Optimal international technology cooperation for the low-carbon transformation     

Anselm Schultes  Marian Leimbach  Gunnar Luderer  Robert C. Pietzcker  Lavinia Baumstark  Nico Bauer 《Climate Policy》2018,18(9):1165-1176

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An analytical study on turbulence with mixed-flow model and two-phase model     

Dan-xun LI  Marian MUSTE  Qiang ZHONG  Xing-kui WANG 《国际泥沙研究》2012,27(2):235-239

Suspended sediment is carried by turbulent water flows in rivers.Traditional sediment-laden flow analysis treats the suspension as a mixed liquid,and recent two-phase flow model enables separate velocity measurement of the two coupling phases.A simplified theoretical analysis was presented to discuss the differences between the two models in reporting turbulence intensity in experimental research.The turbulence intensity of the mixture is lower than the weighted average of those of the two phases in mixed-flow experiments.The mixture’s turbulence intensity becomes higher than the average of the two phases in two-phase experiments due to the presence of velocity lag.The same set of data may lead to either an underestimation or an overestimation of actual turbulence levels when different models are used.  相似文献   

The Influence of a Local Fault Zone on High Energy Tremor Occurrence During Longwall Mining of a Coal Seam     

Łukasz Wojtecki  Małgorzata Knopik  Wacław Marian Zuberek 《Acta Geophysica》2016,64(4):1164-1175

Underground mining of coal seams in the Upper Silesian Coal Basin in Poland is accompanied by seismic activity of varying magnitude. The investigations which have been performed for several years distinguished high energy mine tremors connected directly with mining or coupled with geological structures, such as large faults. In mined seams, local fault zones occur. Faults in these zones are usually small, with throws comparable with coal seams thicknesses. Local fault zone may be responsible for the occurrence of high energy tremors as well as large faults, as presented in this article. An analysis of source mechanism of high energy tremors generated during longwall mining of the coal seam No. 510, with presence of a local fault zone, in one of the Polish hard coal mines in the Upper Silesian Coal Basin was performed. For this purpose, the seismic moment tensor inversion method was used. In most of foci, the process of shear predominated. Determined nodal plane parameters were correlated with parameters of faults forming the local fault zone. High energy tremors were generated mostly by dislocations on faults of the local fault zone. Weakening of roof rocks in the neighborhood of local fault zone takes an important role too, and was responsible for share of implosion in the focal mechanism.  相似文献   

Human impact on the transport of terrigenous and anthropogenic elements to peri-alpine lakes (Switzerland) over the last decades     

Florian Thevenon  Stefanie B. Wirth  Marian Fujak  John Poté  Stéphanie Girardclos 《Aquatic Sciences - Research Across Boundaries》2013,75(3):413-424

Terrigenous (Sc, Fe, K, Mg, Al, Ti) and anthropogenic (Pb and Cu) element fluxes were measured in a new sediment core from Lake Biel (Switzerland) and in previously well-documented cores from two upstream lakes (Lake Brienz and Lake Thun). These three large peri-alpine lakes are connected by the Aare River, which is the main tributary to the High Rhine River. Major and trace element analysis of the sediment cores by inductively coupled plasma mass spectrometry (ICP-MS) shows that the site of Lake Brienz receives three times more terrigenous elements than the two other studied sites, given by the role of Lake Brienz as the first major sediment sink located in the foothills of the Alps. Overall, the terrigenous fluxes reconstructed at the three studied sites suggest that the construction of sediment-trapping reservoirs during the twentieth century noticeably decreased the riverine suspended sediment load at a regional scale. In fact, the extensive river damming that occurred in the upstream watershed catchment (between ca. 1930 and 1950 and up to 2,300 m a.s.l.) and that significantly modified seasonal suspended sediment loads and riverine water discharge patterns to downstream lakes noticeably diminished the long-range transport of (fine) terrigenous particles by the Aare River. Concerning the transport of anthropogenic pollutants, the lowest lead enrichment factors (EFs Pb) were measured in the upstream course of the Aare River at the site of Lake Brienz, whereas the metal pollution was highest in downstream Lake Biel, with the maximum values measured between 1940 and 1970 (EF Pb > 3). The following recorded regional reduction in aquatic Pb pollution started about 15 years before the actual introduction of unleaded gasoline in 1985. Furthermore, the radiometric dating of the sediment core from Lake Biel identifies three events of hydrological transport of artificial radionuclides released by the nuclear reactor of Mühleberg located at more than 15 km upstream of Lake Biel for the time period 1970–2000.  相似文献   

