Dissertations / Theses on the topic 'Bowen Basin'

Igneous intrusions, in the form of stocks, sills and dykes are abundant in the Bowen Basin. They are predominantly Early Cretaceous in age, exclusively epizonal in origin and range in composition from dolerite to granodioriteldacite. All rock units within the basin, up to and including the Clematis Group, are intruded to some degree. This study assesses the distribution, form, petrology and mode of emplacement of plutons, igneous sills and dykes occurring in the Bowen Basin, and considers their relationship to the prevailing structure. The tectonic implications of the findings are then assessed. Igneous sills occur in two geographically distinct domains, one in the northern Bowen Basin and the other in the central Bowen Basin. The sills emanated from pre-existing, north to north-northwest trending reverse faults, and preferentially intruded coal seams. The boundaries to sill intrusion are marked by major northeast trending basement structures. These basement structures occur at regular intervals throughout the basin, and correspond with the localisation of plutonic and dyke activity, anomalous structural disturbance, and changes in the gross structure of the basin. They are interpreted as transfer faults that were inherited from an Early Permian, basin-forming extensional episode. Petrological evidence indicates that the plutons and sills occurring in the northern Bowen Basin are petrogenetically related, and that a progressive variation in their chemistry occurs across the axis of the basin from east to west. Intrusions in the east belong to the calc-alka1ine rock suite, while those in the west belong to the syenitic suite. This transition is inte1preted in terms of increased crustal contamination as the magma migrated from a source area to the east along a buried, shallow-dipping detachment surface that extends under the basin. This detachment was inherited from the above mentioned extensional phase and is intimately linked to structures that penetrate up-section through the basin succession. Reactivation of the transfer faults during the Early Cretaceous initiated the emplacement of dykes, and the synchronous development of northeast trending normal and wrenchstyle faults. The dykes exhibit characteristics that indicate they were self-propagating, and can be regarded as good palaeostress indicators. This phase corresponded with a major compressional event that involved the reactivation of pre-existing thrust structures, deformation of the Folded Zone and eastern margins of the Nebo Synclinorium and Mimosa Syncline, and the rapid preferential uplift of the central Bowen Basin region.

The three-dimensional thermal maturity pattern has been investigated and the hydrocarbon generation potential assessed for the Permian and Triassic sequences of the southern Bowen and northern Gunnedah Basins and the lower part of the overlying Jurassic Cretaceous Surat Basin sequence in northern New South Wales. An oil-source rock correlation also has been investigated in the Gunnedah Basin. Vitrinite reflectance measurements were conducted on 256 samples from 28 boreholes. A total of 50 of these samples were subjected to Rock-Eval pyrolysis analysis, and 28 samples extracted for additional organic geochemical studies (GCMS). A re-evaluation of the stratigraphy in the southern Bowen Basin and a stratigraphic correlation between that area and the northern Gunnedah Basin was also included in the study. An overpressured shaly interval has been identified as a marker bed within the lower parts of the Triassic Moolayember and Napperby Formations, in the Bowen and Gunnedah Basins respectively. Suppressed vitrinite reflectance in the Permian sequence was used as another marker for mapping the stratigraphic sequence in the southern Bowen Basin. The Permian sequence in the Bowen Basin thins to the south, and probably pinches out over the Moree High and also to the west. The coal-bearing Kianga Formation is present in the north and northeastern parts of the study area. A disconformity surface between Digby and Napperby Formations in the Gunnedah Basin is probably time-equivalent to deposition of the Clematis Group and Showgrounds Sandstone in the Bowen Basin. The Clematis Group is absent in the study area, and the Moolayember Formation considered equivalent to the Napperby Formation. Although in many cases core samples were not available, handpicking of coal or shaly materials from cuttings samples where geophysical log signatures identify these materials helped in reducing contamination from caved debris. Histogram plots of reflectance also helped where the target and caved debris were of similar lithology. Vertical profiles of the vitrinite reflectance identified suppressed intervals in the study area due to marine influence (Back Creek Group and Maules Creek Formation) and liptinite rich source organic matter (Goonbri Formation). The suppression occurs due to the perhydrous character of the preserved organic matter. High reflectance values were noted within intrusion-affected intervals, and two types of igneous intrusion profiles were identified; these are simple and complex profiles. An isoreflectance map for the non-suppressed interval at the base of the Triassic sequence in the southern Bowen Basin shows