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1.
We measured the spatial variation of aluminium concentrations and computed its species distribution before and during mixing of acid mine drainage containing waters with near neutral receiving waters. Acid mine drainage was collected from the Loquitz Creek, Thuringia, Germany, and Garvey Creek, Westland, New Zealand, which drain slate mine workings and coal mine workings, resp. The acidneutralizing capacity (ANC) of the receiving streams and the mixing with waters having low Al-concentrations cause a decrease of aluminium concentrations below the confluence. Depending on volumes and ANCs involved, the content of free Al and sulphate bound Al decreases after mixing in favour of organic and hydroxide bound Al. In addition, below the junction of the Loquitz Creek and the Aue Creek with its high ANC, we observe the precipitation of aluminium hydroxides and Al hydroxysulphates.
Zusammenfassung Wir haben die räumliche Änderung der Aluminiumkonzentrationen vor und nach der Mischung von Flußwasser, versauert durch Bergwerksabwässer, mit nahezu neutralem Wasser der Vorfluter gemessen und haben dazu die Speziesverteilung berechnet. Saure Bergwerksabwässer sickern aus Halden eines Schiefertagebaus in Thüringen in die Loquitz ebenso wie aus Halden eines Kohletagebaus in den Garvey Creek, Westland, Neuseeland. Die Säuren-Neutralisierungskapazität der Vorfluter und die Mischung mit Al-armem Wasser bewirken eine Abnahme der Aluminiumkonzentrationen nach dem Zusammenfluß. In Abhängigkeit von beteiligten Abflüssen und Säuren-Neutralisierungskapazitäten nimmt der Gehalt an freiem Aluminium und sulfatgebundenem Aluminium nach der Mischung zugunsten von organisch- und hydroxy-gebundenem Aluminium ab. Ferner beobachten wir unterhalb des Zusammenflusses von Loquitz und Aue, der eine hohe Säuren-Neutralisierungskapazität eigen ist, eine Ausfällung von Aluminiumhydroxyden und Aluminiumhydroxysulfaten.

Résumé Nous avons mesuré la variation spatiale de la teneur en Al et calculé la distribution de ses différentes formes dans deux cours d'eau différents, qui reçoivent des eaux acides venant de mines situées sur leur cours. Ces mesures ont été faites d'une part sur le cours du Loquitz (Thuringe-Allemagne) qui reçoit des aux acides venant d'une mine d'ardoise et d'autre part sur le cours du Garvey (Westland - Nouvelle Zélande) qui reçoit les eaux d'une mine de charbon. Pour chaque cours d'eau, les mesures ont été faites en amont de la source d'apport, puis en aval, c'est-à-dire après le mélange avec les eaux acides. La capacité de neutralisation des acides (ANC) des eaux des cours d'eau récepteurs et la basse teneur en Al des eaux d'apport provoquent une diminution de la teneur en Al après le mélange. Dans une mesure liée aux volumes en jeu et à l'ANC, la teneur en Al libre et en Al lié au sulfate diminue près le mélange au profit de l'Al lié soit à des substances organiques, soit à des hydroxydes. De plus, en aval du confluent du Loquitz et de l'Aue, rivière à ANC élevé, nous observons la précipitation d'hydroxydes d'Al et d'hydroxisulfates d'Al.

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Beds of sedimentary barytes are found in late Paleozoic sediments in the northeasternmost part of South Africa and adjoining parts of Rhodesia. The baryte horizon consists of 2 beds of composite thickness of up to 50 cm within a sequence of partly porcellaneous shales. It is dark gray to redbrown in colour, in places also black, and then contains traces of H2S. It usually consists of fine-grained subrounded tabular grains of detrital origin. This horizon frequently contains aggregates of upward diverging acicular baryte which formed diagenetically within the detrital baryte. The deposit was formed through reworking of semiconsolidated clays containing baryte concretions. Such shales are known to occur to the west of the baryte deposit in contemporaneous sediments.
