Column tests to enhance sulphide precipitation with liquid organic electron donators to remediate AMD-influenced groundwater     

Felix Bilek 《Environmental Geology》2006,49(5):674-683

Dump groundwaters in the former East-German lignite-mining district are characterized by high amounts of ferrous iron and sulphate. Both the pyrite weathering products endanger the surface water quality when discharged into lakes. Only the precipitation of both contaminants in the subsurface can prevent the further contamination of surface waters. The two-step process of microbial catalyzed sulphate reduction and iron sulphide precipitation is limited by the low availability of natural organic substances as electron donators. Therefore, a new remediation technique is developed based on the injection of a liquid organic electron donator (methanol) into the contaminated aquifer. The saturated aquifer is used as a bioreactor, where iron monosulphides are precipitated in the groundwater-filled pore space. Column experiments were performed under natural pressure and temperature conditions with natural anoxic groundwater and original sediments to test the remediation technology. The test showed that a complete iron removal (4 mmol/l), even under rather acid conditions (pH 3.8), is possible after having established an active sulphate reducer population. The turnover of the added organic substance with sulphate is complete and the amount of the resulting sulphide controls the effluent pH. In addition, intensified microbial activity triggers the turnover of natural organic substances. Also, natural Fe(III) hydroxides react with the sulphide produced. Considering the long natural retention times (decades), artificially enhanced FeS precipitation is spontaneous, although it shows kinetic behaviour in the range of days. In light of the promising results, the development of a field scale application of this technique is considered to be necessary. It will have to focus on the improved precipitation control of the FeS in the subsurface.  相似文献   

Capital and Empire: Geographies of Imperial London     

David Gilbert  Felix Driver 《GeoJournal》2000,51(1-2):23-32

The notion of empire has often been regarded in Europe as a matter of diffusion and expansion; something which happened over there rather than close to home. Yet the form, use and representation of modern European cities have been shaped by the global history of imperialism in ways that continue to matter even in an apparently post-imperial age. The signs of empire were prominently displayed within the built environments of all the major cities of late-nineteenth century Europe, as they came (in different ways) to play the role of regional, national and imperial capitals. In what was evidently a pan-European discourse on the imperial city between the mid-nineteenth century and the mid-twentieth, national models were defined in relation to other national models, in a spirit of competition as much as emulation. This paper examines the case of London. British architects and planners frequently complained that London lagged behind its rivals in the struggle for imperial primacy, given the absence of state-sponsored projects to parallel Haussmann's rebuilding of Paris or Leopold's grand plans for Brussels. At the intra-urban scale, the imperial city had a geography which mattered: in the case of London, different parts of the city were associated with different aspects of empire. More generally, it is clear that national debates over imperial urbanism were conditioned not simply by understandings of the global reach of European empires, but also by attitudes towards social, cultural and political change within Europe itself.  相似文献   

The relationship between the distribution of nitrogen impurity centres in diamond crystals and their internal structure and mechanism of growth   总被引：1，自引：0，他引：1  

Felix V. Kaminsky  Galina K. Khachatryan 《Lithos》2004,77(1-4):255-271

Fifty diamond crystals of different morphological types (octahedra, dodecahedroids, cubes and single tetrahexahedroid) with differing internal structures were examined using methods of cathodoluminescence (CL), anomalous birefringence and local infrared (IR) analysis. The main objective of the study was to examine the regularities of nitrogen impurity distribution in diamond with differing internal structures. Almost all the analyzed octahedra, as well as dodecahedroids with zonal structures and the blocky dodecahedroids, are characterized either by nearly isothermic growth conditions or by a decrease in formation temperature during the crystallization process. In contrast to zoned octahedra and dodecahedroids, dodecahedroids with zonal–sectorial and sectorial internal structures show a notably different distribution of nitrogen defects, with N_tot generally decreasing from crystal cores to marginal areas, and degree of nitrogen aggregation increasing in the same direction. From this, it would follow that in these crystals, the temperature of diamond formation of the outer crystal zones is approximately 40–50 °C higher than that of the inner zones. The same result (15 to 80 °C) was obtained for diamond crystals with cubic habit, which generally show a fibrous internal structure, reflecting normal mechanisms of growth. The anomalous distribution of nitrogen centres in diamond crystals that grew through the normal mechanism, with a high rate of growth and in an oversaturated medium, might point to non-equilibrium relationships between the concentrations of different nitrogen centres. It is likely that in crystals of this type, the rate of growth is higher than the rate of structural nitrogen aggregation. Thus, it appears that in these peculiar crystals of diamond we deal with non-equilibrium concentrations of nitrogen B centres and, consequently, with anomalous, non-actual diamond formation temperatures.  相似文献   