Copper isotope fractionation during surface adsorption and intracellular incorporation by bacteria   总被引：1，自引：0，他引：1  

Navarrete JU  Borrok DM  Viveros M  Ellzey JT 《Geochimica et cosmochimica acta》2011,75(3):784-799

Copper isotopes may prove to be a useful tool for investigating bacteria-metal interactions recorded in natural waters, soils, and rocks. However, experimental data which attempt to constrain Cu isotope fractionation in biologic systems are limited and unclear. In this study, we utilized Cu isotopes (δ⁶⁵Cu) to investigate Cu-bacteria interactions, including surface adsorption and intracellular incorporation. Experiments were conducted with individual representative species of Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, as well as with wild-type consortia of microorganisms from several natural environments. Ph-dependent adsorption experiments were conducted with live and dead cells over the pH range 2.5-6. Surface adsorption experiments of Cu onto live bacterial cells resulted in apparent separation factors (Δ⁶⁵Cu_{solution-solid} = δ⁶⁵Cu_solution − δ⁶⁵Cu_solid) ranging from +0.3‰ to +1.4‰ for B. subtilis and +0.2‰ to +2.6‰ for E. coli. However, because heat-killed bacterial cells did not exhibit this behavior, the preference of the lighter Cu isotope by the cells is probably not related to reversible surface adsorption, but instead is a metabolically-driven phenomenon. Adsorption experiments with heat-killed cells yielded apparent separation factors ranging from +0.3‰ to −0.69‰ which likely reflects fractionation from complexation with organic acid surface functional group sites. For intracellular incorporation experiments the lab strains and natural consortia preferentially incorporated the lighter Cu isotope with an apparent Δ⁶⁵Cu_{solution-solid} ranging from ∼+1.0‰ to +4.4‰. Our results indicate that live bacterial cells preferentially sequester the lighter Cu isotope regardless of the experimental conditions. The fractionation mechanisms involved are likely related to active cellular transport and regulation, including the reduction of Cu(II) to Cu(I). Because similar intracellular Cu machinery is shared by fungi, plants, and higher organisms, the influence of biological processes on the δ⁶⁵Cu of natural waters and soils is probably considerable.  相似文献   

UHP metamorphism recorded by kyanite-bearing eclogite in the Seve Nappe Complex of northern Jämtland,Swedish Caledonides     

Marian Janák  Herman van Roermund  Jarosław Majka  David Gee 《Gondwana Research》2013,23(3):865-879

The first evidence for ultrahigh-pressure (UHP) metamorphism in the Seve Nappe Complex of the Scandinavian Caledonides is recorded by kyanite-bearing eclogite, found in a basic dyke within a garnet peridotite body exposed close to the lake Friningen in northern Jämtland (central Sweden). UHP metamorphic conditions of ~ 3 GPa and 800 °C, within the stability field of coesite, are constrained from geothermobarometry and calculated phase equilibria for the peak-pressure assemblage garnet + omphacite + kyanite + phengite. A prograde metamorphic evolution from a lower P–T (1.5–1.7 GPa and 700–750 °C) stage during subduction is inferred from inclusions of pargasitic amphibole, zoisite and kyanite in garnet cores. The post-UHP evolution is constrained from breakdown textures, such as exsolutions of kyanite and silica from the Ca-Eskola clinopyroxene. Near isothermal decompression of eclogite to lower crustal levels (~ 0.8–1.0 GPa ) led to formation of sapphirine, spinel, orthopyroxene and diopside at granulite facies conditions. Published age data suggest a Late Ordovician (460–445 Ma) age of the UHP metamorphism, interpreted to be related to subduction of Baltoscandian continental margin underneath an outboard terrane, possibly outermost Laurentia, during the final stages of closure of the Iapetus Ocean. The UHP rocks were emplaced from the hinterland collision zone during Scandian thrusting of the nappes onto the Baltoscandian foreland basin and platform. The record of P–T conditions and geochonological data from UHP rocks occurring within the allochthonous units of the Scandinavian Caledonides indicate that Ordovician UHP events may have affected much wider parts of the orogen than previously thought, involving deep subduction of the continental crust prior to final Scandian collision between Baltica and Laurentia.  相似文献   

