Coupling Size-Exclusion Chromatography and ICP-MS to Investigate the Speciation of Platinum-Group Elements in Environmental Samples

The applicability of size-exclusion chromatography (SEC) coupled online with a high resolution ICP-MS (HR-ICP-MS) to investigate the speciation of the platinum-group elements (PGE), Rh, Pd and Pt, was evaluated. Experiments were carried out to determine the efficiency of different hydrophilic and hydrophobic size-exclusion gel materials to select the optimal eluent in respect of resolution, recovery, reproducibility and limit of detection. The suitability of HR-ICP-MS as a reliable detection instrument at low pg ml⁻¹ levels was investigated by examining possible mass interferences with Rh, Pd and Pt. Laboratory experiments demonstrated the interaction and capability of forming complexes of humic substances with PGE, demonstrating the potential role of these ubiquitous natural substances in the mobilisation of PGE in the environment.     

Zur Messung der Fahrt über Grund an Bord von Schiffen

Zusammenfassung Es wird gezeigt, wie mit einem Zweikreiselsystem, das gleichzeitig die Nordrichtung und den Horizont liefert, ein Trägheits-Navigationssystem unter Verwendung von Beschleunigungsmessern und eines Rechenaggregates aufgebaut werden kann. Die Beschleunigungsmesser werden von einer kreiselstabilisierten Plattform getragen, die über Stützmotore in den drei Freiheitsgraden parallel zum Zweikreiselsystem gehalten wird.

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On measuring a ship's speed over ground from board of ships

Summary The following paper explains how to assemble an inertial navigation system with the aid of accelerometers, a calculating unit and a two gyro system that simultaneously indicates the north direction and the horizon. The accelerometers are carried by a gyro stabilized platform that, on its part, is kept in the three degrees of freedom parallel to the two gyro system by three torques generators.

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Sur la mesure à bord d'un bâtiment pour déterminer la vitesse par-dessus le fond de la mer

Résumé Le travail suivant expose de quelle manière on peut construire un système de navigation d'inertie en joignant des accéléromètres, un aggrégat à calculer et un système à deux gyroscopes; ce dernier fournit simultanément la direction nord et l'horizon. Une plate-forme, également stabilisée par un système à deux gyroscopes, porte les accéléromètres. Cette plate-forme se maintient à l'aide de trois génératrices du moment de couple dans les trois degrés de. liberté parallèle au système à deux gyroscopes.

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Elastic properties from acoustic and volume compression experiments

Hydrostatic compression data for a number of high-pressure phases of oxides and silicates, which have been studied independently by acoustic techniques, have been analyzed by least-squares fitting of the Birch-Murnaghan equation of state to determine the zero-pressure bulk modulus K₀ and its pressure derivative K′₀ for each material. The standard deviations of K₀ and K′₀ so determined are generally underestimated unless the experimental errors in the measurements of volume and pressure are explicitly included. When the values of K₀ determined from the acoustic and compression techniques are consistent, test results for quartz and rutile demonstrate that constraining K₀ to be equal to the acoustic value significantly improves both the accuracy and the precision of K′₀ obtained from the compression data. Similar analyses for high-pressure phases (e.g., pyrope garnet and silicate spinels) indicate that by combining the acoustic and P-V data, the standard deviation of K′₀ is typically reduced by a factor of three. Thus, we conclude that this approach does allow precise determinations of K′₀ even when neither technique alone is able to resolve this parameter. For some materials, however, the P-V and acoustic experiments do not define mutually consistent values of K₀, invalidating any combination of these data. The compression data for stishovite clearly exhibit run to run effects, and we infer that systematic errors are present in some of the P-V data which are responsible for many of the interlaboratory inconsistencies. Such systematic biases in the P-V data can at least be partially compensated for by performing several duplicate experimental runs.     

Elasticity of diopside

The thirteen single-crystal elastic moduli for diopside as determined by the acoustic technique based on Brillouin scattering are: c₁₁=2.23, c₂₂=1.71, c₃₃=2.35, c₄₄=0.74, c₅₅=0.67, c₆₆=0.66, c₁₂=0.77, c₁₃=0.81, c₁₅=0.17, c₂₃=0.57, c₂₅=0.07, c₃₅=0.43, c₄₆=0.073. The Reuss bound of the adiabatic bulk and shear moduli calculated from these data are K _s=1.08 Mbar and G=0.651 Mbar. The room-pressure isothermal bulk modulus, K _T , and the pressure derivative of the bulk modulus, K′ _T have also been determined on a four-circle diffractometer, from a single crystal mounted in a gasketed opposed-anvil diamond cell, giving values of K _T =1.13 Mbar and K′ _T =4.8. The principal axes of the strain ellipsoid, calculated from the elastic moduli and observed in the static compression data, are identical, and the linear compressibilities are in reasonable agreement. The single-crystal elastic moduli can be correlated with the structural features of diopside.     

