Structure and origin of terpenoid hydrocarbons in some German coals

Hydrocarbon extracts of coal samples from major coal fields in West Germany have been investigated by gas chromatography-mass spectrometry (GC/MS). The samples are of Carboniferous and Tertiary age and derive from limnic and paralic environments, the Saar District, the Ruhr Area and the Lower Rhine Basin.Differences in facies, maturity and age reflected in the distribution patterns of the extracted alkylcyclohexanes. An unexpected occurrence of cyclic diterpenoid hydrocarbons in some samples of Carboniferous age has been found. The tetracyclic compounds mainly show phyllocladane type structures and can serve as source indicators.Hydrocarbons obtained from chemical degradation of the macromolecular material of the samples also revealed phyllocladane-type compounds which are normally associated to resins of modern and extinct familes of conifers. Origin and structural variations of this class of hydrocarbons are discussed in terms of maturity and palaeobotanical implications.     

Petrology, depositional environment and utilization potential of Late Paleocene coals from the Obed-Marsh deposit, West-Central Alberta, Canada

The Obed-Marsh coal deposit is of Late Paleocene age, and contains over 200 million tons of subbituminous-B to high-volatile bituminous-C coal.Petrographic analysis of three sections from seams 1 and 2 reveals high amounts of huminite and relatively low amounts of liptinite and inertinite, with the exception of some intervals in both seems. The persistent high ratio of huminite to liptinite and inertinite indicates a relatively reducing environment, a feature also expressed by the relatively low inertinite content. Examination of the in-seam profiles also indicates undisturbed peat accumulation over long periods of time.The Obed coals, similar in rank and composition to the Hat Creek coals of British Columbia, formed in a freshwater environment and can be used as feedstock for combustion/gasification. Furthermore, the intervals rich in liptinite and petroleum-like substances may be utilized for liquefaction (hydrogenation).     

The lateral and vertical reflectance and petrological variation of a heat-affected bituminous coal seam from southeastern British Columbia, Canada

Thermally altered pods of coal of very high rank have been observed in a high-volatile-bituminous coal seam in the eastern side of Eagle Mountain, Elk Valley Coalfield, British Columbia. Rank changes have been measured over a strike distance of 7.5 m from 1.24% to 7.1% R_{o max}, corresponding to a rank gradient of 0.78% R_om⁻¹.Petrologically, unaltered to extremely altered vitrinite showing nongranular (basic) anisotropy, mosaic-textured liptinite and pyrolytic carbon are the most abundant components. The limited presence of mosaic on vitrinite is an indication that the coal seam may have been weathered prior to being heat-affected.Evidence points to localized temperatures as high as 1,000°C, which could have been caused by a lightning strike. The eastern side of Eagle Mountain has experienced higher temperatures than the western side, and it appears that the heat ‘front’ and zone of alteration have an irregular pattern, pointing to saturation of parts of the coal seam by water.Four types of pyrolytic carbon having distinct morphology, anisotrophy and optical path with increasing temperature were observed. Reflectance of pyrolytic carbon falls within the zone of heat-affected coals, whereas the optical path of heat-affected Seam 15 samples is different from that of fresh coal with increasing rank.Finally, the reflectance of vitrinite in heat-affected coal is higher than the reflectance of vitrinite in carbonaceous shale in the Seam 15 section.     

P-waveform analysis for local subduction geometry south of Puget Sound,Washington

The local subduction geometry at a site south of Puget Sound in western Washington is investigated using teleseismicP-waveforms recorded on a three-component event triggered seismograph. The data are processed using source equalization deconvolution in order to isolate locally convertedP-to-S arrivals and stacked to improve the signal-to-noise ratio. Stable arrivals in the radial component indicate an oceanic Moho within the subducted slab at a depth of about 53 km beneath the station. Observed amplitude variations with azimuth in the radial data, as well as qualitative aspects of the tangential data, are used to establish a slab dip of 16° to the southeast. Our results are compatible with previous results from a site 60 km to the west, and further confirm a substantial warp in the regional geometry of the subducted Juan de Fuca plate.     