that the organic matter is mature more towards the east close to the Goondiwindi Fault, and also towards the west where the Triassic sequence directly overlies the basement. High values also occur over the Gil Gil Ridge in the middle, to the south over the Moree High, and to the north where the sequence is thicker. The reflectance gradient in the suppressed intervals is higher than in the overlying non-suppressed sequences, especially when the rank has resulted from burial depth. Tmax from Rock-Eval pyrolysis was found to be lower in the perhydrous intervals, and was high in mature and igneous intrusion-affected intervals. Based on the source potential parameters, the Permian Back Creek Group is a better source than the Kianga Formation, while the Goonbri Formation is better than the Maules Creek Formation. The Triassic Napperby Formation has a fair capacity to generate oil, and is considered a better source rock than the equivalent Moolayember Formation. The Jurassic Walloon Coal Measures is a better source than Evergreen Formation, and has the best source rock characteristics, but is immature. The Rock-Eval S1 value shows better correlation with extracted hydrocarbon compounds (saturated and aromatics) than the total extractable organic matter. This suggests that solvent extraction has a greater ability to extract NSO compounds than temperature distillation over the Rock-Eval S1 interval. Terrestrial organic matter is the main source input for the sequences studied. This has been identified from organic petrology and from the n-alkane distributions and the relatively high C29 steranes and low sterane/hopane ratios. The absence of marine biomarker signatures in the Permian marine influenced sequence, could be attributed to their dilution by overwhelming amounts of non-marine organic matter. A mainly oxic to suboxic depositional environment is inferred from trace amounts of 25-NH, BNH and TNH. This is further supported by relatively high pr/ph ratios. Although C29/C30 is generally regarded as an environmental indicator, high values were noted in intrusion-affected samples. The 22S and 20S ratios were inverted ????reaches pseudo-equilibrium???? in such rapidly heated, high maturity samples. The ratio of C24 tetracyclic terpane to C21-C26 tricyclic terpanes decreases, instead of increasing, within the Napperby Formation close to a major igneous intrusive body. The 22S ratio, which is faster in reaction than the other terpane and sterane maturity parameters, shows that the Permian sequence lies within the oil generation stage in the Bowen Basin, except for a Kianga Formation sample. The Triassic sequence is marginally mature, and the Jurassic sequence is considered immature. In the Gunnedah Basin, the Permian sequence in Bellata-1 and Bohena-1, and the Triassic sequence in Coonarah-1A, lie within the oil generation range. In the intrusion-affected high maturity samples, the ratio is reaches pseudo-equilibrium. This and other terpane and sterane maturity parameters are not lowered (suppressed) in the perhydrous intervals. The ???????? sterane ratio, however, is slowest in reaction to maturity, and variations in low maturity samples are mainly due to facies changes. Diasterane/sterane ratios, in the current study, increase with increasing TOC content up to 5% TOC, but decrease in rocks with higher TOC contents including coals. Highly mature samples, as expected, in both cases are anomalous with high ratios. Calculated vitrinite reflectance based on the method of Radke and Welte (1983), as well as MPI 1 and MPI 2, shows the best comparison to observed values. These aromatic maturity parameters are lowered within the reflectance-suppressed intervals. Oil stains in the Jurassic Pilliga Sandstone in the Bellata-1 well have been identified as being indigenous and not due to contamination. The vitrinite reflectance calculated to the oil stain suggests that the source rock should be within a late mature zone. Such high maturity levels are only recognised within intrusion-affected intervals. A close similarity between the oil stain sample and the intruded interval of the Napperby Formation is evident from the thermal maturity and biomarker content. Hydrocarbon generation and expulsion from the lower part of the Napperby Formation as a result of igneous intrusion effects is suggested as the source of the oil in this particular occurrence. Terpane and sterane maturity parameters increase with increasing burial depth in the intervals with suppressed (perhydrous) vitrinite reflectance. The generation maturity parameters also increase through intervals with perhydrous vitrinite, which suggests that hydrocarbons continue to be generated and the actual amount is increasing even though traditional rank ????????????stress???????????? maturity parameters are lowered. Accordingly, the Permian sequences in the lower part of the Bowen Basin are at least within the peak oil generation zone, and probably within late oil generation in the north and northeast of the study area. To generate significant amounts of hydrocarbon, however, the thickness of the shaly and coaly intervals in the Permian sequence is probably a critical parameter. In the Gunnedah Basin, a significant amount of hydrocarbon generation is probably only possible as a result of igneous intrusions.