Neoproterozoic ‘anomalous’ kimberlites of Guaniamo, Venezuela: Mica kimberlites of ‘isotopic transitional’ type     

Felix V. Kaminsky  Sergei M. Sablukov  Ludmila I. Sablukova  Dominic M.DeR. Channer 《Lithos》2004,76(1-4):565-590

In Venezuela, kimberlites have so far only been found in the Guaniamo region, where they occur as high diamond grade sheets in massive to steeply foliated Paleoproterozoic granitoid rocks. The emplacement age of the Guaniamo kimberlites is 712±6 Ma, i.e., Neoproterozoic. The Guaniamo kimberlites contain a high abundance of mantle minerals, with greater than 30% olivine macrocrysts. The principal kimberlite indicator minerals found are pyrope garnet and chromian spinel, with the overwhelming majority of the garnets being of the peridotite association. Chrome-diopside is rare, and picroilmenite is uncommon. Chemically, the Guaniamo kimberlites are characterized by high MgO contents, with low Al₂O₃ and TiO₂ contents and higher than average FeO and K₂O contents. These rocks have above average Ni, Cr, Co, Th, Nb, Ta, Sr and LREE concentrations and very low P, Y and, particularly, Zr and Hf contents. The Nb/Zr ratio is very distinctive and is similar to that of the Aries, Australia kimberlite. The Guaniamo kimberlites are similar in petrography, mineralogy and mantle mineral content to ilmenite-free Group 2 mica kimberlites of South Africa. The Nd-Sr isotopic characteristics of Guaniamo kimberlites are distinct from both kimberlite Group 1 and Group 2, being more similar to transitional type kimberlites, and in particular to diamondiferous kimberlites of the Arkhangelsk Diamond Province, Russia. The Guaniamo kimberlites form part of a compositional spectrum between other standard kimberlite reference groups. They formed from metasomatised subcontinental lithospheric mantle and it is likely that subduction of oceanic crust was the source of this metasomatised material, and also of the eclogitic component, which is dominant in Guaniamo diamonds.  相似文献   

Two Creeks Interstade Dated through Dendrochronology and AMS     

Klaus Felix Kaiser 《Quaternary Research》1994,42(3)

Dendrochronological analysis of fossil wood from Two Creeks, Wisconsin, reveals that the Two Creekan Intetstade lasted at least 252 yr. The sites crossdated by tree rings cover an area of about 970 km². AMS determinations from the beginning and end of the chronology open a ¹⁴ C time window for the episode from 12,050 to 11,750 yr B.P. The interval is contemporaneous with the Older Dryas in northern Europe. The development of a forest covering at least 970 km² on the western shore of Lake Michigan indicates a water level about as low as in modern times. Glacier retreat must have opened drainage channels either through the Straits of Mackinac or via the Indian River Plateau into the eastern lakes. The beginning of the tree-ring chronology coincides with the peak of meltwater pulse 1A at 12,000 yr B.P. Increased amounts of meltwater seem to have disturbed the heat exchange between the waters and the atmosphere in the North Atlantic off the Gulf of St. Lawrence or affected the δ¹⁸O-ratio of the evaporation, causing the climatic or isotopic reversal of the Older Dryas in Greenland and northern Europe.  相似文献   

Spatial structure of standing wave electromagnetic fields at the lower harmonics of the ionospheric Alfvén resonator     

Karel Prikner  Felix Z. Feygin  Tero Raita 《Studia Geophysica et Geodaetica》2014,58(2):326-337

During the multiband wave Pc1 event on March 7, 2001 the EISCAT UHF and VHF incoherent scatter radars operated simultaneously covering an exceptionally wide altitude range of the ionosphere ～90—2000 km. This made possible to test the ionospheric Alfvén resonator (IAR) model over a large altitude range. The three lowest IAR eigenfrequencies, where the most of the Pc1 pulsation signal bands occur, were selected for the spatial analysis of the standing wave electromagnetic fields, applying the full-wave numerical simulation method. The altitude spread of amplitude maxima and nodes together with polarization characteristics of oscillation maxima in the horizontal plane are presented. The comparison of the standing wave oscillations on the altitude profile with the signal amplitude observed on the ground is also presented.  相似文献   

