Relaxed Eddy Accumulation Simulations of Aerosol Number Fluxes and Potential Proxy Scalars   总被引：1，自引：1，他引：0  

Andreas Held  Edward Patton  Luciana Rizzo  Jim Smith  Andrew Turnipseed  Alex Guenther 《Boundary-Layer Meteorology》2008,129(3):451-468

Direct eddy-covariance measurements of aerosol number fluxes obtained during the 2007 CHATS field experiment in Dixon, California, USA are compared with relaxed eddy accumulation simulations using temperature and water vapour concentration as proxy scalars. After a brief discussion of the limited time response of the aerosol measurement, the applicability of temperature and water vapour concentration as proxy scalars for aerosol number concentration is investigated by evaluating scalar and spectral correlation coefficients as simple measures of scalar similarity. In addition, the proportionality factor b, which compensates for the use of a constant sampling flow in relaxed eddy accumulation, is derived from the time series of aerosol number, temperature and water vapour, and its variability is analyzed. The reduction of the b factor due to application of a deadband, i.e. the rejection of data when the vertical wind speed is close to zero, is evaluated for all three studied scalars, and compared with published functional relationships. In this study, using temperature or water vapour as proxy scalars for aerosol number shows no advantage over the use of a constant b factor. Thus, it is suggested to apply a deadband H _REA  = w′/σ _w  = 0.6 to 0.8 (where w′ is the vertical velocity fluctuation and σ _w is its standard deviation), to use a theoretical b factor based on a parameterization that includes a stability dependence, and to calculate the deadband effect according to a derived relation for aerosol relaxed eddy accumulation.  相似文献   

Geochemical investigations of slags from the historical smelting in Freiberg, Erzgebirge (Germany)   总被引：1，自引：0，他引：1  

Madlen Scheinert  Hermann Kupsch 《Chemie der Erde / Geochemistry》2009,69(1):81-699

The Freiberg area in the Saxon Erzgebirge (Ore Mountains) represents one of the oldest mining districts in Germany. Argentiferous ore mineralizations with lead, zinc and copper are dominating in this region. Various waste products of mining can be found around Freiberg. In particular, the slags from ore smelting were and are regarded as unusable waste products. However, they preserve information on the smelting and weathering behaviour of slag, which makes them very useful sources of information for our purposes. To reconstruct the chemical processes during ore smelting, historical slag represents a most valuable archive. Therefore, the historical slag dump in Halsbach (Germany) was examined exemplarily for the Freiberg deposit. The slag was dumped approx. 400 years ago and is rich in lead. An interrelation between the slag and the metallurgical process applied can be made on the basis of chemical composition, appearance and microscopic results. The slags of the heap in Halsbach contain high concentrations of heavy metals (average contents in mg kg⁻¹: Zn 40,000; Pb 10,000; Cu 1500; U 1000). Enrichments of heavy metals in the organic-rich soil horizons within the range of the dump foot (maximum contents in the A-horizon in mg kg⁻¹: Zn 3719; Pb 9198; As 3017; Cu 963) imply a faint discharge of metals from the dump.  相似文献   

Protracted fluid-induced melting during Barrovian metamorphism in the Central Alps   总被引：3，自引：0，他引：3  

Daniela Rubatto  Jörg Hermann  Alfons Berger  Martin Engi 《Contributions to Mineralogy and Petrology》2009,158(6):703-722

