煤中残余气含量及其影响因素   总被引：1，自引：0，他引：1  

《煤田地质与勘探》1999,27(2):3

煤中残余气是煤层气的一个组成部分,其含量直接影响到煤层气含量和煤的含气饱和度。本文对不同地区、各种煤级的近100个煤心煤样的残余气含量测试结果进行了综合分析研究,找出了煤中残余气含量的分布变化规律,探讨了其影响因素。结果表明不同煤的残余气含量不相同,变化范围为0～3 m  相似文献   

施粉煤灰农田和作物的有害元素含量及影响评价   总被引：2，自引：0，他引：2  

徐红 《矿物岩石地球化学通报》1999,(1)

我国能源结构中燃煤火电占绝对优势,粉煤灰的处置和综合利用是关系到可持续发展的重大问题。南京市利用原状粉煤灰改良农田,获得了明显的增产效果。但粉煤灰所含的有害元素在施用过程中的富集、富集部位及由此是对人体和动物健康的影响等,目前还不十分清楚。１样品与分...  相似文献   

Co-ignimbrite ash-fall deposits of the 1991 eruptions of Fugen-dake, Unzen Volcano, Japan     

Kazunori Watanabe  Koji Ono  Keiichi Sakaguchi  Akira Takada  Hideo Hoshizumi 《Journal of Volcanology and Geothermal Research》1999,89(1-4)

Fugen-dake, the main peak of Unzen Volcano, began a new eruption sequence on November 17, 1990. On May 20, 1991, a new lava dome appeared near the eastern edge of the Fugen-dake summit. Small-scale, 10⁴–10⁶ m³ in volume, Merapi-type block and ash flows were frequently generated from the growing lava dome during May–June, 1991. These pyroclastic flows were accompanied by co-ignimbrite ash plumes that deposited ash-fall deposits downwind of the volcano. Three examples of co-ignimbrite ash-fall deposits from Unzen pyroclastic flows are described. The volume of fall deposits was estimated to be about 30% by volume of the collapsed portions of the dome that formed pyroclastic flows. This proportion is smaller than that described for other larger co-ignimbrite ash-fall deposits from other volcanoes. Grain size distributions of the Unzen co-ignimbrite ash-fall deposits are bi-modal or tri-modal. Most ashes are finer than 4 phi and two modes were observed at around 4–7 phi and 9 phi. They are composed mainly of groundmass fragments. Fractions of another mode at around 2 phi are rich in crystals derived from dome lava. Some of the fine ash component fell as accretionary lapilli from the co-ignimbrite ash cloud indicating either moisture or electrostatic aggregation. We believe that the co-ignimbrite ash of Unzen block and ash flows were formed by the mechanical fracturing of the cooling lava blocks as they collapsed and moved down the slope. These ashes were entrained into the convective plumes generated off the tops of the moving flows.  相似文献   

Generation of block and ash flows during the 1990–1995 eruption of Unzen Volcano, Japan     

Tadahide Ui  Norimichi Matsuwo  Mari Sumita  Akihiko Fujinawa 《Journal of Volcanology and Geothermal Research》1999,89(1-4)

Processes generating block and ash flows by gravitational dome collapse (Merapi-type pyroclastic flow) were observed in detail during the 1990–1995 eruption of Unzen volcano, Japan. Two different types were identified by analysis of video records and observations during helicopter flights. Most of the block and ash flows erupted during the 1991–1993 exogenous dome growth stage initially involved crack propagation due to cooling and flowage of the dome lava lobes. The mass around the crack became unstable, locally decreasing in tensile strength. Finally, a slab separated from the lobe front, fragmented progressively from the base to the top within a few seconds, and became a block and ash flow. Rock falls immediately followed, in response to local instability of the lobe front. Clasts in these rock falls fragmented and merged with the preceding flow. In contrast, block and ash flows during the endogenous dome growth stage in 1994 were generated due to local bulge of the dome. Unstable lava blocks collapsed and subsequently fragmented to produce block and ash flows.  相似文献   

