To better quantify the behaviour of rare earth elements (REE) in low temperature natural systems, calcite was precipitated from NaCl-bearing aqueous solutions in the presence of La and Yb using a constant addition technique at pH ~ 6 and 25 °C under steady-state conditions. The presence of REE in the fluid significantly slows calcite growth rates.

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As reuse and technology-independence are key issues of both software and web engineering, web services have gained momentum and are heavily used in modern web-based applications. However, they are only expedient for the business logic layer, while the Web lacks uniform models for the encapsulation and reuse of UI components. Thus, web UIs are usually hand-crafted and static, which complicates both development as well as maintenance and upgrade. We address these issues with a novel approach facilitating dynamic, service-oriented composition of user interfaces for web applications. UI parts therein are provided as reusable services and can therefore be selected, customized and exchanged dynamically with respect to a particular context.

The fluid-rock interactions occurring in hydrothermal systems at or near mid-oceanic ridges (MOR) were studied experimentally by reacting crystalline and glassy basalt with seawater at 250 and 290 °C while monitoring the fluid phase Sr isotopic evolution (87 Sr/ 86 Sr and δ 88/86 Sr). The results indicate that seawater Sr was incorporated into anhydrite during the early stages of seawater-basalt interaction. Fluid 87 Sr/ 86 Sr values trend towards the basaltic signature as non-stoichiometric basalt dissolution became the dominant process. This suggests that the interplay between fast Sr incorporation into secondary sulfates versus slow and continuous Sr liberation due to basalt dissolution at intermediate temperatures could partly explain previously identified discrepancies between MOR heat budget constraints and the marine 87 Sr/ 86 Sr budget. Late-stage anhydrite re-dissolution, likely caused by the fluid phase becoming more reducing through further basalt dissolution, as well as by quenching of the 2 experiments, represents a potential explanation for the low amounts of anhydrite found in naturally altered oceanic basalt samples. Relatively strong decreases in fluid δ 88/86 Sr values in experiments with crystalline basalt suggest that isotopically light Sr was preferentially released due to non-stoichiometric dissolution. A slight preference of anhydrite for isotopically heavy Sr (Anhydrite−Liquid 88/86 = 0.33 ± 0.020 ‰) is indicated by the data, suggesting that changes in MOR spreading rates and Sr removal could be recorded in the isotope compositions of authigenic, sedimentary Sr phases. Such insights will help to constrain the influence of hydrothermal systems on the oceanic stable Sr cycle.