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71.
Hakan Hogrmez M Namk Yaln Bernhard Cramer Peter Gerling Eckhard Faber Rainer G Schaefer Ulrich Mann 《Organic Geochemistry》2002,33(12)
Previous studies on the coal-bed methane potential of the Zonguldak basin have indicated that the gases are thermogenic and sourced by the coal-bearing Carboniferous units. In this earlier work, the origin of coal-bed gas was only defined according to the molecular composition of gases and to organic geochemical properties of the respective source rocks, since data on isotopic composition of gases were not available. Furthermore, in the western Black Sea region there also exist other source rocks, which may have contributed to the coal-bed gas accumulations. The aim of this study is to determine the origin of coal-bed gas and to try a gas-source rock correlation. For this purpose, the molecular and isotopic compositions of 13 headspace gases from coals and adjacent sediments of two wells in the Amasra region have been analyzed. Total organic carbon (TOC) measurements and Rock-Eval pyrolysis were performed in order to characterize the respective source rocks. Coals and sediments are bearing humic type organic matter, which have hydrogen indices (HI) of up to 300 mgHC/gTOC, indicating a certain content of liptinitic material. The stable carbon isotope ratios (δ13C) of the kerogen vary from −23.1 to −27.7‰. Air-free calculated gases contain hydrocarbons up to C5, carbon dioxide (<1%) and a considerable amount of nitrogen (up to 38%). The gaseous hydrocarbons are dominated by methane (>98%). The stable carbon isotope ratios of methane, ethane and propane are defined as δ13C1: −51.1 to −48.3‰, δ13C2: −37.9 to −25.3‰, δ13C3: −26.0 to −19.2 ‰, respectively. The δD1 values of methane range from −190 to −178‰. According to its isotopic composition, methane is a mixture, partly generated bacterially, partly thermogenic. Molecular and isotopic composition of the gases and organic geochemical properties of possible source rocks indicate that the thermogenic gas generation took place in coals and organic rich shales of the Westphalian-A Kozlu formation. The bacterial input can be related to a primary bacterial methane generation during Carboniferous and/or to a recent secondary bacterial methane generation. However, some peculiarities of respective isotope values of headspace gases can also be related to the desorption process, which took place by sampling. 相似文献
72.
天然气中氮的地球化学特征 总被引:23,自引:0,他引:23
本文研究了天然气中氮的地球化学特征,并讨论了氮的成因。 相似文献
73.
74.
Christopher E. Holloway Allison A. Wing Sandrine Bony Caroline Muller Hirohiko Masunaga Tristan S. L’Ecuyer David D. Turner Paquita Zuidema 《Surveys in Geophysics》2017,38(6):1199-1236
Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network. 相似文献
75.
Continuous gas monitoring in the West Bohemian earthquake area,Czech Republic: First results 总被引:1,自引:1,他引:0
Eckhard Faber Josef Horálek Alena Boušková Manfred Teschner Ulrich Koch Jürgen Poggenburg 《Studia Geophysica et Geodaetica》2009,53(3):315-328
Two stations monitoring concentrations of carbon dioxide and radon in soil gas (Oldřišská and Novy Kostel) and one station
monitoring flow of carbon dioxide at a mofette (Soos) have been operated in the area of the West Bohemian earthquake swarms.
We present preliminary results obtained on the base of four-year observations. We found that data are not influenced considerably
by barometric pressure. Although the CO2 concentration varies greatly, the long-term trends at stations Oldřišská and Novy Kostel are similar, which indicates that
the CO2 flow is controlled by common geogenic processes. Also temporal trends of CO2 and Rn concentrations in soil gas at individual stations are analogous. We found diurnal variations of both CO2 concentration in soil gas and the CO2 flow at mofettes due to the earth tides. A response to tides of semi-diurnal period is insignificant in CO2 concentration and only weak in the CO2 flow. We also examined possible pre-seismic, co-seismic and post-seismic effects of the intensive 2008 earthquake swarm on
the CO2 concentration at Oldřišská and Novy Kostel, and on the CO2 flow at Soos. However, all potential indications were insignificant and there has not been proven any influence of the swarm
on the CO2 concentration as well as on the CO2 flow. Nevertheless, a gradual decrease of amplitudes of diurnal variations before the swarm and the lowest amplitudes during
the swarm is a noteworthy phenomenon, which might indicate the strain changes of the rock associated with earthquake swarm. 相似文献
76.
Tristan D. Pearce James D. Ford Gita J. Laidler Barry Smit Frank Duerden Mishak Allarut Mark Andrachuk Steven Baryluk rew Dialla Pootoogoo Elee Annie Goose Theo Ikummaq Eric Joamie Fred Kataoyak Eric Loring Stephanie Meakin Scott Nickels Kip Shappa Jamal Shirley & Johanna Wandel 《Polar research》2009,28(1):10-27
Research on climate change impacts, vulnerability and adaptation, particularly projects aiming to contribute to practical adaptation initiatives, requires active involvement and collaboration with community members and local, regional and national organizations that use this research for policy-making. Arctic communities are already experiencing and adapting to environmental and socio-cultural changes, and researchers have a practical and ethical responsibility to engage with communities that are the focus of the research. This paper draws on the experiences of researchers working with communities across the Canadian Arctic, together with the expertise of Inuit organizations, Northern research institutes and community partners, to outline key considerations for effectively engaging Arctic communities in collaborative research. These considerations include: initiating early and ongoing communication with communities, and regional and national contacts; involving communities in research design and development; facilitating opportunities for local employment; and disseminating research findings. Examples of each consideration are drawn from climate change research conducted with communities in the Canadian Arctic. 相似文献
77.
78.
Edward Cripps Anthony O’Hagan Tristan Quaife 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(5):1239-1251
Remotely sensed land cover maps are increasingly used as inputs into environmental simulation models whose outputs inform decisions and policy-making. Risks associated with these decisions are dependent on model output uncertainty, which is in turn affected by the uncertainty of land cover inputs. This article presents a method of quantifying the uncertainty that results from potential mis-classification in remotely sensed land cover maps. In addition to quantifying uncertainty in the classification of individual pixels in the map, we also address the important case where land cover maps have been upscaled to a coarser grid to suit the users’ needs and are reported as proportions of land cover type. The approach is Bayesian and incorporates several layers of modelling but is straightforward to implement. First, we incorporate data in the confusion matrix derived from an independent field survey, and discuss the appropriate way to model such data. Second, we account for spatial correlation in the true land cover map, using the remotely sensed map as a prior. Third, spatial correlation in the mis-classification characteristics is induced by modelling their variance. The result is that we are able to simulate posterior means and variances for individual sites and the entire map using a simple Monte Carlo algorithm. The method is applied to the Land Cover Map 2000 for the region of England and Wales, a map used as an input into a current dynamic carbon flux model. 相似文献
79.
80.
Interpretation of both P- and S-wave data from the 1974 LISPB seismic experiment has resulted in a detailed cross-section across the Caledonian orogenic belt of northern Britain. This section provides clear evidence of lateral variations in lithospheric structure, comparable with the gross geological variations. In particular, lithospheric structure is asymmetric across the orogenic belt: however, the axis of this asymmetry seems to vary with depth within the central part of the belt. Thus the identification of a possible lapetus suture remains moot. 相似文献