Conduit margin heating and deformation during the AD 1886 basaltic Plinian eruption at Tarawera volcano,New Zealand     

Jenny Schauroth  Fabian B. Wadsworth  Ben Kennedy  Felix W. von Aulock  Yan Lavallée  David E. Damby  Jérémie Vasseur  Bettina Scheu  Donald B. Dingwell 《Bulletin of Volcanology》2016,78(2):12

  相似文献   

PC1 with a broad frequency spectrum — “Goose pulsations”     

Felix Z. Feygin  Karel Prikner  Jorma Kangas 《Studia Geophysica et Geodaetica》2009,53(4):519-536

Geomagnetic pulsations in the frequency range of Pc1 pearl waves with the dynamic spectra having a very narrow spectrum width at the beginning of the event and a very broad spectrum width (Δf/f₀ ∼ 1) in the later part of the event are analyzed. One of the observed events shown by the dynamic spectrum resembles a goose with the beak at the beginning of the event and with the wing in the later part of the event. Various interpretations of these geomagnetic pulsations are presented taking into account nonlinear effects, quasilinear interaction of electromagnetic ion-cyclotron waves with energetic, anisotropic protons and modulation of plasma parameters in the magnetosphere by Pc3–5 hydromagnetic waves. The ionospheric effect in the signal formation is determined by the ionospheric Alfvén resonator. It can control the frequency range of the dynamic spectra, but not the internal structure of the signal.  相似文献   

A stochastic differential equation model for assessing drought and flood risks   总被引：4，自引：3，他引：1  

Koichi Unami  Felix Kofi Abagale  Macarius Yangyuoru  Abul Hasan M. Badiul Alam  Gordana Kranjac-Berisavljevic 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(5):725-733

Droughts and floods are two opposite but related hydrological events. They both lie at the extremes of rainfall intensity when the period of that intensity is measured over long intervals. This paper presents a new concept based on stochastic calculus to assess the risk of both droughts and floods. An extended definition of rainfall intensity is applied to point rainfall to simultaneously deal with high intensity storms and dry spells. The mean-reverting Ornstein–Uhlenbeck process, which is a stochastic differential equation model, simulates the behavior of point rainfall evolving not over time, but instead with cumulative rainfall depth. Coefficients of the polynomial functions that approximate the model parameters are identified from observed raingauge data using the least squares method. The probability that neither drought nor flood occurs until the cumulative rainfall depth reaches a given value requires solving a Dirichlet problem for the backward Kolmogorov equation associated with the stochastic differential equation. A numerical model is developed to compute that probability, using the finite element method with an effective upwind discretization scheme. Applicability of the model is demonstrated at three raingauge sites located in Ghana, where rainfed subsistence farming is the dominant practice in a variety of tropical climates.  相似文献   

Shallow reflection seismic evidence of tectonic activity in the Cheb Basin,NW Bohemia     

Felix Halpaap  Marco Paschke  Florian Bleibinhaus 《Studia Geophysica et Geodaetica》2018,62(1):80-101

With a high-resolution seismic survey, we targeted the shallow structural features of the Cheb Basin, Northwest Bohemia. The aim of this study was to evaluate these features’ relation to seismic activity below the Cheb Basin with the first reflection seismic image of parts of the basin. We recorded a densely sampled, 3200 m long seismic survey stretching from Kopanina towards SE, into the basin. From the recordings of 170 shots at 192 geophones with 384-m total spread, we obtained a reflection seismic image down to the basement at 300-m depth, supplemented by a shallow tomographic velocity model for the uppermost 40 m. Strong lateral velocity contrasts indicate Quaternary river terraces, into which the Plesná river incises. We observe reverse faults in the lower basin sediments, which we interpret as signs of a push-up structure related to the N-S oriented Po?átky-Plesná Zone (PPZ). However, we do not observe any vertical fault offsets in the younger sedimentary layers, which suggests that any normal or reverse faulting must be older than 20 Ma. The image agrees well with previous lithostratigraphic borehole data and previous sedimentological and tectonic models. Our explanation for the formation of the escarpment at the eastern bank of the Plesná valley, previously interpreted as outcrop of the PPZ, relies solely on incision of the Plesná river into weak sediments.  相似文献