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排序方式: 共有164条查询结果,搜索用时 104 毫秒
121.
A field trial for in-situ bioremediation of 1,2-DCA 总被引:2,自引:0,他引:2
Historic spillages of chlorinated hydrocarbons at a vinyl chloride plant in the Rotterdam Botlek area in The Netherlands have lead to contamination of the underlying aquifer. The principal contaminant is 1,2-dichloroethane (1,2-DCA). The contamination is temporarily contained by a pump-and-treat system. A field trial was carried out to investigate the feasibility of treating the dissolved phase of 1,2-DCA via reductive dechlorination by injection of an aqueous solution of methanol, ammonium chloride and sodium chloride into the confined aquifer using an array of eight boreholes. Biodegradation of 1,2-DCA was localised. This was attributed to limited mixing of the carbon substrate within the test zone. In addition, clogging of recharge wells complicated groundwater circulation. 相似文献
122.
A Metamorphosed, Early Archaean Chromitite from West Greenland: Implications for the Genesis of Archaean Anorthositic Chromitites 总被引:2,自引:0,他引:2
An early Archaean (>3·81 Ga) chromititeultramaficlayered body from the Ujaragssuit nunât area, west Greenland,may represent the Earths oldest chromitite. The layeredbody occurs as a large xenolith (800 m x 100 m) entrained withintonalitic gneisses and preserves primary igneous layering andtextures. New ReOs and PbPb isotope results supportthe view that it has been metamorphosed twice, in the earlyand late Archaean at 3·75 Ga and 2·8 Ga. Mineralchemistry and textures indicate that the chromite compositionspreserve two different evolutionary trends. There is a mainmagmatic trend in which Cr/(Cr + Al) ratios remain relativelyconstant but in which there is strong enrichment in Fe3+, Fe2+and Ti with progressive differentiation. This trend is a compositeof magmatic-liquidus, magmatic-cooling and subsolidus re-equilibrationprocesses. A second trend is defined by chromites from harzburgitesin the upper part of the layered body. These chromites showmagmatic replacement textures in which Fe-rich chromites arealtered to aluminous chromites. Chromites showing magmatic replacementtextures are thought to have formed by reaction with a late,interstitial melt during the solidification of the layered body.The close association between the Fe3+Cr-chromites ofthe main trend and Al-rich chromites of the type found in otherArchaean megacrystic anorthosites suggest a magmatic-geneticrelationship between the two types of chromite. We propose thatanorthositic chromites form in an Fe-rich basaltic melt derivedfrom a komatiitic, boninitic or basaltic parent magma throughreaction between the melt and early-formed Fe-rich chromite. KEY WORDS: chromite; anorthosite; Archaean; Greenland; ReOs 相似文献
123.
Werner F. Thöny Peter Tropper Friederike Schennach Erwin Krenn Friedrich Finger Reinhard Kaindl Franz Bernhard Georg Hoinkes 《Swiss Journal of Geoscience》2008,101(1):111-126
Within the Ötztal Complex (ÖC), migmatites are the only geological evidence of the pre-Variscan metamorphic evolution, which led to the occurrence of partial anatexis in different areas of the complex. We investigated migmatites from three localities in the ÖC, the Winnebach migmatite in the central part and the Verpeil- and Nauderer Gaisloch migmatite in the western part. We determined metamorphic stages using textural relations and electron microprobe analyses. Furthermore, chemical microprobe ages of monazites were obtained in order to associate the inferred stages of mineral growth to metamorphic events. All three migmatites show evidence for a polymetamorphic evolution (pre-Variscan, Variscan) and only the Winnebach migmatite shows evidence for a P-accentuated Eo-Alpine metamorphic overprint in the central ÖC. The P-T data range from 670–750 °C and < 2.8 kbar for the pre-Variscan event, 550–650 °C and 4–7 kbar for the Variscan event and 430–490 °C and ca. 8.5 kbar for the P-accentuated Eo-Alpine metamorphic overprint. U-Th-Pb electron microprobe dating of monazites from the leucosomes from all three migmatites provides an average age of 441 ± 18 Ma, thus indicating a pervasive Ordovician-Silurian metamorphic event in the ÖC. 相似文献
124.
125.
Erwin Groten 《Journal of Geodesy》1975,49(1):41-56
The application of a Sartorius 4104 microbalance after Gast in vertical gradiometry was tested. A small mass of about 20 grams
is suspended on thin fibers of different lengths Δℓ≤80 cm. From the weight difference of the small mass obtained at different
levels along the plumb line the corresponding differences of gravity along the plumb line are inferred. The microbalance is
mounted on a steal rack; measurements at constant low pressure (moderate vacuum) show the applicability of the balance as
gravity difference sensor for field work. When environmental effects are further reduced (i,e, temperature is kept constant
within ±0.1°C; pressure is controlled within 0.1 Torr etc.) the resolution of the balance can be fully exploited so a relative
accuracy of ±10−9 should be feasible and for laboratory experiments should be of the order of a few parts in ±10−10.
Vertical gravity gradients as observed on an improved moving platform with a LaCoste model G gravimeter are discussed. New
possibilities of microgravimetry are pointed out.
High precision observations and establishment of a system in an area of tectonic interest for detecting secular gravity changes
are described.
Paper presented at the meeting of the “International Gravity Commission”, Paris, September 1974. 相似文献
126.