The Bowen Basin is one of the most intensely explored sedimentary basins in Australia and hosts one of the world’s largest coking coal deposits. This study focuses on the Lenton deposit in the north-central part of the Bowen Basin and targets the Rangal Coal Measures, which are the youngest (245 Ma), most areally extensive and least structurally deformed coal measures in the study area. Six lithofacies were identified from detailed bed-by-bed logging of two cores and stratigraphically-upward comprise peatmire deposits of the Permian Blackwater Group overlain unconformably by braided fluvial strata of the Triassic Rewan Group. Coal-bearing strata of the Blackwater Group form a large-scale drying up sequence showing a change from permanent to seasonal waterlogged conditions related to the onset of regional uplift. Sedimentation was then terminated and a regional erosion surface formed by uplift related to the Hunter Bowen Orogeny. This, then, was overlain by braided fluvial strata of the Triassic Rewan Group.

The Rangal Coal Measures are the uppermost coal bearing formation of the late Permian Blackwater Group in the North Bowen Basin, Queensland. They are conformably overlain by the Early Triassic Rewan Group and themselves conformably overlie the tuffaceous Fort Cooper Coal Measures. Throughout the North Bowen Basin one or two important coal seams are present within the Rangal Coal Measures. At South Walker Creek these seams are high rank, low ash, inertinite-rich coals attaining individual thicknesses up to 12 metres. The South Walker Creek Coalfield is unique in the North Bowen Basin because it contains an extensive reserve of potential opencut coal with poor coking characteristics, and very limited prospect for use as an export steaming coal in current overseas markets. It would, however, be ideal for use in a dedicated power station. Based on work from two GSQ drillholes, limited outcrop information, and some 370 chip hole logs compiled into a computer data base, it has been possible to produce a detailed model of the South Walker Creek Coalfield. This model helps to place the Rangal Coal Measures within the structural setting of the region while at the same time providing a framework for detailed mine planning. In the South Walker Creek region, the Rangal Coal Measures consist of lithic sandstone, mudstone, and siltstone plus rare conglomerate, (all derived from a metamorphic and volcanic provenance to the north and east) and coal. From the cored drillhole data and observations of the sparse outcrop, it has been possible to identify several lithofacies which can be related to a flood plain environment. This interpretation is based on the lithology, texture, grainsize, internal bedding structures and vertical lithofacies exhibit erosional bases in core and deposits, other than intraformational associations. The sandstones outcrop, although pebble lag mudstones and peat "rip-up" clasts, are rare. Massive and fining upward sequences predominate with trough cross-bedding being common in outcrop. The sandstone/shale ratio is approximately equal throughout the South Walker Creek Coalfield. A lateral lithofacies distribution can be clearly interpreted from the South Walker Creek isopachs and cross-sections through the interseam material. These indicate relatively fixed sandstone channel positions and an anastomosing distribution pattern with substantial fine grained overbank deposits. Several faults in the area can be related to these paleochannel margins. Prodeltaic or marine sequences have not been recognised within the Rangal Coal Measures or within contemporaneous sequences throughout the South Walker Creek region. On the basis of the lithofacies present, a flood plain environment is suggested as the likely depositional setting. The most important coal seam at South Walker Creek represents a thick, low ash, widely distributed peat accummulation. This was terminated over much of the area by predominantly vertically accreted fluvial deposits up to 60 metres thick associated with an anastomosing channel system. Following this, widespread peat swamp conditions recurred. A possible mechanism to account for interseam sedimentation at South Walker Creek is avulsion initiated by levee breaching during a flood peak.