Zusammenfassung In spätpaläozoischen Sedimenten im Nordosten Südafrikas und dem angrenzenden Bereich Rhodesiens treten sedimentäre Barytlagen auf. Die Barytzone besteht aus zwei Lagen mit einer gemeinsamen größten Mächtigkeit von 50 cm, innerhalb einer Abfolge teilweise verkieselter Tonschiefer. Der Baryt ist dunkelgrau bis rotbraun, stellenweise auch schwarz, und enthält dann Spuren von H2S. Er besteht meist aus feinkörnigen kantengerundeten schwach plattigen Kristallen detritischer Herkunft. Die Zone enthält häufig Aggregate aus nach oben divergierenden nadeligen Barytkristallen, die sich frühdiagenetisch im detritischen Baryt bildeten. Das Vorkommen entstand durch Aufarbeitung von Barytkonkretionen in schwach verfestigten Tonen. Entsprechende Tonschiefer treten in gleichaltrigen Sedimenten westlich des Barytvorkommens auf.
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In this paper, we show that the rate of ozone loss in both polar and mid-latitudes, derived from ozonesonde and satellite data, has almost the same vertical distribution (although opposite sense) to that of ozone laminae abundance. Ozone laminae appear in the lower stratosphere soon after the polar vortex is established in autumn, increase in number throughout the winter and reach a maximum abundance in late winter or spring. We indicate a possible coupling between mid-winter, sudden stratospheric warmings (when the vortex is weakened or disrupted) and the abundance of ozone laminae using a 23-year record of ozonesonde data from the World Ozone Data Center in Canada combined with monthly-mean January polar temperatures at 30 hPa.Results are presented from an experiment conducted during the winter of 1994/95, in phase II of the Second European Stratospheric And Mid-latitude Experiment (SESAME), in which 93 ozone-enhanced laminae of polar origin observed by ozonesondes at different time and locations are linked by diabatic trajectories, enabling them to be probed twice or more. It is shown that, in general, ozone concentrations inside laminae fall progressively with time, mixing irreversibly with mid-latitude air on time-scales of a few weeks. A particular set of laminae which advected across Europe during mid February 1995 are examined in detail. These laminae were observed almost simultaneously at seven ozonesonde stations, providing information on their spatial scales. The development of these laminae has been modelled using the Contour Advection algorithm of Norton (1994), adding support to the concept that many laminae are extrusions of vortex air. Finally, a photochemical trajectory model is used to show that, if the air in the laminae is chemically activated, it will impact on mid-latitude ozone concentrations. An estimate is made of the potential number of ozone molecules lost each winter via this mechanism.  相似文献   
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Gamma-ray astrophysics depends in many ways on multiwavelength studies. The Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority multiwavelength needs include: (1) availability of contemporaneous radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements; (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-band blazar monitoring; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for reliable and effective sources identification and characterization. Several of these activities are needed to be in place before launch.   相似文献   
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A large fraction of the anticipated source detections by the Gamma-ray Large Area Space Telescope (GLAST-LAT) will initially be unidentified. We argue that traditional approaches to identify individuals and/or populations of gamma ray sources will encounter procedural limitations. Those limitations are discussed on the background of source identifications from EGRET observations. Generally, our ability to classify (faint) source populations in the anticipated GLAST dataset with the required degree of statistical confidence will be hampered by sheer source wealth. A new paradigm for achieving the classification of gamma ray source populations is discussed.  相似文献   
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The COMPTEL unidentified source GRO J 1411-64 was observed by INTEGRAL and XMM-Newton in 2005. The Circinus Galaxy is the only source detected within the 4σ location error of GRO J1411-64, but in here excluded as the possible counterpart. At soft X-rays, 22 reliable and statistically significant sources (likelihood >10) were extracted and analyzed from XMM-Newton data. Only one of these sources, XMMU J141255.6-635932, is spectrally compatible with GRO J1411-64 although the fact the soft X-ray observations do not cover the full extent of the COMPTEL source position uncertainty make an association hard to quantify and thus risky. At the best location of the source, detections at hard X-rays show only upper limits, which, together with MeV results obtained by COMPTEL suggest the existence of a peak in power output located somewhere between 300–700 keV for the so-called low state. Such a spectrum resembles those in blazars or microquasars, and might suggest at work by the models accordingly. However, an analysis using a microquasar model consisting on a magnetized conical jet filled with relativistic electrons, shows that it is hard to comply with all observational constrains. This fact and the non-detection at hard X-rays introduce an a-posteriori question mark upon the physical reality of this source, what is discussed here.  相似文献   
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