加高扩容贮灰场地震响应特性及其稳定性评价          下载免费PDF全文

(佘芳涛    李超  周庆怡  王松鹤  )) 《世界地震工程》2023,39(2):062-70

贮灰场主要用于储存燃煤电厂排出的粉煤灰和炉渣,在加高扩容时应特别注意地震作用下的稳定性。通过现场试验和数值模拟手段,研究了某贮灰场加高扩容前后的液化可能性、动力响应及稳定性。结果表明:(a)加高扩容后四级坝的峰值加速度和峰值水平位移相比现状三级坝响应更加显著。(b)子坝坝体粉煤灰不液化,库内可能出现液化。输入地震动峰值加速度越高,库内液化区明显增大,加高扩容后库内液化区域增大。(c)地震作用下贮灰场三级坝与拟筑四级坝的潜在滑动面位置均位于子坝坝系。随拟筑四级坝高程增加,最小安全系数减小。根据该贮灰场Ⅷ度抗震设防烈度要求,加高扩容前后贮灰场的稳定性均满足抗震规范要求。研究成果可为贮灰场加高扩容后的抗震设计提供理论依据。  相似文献   

钙离子添加对沉水植物菹草(Potamogeton crispus L.)和金鱼藻(Ceratophyllum demersum L.)富集水体磷的影响     

陈琦  王和云 《湖泊科学》2020,32(2):406-416

沉水植物光合作用形成的微环境有利于水体中钙和磷形成CaCO_3-P共沉淀,从而将水体中的磷永久性去除,避免植物腐烂后的二次污染但不同的沉水植物种类形成CaCO_3-P共沉淀的能力不同本文以沉水植物菹草(Potamogeton crispus L)和金鱼藻(Ceratophyllum demersum L)为实验对象,研究水体中添加钙离子(0、100 mg/L)对水体磷(磷浓度:0、0.2、2 mg/L)的去除和植物富集磷的差异,并通过植物灰分磷的组分分析,聚焦植物钙磷的变化,为生态修复中沉水植物的选择提供理论依据结果表明:(1)菹草和金鱼藻体系中总磷(TP)和溶解性反应磷(SRP)浓度显著下降,添加钙离子使降幅升高,且菹草体系中水体TP和SRP降幅均高于金鱼藻TP和SRP降幅;(2)菹草的干重全磷在高磷低钙(2-0)水平最高,灰分总磷在高磷高钙(2-100)水平最高,而金鱼藻干重全磷在高磷高钙(2-100)水平最高,灰分总磷在中等磷低钙(0.2-0)水平最高;(3)在2 mg/L的磷浓度下,添加钙离子使菹草的钙磷(HCl-P)和水溶性磷(H_2O-P)含量升高,有机磷(NaOH-P)含量降低,结果使灰分总磷含量升高,而金鱼藻NaOH-P升高,HCl-P和H_2O-P含量均降低,结果使灰分总磷降低这表明菹草通过提高吸附性磷和钙磷含量增强磷的富集,而金鱼藻则只显著升高了灰分中有机磷的含量显然,水体富营养化背景下,相较于金鱼藻,菹草具有更强的形成CaCO_3-P共沉淀的能力,具备竞争优势.  相似文献   

Volcanic ash and tsunami record of the Minoan Late Bronze Age Eruption (Santorini) in a distal setting,southwestern Turkey     

Erkan Aydar  Attila ÇİNer  Orkun Ersoy  Emilie ÉCochard  Eric G. Fouache 《第四纪科学杂志》2021,36(4):586-597

