Bio- and chronostratigraphy of the Middle Triassic Reifling Formation of the westernmost Northern Calcareous Alps

New finds of fossils including bivalves, ammonoids, brachiopods and palynomorphs from the Middle Triassic Reifling Formation significantly improve the age assignment for this unit in Liechtenstein and Vorarlberg. The lower part of the Reifling Formation is tentatively referred to the Late Anisian Paraceratites trinodosus Zone and somewhat older levels, whereas the uppermost part reaches the Ladinian Protrachyceras archelaus Zone (ammonoid zonation). The Middle Triassic successions of the study area are correlated with the coeval South Alpine reference section at Bagolino (Brescian Prealps), which also bears the Ladinian GSSP. The comparison shows that the Reifling Formation in the study area is age-equivalent with the South Alpine Prezzo Limestone and the Buchenstein Formation. A volcanoclastic layer in the upper part of the Reifling Formation at Flexenpass yields a U-Pb zircon age of 239.3 +/- 0.2 Ma. This value is slightly older than previously published minimum ages from equivalent horizons in the Southern Alps; the difference is thought to be mainly due to improved pre-treatment of zircons (annealing/chemical abrasion), which significantly reduces the effects of Pb loss. The new radio-isotope age further constrains the stratigraphical age of the Reifling Formation and supports the proposed biostratigraphy-based correlation of Middle Triassic successions in the Eastern and Southern Alps. Editorial handling: E. Erba & J.-P. Billon-Bruyat     

D/H exchange in pure and Cr-doped enstatite: implications for hydrogen diffusivity

The kinetics of hydrogen diffusion in enstatite was studied by hydrogen–deuterium exchange experiments in the range of 1–5,000 bar and 700–850°C using synthetic single crystals of pure and Cr-doped enstatites. The OH- and OD-content in the samples was quantified after each thermal treatment with Fourier transformed infrared spectroscopy. H–D-exchange rates were measured parallel to the three crystallographic axes. In addition, in order to visualize diffusion profiles, OH and OD were mapped for some samples, utilizing synchrotron IR micro-spectroscopy. Hydrogen self-diffusivities derived from D/H exchange experiments at one atmosphere are very similar to the chemical diffusivity of hydrogen in natural Fe-bearing orthopyroxene, which was reported previously (Stalder and Skogby 2003) to exhibit a small, but significant anisotropy (D[001] > D[100] > D[010]). Activation energies are estimated to be 211 (±31) kJ/mol for diffusion parallel [100] and 185 (±28) kJ/mol for diffusion parallel [010]. Lattice diffusion of hydrogen is decelerated by more than one order of magnitude when Cr is dissolved in enstatite. In comparison to the chemical composition, pressure seems to have only a minor influence on hydrogen diffusion. Compared to other minerals in the Earth’s upper mantle, enstatite exhibits the highest activation energy for hydrogen diffusion, suggesting faster diffusion than in other mafic minerals at mantle temperatures, but slower diffusion at crustal conditions. Thus under upper mantle conditions, physical properties that are expected to be influenced by hydrogen mobility, such as electrical conductivity, may in enstatite be more intensely affected by the presence of hydrogen than in other upper mantle minerals.     

Tropospheric water vapour soundings by lidar at high Arctic latitudes

Ground-based lidars can provide continuous observations of tropospheric humidity profiles using the Raman scattering of light by water vapour and nitrogen molecules. We will present specific humidity profiles obtained at the high Arctic location Ny-Ålesund (Spitsbergen, 79°N). Under nighttime conditions the observations cover a range from about 500 m altitude up to the upper troposphere. Daylight limits the observations to the lower troposphere, depending on atmospheric transmission and the water vapour content. In a case study on 29 January, simultaneous observations of humidity and aerosol extinction show distinct differences in the various altitudes during the advection of aerosol-rich air masses. In the boundary layer, the aerosol is less affected by the humidity. In the free troposphere, the lidar ratio was observed to be up to 60 sr with some evidence for the uptake of water vapour by the aerosol particles. In another case study from 28 February 2002, the influence of the mean wind direction and the orography on the water vapour concentration near the ground and in the free troposphere will be discussed. During wintertime, a humidity inversion up to about 1.5 km altitude with dry air near the ground has frequently been found with wind from the southeast. Such local effects and small-scale structures observed by stationary lidar mostly cannot be resolved by other sounding methods like passive satellite soundings.     