The timing and dynamics of fluid-induced melting in the typical Barrovian sequence of the Central Alps has been investigated using zircon chronology and trace element composition. Multiple zircon domains in leucosomes and country rocks yield U–Pb ages spanning from ~32 to 22 Ma. The zircon formed during Alpine melting can be distinguished from the inherited and detrital cores on the basis of their age, Th/U (<0.1) and trace element composition. Ti-in-zircon thermometry indicates crystallization temperatures around 620–700°C. Their composition allows discriminating between (1) zircon formation in the presence of early garnet, (2) zircon in equilibrium with abundant L-MREE-rich accessory phases (allanite, titanite and apatite) typical of metatonalites, and (3) zircon formed during melting of metasediments in feldspar-dominated assemblages. The distribution of zircon overgrowths and ages indicate that repeated melting events occurred within a single Barrovian metamorphic cycle at roughly constant temperature; that in the country rocks zircon formation was limited to the initial stages of melting, whereas further melting concentrated in the segregated leucosomes; that melting occurred at different times in samples a few meters apart because of the local rock composition and localized influx of the fluids; and that leucosomes were repeatedly melted when fluids became available. The geochronological data force a revision of the temperature–time path of the migmatite belt in the Central Alps. Protracted melting over 10 My followed the fast exhumation of Alpine eclogites contained within the same region and preceded fast cooling in the order of 100°C/Ma to upper crustal levels.  相似文献   

Redistribution of trace elements during prograde metamorphism from lawsonite blueschist to eclogite facies; implications for deep subduction-zone processes   总被引：3，自引：0，他引：3  

Carl?SpandlerEmail author  J?rg?Hermann  Richard?Arculus  John?Mavrogenes 《Contributions to Mineralogy and Petrology》2003,146(2):205-222

The transfer of fluid and elements from subducting crust to the overlying mantle wedge is a fundamental process affecting arc magmatism and the chemical differentiation of the Earth. While the production of fluid by breakdown of hydrous minerals is well understood, the liberation of trace elements remains generally unconstrained. In this paper, we evaluate the behaviour of trace elements during prograde metamorphism and dehydration using samples of high-pressure, low-temperature metamorphic rocks from New Caledonia. Samples examined include mafic and pelitic rock-types that range in grade from lawsonite blueschist to eclogite facies, and represent typical lithologies of subducting crust. Under lawsonite blueschist facies conditions, the low temperatures of metamorphism inhibit equilibrium partitioning between metamorphic minerals and allow for the persistence of igneous and detrital minerals. Despite this, the most important hosts for trace-elements include lawsonite, (REE, Pb, Sr), titanite (REE, Nb, Ta), allanite (LREE, U, Th), phengite (LILE) and zircon (Zr, Hf). At epidote blueschist to eclogite facies conditions, trace-element equilibrium may be attained and epidote (REE, Sr, Th, U, Pb), garnet (HREE), rutile (Nb, Ta), phengite (LILE) and zircon (Zr, Hf) are the major trace-element hosts. Chlorite, albite, amphibole and omphacite contain very low concentrations of the investigated trace elements. The comparison of mineral trace-element data and bulk-rock data at different metamorphic grades indicates that trace elements are not liberated in significant quantities by prograde metamorphism up to eclogite facies. Combining our mineral trace-element data with established phase equilibria, we show that the trace elements considered are retained by newly-formed major and accessory minerals during mineral breakdown reactions to depths of up to 150 km. In contrast, significant volumes of fluid are released by dehydration reactions. Therefore, there is a decoupling of fluid release and trace element release in subducting slabs. We suggest that the flux of trace elements from the slab is not simply linked to mineral breakdown, but results from complex fluid-rock interactions and fluid-assisted partial melting in the slab.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00410-003-0495-5.Editorial responsibility: J. Hoefs  相似文献   

Ethnic minorities and marginality in the Pamirian Knot: survival of Wakhi and Kirghiz in a harsh environment and global contexts   总被引：1，自引：0，他引：1  

Hermann Kreutzmann 《The Geographical journal》2003,169(3):215-235

This paper challenges the thesis that mountain areas are regions of refuge. The refuge concept attributes irrelevant exchange and limited communication to isolated mountain habitats which mainly depend on production for home consumption. In contrast, it is shown that exchange relations in all walks of life have been affected not only recently but for nearly two centuries in Central Asia, although the continued importance of subsistence strategies in the agricultural sector can be observed. The Pamirian Knot provides the mountainous interface between South and Central Asia for case studies of two ethnic communities – Wakhi mountain farmers and Kirghiz pastoralists – in order to exemplify socio-political developments in similar mountain environments. Examples are presented from Afghanistan, Tajikistan, Pakistan, and the People's Republic of China. The territories have been separated since the late nineteenth century by international boundaries conceived as the result of the imperial 'Great Game'. Emphasis is placed on developments in the livestock sector and it is shown that adaptation to changing socio-political frameworks has affected the livelihood strategies of nomads and mountain farmers alike.  相似文献   

