Characterization of ultrafine aerosol particles in Mt. Etna emissions

Particulate emissions from Mt. Etna in the fine-size range below 100 nm were studied in June and September 1989. The aerosol particles were characterized by size, concentration and photoelectric activity. These quantities are sensitive to the physical and chemical properties of the magma. Concentrations varied from 10⁴ to 10⁷ cm^-3. The size distributions peak below 20 nm (radius) and are very narrow. The particles are generated mainly by nucleation and condensation of magmatic volatiles in a strong temperature gradient. The photoelectric activity of these particles can indicate high magma levels and increased exsolution of volatiles. It is therefore related to the observed activity of the respective crater and may be helpful as a prediction tool when used in conjunction with other volcano-monitoring techniques.     

Das Relief des Mars' Versuch einer zusammenfassenden Übersicht

The analysis of the martian relief leads to the conclusion that some of the most important relief elements are either concentrically or radially arranged with respect to a central structure and hence form aureoles. In this paper four different types of aureoles are identified and described:

1. impact aureoles (as result of extradynamics),
2. volcanic aureoeles (as result of lava flow through vents),
3. tectonic aureoles (as result of isostatic adjustment and/or settlement),
4. permafrost-related aureoles and mega-aureoles (as result of migration above thawing permafrost in areas with high relief).

The spatial distribution of these different types of aureoles indicates the predominant type of relief-forming dynamics in the area of their distribution (impact-related aureoles occur predominantly in the area of the Southern Uplands; volcanic, tectonic and permafrost-related aureoles in the area of large-scale updomings-TaNoVa, Elysiumand their volcanic provinces).     

Interdecadal modulation of the relationship between ENSO,IPO and precipitation: insights from tree rings in Australia

Australian climate-proxy reconstructions based on tree rings from tropical and subtropical forests have not been achieved so far due to the rarity of species producing anatomically distinct annual growth rings. Our study identifies the Australian Red Cedar (Toona ciliata) as one of the most promising tree species for tree-ring research in Australasia because this species exhibits distinct annual tree rings, a prerequisite for high quality tropical dendroclimatology. Based on these preliminary studies, we were able, for the first time in subtropical and tropical Australia, to develop a statistically robust, precisely dated and annually resolved chronology back to AD1854. We show that the variability in ring widths of T. ciliata is mainly dependent on annual precipitation. The developed proxy data series contains both high- and low-frequency climate signals which can be associated with the El Niño Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO). A comparison of different data sets (Brisbane precipitation, tree rings, coral luminescence record from the Great Barrier Reef, ENSO and IPO) revealed non-stationary correlation patterns throughout the twentieth century but little instability between the new tree-ring chronology and Brisbane precipitation.     

The O'Neill experiment of 1953

The official report on this first comprehensive field experiment in boundary-layer meteorology was published 1957 in two volumes, edited by Lettau and Davidson (hereafter L&D). The official report is supplemented in this paper by relevant pre-history developments and a discussion of some selected post-history interpretations and follow-up experiments.     

Glaciological research relevant to the construction of ice-going ships

The transportation of rich mineral resources from the Arctic by means of large ice-going bulk and oil carrier, is expected to be a suitable and economical technique. The construction of such large vessels requires the knowledge of various glaciological parameters of the sea ice and their dependence on Arctic environmental conditions. Of particular interest on the small scale are the strength, elasticity, and metal to ice friction characteristics, on a larger geophysical scale relevant parameters are the ice stress, pressure, and movement rates and the relation of these parameters to the temperature and salinity of the ice and to the wind field and the ocean current. Furthermore electrical and electromagnetical properties of the ice are relevant to the navigation in ice covered waters by the aid of remote sensing techniques.The German shipyard A.G. Weser in Bremen initiated in 1972 an expedition to the Canadian Arctic to study all relevant physical properties at one location and at the same time to comprehend the whole glaciological regime. The expedition was a cooperative effort between Brook University, St. Catherines (Canada) and the University of Münster (W. Germany). The field measurements were carried out in May and June 1972 on the sea ice between Pond Inlet (Northern Baffin Island) and Bylot Island, N.W.T. This article sumarizes the essential results and presents a synthesis of all the results.     

