广西晚二叠世成煤模式探讨     

蒋博宇 《南方国土资源》1997,(4)

广西晚二叠世成煤模式划分为“两类三型”,即泥炭沼泽成煤模式和泥炭坪成煤模式两类,沼泽型、潮坪型和泥炭坪型等三型。文章阐述了这些成煤模式在吴家坪期和长兴期形成的特征,分布状况,以及代表煤层,指出潮坪型是广西晚二叠世时期最主要的成煤模式。  相似文献   

On the performance of SCF in seismic isolation of the interior equipment of buildings     

M. Hamidi  M. H. El Naggar 《地震工程与结构动力学》2007,36(11):1581-1604

The dynamic response of equipment mounted on an isolated raised floor inside a building while the primary fixed base structure is subjected to harmonic and earthquake ground motions is numerically investigated. Sliding concave foundation (SCF) system is utilized for isolating the raised floor. The equations of motion for a MDOF shear building containing a SCF isolated raised floor with a mounted equipment are developed and the rigid link method is utilized to handle the non‐linearity of the system. The equipment, which can be modelled as a SDOF or MDOF system, may represent a critical computer unit or telecommunication processing system. SCF can be used easily to achieve the desired long period, necessary for protecting sensitive equipment. In this investigation, the ability of SCF in reducing the acceleration level experienced by the equipment inside a building is demonstrated while the lateral displacement is still within an acceptable range. The analysis considered the case of equipment housed in the upper floors of a building where the acceleration is amplified and the motion contains strong components at long periods. For this purpose, different excitations including both harmonic and real earthquake ground motions are employed and the performance of the system is evaluated. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Accumulation of heavy metals in Oostriku peat bog,Estonia: -site description,conceptual modelling and geochemical modelling of the source of the metals     

Syrovetnik  K.  Puura  E.  Neretnieks  I. 《Environmental Geology》2004,45(5):731-740

Oxidation of sulphides leads to the dissolution of metals, which are transported with water and accumulate at geochemical barriers. Such barriers can form in peat bogs. This paper gives an introduction into the long-term processes in Oostriku peat bog where high accumulations of heavy metals are observed. Peat and water samples are analysed for Fe, As and heavy metals (Cd, Cu, Mn, Ni, Pb and Zn) using different methods. A concept is based on the observations. Metals are leached by sulphide oxidation in the carbonate rocks upstream of the peat. The water feeds the peat from below. The metals are sorbed and precipitated in the peat. The sulphide oxidation is simulated to examine the origin and metal speciation in the water. The simulated solution is compared with the groundwater entering the peat. The results showed a fair agreement for the major constituents. There were considerable differences for species with low concentrations.  相似文献   

Landslides in blanket peat on Cuilcagh Mountain, northwest Ireland   总被引：1，自引：0，他引：1  

Alan P. Dykes  John Gunn  Katie J. Convery 《Geomorphology》2008,102(3-4):325-340

The northern and eastern sides of the Cuilcagh Mountain upland, in northwest Ireland, are mantled with over 50 km² of blanket bog that has experienced an unusually high spatial and temporal frequency of peat mass movements. In all, 29 peaty-debris slides, nine bog slides, two peat slides and five more peat landslides of uncertain type have been recorded within this study area. More than 27 km² of this peatland has been afforded several levels of statutory protection as well as international recognition of its geo-environmental importance. Field and laboratory investigations of the peat at several of the more recent failure sites showed it to be typical of Irish and Pennine (northern England) blanket bogs in most physical and hydrological respects. Field geomorphological evidence and modelling of stability thresholds indicate that the particular susceptibility of the Cuilcagh Mountain blanket bog to failure arises from two local factors: (i) the attainment of threshold maximum peat depths on the East Cuilcagh plateau, and (ii) the unconformable deposition of thin layers of glacial till (in places) and blanket peat over the pre-existing topographic surface formed from the major shale formations that underlie the northern slopes. With two exceptions, there is no conclusive evidence that human activities and management strategies for the area have had any significant influence on the occurrence of the peat landslides. The high frequency of large rainfall events since 1961 that did not trigger landslides suggests that failures are unlikely to become more frequent in response to climate change effects because they are controlled by slowly changing internal thresholds.  相似文献   

低洼地地区典型水土地利用为特征的全球重要农业文化遗产——以兴化垛田传统农业系统为例(英文)   总被引：1，自引：0，他引：1  

白艳莹  孙雪萍  田密  Anthony M.FULLER 《资源与生态学报(英文版)》2014,5(4):320-327

兴化垛田传统农业系统具有典型的水土利用方式,于2014年4月被联合国粮农组织评选为全球重要农业文化遗产。基于文献资料和实地调研,本文分析了兴化垛田传统农业系统的历史与发展、结构与特征、以及功能与价值。兴化垛田传统农业系统具有悠久的历史、丰富的生物多样性、重要的生态服务功能、传统农业技术和文化、以及独特水土利用方式形成的优美景观,并对当地农民的生计安全做出了重要的贡献。然而,这一宝贵的全球重要农业文化遗产系统面临着一系列威胁和挑战。本文的研究一方面可以更深入地认识兴化垛田传统农业系统,为其保护与发展提供科学支持,另外一方面也为我国及世界上的类似地区提供经验借鉴。  相似文献   