Rb-Sr systematics on paragneiss series from the Bavarian Moldanubicum,Germany     

Hermann Köhler  Dieter Müller-Sohnius 《Contributions to Mineralogy and Petrology》1980,71(4):387-392

The Nicolaysen-diagram is a means to present mineral or whole rock isochrons. The age values derived from mineral isochrons are normally interpreted as cooling ages, those given by whole rock isochrons as the age of an intrusion or a metamorphic event. Mineral isochrons reflect samples in the order of few mm to cm, whole rock isochrons those of a few decimeter to meter.The investigation presented here deals with samples representing regions of about 100 m to some kilometers in diameter. These regions we are going to name areals.Five areals of the Moldanubicum of Eastern Bavaria (West Germany) consisting of similar paragneisses are yielding mineral ages of about 315 Ma and whole rock ages of about 450 Ma. We calculated mean ⁸⁷Sr/ ⁸⁶Sr- and ⁸⁷Rb/⁸⁶Sr-values of these areals and displayed them in a Nicolaysen-diagram. The areal values define a straight line, yielding an age of 544±29 Ma with a ⁸⁷Sr/⁸⁶Sr-intercept at 0.7048±0.0014.Discussion arises whether or not this line can be interpreted as an isochron. We favour the interpretation of it as an isochron reflecting the possible age of sedimentation or of a metamorphic event which the paragneiss series has undergone. At present it can not be unequivocally decided which of the two possibilities will prove right. The areal isochron, however, appears to indicate a petrogenetic event which is older than the last Sr-isotope equilibration in the whole rocks within an individual areal of this Moldanuvian polymetamorphic region.  相似文献   

Glendonite — Indikatoren des polarmarinen Ablagerungsmilieus     

Dr. Edwin Kemper  Dr. Hans Hermann Schmitz 《International Journal of Earth Sciences》1981,70(2):759-773

Zusammenfassung Glendonite sind Pseudomorphosen von überwiegend Calcit (in mehreren Generationen) nach Thenardit (Na₂SO₄). Die meistens sternförmigen Kristallaggregate von Walnuß- bis Faustgröße bildeten sich im unterkühlten Meereswasser (cold salinity currents) in oder auf der oberen Lage des Meeresbodens. Sie sind an marine Tonsteine gebunden und kommen in ihrem Verbreitungsgebiet in großer Zahl vor. Rezente Glendonite treten nur im Arktischen Ozean und seinen Nebenmeeren (Weißes Meer) auf. Fossile gibt es in Perm und Kreide Australiens (permisches Vereisungsgebiet) und in den jeweils hohen Breiten der Nordhalbkugel im Domerium, mittleren Jura, Valangin, Ober-Apt/Unter-Alb, Oligozän/Miozän und Pleistozän/Holozän. Für diese Zeiten ist eine erhebliche Abkühlung zu postulieren.Beim Vergleich mit den entsprechenden Schichtenfolgen Mitteleuropas fällt auf, daß in den Zeiten der Glendonit-Vorkommen der arktischen Gebiete im borealen Europa dunkle Tonsteine abgelagert wurden. In Zeiten starker Kalksedimentation (Ober-Oxford, Kimmeridge, Ober-Kreide) und arider oder subtropischer Klimate in Mitteleuropa (Tithon: Münder Mergel-Fazies und Berrias: Wealden-Fazies) fehlen Glendonite auch im hohen Norden.Alle diese Befunde verweisen auf ausgeprägte, langfristige Klimaschwankungen vom Lias ab. Zur Zeit der kälteren Phasen müssen in den hohen Breiten mit den heutigen Verhältnissen vergleichbare polare Klimate geherrscht haben.

