron-sulphides (As, Cd, Cr, Cu, Ni, Tl, and V), and carbonates (Sr, Mn, and W). Abnormally high organic sulphur content, high ash yields, relatively high GI values, very low TPI values, very high U contents, and very low Th/U ratios suggest that the Heshan coals accumulated in low-lying, marine-influenced palaeomires, developed on carbonate platforms. Many of these characteristics have also been recorded in the Tertiary coals of the circum-Mediterranean coal basins, where no marine influence is present. The similarities are thought to be produced by strongly alkaline groundwater chemistry, common to both environments.

Impact of sulphur and trace element geochemistry on the utilization of a marine-influenced coal-case study from the South Wales Variscan foreland basin

Abstract Incremental channel samples through two high volatile A bituminous coal seams, the Amman Rider and Bute seams, below and above the Vanderbeckei Marine Band at the Westphalian A/B boundary, have been analysed using proximate, petrographic, inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF) and scanning electron microscopy with energy-dispersive X-ray (SEM-EDX) techniques. The results show that both coals are vitrinite-rich and indicate a similar history of palaeomire development, with a period of falling water tables towards the middle plies of each seam. Mean sulphur contents in the coal with the marine roof, the Amman Rider seam (4.19 wt.%) are almost 4 times higher than in the coal with a non-marine roof, the Bute seam (1.09 wt.%), implying that high sulphur contents are derived from sea water sulphate. In both coals, sulphur is predominantly in the form of pyritic sulphur. Both syngenetic, framboidal and euhedral crystals, and epigenetic vein and cleat-fill pyrite are present. Relatively constant levels of organic sulphur at around 2% have been recorded in the Amman Rider seam. Sulphur levels in the basal and top plies of each seam are at least twice that of the ply with the lowest sulphur content in the seam, reflecting the stages in palaeomire development most strongly influenced by sulphate-containing waters. Thorium/Uranium ratios are below 2.9 in the coal with a marine roof, the Amman Rider seam, indicating an enrichment of U from sea water, most marked at the top and bottom of the seam. The seam without a marine roof shows Th/U ratios between 2.5 and 4.9, indicating mild marine enrichment of U. The concentrations of environmentally significant trace elements (ESEs) are correlated with either the ash or sulphur contents, or both. The correlation between S and Pb, As, Cu, Ni in the coal with a marine roof implies an origin of these ESEs from sea water and their mode of occurrence in sulphide minerals. Most ESEs in this coal are present at levels at least twice that of the global average in coals, the exceptions being Pb and Zn which have concentrations less than half the global average. By contrast, the coal without a marine roof and with lower sulphur contents has most ESEs present at concentrations less than a third of the global average, the exceptions being Ni and Cu. Diagenetic hydrothermal activity is documented in the middle ply of the coal with a marine roof. This hydrothermal system redistributed the sulphur, Pb and As in this ply. The principal utilization of bituminous coals in the South Wales coalfield is as feed coals in power station boilers. The resultant concentration of most ESEs in the solid residues from power plant coal combustion theoretically can be alleviated by careful blending of feed coals with low and high ESE contents.

Paleoenvironments and paleogeography of the Lower and lower Middle Jurassic coal measures in the Turpan-Hami oil-prone coal basin, northwestern China

Detailed facies and paleogeographical analyses of extensive borehole and outcrop data from Lower and lower Middle Jurassic oil-prone coal-bearing sequences in the Turpan-Hami oil-producing basin of northwest China have led to the reconstruction of a basinwide depositional model. A total of 20 distinct lithofacies have been identified and grouped into braided fluvial plain, meandering fluvial plain, braided delta, meandering channel delta, and lacustrine depositional systems. Coal-forming swamps occur in each depositional system, but the preferred sites of accumulation are interdelta bay and lower delta-plain environments in the braided delta and meandering channel depositional systems, and it is in these sites that major oil-prone source rocks are located. A series of age-specific, basinwide, paleogeographical maps have been constructed leading to a depositional model for the basin. Results indicate that the basin experienced cyclic flooding to produce swamps and lakes, and that these characterize the deposition of the Lower and lower Middle Jurassic coal measures. Analyses indicate that both the Bogda and Harlik Mountains were uplifted prior to the Early Jurassic, and a lake separated the two mountain regions during the Early and early Middle Jurassic. From these results, it is interpreted that major oil-prone coal sequences are to be found in the western part of the Taibei depression of the basin, and thus, the full economic potential of the basin has yet to be fully realized.