Existing field data for Rangal coals (Late Permian) of the Bowen Basin, Queensland, Australia, are inconsistent with the depositional model generally accepted in the current geological literature to explain coal deposition. Given the apparent unsuitability of the current depositional model to the Bowen Basin coal data, a new depositional model, here named the Cyclic Salinity Model, is proposed and tested in this study.

In recent decades, changes in land use and land cover (LULC) arising from socio-economic development, coupled with climate change, have severely undermined and compromised the environmental sustainability of the upper part of Dong Nai (UPDN) river basin. Assessing the long-term impacts of climate change and changes in LULC on hydrological conditions and water balance in the UPDN river basin is essential for sustainable watershed management. In the present study, Landsat images and SWAT (Soil and Water Assessment Tool) model were used to assess water balance changes due to changes of climate and LULC at three different intervals: 1994, 2004, and 2014. The results of Landsat images classification indicated that forest land was the main LULC type in the basin. In 1994 the forest cover was 706,803 ha (72.68% of the total landmass). In 2004 the forest area dropped to 520,359 ha (53.51%). In 2014 the forest area dropped further to 485,908 ha (49.97%). The change in LULC has caused changes in the annual and peak water flows. The analysis of the results revealed that the effect of historical climate variations on water yield was greater than the LULC change. With the scenario of LULC 2014, the consumption of irrigation water was the highest and mainly in the dry season. The findings can provide useful information for decision-makers in planning and formulating policies for sustainable watershed management and climate change adaptation.
Trong những thập niên gần đây, sự thay đổi về sử dụng đất và thực phủ (LULC) do những hoạt động phát triển kinh tế - xã hội cùng với biến đổi khí hậu đã đặt ra những thách thức cho sự bền vững về môi trường ở lưu vực thượng nguồn sông Đồng Nai (UPDN). Đánh giá các tác động lâu dài của biến đổi khí hậu và những thay đổi trong LULC đến điều kiện thủy văn và cân bằng nước là việc cần thiết cho quản lý bền vững nguồn nước. Trong nghiên cứu này, các ảnh vệ tinh Landsat, công cụ đánh giá đất và nước (SWAT) được sử dụng để đánh giá sự thay đổi cân bằng nước do sự thay đổi khí hậu và LULC tại ba thời điểm khác nhau 1994, 2004 và 2014. Kết quả phân loại các ảnh Landsat cho thấy rừng là loại thực phủ chính trong lưu vực. Diện tích rừng của năm 1994 là 706.803 ha (72,68%). Diện tích rừng của năm 2004 đã giảm xuống còn 520.359 ha (53,1%) và đến năm 2014 chỉ còn 485.908ha (49,97%). Thay đổi sử dụng đất và thực phủ đã làm thay đổi chế độ thủy văn và dòng chảy đỉnh. Phân tích kết quả đã xác định rằng những sự thay đổi về điều kiện khí hậu trong quá khứ có ảnh hưởng đến lượng nước lớn hơn so với thay đổi về thực phủ. Với kịch bản LULC năm 2014, nhu cầu sử dụng nước tưới cho cây trồng là lớn nhất và chủ yếu trong mùa khô. Những kết quả đạt được trong nghiên cứu này sẽ cung cấp thông tin hữu ích cho các nhà hoạch định trong lập kế hoạch và ban hành chính sách cho quản lý lưu vực bền vững, thích ứng với biến đổi khí hậu.

"October 2004"
Includes bibliographical references (leaves 280-291)
291 leaves : ill.(some col.), maps (col.), plates (col.), photos. (col.) ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, Australian School of Petroleum, 2005

"October 2004"
Includes bibliographical references (leaves 280-291)
291 leaves : ill.(some col.), maps (col.), plates (col.), photos. (col.) ; 30 cm.
