Long-term behaviour and mineralogical reactions in hazardous waste landfills: a comparison of observation and geochemical modelling

 Drill cores from a Bavarian hazardous waste landfill were investigated for their mineralogical composition. Because of the formation of many new minerals, geochemical equilibrium calculations were performed to find the most stable state of the waste body. A comparison of mineralogical observations and geochemical modelling was undertaken. The remaining solubilities of the newly formed secondary mineral assemblages were calculated. Newly formed minerals were shown using electron microscopy. Received: 26 November 1999 · Accepted: 15 May 2000     

Synchysite-(Y)–synchysite-(Ce) solid solutions from Markersbach, Erzgebirge, Germany: REE and Th mobility during high-T alteration of highly fractionated aluminous A-type granites

Summary The Ca,REE-fluorocarbonate synchysite, which forms anhedral grains hosted in albite, was identified in the Markersbach pluton (Erzgebirge, Germany) composed of F-rich, highly fractionated and autometasomatically altered granites. These granites were emplaced in a post-collisional setting and are of aluminous A-type affinity. The grains were identified by electron microprobe analysis as intermediate members of the probably complete solid-solution series between synchysite-(Y) and synchysite-(Ce). The rareearth elements likely were liberated upon complete destruction of magmatic monazite and xenotime during interaction with a F-CO₂-Ca-bearing, late-magmatic fluid at relatively high temperatures. The geochemical patterns of different granite samples from Markersbach indicate that the REE and Th were not trapped immediately at the site of their release but mobilized over distances of at least decimeters. During transport of the elements in the fluid, presumably as fluoride (HREE) and chloride (LREE) complexes, no significant fractionation took place among the REE. Received May 8, 2000; revised version accepted November 21, 2000     

Retrieval of land surface temperature and emissivity from satellite data: Physics, theoretical limitations and current methods

Remote sensing from satellites is the only means to obtain land surface temperature (LST) and emissivity on a larger scale. LST has many applications, e.g., in radiation budget experiments and global warming, and desertification studies. Over the last decades, substantial amount of research was dedicated towards extracting LST and emissivity from surface-leaving radiance and de-coupling the two from each other. This paper provides the physical basis, discusses theoretical limitations, and gives an overview of the current methods for space-borne passive sensors operating in the infrared range, e.g., NOAA-AVHRR, Meteosat, ERS-ATSR, TERRA-MODIS, and TERRA-ASTER. Atmospheric effects on estimated LST are described and atmospheric-correction using a radiative transfer model (RTM) is explained. The methods discussed are the single channel method, the split window techniques (SWTs), and the multi-angle method.     

Momentum transfer at the ocean–atmosphere interface: the wave basis for the inertial coupling approach

 The inertial coupling approach for the momentum transfer at the ocean–atmosphere interface, which is based on the assumption of a similarity hypothesis in which the ratio between the water and air reference velocities is equal to the square root of the ratio between the air and water densities, is reviewed using a wave model. In this model, the air and water reference velocities are identified, respectively, with the spectrally weighted phase velocity of the gravity waves and the Stokes velocity at the water roughness length, which are evaluated in terms of the dimensionless frequency limits in Toba's equilibrium spectrum. It is shown that the similarity hypothesis is approximately satisfied by the wave model over the range of wave ages encountered in typical sea states, and that the predicted values of the dimensionless surface drift velocity, the dimensionless water reference velocity, and the Charnock constant are in reasonable agreement with observational evidence. The application of the bulk relationship for the surface shear stress, derived from the inertial coupling hypothesis in general circulation modeling, is also discussed. Received: 6 January 2001 / Accepted: 28 June 2001     

A theoretical interpretation of ion composition measured on board the ‘Active’ satellite in the European sector during April 10-12, 1990 geomagnetic storm

Ion composition measurements on board the ACTIVE satellite during the recovery phase of a strong geomagnetic storm of 10–12 April 1990 revealed extremely high concentrations (up to 10³ cm⁻³) of the NO⁺, O⁺₂, N⁺₂ molecular ions in the topside F2-region of the European high-latitude zone. Concentrations of O⁺, N⁺, He⁺, H⁺ light ions were slightly decreased relative to prestorm quite conditions. Theoretical calculations were used to analyze the observed variations in ion concentration. Increased neutral temperature and [O₂], [N₂] are shown to be the main reasons for the observed ion concentration variations.     