Erwin Moritz 《Boundary-Layer Meteorology》1989,49(3):317-329
With the use of a sonic anemometer, vertical heat and momentum fluxes were measured at three different levels in an oak forest canopy. A quadrant analysis of the resulting data shows that approximately half of the transport occurs in extreme events lasting about 5 to 10% of the time. The partition of transport into momentum sweeps, bursts and interactions shows good agreement with existing data. The heat flux is analysed by observing the fluxes during the different momentum events and considering concurrent momentum and heat flux intensities by means of conditional probabilities. While low intensity (normal) events show similar probability distributions throughout the canopy, different structures appear at the three measurement heights for high intensity (extreme) events that can tentatively be explained by taking the temperature profile into account. This supports the idea that these events are coherent motions with scales comparable to the canopy height. 相似文献
127.
Dozent Dr. Erwin Hardtwig 《Pure and Applied Geophysics》1949,14(3-4):203-224
Zusammenfassung An Hand einiger Wetterlagen mit besonders starker Mikroseismik wird der Verlauf von Amplituden und Perioden in Stuttgart verfolgt. Das Gesetz der Abhängigkeit zwischen Periode und Amplitude wird empirisch ermittelt, das Periodenspektrum gezeichnet. Die am häufigsten auftretende Periode wird zur Berechnung der Dicke der schwingenden Schicht benutzt unter der Annahme, dass diese Schicht mit ihrer Unterlage lose verbunden ist und die Art der Schwingungen sich nicht wesentlich von Rayleighwellen unterscheidet. Es ergibt sich so der theore tische Zusammenhang zwischen Periode und Amplitude einerseits und der Schichtdicke andrerseits. Sie beträgt für Norwegen etwas über 40 km.
Summary With the help of several weather-situations with particularty violent microseism the progress of amplitudes and periods as perceived at Stuttgart is examinated. The law of dependency between period and amplitude is found empirically, the spectrum of periods is drawn up. The period, which occurs most frequently is used for calculating the thickness of the swinging layer as this layer is supposed to be in loose connection with its support and as the sort of oscillations is not essentially different from Rayleight waves. Thus there is found the theoretical connection between periods and amplitudes and, on the other side, the thickness of layer of something more than 40 km for Norway.相似文献
128.
Dr. Erwin Nickel 《Contributions to Mineralogy and Petrology》1949,2(1-2):176-188
Ohne Zusammenfassung 相似文献
129.
The evolution of Ancient Silk Road(ASR) was deeply influenced by late Holocene moisture changes in Arid Central Asia(ACA). Nevertheless, controversies in Holocene moisture change pattern of ACA and poorly–constrained age models of related studies have made the discussion about late Holocene moisture changes in ACA and their influences on the evolution of ASR difficult. Recently, a high–resolution age model during the late Holocene was established for Kalakuli Lake, a small glacier lake located in the core area of ACA. A thorough rock magnetic investigation was carried out on Kalakuli Lake sediments based on this age model. The magnetic mineral assemblage of Kalakuli Lake sediments is still dominated by primary magnetite despite minor diagenetic effects. Comparisons of rock magnetic records to parameters previously used as indicator of glacier fluctuations suggest that clastic input to Kalakuli Lake was high(low) and magnetic grain size is relatively larger(smaller), when glaciers on Muztagh Ata advanced(retreated). The ARM/SIRM ratio, a magnetic grain size proxy, is directly related to lake hydrodynamics, which are ultimately controlled by glacier fluctuations on Muztagh Ata as the result of regional moisture changes. Late Holocene moisture changes indicated by the ARM/SIRM ratio are consistent with cool/wet and warm/dry oscillations indicated by the unweighted average of biomarker hydrogen isotopic data of the C_(26) and C_(28) n–alkanoic acids in a previous study about Kalakuli Lake, most moisture change records of the core area of ACA and winter insolation of the Northern Hemisphere, but opposite to Asian monsoon evolution. Given Asian monsoon and the westerlies are mutually inhibited, we propose that late Holocene moisture changes in the core area of ACA were controlled by the intensity of Asian monsoon versus the westerlies under the governance of solar insolation. Generally increased moisture since the late Holocene indicated by the ARM/SIRM ratio favored cultural exchange and integration between the western and the eastern Eurasia, which paved the way for the formation of ASR. Coincidence between significant increase in moisture at ~200 BC suggested by the ARM/SIRM ratio and the formation of ASR indicates moisture as an important factor that facilitated the formation of ASR. The onsets of three prosperity periods of ASR in the history generally correspond to periods when moisture was relatively high, nevertheless, stagnant periods of ASR do not coincide with periods when moisture was relatively low in the core area of ACA. Disorganized correlations between stagnant periods of ASR and moisture changes in the core area of ACA suggest that moisture is not the decisive factor influencing the evolution of ASR. 相似文献
130.
Erwin Suess 《Geochimica et cosmochimica acta》1973,37(11):2435-2447
Surface area measurements as well as organic carbon, nitrogen and phosphorus analyses on various grain size fractions of carbonate mud samples confirm that in natural environments of carbonate deposition, surface sorption processes take place which are similar to those described earlier for dissolved organics and artificially suspended calcite particles in both seawater and synthetic solutions.The specific surface area of the sediment increases from 1.8m2/g for the coarse-grained fraction to 12.5 m2/g for the fine material; likewise organic carbon, nitrogen and phosphorus increase with increasing surface area so that there are 1.20 mg C, 0.175 mg N and 0.06–0.20 mg P associated with every square meter of carbonate surface irrespective of the mineralogy of the sediment particles.It appears that the organic matter in these sediments is similar in composition, structure and quantity to the organic layers produced in sorption experiments. With their apparently defined structure and ubiquitous nature, these layers could determine the mineralogy and orientation of submarine carbonate cement or could even be a prerequisite to calcification in general. 相似文献