Natural and synthetic ferroglaucophane

Amphiboles approximating the composition of the ferroglaucophane end member, Na₂Fe₃Al₂Si₈O₂₂(OH)₂, have not been found in nature prior to 1969. Chemical, physical and petrologic data of four specimens of that mineral are given, two from Southern Italy and two from New Caledonia (Black, 1970). The ferroglaucophane end member was synthesized in seeded runs at 500° C, 5000 bars fluid pressure with oxygen fugacity defined by the wüstite-magnetite (WM) buffer. X-ray data and cell dimensions (a=9.686 Å, b=17.89, c=5.317, β=103° 45.2′ V=894.9 ų) are presented along with microprobe data that confirm the end member composition. Under these conditions of synthesis the ferroglaucophane grew metastably, however. Stability relations of the synthetic end member and of one natural specimen were investigated in a temperature range from 250° C to 500° C and at 3 and 5 kb with different oxygen buffers. At relatively low oxygen fugacities (WM buffer, QFM buffer) ferroglaucophane breaks down above 350–360° C. Under more oxidizing conditions (HM buffer) ferroglaucophane may not be stable even at very low temperatures. Mineral facies and chemical bulk composition of rocks that would favor the natural occurrence of ferroglaucophane are discussed. As assemblages with ferroglaucophane can have crystallized only below a very specific upper temperature limit, it is proposed to direct some attention towards that mineral.     

Laser-ablation ICP-MS analysis of silicate and sulfide melt inclusions in an andesitic complex I: analytical approach and data evaluation

Quantitative microanalysis of entire silicate and sulfide melt inclusions by Excimer Laser-ablation inductively-coupled-plasma mass-spectrometry (LA-ICPMS) has been applied to extrusive and shallow intrusive rocks from the andesitic Farallón Negro Volcanic Complex (northwestern Argentina). Silicate melts are trapped in pyroxene, amphibole, plagioclase and quartz, and sulfide melts are trapped in amphibole. Details of the analytical approach and the quantification procedure are given and the results are evaluated to test the accuracy of the technique and the validity of the interpretation of analytical signals. Similar compositions of silicate melt inclusions trapped in truly co-precipitating minerals show that the quantification approach of melt inclusion compositions from LA-ICPMS signals through an internal standard is valid. This correspondence also shows that melt inclusions investigated in this study are not significantly influenced by the boundary layer around a growing crystal or by post-entrapment modifications. Post-entrapment diffusive re-equilibration only affected the Fe and Mg content of melt inclusions in mafic phases. Thus, melt inclusions are representative samples of the melt from which the host mineral crystallized, with regard to most major and trace elements. Sulfide melt inclusions (present as pyrrhotite with exsolution of Au and Cu in phases separated during cooling) were analyzed for their bulk Fe, Cu and Au content, and the abundance of these elements was quantified using a silicate glass as external standard. The validity of this calibration was tested by comparing electron microprobe analyses of Fe, Cu, Ni and Co in homogeneous sulfide minerals with LA-ICPMS results. Identical results within calculated uncertainty (one standard deviation of five to nine analyses, mostly between 1 and 5 wt% RSD) demonstrate that for these elements, measured element ratios are independent of the matrix using our analytical setup.Editorial responsibility: T.L. Grove     

Zircon and apatite fission-track thermochronology of Late Carboniferous volcanic rocks of the NE German Basin

Zircon and apatite fission-track analyses from Late Carboniferous felsic volcanic rocks of the NE German Basin (Halle area and Friedland drilling) reveal at least two major post-emplacement thermal events. After initial cooling at ca. 300 Ma, the volcanic pile underwent a major thermal event at ca. 200 Ma that reached in most places ca. 250-280 °C and led to the new growth of clay minerals. This event is recorded in the zircon fission-track data and can be related to Jurassic-Triassic rifting in Europe. Another thermal event is recorded in the apatite samples at ca. 100 Ma. A close correlation is observed between apatite fission-track age, texture, and sample alteration. Coarse-grained samples are stronger altered and have younger fission-track ages. Hydrothermal alteration coupled with advective heating probably caused these Upper Cretaceous fission-track ages. The latter event can be related to block faulting and inversion of the European plate during the early stages of the Alpine orogeny.     

The thermal regime of the Northeastern-German Basin from 2-D inversion

The thermal regime and the distribution of heat flow at the base of sedimentary basins is fundamental to the understanding of the process of basin evolution and the associated mobilization and migration of hydrocarbon and other fluids. For the Northeastern-German sedimentary basin, available information on structure, temperature, and thermal properties along a seismic DEKORP reflection profile allow high resolution 2-D forward and inverse simulations. This approach is attractive in situations where much information is available, if only with considerable uncertainty. In particular, this allows to introduce “soft” information into the analysis. In our case, forward simulations yield initial a priori estimates of the parameters while inversion calculations yield a posteriori estimates of the parameters and their uncertainty. The a priori parameters as well as their assumed uncertainty are input for a Bayesian parameter estimation scheme. In respect to the Northeastern-German sedimentary basin, the inverse analysis postulates a significant and characteristic a posteriori variation of thermal conductivity of the Zechstein unit along the entire profile as well as a generally large a posteriori thermal conductivity of the (pre-Permian) basement in the northern part of the basin. For inverse calculations, we used two alternative scenarios: One assumes the thermal conductivity of the Zechstein unit to be homogeneous along the profile while the other allows a lateral variation. A posteriori heat flow across the base of the model varies from 40 to 60 and 50 to 65 mW m⁻² for models in which values for thermal conductivity and radiogenic heat generation rate were either based on literature values or direct measurements, respectively.