We present the volcanic ash and tsunami record of the Minoan Late Bronze Age Eruption of Santorini (LBAES) in a distal setting in southwestern Turkey. In one of the drilled cores at the Letoon Hellenic antique site on Eşençay Delta, we encountered a 4 cm thick tephra deposit underlain by 46 cm thick tsunami-deposited sand (tsunamite), and an organic-rich layer that we ¹⁴C dated to 3295 ± 30 bp or 1633 bc. The relationship between Santorini distal volcanic ash and underlying tsunamite is described and interpreted. LBAES occurred in four main phases: (1) plinian; (2) phreatomagmatic; (3) phreatomagmatic with mudflows; and (4) ignimbritic flows and co-ignimbrite tephra falls. In this study, we aim to understand which eruptive phases generate distal ash during the Minoan eruptive sequence by examining the 3D surface morphology of ash formed by different fragmentation processes. To that end, we used numerous statistical multivariates, 3D fractal dimension of roughness, and a new textural parameter of surface area-3D/plotted area-2D to characterise the eruption dynamics. Based on ash surface morphologies and the calculated statistical parameters, we propose that that distal ash is represented by a single layer composed of well-mixed (coarse to fine) magmatic and phreatomagmatic ash.  相似文献   

Implementation of porous material through eco-tech for deep cement–soil mixing     

You-Seong Kim  Se-Gwan Seo  Hyoung-Woo Ko 《Marine Georesources & Geotechnology》2018,36(8):931-939

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The effects of coal gangue and fly ash on the hydraulic properties and water content distribution in reconstructed soil profiles of coal‐mined land with a high groundwater table          下载免费PDF全文

Jinman Wang  Xinfeng Li  Zhongke Bai  Longbin Huang 《水文研究》2017,31(3):687-697

Soil water systems have been severely degraded in coal‐mined and subsiding land, where a shallow groundwater table is also present. The present paper discussed the effects of fly ash (FA) and coal gangue (CG) as filling materials on the hydraulic properties and water content distribution in a profile for the purpose of rehabilitating subsided lands. The saturated water content, water characteristic curve, and water diffusivity of local soil, FA, CG, and a mixture of FA and CG (“mixed filling”) were characterized. A column experiment was conducted to investigate the changes of water content in profiles reconstructed from the combination of soil and filling materials, including soil only, FA, CG, and a mixture of FA and CG, which were used to fill the lower part of the reconstructed profile. The mixture of FA and CG was found to possess similar hydraulic properties to those of the soil, particularly high water‐holding capacity and permeability. Moreover, the volumetric water contents in the whole profile containing the mixture of FA and CG were consistent with those of the profile reconstructed with soil only. As a result, it is recommended to adopt the mixture of FA and CG for reconstructing the lower profile of the land to alleviate or rehabilitate subsided land in coal mines.  相似文献   

Itrax μ-XRF core scanning for rapid tephrostratigraphic analysis: a case study from the Auckland Volcanic Field maar lakes     

Leonie Peti  Patricia S. Gadd  Jenni L. Hopkins  Paul C. Augustinus 《第四纪科学杂志》2020,35(1-2):54-65

Itrax micro X-ray fluorescence (μ-XRF) core scanning is a non-destructive, rapid approach to measuring elemental concentrations and their variability in sediment cores. As such, it records elemental signatures of tephra layers, which serve as correlation tie points and chronological markers for these sedimentary archives of past climatic changes. The traditional tephra identification approach using electron microprobe-based geochemical fingerprinting of glass shards is a slow and invasive process, whilst μ-XRF scanning of rhyolite tephra in sediment cores from Auckland (New Zealand) could provide a faster, non-invasive approach to aid the recognition of tephra layers. This study highlights the potential and pitfalls in this novel approach: changes in most scanning parameters, and the use of two different Itrax core scanners, still led to similar chemical characterizations of the tephra layers. Changes in other scanning parameters have a biasing influence on the chemical characterization of the tephra, which would lead to misidentification of unknown layers. We demonstrate that μ-XRF core scanning provides a faster and non-invasive approach to correlation of sediment sequences using chemically distinct, visually pure tephra layers if a strict scanning protocol is followed. Nevertheless, an extensive database of μ-XRF-scanned rhyolite tephra is required for recognition of unknown tephra units using this approach.  相似文献