Thesis (Ph.D.)--University of Adelaide, Australian School of Petroleum, 2005

Bibliography: p. 335-349.
xxix, 394 p. : ill. (some col.), maps (some col.), plates (col.) ; 30 cm.
Thesis (Ph.D.) -- University of Adelaide, National Centre for Petroleum Geology and Geophysics, 2004

"February 2001"
Bibliography: p. 335-349.
xxix, 394 p. : ill. (some col.), maps (some col.), plates (col.) ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, National Centre for Petroleum Geology and Geophysics, 2004

Analysis of samples gathered during delineation of a coal resource is becoming increasingly sophisticated as various organisations attempt to predict and understand the technological behaviour of the mined product. Analysis to determine the concentration of trace elements in coal is becoming more prevalent, and not just merely for academic curiosity. Increased environmental awareness has impelled the need to consider potential negative impacts on the ecosystem caused by liberation of trace elements from coal during utilisation. The aims of this thesis are to: 1) Determine the concentration of trace elements in coal seams mined to supply the Collinsville pulverised fuel combustion plant at the Collinsville open cut, Northern Bowen Basin, Australia; 2) Determine the mineralogy and, using graphical relationships, the likely mode of occurrence of trace elements in the sampled pits; 3) Determine the mode of occurrence of trace elements in the pulverised fuel of the Collinsville power plant using the USGS sequential leaching method, and contrast the results with the same analysis for an unrelated fuel from another coal fired power utility (Mitsui Mining’s Omutu City plant, Kyushu, Japan); 4) Examine the partitioning behaviour of trace elements in the Collinsville power utility, and contrast the results with the partitioning behaviour of trace elements in the Mitsui combustion utility to assess the influence of trace element mode of occurrence on partitioning behaviour; 5) Examine the mobility of trace elements from solid ash waste from the Collinsville power utility, and compare with the mobility of trace elements from the Mitsui power utility solid waste to assess the influence of mode of occurrence on the leachability of trace elements and; 6) Determine the partitioning behaviour of trace elements in carbonisation of Bowen seam coal at the Bowen coke works and compare with the partitioning behaviour of the same elements in combustion. Lithotype logging of coal exposed in the highwalls of the Blake Central, Blake West and Bowen No.2 pits was undertaken. Of particular note was the presence of dull heat affected coal toward the roof of the Blake Central pit seam, toward the floor of the Bowen No.2 pit seam, and the presence of bed-parallel intrusions within the seam in the Blake West pit. In the Blake West pit seam, the intrusion caused thermal alteration of the coal to coke over a 60cm zone immediately adjacent to the intrusion with a further 1.10- 1.25m zone of dull heat altered coal beyond the coked zone. In the Blake Central, 4.5m of dull heat-affected coal occurred near the roof of the seam. In the Bowen No.2 pit, 1.2m of heat-affected coal occurred near the floor of the seam. Beyond the heat affected zone, lithotype logging of the Blake seams noted a number of rock partings, but no convincing dulling upward cycles due to progressive drying of the mire, noted in other studies of Permian coal, were found. No partings were found in the Bowen seam and only one convincing dulling upward cycles was logged. In part the absence of dulling upward cycles is due to heat alteration of the coal, but the numerous influxes of sediment laden water into the Blake seam mire also acted to terminate any significant dulling upward cycles by raising both nutrient levels and the water table. Following lithotype logging, channel sampling of the pits resulted in a total of 76 samples, 25 from the Blake Central pit, 36 from the Blake West pit and 15 from the Bowen No.2 pit. The channel sampling intervals were determined approximately by coal lithotype interval, with some amalgamations to restrict sample numbers. The channel samples were analysed for proximate analysis, coal petrography and vitrinite reflectance (selected samples) and for major and trace elements using XRF and INAA. The lithotype logs, proximate analysis data and coal petrography were integrated to infer the depositional environment of the Blake and Bowen seams. The generally high ash yield, common stone bands, low sulphur content of the coal and rare pyrite in the Blake seam suggests the depositional environment was a Class 3 topotelmitic peat with a variable water table. The moderate ash yield, the absence of common stone bands, sulphur contents of ~2% and the moderate pyrite content of the coal