The system Pb-As-S

Silica-tube quenching experiments and gold-tube pressure experiments were used to study phase relations in the PbS-rich portion of the system Pb-As-S. Emphasis was placed on determining the P-T-X stability relations of jordanite, the most Pb-rich of the synthetic Pb-As-S compounds. Jordanite, Pb₉As₄S₁₅, is stable below 549 ± 3° C, at which temperature it melts to galena, liquid, and a sulfur-rich vapor phase. Confining pressures of up to 2 Kb do not measurably change this reaction temperature. Density measurements on synthetic material show that the jordanite cell contains 3 (Pb₉As₄S₁₅); space group P2₁/m requires that the cell content be expressed as either Pb_28–xAs₁₂S_46–x or Pb_26+xAs₁₂S_44+x, with the former much more probable from a structural point of view. In both cases 0.8 < x < 1.4 and the situation is thus quite different from the usual case of defect structures, such as pyrrhotite, Fe_1–xS, which shows considerable range of solid solution. Heating experiments on natural gratonite (Pb₉As₄S₁₅) show that this mineral is most probably a low-temperature dimorph of jordanite, the inversion occurring below 250° C. Experiments have also confirmed the extensive substitution of Sb for As in jordanite, as suspected from chemical analyses of the isostructural mineral geocronite (Pb_28–x(As,Sb)₁₂S_46–x).

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Zusammenfassung Durch Abschreckversuche mit Hilfe von Quarz- und Gold-Druckampullen wurden die Phasenbeziehungen im PbS-reichen Teil des Pb-As-S-Systems studiert. Besonderer Wert wurde auf die Feststellung der P-T-X-Stabilitätsverhältnisse des Jordanits, des Pb-reichsten Phase der synthetischen Pb-As-S-Reihe, gelegt. Jordanit (Pb₉As₄S₁₅) ist unterhalb 549 ± 3° C stabil, wo er sich semikongruent zu PbS, einer Schmelze und einer schwefelreichen Dampfphase zersetzt. Drucke bis zu 2 kb ergaben keine meßbaren Änderungen dieser Reaktionstemperatur. Dichtemessungen am synthetischen Material weisen darauf hin, daß die Jordanitzelle 3 × (Pb₉As₄S₁₅) enthält. Die Raumgruppe P2₁/m fordert entweder die Formel Pb_28–xAs₁₂S_46–x oder Pb_26+xAs₁₂S_44+x, wobei die erstere Form strukturell wahrscheinlicher zu sein scheint. In beiden Fällen ist 0.8 < x < 1.4 und weicht vom gebräuchlichen Begriff der Defektstrukturen, wie z.B. beim Pyrrhotin (Fe_1–xS) ab, wie das bemerkenswerte Mischkristallfeld zeigt. Erhitzen von natürlichem Gratonit (Pb₉As₄S₁₅) zeigt, daß dieses Mineral sehr wahrscheinlich eine dimorphe Tieftemperaturphase des Jordanits ist. Die Umwandlung erfolgt unterhalb 250° C. Außerdem wurde eine umfangreichere Substitution von As durch Sb im Jordanit festgestellt, was nach den chemischen Analysen des isostrukturellen Geochronits Pb_28–x(As,Sb)₁₂S_46–x) zu erwarten war.

     

Deuterium-Isotopengeochemie des Grund- und Oberflächenwassers

Zusammenfassung Die Niederschlag- und Quellwässer einiger Gebiete Mitteleuropas sowie Sickerwässer aus Lysimetern und Bodenprofilen wurden vergleichend auf ihren Wasserstoffisotopen-Gehalt untersucht. Regionale Unterschiede sind vorhanden. Im Deuterium-Gehalt von Niederschlag-, Boden- und z.T. Lysimeterwasser treten regelmäßige Variationen auf. Sie fehlen im Quellwasser natürlicher Gebiete. Die Anwendbarkeit von Deuteriumuntersuchungen zur Ermittlung der Sickergeschwindigkeit und des Verdunstungsanteils wird angedeutet.

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Rain- and spring water of several regions of Central Europe as well as water from lysimeters and soil profiles have been compared with respect to their hydrogen isotope content. Regional differences can be stated. Systematic variations in the deuterium content of rain-, soil- and in part of lysimeterwater are found to exist. They do not exist in natural spring water. The applicability of deuterium investigations to the determination of percolation velocity and evaporation is indicated.

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Résumé L'eau de précipités et des eaux de sources de quelques régions de l'Europe Central ainsi que des eaux de lysimètres et de profils de terre sont investigées comparativement pour leur contenu d'isotopes d'hydrogène. Des différences régionales sont présentes. Il y a des variations systematiques dans le contenu de deuterium des eaux de pluie, de terre et en part de lysimètres. Elles sont absentes dans les eaux de sources naturelles. L'application des investigations de deuterium pour la détermination d'évaporation et de la vitesse d'écoulement est indiquée.