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Glendonites are pseudomorphs of mainly calcite (in several generations) after Thenardit (Na₂SO₄). The crystal aggregates are preponderantly star shaped and range in size between walnut and fist dimensions. They were formed by cold salinity currents in the uppermost layer of the ocean floor. They are restricted to marine shales and mudstones and occur in great quantities in their area of distribution. Recent glendonites are known only from the Arctic Ocean and adjacent seas (e. g. the White Sea). Fossil glendonites occur in the Permian and Cretaceous of Australia (Permian area of glaciation) and in high latitudes of the Northern hemisphere in the Domerian, middle Jurassic, Valanginian, late Aptian — early Albian, Oligocene — Miocene, and Pleistocene — Holocene. For these periods a considerable cooling has to be postulated.If the sediments of these periods are compared with the corresponding ones of central Europe it is obvious that in those periods during which glendonites were formed in high latitudes dark shales were deposited in the boreal part of Europe. In periods of high lime accumulation (Upper Oxfordian, Kimmeridgian, Upper Cretaceous) and arid or subtropical climates in central Europe (e. g. the Münder Mergel facies of the Tithonian and the Purbeck and Wealden facies of the Berriasian) glendonites are absent from the high latitudes.All these observations point to intensive and long term variations of climate from the early Jurassic on. During the cold phases, comparable polar climates must have predominated in the high latitudes as exist today.

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Résumé Les glendonites sont des pseudomorphoses, principalement de calcite (en plusieurs générations), de thénardite (Na₂SO₄). Les agrégats, le plus souvent de forme radiée, de la taille d'une noix à celle du poing, se sont formés dans de l'eau marine surrefroidie (»courants de salinité froide«) dans la couches supérieure des fonds marins ou à sa surface. Ils sont liés à des argiles marines et se présentent en grande quantité dans leur aire d'extension. Les glendonites récentes se rencontrent seulement dans l'Océan arctique et dans les mers annexes (Mer blanche). Elles existent à l'état fossile dans le Permien et le Crétacique de l'Australie (région de la glaciation permienne) et dans les hautes latitudes de l'époque de l'hémisphère nord dans le Domérien, le Jurassique moyen, le Valanginien, l'Aptien supérieur/inférieur, l'Oligocène/Miocène, et le Pleistocène/Holocène. Pour ces périodes il y a lieu de postuler un net refroidissement.Par comparaison avec les séries correspondantes de l'Europe centrale, il apparaît que des argiles foncées ont été déposées, lors des occurrences de Glendonites des régions arctique, dans l'Europe boréale. Lors de sédimentations calcaires intenses (Oxfordien supérieur, Kimméridgien, Crétacique supérieur) et dans les climats arides ou subtropicaux dans l'Europe centrale (Tithonique: facies marneux de Münder, et Berriasien: facies wealdien) les glendonites sont absentes également dans les hautes latitudes septentrionales.Toutes ces occurrences indiquent des modifications climatiques bien marquées, de longue durée à partir du Lias. Au moment des phases plus froides, il a dû régner dans les hautes latitudes un climat polaire comparable à celui de nos jours.

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( ) . — cold salinity currents, . . — . — — , , , / , / / . . , . ( , , ) , (; : ) . . , .

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Elektronenstrahlmikroanalyse der graphit-troilitphase des cañon diablo-eisenmeteorits     

H. H. Weinke  Dr. W. Kiesl  F. Kluger  Dr. F. Hermann 《Mineralogy and Petrology》1971,16(4):215-226

Zusammenfassung Der vom American Meteorite Laboratory, Denver (Colorado), erworbene Eisenmeteorit Cañon Diablo mit drei sphärischen Graphit-Troiliteinschlüssen wurde von uns mit einer Elektronenstrahlmikrosonde JEOL JXA-3 A untersucht. Dabei wurde in den Graphit-Troiliteinschlüssen eine bisher noch nicht festgestellte Phase der Zusammensetzung (C_0,250,Ni_0,321,Fe_0,429)S_1,013 und (Co_0,144,Ni_0,391,Fe_0,465)S_1,016 aufgefunden. Diese Phase ist in ihrer Zusammensetzung von den bereits bekannten Mineralen Pentlandit (Fe,Ni)₉S₈ und Kobaltpentlandit (Co,Fe,Ni)₉S₈ deutlich verschieden. Sie bildet in der Troilit-Graphitmatrix Einsprenglinge von 3–6 m Durchmesser. Aus diesem Grunde war es bisher nicht möglich, ihre Kristallstruktur zu ermitteln.