in the Bowen seam suggests the depositional environment was a Class 2 topotelmitic peat with a high water table. The igneous intrusions have caused extensive alteration of vitrinite to semi-coke, a general decrease in the volatile matter content and an increase in the vitrinite reflectance [Ro(max)] toward the intrusion. Mineralogy was calculated from major and trace elements using normative analysis, calibrated by XRD analysis of low temperature ash from selected samples. The mineralogy of the Blake seam samples is dominated by kaolinite, with subordinate quartz, illite, feldspar, and siderite, and minor concentrations of pyrite, gorceixite, goyazite and anatase. The mineralogy of the Bowen seam samples is dominated by kaolinite, with subordinate quartz, illite and pyrite, and minor concentrations of siderite, gorceixite, goyazite and anatase/ rutile/ iron oxides. The concentration of trace elements in the channel samples was determined by INAA and XRF. The INAA and XRF concentrations of iron and uranium show a reasonable statistical relationship suggesting the two analysis methods are consistent with each other. The concentration of trace elements in the Blake and Bowen seams is generally low compared to world average ranges for coal and to crustal averages. Only gold, copper, hafnium, thorium and ytterbium were found to be above the world coal average range in the Blake seam. Only gold and copper were found to be above world coal average range in the Bowen seam coal. Trace element mode of occurrence was inferred using graphical relationships between normative mineral and trace element concentrations. In the Blake seam, arsenic, possibly chromium, copper, mercury, nickel and lead were inferred to be associated with pyrite. Bromine, cobalt, selenium, and zinc appeared to be organically bound. Cerium, caesium, europium, lanthanum, rubidium, and scandium showed a graphical relationship with illite. However, cerium, europium, lanthanum and scandium, along with hafnium, lutetium, neodymium, samarium, terbium, thorium, uranium and vanadium also showed a graphical relationship with gorceixite or gorceixite plus goyazite. It was inferred the latter group of elements are associated with monazite or zircon. In addition to the REE phosphate mode of occurrence, some rare earth elements also showed an affinity for kaolinite. Thorium and uranium were also inferred to be associated with feldspars. Antimony, tantalum and ytterbium were found to be dominantly associated with kaolinite. In the Bowen seam, arsenic, cobalt, possibly chromium, copper, mercury, molybdenum, nickel, lead, antimony, selenium and zinc showed a graphical relationship with pyrite. The elements cerium, hafnium, neodymium, rubidium, samarium, tantalum, thorium, uranium and tungsten all showed significant graphical relationships with the anatase/ rutile/ FeO grouping of minerals. It is inferred that the relationship is due to the presence of monazite, zircon, xenotime, REE phosphates, tungstates or other trace minerals, the distribution of which mirrors the distribution of the anatase/ rutile/ FeO grouping. Uranium and thorium were inferred to be associated with REE phosphates and zircon respectively, plus illite. The elements bromine, europium, lanthanum, terbium and vanadium were inferred to be associated with illite. A mixed illite/ heavy mineral suite mode of occurrence is inferred for samarium, tantalum, thorium and uranium. The elements caesium, lutetium, scandium, and ytterbium were inferred to be associated with kaolinite. The effect of igneous intrusions on the concentration of a number of minerals and trace elements was also examined. The presence of semi-coke or an inferred distance of heat alteration was used to distinguish heat affected and unaffected samples. Depletion or enrichment of minerals and elements was inferred using ply thickness weighted average concentration figures for altered and unaltered samples and trends of concentration change toward the intrusion. Some consistent changes in the concentration of trace elements and minerals were found across all three pits sampled. The minerals siderite and pyrite are depleted in the heat affected zone, but goyazite is enriched, particularly toward the margins of the heat affected zone. The elements bromine and strontium (the latter mirroring the goyazite trend) are concentrated in the heat affected zone. The elements cobalt, mercury, manganese (mirroring the pyrite trend), nickel and possibly arsenic and zinc are depleted in heat affected samples from all three pits sampled. The inconsistent behaviour of some other trace elements (molybdenum, chromium and possibly selenium) in response to the igneous intrusion appears to be the result of different modes of occurrence of trace elements between pits. Samples of