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Characterization and low-cost treatment of an industrial arid soil polluted with lead sulfide in northern Chile

Lead (Pb) dust exposure can have detrimental environmental and human health effects. Improperly enclosed stockpiles of Pb concentrates can cause dust emissions, subsequent pollution of the soil and environmental risk. The aim of this work was to study Pb form, distribution and immobilization (by using eggshell and seashell) in an industrial arid soil near a storage area of Pb mineral concentrates in northern Chile. High amounts of sulfur (S; 9900 mg kg^?1) and Pb (6530 mg kg^?1) were found in the polluted soil. The energy-dispersive X-ray spectroscopy analysis revealed a lead sulfide (PbS: galena). Metallic Pb particles, which were between 41 and 46 µm, were identified in the soil. After eggshell and seashell (20%) were applied, the soil pH increased from 6.0 to 7.84 and 8.07, respectively. In the studied soil, the leaching test showed a 59 mg L^?1 average Pb extractable concentration. After 240 days, extractable Pb by toxicity characteristics leaching procedure decreased to 4.79 mg L^?1 (93.3%) with the application of seashell at 20% compared with a decrease of 33.33 mg L^?1 (53.6%) using eggshell. Pb in the polluted soil was mainly found in the exchangeable fraction (66%), followed by the reducible (24%), residual (7%) and oxidizable (6%) fractions. According to the risk assessment code, the contaminated soil before treatment was classified as very high risk. Adding eggshell (20%) and seashell (20%) decreased the exchangeable fractions to 39 and 35%, respectively. Applying these liming materials achieved Pb immobilization in the soil, but the soil remained in the high environmental risk category. We conclude that the application of seashell waste, resulting from high aquaculture activity, opens an interesting window to the treatment of contaminated arid soils.     

Assessing the spatial probability of landslides using GIS and informative value model in the Bamenda highlands

Landslides are a major natural hazard in the Bamenda highlands of Cameroon, and their occurrence in this region has most often been studied using qualitative methods. The aim of this research is to quantitatively assess the spatial probability of landslides using GIS and the informative value model. Landslide inventory was done through literature review, aerial photo-interpretation, participatory GIS and field survey. Six geo-environmental factors including slope, curvature, aspect, land use, lithology and geomorphology were used as landslide conditioning (static) factors. The susceptibility of the area to future landslide events was assessed by making a correlation between past landslides and geo-environmental factors using the informative value model. The landslide inventory involving 110 landslides was divided into two equal groups using random division criterion and was used to train and validate the model. The analysis showed that slope and land use are the most important causal factors of landslides in the area. The susceptibility index map predicted most landslides to occur around the steep slopes of the Bamenda escarpment that is being used for multiple anthropic activities. The training model had a success rate of 87%, and the validation model had a prediction rate of 90%. The prediction rate curve shows that 44, 32, 18 and 6% of future landslides will occur on 3, 8, 21 and 68% of the study area. The model correctly classified 89% of unstable areas and 81% of the stable areas with an accuracy rate of 0.90. This quantitative result complement other qualitative assessment results that show the Bamenda escarpment zone as a high-risk area. However, the area susceptible to landslide in this study goes beyond what earlier studies had indicated as houses and other infrastructure were found on old landslide sites whose scars have been eroded by human activities. This new input thus improves the quality of information placed at the disposal of civil protection units and land use managers during decision making.     

Late quaternary sea‐level changes,crustal movements and coastal evolution in Northumberland,UK

Northumberland lies in the transition between Holocene emergence and submergence and is thus a critical zone for testing models of isostatic rebound. We have collected data from this area to reconstruct relative sea‐level changes and lateral coastline movements for the last 14000 y. These are deposits from tidal marsh, back‐barrier wetland and terrestrial environments producing 47 sea‐level index points from 12 sites. There is no unequivocal evidence for Late Devensian sea levels above present and the reliable sea‐level index points are restricted between −6 m and +2.5 m relative to present and 9.0–2.5 kyr cal. BP. Analysis of these quantifies differential responses to glacio‐ and hydroisostatic rebound, with the northern sites recording a mid‐Holocene sea‐level maximum ca. 2.5 m above present, whereas the southern sites show a maximum ca. 0.5 m above present. These observations show a reasonable fit with the predictions from quantitative models of glacio and hydroisostatic rebound, but there is currently no unique solution of Earth and ice model parameters that will explain all the sea‐level observations. Copyright © 2000 John Wiley & Sons, Ltd.     

Copper- and iron-induced injuries in roots and rhizomes of reed (Phragmites australis)

About 1 mg/g dw Cu²⁺ and 8 mg/g dw Fe²⁺ were found in roots of reed plants when fed with heavy metal concentrations of 100 μM Cu²⁺ and 10 mM Fe²⁺ under hypoxia. Roots seemed to act as a kind of filter since the amounts in rhizomes were only 0.06 mg Cu²⁺/g dw and 2 mg Fe²⁺/g dw. Increased contents of both ions reduced posthypoxic respiration capacity by 40–50% and also the sum of adenylates (ATP, ADP, AMP) by the same order of magnitude, although energy charge values remained above 0.85 in Cu²⁺ and 0.79 in Fe²⁺ treatments. Energy metabolism of rhizomes was not affected. Copper and iron contents of roots as well as of rhizomes were high enough to induce oxidative stress when roots were fed with 40 μM Cu²⁺ and 1 mM Fe²⁺, respectively.From our results we conclude that increased, but environmentally attainable, amounts of copper and reduced iron ions disturb root energy metabolism, and therefore root functioning and development. Latent injuries, based on oxidative stress, may be harmful for roots and rhizomes under long term exposure.