Sustainable Chemical Technologies in Production of Clean Fuels from Fossil Fuels     

Marian Taniewski 《洁净——土壤、空气、水》2008,36(4):393-398

Some aspects of the present and the possible future role of sustainable chemical technologies in the production of clean liquid and gaseous fuels from fossil fuels are discussed. The state‐of‐the‐art and the vision of possible sources and alternative routes which may lead to clean fuels from fossil fuels due to the progress in crude oil, natural gas and coal processing are briefly presented. The possible future role of the Fischer‐Tropsch synthesis, methanol synthesis, dimethylether synthesis, and a group of methanol transformation processes is also discussed.  相似文献   

Appropriate teaching materials for Africa: local is ‘lekker’!     

Marian Tredoux 《Journal of African Earth Sciences》1999,28(4):887-888

Most of the statistics given in this overview of the history and current status of Geoscience Education in South Africa pertain to the more geologically inclined disciplines; while the report does mention the extent to which earth sciences are taught in mining and geography departments, no detailed information about these activities are given. There are 13 active geoscience departments countrywide (eleven at universities and two at technical institutions) teaching a wide range of geological topics, some at a highly specialised level. There are just over 100 academic staff members engaged in teaching, supported by 65 technical and administrative staff. Of the teaching staff, 89% have Ph.D. degrees, and most are engaged in active research. About 150 three-year B.Sc., slightly fewer B.Sc. (Hons.), graduates, plus 10 geological technicians pass through the system every year, with most finding employment in the mining industry. Approximately 120 M.Sc. and 60 Ph.D. candidates are currently registered at the universities, about 40% of whom graduate in any particular year.  相似文献   

Economic Development and Emission Control over the Long Term: The ICLIPS Aggregated Economic Model     

Marian Leimbach  Ferenc L. Toth 《Climatic change》2003,56(1-2):139-165

In integrated assessments of climate change, greenhouse-gasemissions and climate change impacts provide the linkages betweenthe world economy and the climate system. Key climatic processesoperate at the scales of centuries. This requires highlyaggregated models for portraying the dynamics of the economicsystem. An extended Ramsey-type optimal growth model is presentedas the appropriate tool to be integrated with a reduced-formclimate model in the ICLIPS integrated assessment. Theeleven-region model of the world economy involves exogenouspopulation and endogenous investment dynamics with productivityprogress based on a technological diffusion model. World regionsare linked via intertemporal trade flows of the compositeconsumption/investment good, capital mobility, and emission permittrading. Coupled with the ICLIPS Climate Model, the AggregatedEconomic Model can determine corridors of permitted long-termcarbon emission paths or, as primarily discussed in this paper,specific cost-effective emission trajectories. The sensitivity ofmitigation costs to externally specified climate change/impactconstraints and to assumptions about non-CO₂ greenhouse-gasemissions is also discussed.  相似文献   

Stable carbon isotope variations in northwest Europe during the last glacial–interglacial transition     

Chris S. M. Turney  David J. Beerling  Douglas D. Harkness  J. John Lowe  E. Marian Scott 《第四纪科学杂志》1997,12(4):339-344

Stable carbon isotope data that span part of the last glacial–interglacial transition (ca. 14-9 ka ¹⁴C BP; ca. 15–11 ka cal. BP), and which derive from organ-specific plant macrofossils recovered from two lake sediment profiles in the UK and one in Norway, are compared. The recorded temporal variations show similar trends, which, over a millennial time-scale appear to parallel the main drift in δ¹⁸O as determined for the GRIP ice-core. It is postulated that some smaller scale variations in the δ¹³C profiles may reflect the shorter term oscillations in δ¹⁸O values evident in the GRIP record, although this is less certain. Overall, however, the results suggest that stable carbon isotope measurements based on organ-specific terrestrial plant macrofossils may provide (i) a means for establishing correlations between terrestrial successions and (ii) additional paleoenvironmental information, as the apparent ‘shadowing’ of the GRIP record indicates a common forcing mechanism for both Greenland δ¹⁸O and northwest European δ¹³C variations. From the evidence available we suggest that the recorded δ¹³C variations reflect fluctuations in air temperature and/or changes in water vapour pressure in the atmosphere. © 1997 John Wiley & Sons, Ltd.  相似文献