pulverised fuel were collected from the Collinsville and Japanese (Mitsui) pulverised fuel utilities. The concentration of major and trace elements was determined by INAA, XRF and (for the Collinsville sample) ICP-MS & ICP-AES. INAA analysis suggests gold, cerium, cobalt, europium, hafnium, lanthanum, lutetium, molybdenum, neodymium, scandium, selenium, samarium, strontium, tantalum, thorium, tungsten and ytterbium are at the upper end or above the world average concentration range in the Collinsville pulverized fuel. Only gold, hafnium and thorium are at the upper end or above the world coal concentration range in the Japanese pulverized fuel. Sequential leaching of the pulverised fuels was undertaken according to the USGS protocol. The sequential leach data was interpreted to infer trace element mode of occurrence in the pulverised fuel. A number of significant differences in the mode of occurrence of antimony, arsenic, chromium, cobalt, nickel, selenium, uranium and zinc were found between the two combustion plants studied. The element vanadium had almost identical modes of occurrence in fuel from both plants studied. A comparison of trace element mode of occurrence determined for the Collinsville power utility pulverised fuel by sequential leaching with mode of occurrence determined for the in-ground feed coals using graphical methods showed a reasonable level of agreement. It is concluded that the use of two methods of determining mode of occurrence provides better definition of mineral type in some cases. For example a siderite mode of occurrence could be determined using graphical relationship whereas the sequential leach data gave only a carbonate mode of occurrence. Further, the sequential leach data solved the problem of parallel graphical relationships. For example, galena was determined to be the mode of occurrence of lead from the sequential leach data, whereas graphical relationships indicated a pyrite mode of occurrence because of the relationship with sulphur. Combustion of coal occurs in three phases, namely devolatilisation, combustion of the volatile matter, and combustion of the residual char. Mineral matter may be excluded from the residual char particles due to desegregation and separation in the milling process, or included within the char particle. During combustion, trace elements partition between the bottom ash, the fly ash, and flue gas (lost up the stack). The concentration of trace elements in ash samples from the Collinsville and Mitsui power utilities was determined by INAA and XRF. The partitioning behaviour of the trace elements is examined by calculating relative enrichment values for the trace elements. Generally the partitioning behaviour and classification of trace elements in this study matched those found in previous published studies for a given element. The relative enrichment trends of elements exhibiting significant differences in mode of occurrence between the two combustion plants sampled (ie antimony, arsenic, chromium, cobalt, nickel, selenium, uranium and zinc plus vanadium) were examined to determine the control of mode of occurrence on the partitioning behaviour. It is hypothesised that the relative volatility of a particular element in combustion reflects the temperature at which the host mineral or the organic matter thermally decomposes. Thus organically bound elements should be more volatile than pyrite associated elements, which should be more volatile than carbonate associated elements, which should be substantially more volatile than silicate associated elements. Other factors that may influence partitioning behaviour such as the major element chemistry of the ash, plant design and operating conditions, and temperature variations within the combustion chamber were discounted as significantly influencing relative enrichment differences for the two combustion plants studied. It is concluded that element mode of occurrence has a strong influence on the relative volatility of a given element, and that comparison of sequential leach results from two pulverised fuel utilities has the potential allow prediction of the relative volatility of trace elements in combustion. Some complications may arise due to exclusion of some mineral grains and localised variations in the oxidation state within the combustion zone. Solid combustion wastes (fly ash and bottom ash) are commonly disposed of in landfill and impoundment facilities. Unless the landfill is impermeable to water, disposal of solid wastes in such fashion allows interaction with the hydrogeological system and could lead to detrimental environmental impacts. Leaching of indicative “total waste” composites made up by blending fly ash and bottom ash samples from each power utility in an 80/20 proportion was undertaken using the