Thermal maturity and hydrocarbon potential of the sedimentary succession from the Hecla field in Sverdrup Basin, Arctic Canada

The thermal maturity and source-rock potential of the Upper Palaeozoic and Mesozoic sediments in the Hecla field, Melville Island, Arctic Canada, have been studied using reflected-light microscopy and Rock-Eval pyrolysis. Approximately 250 polished whole-rock samples were examined and their reflectance (% R₀, random) measured. In addition, approximately 100 samples were subjected to Rock-Eval/TOC analyses.Hydrogen-rich organic matter in the Schei Point Group sediments is dominated by alginite (Tasmanales), dinoflagellate cysts with minor amounts of sporinite, cutinite, resinite and liptodetrinite in an amorphous fluorescing matrix. Vitrinite reflectance in Cretaceous sediments ranges from 0.41 to 0.54%; in Jurassic sediments it ranges from 0.43 to 0.64% and in Triassic sediments from 0.50 to 0.65%. The Triassic Schei Point Group calcareous shales and marlstones contain organic matter mainly of marine origin, whereas the predominantly terrestially-derived organic matter present in the Jameson Bay (Lower Jurassic) and in the Upper Jurassic to Lower Cretaceous Deer Bay formations have ower TOC. Only the Ringnes Formation has a TOC content of equivalent to or greater than Schei Point source rocks. Within the Schei Point Group, the Cape Richards and Eden Bay members of the Hoyle Bay Formation are slightly richer in TOC than the Murray Harbour Formation (Cape Caledonia Member). Higher average TOC contents (>3.0%) have been reported in the Cape Richards and Eden Bay members in almost all Hecla drillholes.Variations in the level of thermal maturity of Mesozoic sediments in the Hecla field are a function of burial depth. The stratigraphic succession thickens towards the main Sverdrup Basin depocentre located in a N-NE direction. The pattern of the isoreflectance contours at the top of the Triassic (Barrow Formation) is similar to that of formation boundary lines of the same formations, an indication that present-day maturation levels are largely controlled by basin subsidence.     

How does landfill leachate affect the chemical processes in a lake system downgradient from a landfill site?

A field study on the geochemical properties of a chemically-stressed limnic environment was performed in Lake Silbersee, which receives leachate water of high inorganic loading from an upgradient landfill site. The highly concentrated sulfate ion in groundwater, when entering the pore water system of the lake, gives rise to an intensive microbial sulfate reduction. A diagenetic approach was used to explain the existence of a marine-like aqueous system within a geologically slightly acidic aquifer, consisting of a well-buffered lake water and an alkalinity producing, excess sulphide containing sediment pore water system.     

Mercuric Chloride Induced Inhibition of Acid and Alkaline Phosphatase Activity in the Kidney of Mudskipper,Boleophthalmus dentatus

The present paper deals with the inhibition of the specific activity of the acid and alkaline phosphatases in the kidney tissue of mudskipper Boleophthalmus dentatus, exposed to different sublethal concentrations of mercuric chloride. There was a more or less linear inhibition of the specific activity of both the enzymes with increasing concentration of mercuric chloride as well as exposure time. The inhibition of acid phosphatase could be due to the rupture of lysosomal membrane in the presence of mercury compound, which acts as a labilizing agent. The inhibition of alkaline phosphatase probably caused a breakdown of the membrane transport system.     

Sediment transport by burrowing mammals,Marin County,California

Field observations suggest that burrowing activity is the primary mode of sediment transport currently active in a small grassland drainage basin in Marin County, California. Spatial concentrations of the 1150 gopher mounds surveyed vary from 0-16 mounds m^?2 on interfluves to 0.32 mounds m^?2 on sideslopes and in the topographic hollow, with localized concentrations of up to 2.88 mounds m^?2 on the margins of the colluvial deposit. Simple models of sediment transport by burrowing activity yield estimates of between 0.91 and 2.33 cm³ cm^?1 yr^?1 for the basin as a whole, with absolute minimum and maximum rates of 0.48 and 631 cm³ cm^?1 yr^?1. These values are similar to those previously estimated for this area (Lehre, 1982) and are nearly an order-of-magnitude less than average long-term sediment transport rates at the same site (Reneau, 1988).     

Optimal carbon emissions trajectories when damages depend on the rate or level of global warming

In this paper we extend our earlier work with the Carbon Emissions Trajectory Assessment model (CETA) to consider a number of issues relating to the nature of optimal carbon emissions trajectories. We first explore model results when warming costs are associated with the rate of temperature rise, rather than with its level, as in our earlier work. We find that optimal trajectories are more strongly affected by the degree of non-linearity in the warming cost function than by whether the cost function is driven by the warming level or the warming rate. Next we briefly explore the implications of simple uncertainty and risk aversion for optimal emissions trajectories. We find that uncertainty and risk aversion cause optimal emissions trajectories to be somewhat lower, but that the effect is not noticeable in the near term and not dramatic in the long term; the long term effect on the shadow price of carbon is more marked, however. Finally, we experiment with scaling up the warming cost functions until optimal policies are approximately the same as a policy of stabilizing emissions at the 1990 level. Based on the results of this experiment, we conclude that damages would have to be very high to justify anything like a stabilization policy; and even in this case, a policy allowing intertemporal variation in emissions would be better.This paper does not represent the position of EPRI or of its members.