A data model for moving regions of fixed shape in databases

Moving object databases are designed to store and process spatial and temporal object data. An especially useful moving object type is a moving region, which consists of one or more moving polygons suitable for modeling the spread of forest fires, the movement of clouds, spread of diseases and many other real-world phenomena. Previous implementations usually allow a changing shape of the region during the movement; however, the necessary restrictions on this model result in an inaccurate interpolation of rotating objects. In this paper, we present an alternative approach for moving and rotating regions of fixed shape, called Fixed Moving Regions, which provide a significantly better model for a wide range of applications like modeling the movement of oil tankers, icebergs and other rigid structures. Furthermore, we describe and implement several useful operations on this new object type to enable a database system to solve many real-world problems, as for example collision tests, projections and intersections, much more accurate than with other models. Based on this research, we also implemented a library for easy integration into moving objects database systems, as for example the DBMS Secondo (1) (2) developed at the FernUniversität in Hagen.     

Immobilization of Ni by Al-modified montmorillonite: A novel uptake mechanism

The sorption capacity of montmorillonite clay minerals for small cations, such as Ni²⁺, can be greatly enhanced by modifying the clay mineral with Al(III). In this study, the mechanisms of Ni uptake by Al-modified montmorillonite were studied using extended x-ray absorption fine structure (EXAFS) spectroscopy of powders and polarized EXAFS spectroscopy of self-supporting clay films to delineate the binding structure of Ni formed as a function of the reaction conditions. Analysis of powder EXAFS spectra of wet pastes, collected from Ni-treated Al-modified montmorillonites reacted at pH 5-8, 25°C or 80°C (to accelerate the reaction process), and reaction times ranging from 1 month to 9 yrs, showed that Ni was surrounded on average by 6 O atoms at a distance of 2.05 Å and 6 Al atoms at 3.01 Å, suggesting the incorporation of Ni into a gibbsite-like structure. Only at pH 8, Ni-containing precipitates were congruently formed. Polarized EXAFS spectroscopy of self-supporting Ni-reacted Al-modified montmorillonite clay films showed a pronounced angular dependency of the spectra of the Ni-doped gibbsite, indicating that the orientation of this Ni-doped gibbsite coincided with the layering of the montmorillonite. Data analysis suggested that Ni is included slightly above and below the vacant octahedral sites of the postulated interstitial gibbsite monolayer. This newly identified mechanism of metal uptake by Al-modified montmorillonite provides a large metal sorption capacity and, because the metal is included in a monolayer gibbsite or gibbsite “islands” formed in the interstitial space of the clay mineral, it potentially leads to a permanent sequestration of the metal from the environment.     

Surface water/groundwater interaction in the Piora Aquifer,Switzerland: evidence from dye tracing tests

Results of seven dye tracing tests done from 1993–1997 to investigate the extent to which lakes and surface water interact with the underlying Triassic Piora Aquifer, Switzerland, are reported here. Two of the dye tracing tests showed that groundwater flows in the Piora Aquifer from the Piora Valley to springs in the adjacent Santa Maria Valley, and even further east to the di Campo Valley considerably outside of the Piora Valley surface water divide. Lake Ritom located in the Piora Valley loses water only to the Canaria Valley outside of the lake's surface-water watershed at the lake's western margin when lake levels are above 1,835 m above sea level. Dye tracing tests show that a major sinkhole in the Piora Valley, Calderoni Sinkhole, is located precisely on the water divide where subsurface flow in the Piora Valley and surface water diverge and move in opposite directions. The dye tracing results also showed no hydraulic connection between surface water in the Piora Valley and the famous Pertusio Spring, located in the upper Santa Maria Valley. Only a small amount of dye from the two dye tracing tests done in 1993 and 1997 entered an exploratory gallery built to test the viability of the AlpTransit tunnel, being built in competent rock under the Triassic Piora Aquifer, effectively perched above. Electronic Publication