Changes in the discharge pattern of a cutover raised bog during rewetting     

J. F. M. Spieksma 《水文研究》1999,13(8):1233-1246

Although rewetting practices have been implemented in several cutover raised bogs, their effects on discharge patterns have not received much attention. In 1983, after peat extraction had stopped in the Leegmoor, a cutover raised bog in Germany, an experimental area was set up in order to monitor rewetting and subsequent restoration. Discharge was measured since 1984. The results suggest that rewetted raised bogs may not be effective as regulators of stream flow. An increase of low flows during a decade of rewetting could partly be attributed to weather variation. A comparison of the Leegmoor with a nearby control catchment produced similar results. A shift in the relationship between discharge and groundwater level over time was recorded. This is probably a result of the development of vegetation and a corresponding reduction of the area of open water, leading to an increase of resistance to water flow. The Leegmoor data demonstrate that the daily discharge pattern is most flashy immediately after the start of rewetting and will gradually smooth. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

HYDROLOGY AND MICROCLIMATE OF A PARTLY RESTORED CUTOVER BOG,QUÉBEC     

JONATHAN S. PRICE 《水文研究》1996,10(10):1263-1272

Peatlands do not readily return to functional wetland ecosystems after harvesting (cutting), because the harsh hydrological and microclimatic conditions are unsuitable for Sphagnum regeneration. In this study, drainage ditches blocked after harvesting restored the water balance to a condition similar to a nearby natural bog. Evaporation averaged 2.9 and 2.7 mm day⁻¹ on the cutover and natural bog, respectively. Evaporation consumed most of the rainfall input (86 and 80%, respectively), whereas runoff was minor at both sites (6 and 4%, respectively). However, the water table position was markedly different at these sites. Median water table depth was 0.05 m below the surface in the natural bog, compared with 0.44 m in the cutover bog (ditches blocked). Changes to the peak soil matrix owing to drainage and cutting reduced the specific yield (Sy) of the peat to 0.04–0.06 from 0.35–0.55, causing exaggerated water table changes in the cutover site. Nevertheless, volumetric soil moisture in the cutover site (0.67 ± .08) had low variability, and was maintained above moisture contents found in Sphagnum hummocks in the natural bog (0.48 ± .10), although less than on Sphagnum lawn (0.84 ± .11). Poor Sphagnum regeneration on cutover surfaces can therefore be attributed to its inability to extract water from the underlying peat, which retains water at matric suction greater than the non-vascular Sphagnum can generate. The corrupted iron pan under main ditches has permitted partial recharge of the underlying aquifer, reducing local hydraulic gradients, thereby decreasing vertical seepage loss.  相似文献   

Relationships between field-measured hydrometeorological variables and satellite-based land surface temperature in a hemiboreal raised bog     

《International Journal of Applied Earth Observation and Geoinformation》2019

Temperature regime is one of the main controlling factors of greenhouse gas (GHG) emissions from peat bogs. Remotely sensed land surface temperature (LST) has a potential to become an efficient instrument in environmental monitoring of carbon dioxide and methane emissions from peat bogs. This paper examines the relationships between field-measured hydrometeorological variables and MODIS LST data in a hemiboreal raised bog for a period from May to September (2008–2016). The Pearson product-moment correlation was used to reveal the relationship between the field-measured parameters and LST over years and months. A multiple linear regression was chosen to model relationships between the hydrometeorological variables and LST by month. It was found that the relationships between the studied parameters and LST were year- and month-dependent. The main factor of LST was air temperature, and the correlation between LST and air temperature was the strongest during the entire period of study. This study has shown that the hydrometeorological factors of LST can explain 67%–81 % of the variance in LST in a hemiboreal raised bog. The relationships between the hydrometeorological variables and LST may be implemented in more accurate GHG emissions estimation from bogs.  相似文献   

Pine stumps in Irish peats: is their occurrence a valid proxy climate indicator?          下载免费PDF全文

ALWYNNE H. MCGEEVER  FRASER J.G. MITCHELL 《第四纪科学杂志》2015,30(5):489-496

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A 9600‐year record of water table depth,vegetation and fire inferred from a raised peat bog,Prince Edward Island,Canadian Maritimes          下载免费PDF全文

Matthew Peros  Kathleen Chan  Gabriel Magnan  Leila Ponsford  James Carroll  Terry McCloskey 《第四纪科学杂志》2016,31(5):512-525

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