Gas Production from an Ombrotrophic Bog-Effect of Climate Change on Microbial Ecology   总被引：1，自引：0，他引：1  

D. Ann Brown 《Climatic change》1998,40(2):277-284

Gases are produced from wetlands when plant biomass is degraded by microbial consortia, producing carbon dioxide aerobically and methane when oxygen is lacking. In anaerobic waterlogged situations, such as the catotelm of ombrotrophic bogs, this methane forms minute gas bubbles that severely reduce the hydraulic conductivity and hence the degradation of biomass due to the lack of nutrients. The bogs thus become carbon sinks, formed from the partially degraded biomass that accumulates as peat. The results of an investigation of an ombrotrophic bog, Mer Bleue, Ontario, Canada are summarized here, and the effects that climate change may have on such bogs are discussed. Any change of the water table in wetlands will have a substantial effect upon their ecology. If the water table should fall allowing bogs to become aerobic, most of the accumulated biomass carbon could be returned to the atmosphere by degradation to carbon dioxide, and as well, methane entrapped within the matrix would be released directly to the atmosphere. If on the other hand, the bogs are flooded, then the entrapped bubbles will coalesce allowing the gas to escape to the atmosphere, while at the same time the degradation of the peat will be enhanced.  相似文献   

论泥浆气测录井在煤层气开发中的作用   总被引：1，自引：0，他引：1  

王彦龙 《煤田地质与勘探》1998,(Z1)

针对我国煤层气开发只重视煤心解析气,泥浆气长期得不到重视的现状,结合作者几年来对泥浆气测录井工作的经验和认识,从录井原理、目的、意义、作用、经济效益等几个方面探讨了泥浆气测录井在煤层气资源评价、开发方面的作用。  相似文献   

煤层含气量预测方法   总被引：11，自引：2，他引：9  

李静  李小彦 《煤田地质与勘探》1998,26(1):31-33

含气量是进行煤层气资源计算与选区评价的关键。在有效含气量数据太少,不能满足研究工作需要的情况下,根据少量实测含气量数据和煤的等温吸附曲线、储层压力梯度、煤的水分、灰分数据,预测未知区煤层气量,是一种行之有效的方法。实践证明,预测含气量数据与实测含气量数据比较接近,能保证资源量计算及资源评价结果的可靠性。  相似文献   

澳大利亚煤层气勘探开发中的关键：原地应力研究     

彭格林  赵志忠 《煤田地质与勘探》1998,26(3):31-34,53

近年来,澳大利亚在煤层气勘探开发中取得了突破性进展。本文根据澳大利亚的研究成果,探讨了原地应力与渗透性和地质构造的关系;详细介绍了运用原地应力测量与力分析预测煤层高渗透区的方法。  相似文献   

Geochemistry of coalbed gas – A review     

J. L. Clayton 《International Journal of Coal Geology》1998,35(1-4)

Coals are both sources and reservoirs of large amounts of gas that has received increasing attention in recent years as a largely untapped potential energy resource. Coal mining operations, such as ventilation of coalbed gas from underground mines, release coalbed CH₄ into the atmosphere, an important greenhouse gas whose concentration in the atmosphere is increasing. Because of these energy and environmental issues, increased research attention has been focused on the geochemistry of coalbed gas in recent years. This paper presents a summary review of the main aspects of coalbed gas geochemistry and current research advances.  相似文献   

Study of the Natural Gas Hydrate “Trap Zone” and the Methane Hydrate Potential in the Sverdrup Basin,Canada     

Majorowicz  J. A.  Hannigan  P. K.  Osadetz  K. G. 《Natural Resources Research》2002,11(2):79-96

The methane hydrate stability zone beneath Sverdrup Basin has developed to a depth of 2 km underneath the Canadian Arctic Islands and 1 km below sea level under the deepest part of the inter-island sea channels. It is not, however, a continuous zone. Methane hydrates are detected in this zone, but the gas hydrate/free gas contact occurs rarely. Interpretation of well logs indicate that methane hydrate occurs within the methane stability zone in 57 of 150 analyzed wells. Fourteen wells show the methane hydrate/free gas contact. Analysis of the distribution of methane hydrate and hydrate/gas contact occurrences with respect to the present methane hydrate stability zone indicate that, in most instances, the detected methane hydrate occurs well above the base of methane hydrate stability. This relationship suggests that these methane hydrates were formed in shallower strata than expected with respect to the present hydrate stability zone from methane gases which migrated upward into hydrate trap zones. Presently, only a small proportion of gas hydrate occurrences occur in close proximity to the base of predicted methane hydrate stability. The association of the majority of detected hydrates with deeply buried hydrocarbon discoveries, mostly conventional natural gas accumulations, or mapped seismic closures, some of which are dry, located in structures in western and central Sverdrup Basin, indicate the concurring relationship of hydrate occurrence with areas of high heat flow. Either present-day or paleo-high heat flows are relevant. Twenty-three hydrate occurrences coincide directly with underlying conventional hydrocarbon accumulations. Other gas hydrate occurrences are associated with structures filled with water with evidence of precursor hydrocarbons that were lost because of upward leakage.  相似文献   

Formulation and Evaluation of IMS, an Interactive Three-Dimensional Tropospheric Chemical Transport Model 2. Model Chemistry and Comparison of Modelled CH4, CO, and O3 with Surface Measurements     

K.-Y. Wang  J. A. Pyle  D. E. Shallcross  D. J. Larry 《Journal of Atmospheric Chemistry》2001,38(1):31-71

