The importance of oxygen isotope provenance in relation to solute content of bulk meltwaters at Imersuaq Glacier,West Greenland

Stable oxygen isotope analysis and measurement of several dissolved cations and anions of bulk meltwater samples have provided information about the hydrochemical environment of the glacial hydrological system at Imersuaq Glacier, an outlet tongue from the Greenland ice‐sheet, West Greenland. The samples were collected at frequent intervals during the period 20–28 July 2000 in a small (<20 L s^?1) englacial meltwater outlet at the glacier margin. The results document the following findings: (i) a marked diurnal variation of δ¹⁸O is related to the composition of oxygen isotope provenances, mainly near‐marginal local superimposed ice and basal up‐sheared ice further up‐glacier; (ii) a relationship is seen between all base cations (Na⁺, K⁺, Ca²⁺, Mg²⁺), SO₄^2? and δ¹⁸O, indicating that solute acquisition is provided by solid–solution contact with the up‐sheared ice—as the relationship with Cl^? is weak the influence of seasalt‐derived solutes is small in the area; (iii) when the melt rate is high, two diurnal maxima of δ¹⁸O values and solute concentrations are measured, and it is suggested that a snow meltwater component is responsible for the second maximum of δ¹⁸O—a short residence time leads to a delayed decrease in ion concentrations. Copyright © 2003 John Wiley & Sons, Ltd.     

Developing a Marine Information System by Integrating Existing Ocean Models Using Object-Oriented Technology

Information systems developed for different applications within the environmental domain have common characteristics, which can potentially be abstracted for sharing and reuse of design and software modules. This article presents an approach to designing for reuse by abstracting commonalities in the design of a Marine Information System (MIS), facilitating data management in a prototype operational monitoring, forecasting, and management system for the North Atlantic and the Nordic Seas. A detailed study of the requirements and data analysis was carried out, and Object-Oriented Technology (OOT) is employed to encapsulate abstractions and to promote reuse of code and design. This article identifies the Object-Oriented Frameworks (OOFW) required to build the MIS. It also provides guidelines to environmental scientists for restructuring legacy software and employing modern programming techniques.     

A mixed spectral finite-difference model for pollutant concentrations over a hill

Given incident logarithmic profiles of wind and pollutant concentration above a rough, absorbing surface, the three-dimensional distribution of pollutant concentration over a hill of gentle slope is determined from a linearized model. The model is applied in neutrally stratified flow, without chemistry, and is integrated using spectral methods in the horizontal and a finite-difference scheme in the vertical. This approach allows for flexibility in choosing a closure scheme and a variety of surface boundary conditions. This was not possible in the analytic approach of Padro (1987) who added pollutant concentration and flux to the MS3DJH/1 model of Walmsley et al. (1980). The present model requires as input the turbulent kinetic energy, E, dissipation, , and the perturbation vertical velocity, w, from the three-dimensional boundary-layer flow model of Beljaars et al. (1987), hereinafter referred to as MSFD, The latter model also supplies wind velocity perturbations at the upper boundary, as input to upper boundary conditions on the pollutant flux perturbations.The present study describes applications of the model to idealized terrain features: isolated two- and three-dimensional hills and ridges and an infinite series of ridges. (Application to real terrain, however, presents no difficulties.) Comparisons were made with different (though uniform) surface roughnesses. Tests were performed to examine the effect of upstream terrain features in the periodic domain and to illustrate the importance of the vertical resolution of the output for interpreting results from the sinusoidal terrain case.     

Review of the neotectonics of the Eastern Turkish–Armenian Plateau by geomorphic analysis of digital elevation model imagery

Digital elevation model (DEM) images provide synoptic views of the Earth’s surface allowing the analysis of landforms of still active tectonic and volcanic structures at regional scale. A DEM at 250 m pixel size constitutes regional scale data particularly efficient to investigate the late Miocene–Quaternary deformation of the Eastern Turkish–Armenian Plateau in the Arabian–Eurasian area of convergence. Geomorphic analysis of the DEM image associated with review of fault-plane solutions of earthquakes show that faults are mostly strike-slip with small vertical component. Here we show that the orientations of the tectonic and volcanic structures fit with a tectonic regime characterized by N–S shortening and E–W lengthening, consistent with westward escape of Anatolia perpendicular to the direction of the Arabia–Eurasia shortening. The uniform uplift of the plateau, the predominance of strike-slip faulting, the lack of major thrusts and the occurrence of normal faults do not support a model of going-on crustal thickening due to intracontinental convergence. On the contrary, our observations can be better interpreted in terms of lithospheric thinning and mantle upwelling related to gravity escape of Anatolia.     