Snow mechanics and avalanche formation: field experiments on the dynamic response of the snow cover

Knowledge about snow mechanics and snow avalanche formation forms the basis of any hazard mitigation measures. The crucial point is the snow stability. The most relevant mechanical properties - the compressive, tensile and shear strength of the individual snow layers within the snow cover - vary substantially in space and time. Among other things the strength of the snow layers depends strongly on the state of stress and the strain rate. The evaluation of the stability of the snow cover is hence a difficult task involving many extrapolations.To gain insight in the release mechanism of slab avalanches triggered by skiers, the skier's impact is measured with a load cell at different depths within the snow cover and for different snow conditions. The study focused on the effects of the dynamic loading and of the damping by snow compaction. In accordance with earlier finite-element (FE) calculations the results show the importance of the depth of the weak layer or interface and the snow conditions, especially the sublayering.In order to directly measure the impact force and to study the snow properties in more detail, a new instrument, called rammrutsch was developed. It combines the properties of the rutschblock with the defined impact properties of the rammsonde. The mechanical properties are determined using (i) the impact energy of the rammrutsch and (ii) the deformations of the snow cover measured with accelerometers and digital image processing of video sequences. The new method is well suited to detect and to measure the mechanical processes and properties of the fracturing layers. The duration of one test is around 10 minutes and the method seems appropriate for determining the spatial variability of the snow cover. A series of experiments in a forest opening showed a clear difference in the snow stability between sites below trees and ones in the free field of the opening.     

Badgastein spa—Austrian central Alps

The Badgastein spa shows almost all the special geological and hydrological features existing in the northeastern central Alps. Situated within the Tauern window, the open joint system enables the infiltration of surface water to great depths. There it becomes heated and loaded with radon and trace elements such as fluor. The water discharges as thermal water springs at the steep right flank of the cascade of the Gastein-Ache. This hydraulic process occurs during a span of 3600–3800 years. The springs are captured in galleries, and the largest discharge is in gallery IX (2518 m³/d^–1). The spa became known worldwide in the 19th century by visiting aristocrats from Central and Eastern Europe. The most important event in the 20th century was the discovery of the heat joint in the Böckstein gallery. In 1940 an effort to reactivate gold mining in the Radhausberg near Böckstein south of Badgastein failed. However, the miners had the unexpected experience of being cured of rheumatism. A connection between the great depth and high temperature in the gallery was made by the discovery of the joint set with heat and radon emanation. In the medical stations of the Böckstein gallery treatment of polyarthritis has become especially successful.     

Zur Albedomessung auf Gletschern

Zusammenfassung Auf Grund gleichzeitiger Messungen der Gletscheralbedo mit einem Solarimeter und einem Selen-Photoelement wird versucht, bei verschiedenen Strahlungsbedingungen eine Beziehung zwischen den mit beiden Empfängern gemessenen Albedowerten zu finden. Bei bedecktem Himmel ohne Sonne werden annähernd gleiche Albedowerte gemessen; bei heiterem Himmel weist ihr Verhältnis einen ausgeprägten Tagesgang auf, wobei um Mittag mit dem Photoelement ein um etwa 25% größerer Wert der Albedo festgestellt wird als mit dem Solarimeter. Albedobestimmungen, die nach diesen zwei Methoden ausgeführt wurden, sind daher nicht unter allen Bedingungen miteinander vergleichbar.

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Summary On the basis of simultaneous measurements of glacier albedo with a solarimeter and a selenium photo-element the author is trying to find a relation between the albedo values measured with the two receivers under different radiation conditions. Approximately equal values of albedo are found with overcast sky without sun; their relation shows on the other hand a pronounced daily course with clear sky, whereby the photo-element yields at noon an albedo value higher than that of the solarimeter by about 25%. Determinations of albedo carried out according to these two methods are thus not comparable under every condition.

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Résumé On a mesuré l'albédo d'un glacier simultanément au moyen d'un solarimètre et d'une cellule photoélectrique au sélénium. On essaie alors d'établir la relation existant entre les valeurs de l'albédo résultant des relevés de ces deux instruments et cela dans des conditions diverses de rayonnement. Ces valeurs sont à peu près égales par ciel couvert et sans soleil. Par ciel serein, le rapport présente par contre une évolution diurne marquée. Dans ce cas, les valeurs fournies par la cellule à midi sont de 25% supérieures à celles du solarimètre. Les mesures de l'albédo faites au moyen de ces deux instruments ne sont donc pas comparables entre elles dans toutes les conditions de nébulosité.

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