In part two of this series of papers on the IMS model, we present the chemistry reaction mechanism usedand compare modelled CH₄, CO, and O₃ witha dataset of annual surface measurements. The modelled monthly and 24-hour mean tropospheric OH concentrationsrange between 5–22 × 10⁵ moleculescm^–3, indicating an annualaveraged OH concentration of about 10 × 10⁵ moleculescm^–3. This valueis close to the estimated 9.7 ± 0.6 × 10⁵ moleculescm^–3 calculated fromthe reaction of CH₃CCl₃ with OH radicals.Comparison with CH₄ generally shows good agreementbetween model and measurements, except for the site at Barrow where modelledwetland emission in the summer could be a factor 3 too high.For CO, the pronounced seasonality shown in the measurements is generally reproduced by the model; however, the modelled concentrations are lower thanthe measurements. This discrepancy may due to lower the CO emission,especially from biomass burning,used in the model compared with other studies.For O₃, good agreement between the model and measurements is seenat locations which are away from industrial regions. The maximum discrepancies between modelled results and measurementsat tropical and remote marine sites is about 5–10 ppbv,while the discrepancies canexceed 30 ppbv in the industrial regions.Comparisons in rural areas at European and American continental sites arehighly influenced by the local photochemicalproduction, which is difficult to model with a coarse global CTM.The very large variations of O₃ at these locations vary from about15–25 ppbv in Januaryto 55–65 ppbv in July–August. The observed annual O₃amplitude isabout 40 ppbv compared with about 20 ppbv in the model. An overall comparison of modelled O₃ with measurements shows thatthe O₃seasonal surface cycle is generally governed bythe relative importance of two key mechanisms that drivea springtime ozone maximum and asummertime ozone maximum.  相似文献   

Global distribution of natural freshwater wetlands and rice paddies,their net primary productivity,seasonality and possible methane emissions   总被引：18，自引：0，他引：18  

I. Aselmann  P. J. Crutzen 《Journal of Atmospheric Chemistry》1989,8(4):307-358

A global data set on the geographic distribution and seasonality of freshwater wetlands and rice paddies has been compiled, comprising information at a spatial resolution of 2.5° by latitude and 5° by longitude. Global coverage of these wetlands total 5.7×10⁶ km² and 1.3×10⁶ km², respectively. Natural wetlands have been grouped into six categories following common terminology, i.e. bog, fen, swamp, marsh, floodplain, and shallow lake. Net primary productivity (NPP) of natural wetlands is estimated to be in the range of 4–9×10¹⁵ g dry matter per year. Rice paddies have an NPP of about 1.4×10¹⁵ g y^–1. Extrapolation of measured CH₄ emissions in individual ecosystems lead to global methane emission estimates of 40–160 Teragram (1 Tg=10¹² g) from natural wetlands and 60–140 Tg from rice paddies per year. The mean emission of 170–200 Tg may come in about equal proportions from natural wetlands and paddies. Major source regions are located in the subtropics between 20 and 30° N, the tropics between 0 and 10° S, and the temperate-boreal region between 50 and 70° N. Emissions are highly seasonal, maximizing during summer in both hemispheres. The wide range of possible CH₄ emissions shows the large uncertainties associated with the extrapolation of measured flux rates to global scale. More investigations into ecophysiological principals of methane emissions is warranted to arrive at better source estimates.  相似文献   

Carbon dioxide and methane in the Arctic atmosphere     

T. J. Conway  L. P. Steele 《Journal of Atmospheric Chemistry》1989,9(1-3):81-99

Fifty flask air samples were taken during April 1986 from a NOAA WP-3D Orion aircraft which flew missions across a broad region of the Arctic as part of the second Arctic Gas and Aerosol Sampling Program (AGASP II). The samples were subsequently analyzed for both carbon dioxide (CO₂) and methane (CH₄). The samples were taken in well-defined layers of Arctic haze, in the background troposphere where no haze was detected, and from near the surface to the lower stratosphere. Vertical profiles were specifically measured in the vicinity of Barrow, Alaska to enable comparisons with routine surface measurements made at the NOAA/GMCC observatory. Elevated levels of both methane and carbon dioxide were found in haze layers. For samples taken in the background troposphere we found negative vertical gradients (lower concentrations aloft) for both gases. For the entire data set (including samples collected in the haze layers) we found a strong positive correlation between the methane and carbon dioxide concentrations, with a linear regression slope of 17.5 ppb CH₄/ppm CO₂, a standard error of 0.6, and a correlation coefficient (r²) of 0.95. This correlation between the two gases seen in the aircraft samples was corroborated by in situ surface measurements of these gases made at the Barrow observatory during March and April 1986. We also find a similar relationship between methane and carbon dioxide measured concurrenty for a short period in the moderately polluted urban atmosphere of Boulder, Colorado. We suggest that the strong correlation between methane and carbon dioxide concentrations reflects a common source region for both, with subsequent long-range transport of the polluted air to the Arctic.  相似文献   

GIS辅助估算南海南部天然气水合物资源量   总被引：10，自引：0，他引：10  

曾维平  周蒂 《热带海洋学报》2003,22(6):35-45

具有低温高压条件的深海是天然气水合物形成的有利场所。从海底天然气水合物稳定分布的赋成条件入手,分别根据Levitus水温数据和Sloan的CSMHYD程序拟合出水温水深方程和相界线方程。假定南海南部温度梯度范围为59—90℃·km-1,得天然气水合物稳定带厚度与水深的关系方程。采用最新的南海南部海底数字地形图数据,在GIS平台上分析得到天然气水合物稳定带的分布图,进而获得南海南部天然气水合物稳定带最大厚度为230—355m,容积为5.7×1013—9.5×1013m3;甲烷量为2.451×1015—4.085×1015m3;资源量为1.729×1013—2.169×1013m3。  相似文献