Silica−Volatile Interaction and the Geological Cause of the Xuan Wei Lung Cancer Epidemic

Parts of Xuan Wei County, Yunnan Province, China have the highest known lung cancer mortality in nonsmoking women. This high mortality displays a clear spatial relationship to the mines producing coal from the uppermost Permian. Geochemical, petrographic, and grainsize analyses were undertaken on a set of coal samples from Xuan Wei. Results demonstrate that the single geochemical property that makes this coal unusual is its high concentration of quartz (13.5 wt %) of which 35-55% occurs as <10 microm grains. We propose the potential for silica-volatile interaction (PSVI) as a new method for assessing the combined influence of silica and volatile organic matter and use this as a basis for re-evaluating existing ecological data. Published lung cancer mortality values are more strongly correlated with PSVI values for Xuan Wei coal than with volatiles or silica alone and the PSVI values measured are distinct from those of other coals. Finally we propose that the localization of this epidemic to Xuan Wei results from enhanced weathering of the local Emeishan basalts as a consequence of geochemical perturbations at the Permo-Triassic Boundary.

Size, composition, and mixing state of individual aerosol particles in a South China coastal city

Aerosol samples were collected in summer in Macao, a coastal city of the Pearl River Delta Region in China. Morphology, size, elemental composition, and mixing state of individual aerosol particles were determined by scanning electron microscopy coupled energy dispersive X-ray (SEM/EDX) and transmission electron microscopy (TEM). Based on the morphologies of 5711 aerosol particles, they consist of soot (32%), mineral (17%), secondary (22%), and unknown fine particles (29%). The sizes of these particles were mostly distributed between 0.1 and 0.4 microm. Compositions of 202 mineral particles were obtained by SEM/EDX. Mineral particles were mainly classified into three types: Si-rich, Ca-rich, and Na-rich. The compositions of typical mineral particles can indicate their sources in sampling location. For example, mineral particles, collected along the main street, were associated with trace amounts of heavy metals, such as Zn, Ti, Mn, Ba, Pb, and As. TEM observations indicate that most Na-rich particles were aged sea salt particles (e.g., Na2SO4 and NaNO3) which formed through heterogeneous chemical reactions between sea salt and acidic gases. Additionally, aging time of soot was short in Macao due to high humidity, high temperature, and high levels of sunlight in Macao. Most of soot and fine mineral dust particles were internally mixed with secondary particles.

Coal in a carbonate sequence stratigraphic framework: the Upper Permian Heshan Formation in central Guangxi, southern China

Microfacies and sedimentological analyses of the Upper Permian coal-bearing Heshan Formation in the Heshan coalfield of central Guangxi suggest that these coal measures formed in a marine carbonate platform setting. Low-volatile bituminous coals with very high organic sulphur overlie either palaeosols or locally developed cherts. The petrography and geochemistry of the coals suggest formation in low-lying mires, in which marine influence increased upwards. In the Heshan and overlying Dalong Formations, four third-order sequences are described based on the recognition of four sequence boundaries. Higher-order sequences within each of these third-order sequences are also documented and, within Sequence III, coal seams are developed above higher-order transgressive surfaces, representing the deposits formed during the lag time between initial flooding of the platform and the onset of carbonate production. In the Heshan Formation, the coals with greatest thickness occur immediately above third-order transgressive surfaces. It is argued that, in some coal-bearing siliciclastic-free marine carbonate-platform settings, accommodation creation rates and peat accumulation rates are balanced, hence greater coal accumulation can be achieved at the transgressive surface rather than at the maximum flooding surface.

Measures of scale based on the wavelet scalogram with applications to seismic attenuation

The attenuation of seismic signal is usually characterized in the frequency domain using Fourier power spectra and is often usefully characterized by average measures, such as the center frequency or spectral mean. Fourier analysis, however, suffers from time-frequency resolution problems. Wavelet analysis has better time-frequency localization and offers superior spectral decomposition. In this paper, we show that seismic attenuation can be characterized by the scalogram (also called energy density) in the wavelet domain. A single scale encompasses a frequency band. The scalogram relates absorption to peak-scale variations. The peak scale is the scale of maximum amplitude in the scalogram. Seismic attenuation can be estimated directly from the scalogram according to the scale shift of the data and can also be described indirectly by the centroid of scale (the mean of a scalogram). In absorbing media, seismic attenuation increases with frequency, i.e., decreases with scale. In the wavelet domain, small-sc...