Impact of UV-B, Heat and Chemicals on Ethylene-Production of Lichens

To assess the impact of UV-B radiation combined with NaHSO₃ in solution under laboratory conditions, we compared the amounts of stress-ethylene produced by two lichen species of the same genus. Ramalina lacera, an epiphytic Mediterranean lichen, was found to be rather sensitive to UV-B combined with NaHSO₃, relative to the epilithic desert lichen R. maciformis. The impact of high temperatures with FeCl₂ in solution, measured by amounts of stress ethylene accentuated the adaptability of R. maciformis to desert conditions, whereas R. lacera appeared to be rather sensitive to extreme temperatures especially in the case of chemical contamination. The adaptability of R. maciformis to UV-B appears to be related to the photoprotective capabilities of lichen substances.     

A Reflection on Mg, Cd, Ca, Li and Si Isotopic Measurements and Related Reference Materials

This contribution aims to report the reflections we had with the scientific community during two international workshops on reference materials for stable isotopes in Davos (2002) and Nice (2003). After evaluating the isotopic homogeneity of some existing reference materials, based on either certificates, literature data or specific inter-laboratory rounds, we confirm these as primary reference materials or propose new ones relative to which stable isotope compositions should be reported. We propose DSM-3 for Mg, NIST SRM 915a for Ca, L-SVEC for Li and NBS28 for Si. Cadmium does not yet have a well identified delta zero material, although three commercial mono-elemental Cd solutions have yielded the same isotopic composition relative to one another. In order to scale the linearity of any mass spectrometer, some secondary reference materials are also proposed: Cambridge-1 solution for Mg, the "Münster-Cd" and JEPPIM Cd solutions for Cd and the "Big Batch" silicate for Si. The team from Nancy propose to prepare a mixed spike solution for Li isotopes. Well-characterised natural samples such as ocean or continental waters, diatoms, sponges, rocks and minerals are needed to validate the entire analytical procedure, particularly to take into account the effect of sample mineralisation and of chemical manipulations for elemental separation prior to analysis.     

Eocene-Pliocene time scale and stratigraphy of the Upper Rhine Graben (URG) and the Swiss Molasse Basin (SMB)

We present a general stratigraphic synthesis for the Upper Rhine Graben (URG) and the Swiss Molasse Basin (SMB) from Eocene to Pliocene times. The stratigraphic data were compiled both from literature and from research carried out by the authors during the past 6 years ; an index of the stratigraphically most important localitites is provided. We distinguish 14 geographical areas from the Helvetic domain in the South to the Hanau Basin in the North. For each geographical area, we give a synthesis of the biostratigraphy, lithofacies, and chronostratigraphic ranges. The relationships between this stratigraphic record and the global sea-level changes are generally disturbed by the geodynamic (e.g., subsidence) evolution of the basins. However, global sea-level changes probably affected the dynamic of transgression–regression in the URG (e.g., Middle Pechelbronn Beds and Serie Grise corresponding with sea-level rise between Ru1/Ru2 and Ru2/Ru3 sequences, respectively) as well as in the Molasse basin (regression of the UMM corresponding with the sea-level drop at the Ch1 sequence). The URGENT-project (Upper Rhine Graben evolution and neotectonics) provided an unique opportunity to carry out and present this synthesis. Discussions with scientists addressing sedimentology, tectonics, geophysics and geochemistry permitted the comparison of the sedimentary history and stratigraphy of the basin with processes controlling its geodynamic evolution. Data presented here back up the palaeogeographic reconstructions presented in a companion paper by the same authors (see Berger et al. in Int J Earth Sci 2005).     

Les laves du mont Bangou : une première manifestation volcanique éocène, à affinité transitionnelle,de la Ligne du Cameroun

Mount Bangou, an Eocene volcano (⁴⁰K–⁴⁰Ar ages between 44.7 and 43.1 ± 1 Ma) is the oldest dated volcano of the Cameroon Line. In this region, two magmatic series, evolving by fractional crystallization, show transitional affinities that are exceptionally known in this sector. Mineral compositions of basaltic rocks (scarce modal olivine and occurrence of normative hypersthene) as well as geochemical characteristics (low Ba, La, Ta contents and high Y/Nb ratios) are in agreement with this trend. The succession of magmas evolving in time from transitional to more typical alkaline compositions is evidenced in a continental setting. To cite this article: J. Fosso et al., C. R. Geoscience 337 (2005).