TCLP protocol. The concentration of trace elements in the leachates was compared to recreational water and drinkwater guideline values. The concentration of barium, manganese, and selenium in the Collinsville leachate exceeds both the recreational and drinkwater guideline concentrations. The concentration of nickel in the Collinsville leachate was found to exceed the recommended drinkwater concentration, but is below recreational water guideline value. The concentration of boron and selenium in the Mitsui leachate was found to exceed both the recreational and drinkwater guideline values. The concentration of barium in the Mitsui leachate was found to exceed the drinkwater standard. The concentration of an element in the ash sample was found to be a poor indicator of the mobility of the element. Elements that showed substantial differences in mode of occurrence in the pulverised fuel (ie antimony, arsenic, chromium, cobalt, nickel, selenium, uranium and zinc plus vanadium) were examined to assess the influence of mode of occurrence on the leachability of the element from solid combustion waste. It is concluded that, where the difference in element mobility between the two composite ash samples is significant, mode of occurrence does exert some control on the proportion of a trace element in the ash that can be mobilised by the TCLP protocol. In particular, trace elements present in coal associated with silicates appear substantially unavailable for mobilisation by the TCLP protocol. The concentration of trace elements in samples of feed coal, coke and breeze from the Bowen coke works was determined by INAA and XRF. A new index (the CRE index) was developed to characterise the enrichment or depletion of trace elements in the coke and breeze. Coke is classified as enriched (Class 1), neither enriched nor depleted (Class 2), depleted (Class 3) or highly depleted (Class 4). Breeze was classified as enriched (denoted “e”), neither enriched nor depleted (denoted “a”) and depleted (denoted “d”). Comparison of the partitioning behaviour of trace elements in combustion and carbonisation was undertaken by comparing the RE and CRE data. It is concluded that all but the most volatile elements (sulphur, selenium, arsenic and tungsten) are substantially retained in the coke. The substantial retention of trace elements in coke is likely due to the lower temperature at which carbonisation occurs compare

The sustainability of groundwater resources is important for the environment, the economy and communities where surface water is scarce. It is a hidden resource, but additional information can be extracted by combining groundwater measurements and lithological information with groundwater flow equations in groundwater models. The models convert data and knowledge about the groundwater systems into information, such as relative inflow and outflow rates and water-level predictions that can be readily understood by groundwater managers. ¶ The development of models to effectively inform groundwater management policies is, however, a complex task that presents a fundamental scientific challenge. This thesis presents methods and results for water balances calculated using groundwater flow models. Groundwater flow modelling methods and approaches are discussed, and their capabilities and limitations are reviewed. Two groundwater systems are studied for the Great Artesian Basin (GAB) and for the irrigation area near Bowen, Queensland. Three approaches to water balance modelling are applied in comprehensive model-development frameworks that take into account model objectives, data and knowledge availability and sensitivity analysis techniques. The three models show numerical methods of increasing complexity...

碩士
國立交通大學
光電系統研究所
101
The auscultation of bowel sounds provides a non-invasive method to diagnosis gastrointestinal motility diseases. However, bowel sounds can be easily contaminated by background noises, and the frequency band of bowel sounds is easily overlapped with background noise. Therefore, it is difficult to enhance the noisy bowel sounds by using precise digital filters. In this study, higher-order-statistics (HOS)-based radial basis function (RBF) network was proposed to enhance noisy bowel sounds. Higher order statistics technique provides the ability to suppress Gaussian noises and symmetrically distributed non-Gaussian noises due to their natural tolerance. Therefore, the influence of additional noises on the HOS-based learning algorithm can be reduced effectively. The simulated and experimental results show that HOS-based RBF can exactly provide better performance for enhancing bowel sounds under stationary and non-stationary Gaussian noises. Therefore, HOS-based RBF can be considered as a good approach for enhancing noisy bowel sounds.