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Electron-probe analysis of the graphite-troilite phase in the cañon diablo iron-meteorite

Summary The Cañon Diablo iron-meteorite, containing three spherical graphitetroilite inclusions has been investigated by means of an electronmicroprobe JEOL JXA-3 A. Within these graphite-troilite inclusions a phase, not known so far, has been noted, whose composition ranges from (Co_0.250,Ni_0.321,Fe_0.429)S_1.013 to (Co_0.144,Ni_0.391,Fe_0.465)S_1.016. This phase is decisively different from pentlandite (Fe,Ni)₉S₈ and Co-pentlandite (Co,Fe,Ni)₉S₈. It forms phenocrysts of 3–6 m in diameter. For this reason it was not possible so far to determine its crystal-structure.

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Mit 5 Abbildungen

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Herrn Prof. DDr.H. Wieseneder zum 65. Geburtstag gewidmet.  相似文献   

Different Behavior of Iron(III) and Aluminum(III) Salts To Coagulate Silica Particle Suspension     

Panyue Zhang  Hermann H. Hahn  Erhard Hoffmann 《洁净——土壤、空气、水》2003,31(2):145-151

The different coagulation‐flocculation behavior of iron(III) and aluminum(III) to coagulate silica particle suspension with four coagulants — FeCl₃, Fe₂(SO₄)₃, AlCl₃, and in our laboratory produced polyaluminum chloride PACl‐2.0 — was investigated through studying particle property changes and coagulation efficiency, for example, variations in zeta potential of particles, particle number, average particle diameter, particle size distribution, and residual turbidity of the supernatant water. Influences of flocculation intensity and pH value on the coagulation‐flocculation process were also studied. The results suggest that, under the test conditions, among these four coagulants FeCl₃ possesses an obviously stronger ability to form larger flocs and to remove turbidity, on the other hand, PACl‐2.0 obviously showed a better charge neutralization ability.  相似文献   

Precipitation Chemistry in Semi-Arid Areas of Southern Africa: A Case Study of a Rural and an Industrial Site   总被引：3，自引：0，他引：3  

J. N. Mphepya  J. J. Pienaar  C. Galy-Lacaux  G. Held  C. R. Turner 《Journal of Atmospheric Chemistry》2004,47(1):1-24

Experimental data on the precipitation chemistry in the semi-arid savanna of South Africa is presented in this paper. A total of 901 rainwater samples were collected with automatic wet-only samplers at a rural site, Louis Trichardt, and at an industrial site, Amersfoort, from July 1986 to June 1999. The chemical composition of precipitation was analysed for seven inorganic and two organic ions, using ion chromatography. The most abundant ion was SO₄ ^{2 –} and a large proportion of theprecipitation is acidic, with 98% of samples at Amersfoort and 94% at LouisTrichardt having a pH below 5.6 (average pH of 4.4 and 4.9, respectively). This acidity results from a mixture of mineral and organic acids, with mineral acids being the primary contributors to the precipitation acidity in Amersfoort, while at Louis Trichardt, organic and mineral acids contribute equal amounts of acidity. It was found that the composition of rainwater is controlled by five sources: marine, terrigenous, nitrogenous, biomass burning and anthropogenic sources. The relative contributions of these sources at the two sites were calculated. Anthropogenic sources dominate at Amersfoort and biomass burning at Louis Trichardt. Most ions exhibit a seasonal pattern at Louis Trichardt, with the highest concentrations occurring during the austral spring as a result of agricultural activities and biomass combustion, while at Amersfoort it is less pronounced due to the dominance of relatively constant industrial emissions. The results are compared to observations from other African regions.  相似文献