The molybdenum isotopic composition of the modern ocean

Natural variations in the isotopic composition of molybdenum (Mo) are showing increasing potential as a tool in geochemistry. Although the ocean is an important reservoir of Mo, data on the isotopic composition of Mo in seawater are scarce. We have recently developed a new method for the precise determination of Mo isotope ratios on the basis of preconcentration using a chelating resin and measurement by multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), which allows us to measure every stable Mo isotope. In this study, 172 seawater samples obtained from 9 stations in the Pacific, Atlantic, and Southern Oceans were analyzed, giving global coverage and the first full depth-profiles. The average isotope composition in δA/95Mo (relative to a Johnson Matthey Mo standard solution) was as follows: δ92/95Mo = –2.54 ± 0.16‰ (2SD), δ94/95Mo = –0.73 ± 0.19‰, δ96/95Mo = 0.85 ± 0.07‰, δ97/95Mo = 1.68 ± 0.08‰, δ98/95Mo = 2.48 ± 0.10‰, and δ100/95Mo = 4.07 ± 0.18‰. The δ values showed an excellent linear correlation with atomic mass of AMo (R2 = 0.999). Three-isotope plots for the Mo isotopes were fitted with straight lines whose slopes agreed with theoretical values for mass-dependent isotope fractionation. These results demonstrate that Mo isotopes are both uniformly distributed and follow a mass-dependent fractionation law in the modern oxic ocean. A common Mo standard is urgently required for the precise comparison of Mo isotopic compositions measured in different laboratories. On the other hand, our results strongly support the possibility of seawater as an international reference material for Mo isotopic composition

Using “Yams” for Enterprise Knowledge Sharing among Knowledge Workers from the Perspective of a Task Categorisation-Knowledge Sharing Systems Fit

Part 2: Key Competencies, Learning and Life TransitionsInternational audienceEmerging digital technologies play a key role in the development of enterprises. Their uses demand a transition on the part of knowledge workers, however. Web 2.0 is an emerging communication technology that supports collaborative knowledge sharing in corporate learning paradigms, changing tailor-made, expensive and high learning curve digital systems to simple but well-accepted ones [1, 2]. These platforms revolutionise how participants share, communicate and create knowledge in a corporate setting [3]. The use of Web 2.0 to support Knowledge Sharing (KS) has been extensively investigated [4, 5]. Studies that use a task-technology fit model on systems such as decision support [6] and eLearning [7] demonstrate that a good fit between tasks and digital technologies is able to improve performance of knowledge workers. This research reports the outcomes on the fit between task categorization and knowledge sharing systems. The task categories and Web 2.0 functions used in knowledge sharing practices were consistent. The outcomes highlighted that intuitive design, ease of use and a low learning curve were able to elicit both tacit and explicit organizational knowledge. Text analysis demonstrated that new knowledge was created, exchanged and shared. The study concluded that knowledge sharing activity and the fit between Web 2.0 functions and task categories were consistent and significant