Strategische verkenningen in woelige tijden; De informatiespecialist, de student en de IDM-opleiding

De functies van bibliotheken en de informatieprofessional zijn aan verandering onderhevig en dit is merkbaar op de arbeidsmarkt. De opleiding IDM in Deventer heeft een contextverkenning uitgevoerd waarvan de conclusie luidt dat het beroepsbeeld van de informatiespecialist onduidelijk is geworden, waardoor er onvoldoende wervingskracht uitgaat naar de arbeids- en studentenmarkt. Toch is er wel degelijk werk genoeg. In de praktijk worden daar echter weinig IDM-ers op gezet. De IDM-opleiding van Saxion Hogescholen besloot op basis van deze verkenning te kiezen voor een duidelijk beroepsprofiel met arbeidsmarktperspectief. Dit artikel beschrijft de discussie die gevoerd is op weg naar een nieuw curriculum. Die discussie leidde tot de ontwikkeling van een drietal scenario’s, die elk bestaan uit de domeinen: informatievaardigheden, ICT en een derde profilerend domein. Gekozen is voor het profiel Informatie, ICT en Educatie. Op basis hiervan ontwikkelt IDM Deventer nu een nieuw competentieprofiel voor het onderwijs. Saxion Hogescholen verwacht zo een aantrekkelijke opleiding met een duidelijke identiteit neer te gaan zetten, die opleidt voor een gezonde arbeidsmarkt

Molecular transformation and degradation of refractory dissolved organic matter in the Atlantic and Southern Ocean

More than 90% of the global ocean dissolved organic carbon (DOC) is refractory, has an average age of 4,000–6,000 years and a lifespan from months to millennia. The fraction of dissolved organic matter (DOM) that is resistant to degradation is a long-term buffer in the global carbon cycle but its chemical composition, structure, and biochemical formation and degradation mechanisms are still unresolved. We have compiled the most comprehensive molecular data set of 197 Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analyses from solid-phase extracted marine DOM covering two major oceans, the Atlantic sector of the Southern Ocean and the East Atlantic Ocean (ranging from 50° N to 70° S). Molecular trends and radiocarbon dating of 34 DOM samples (comprising Δ14C values from -229 to -495‰) were combined to model an integrated degradation rate for bulk DOC resulting in a predicted age of >24 ka for the most persistent DOM fraction. First order kinetic degradation rates for 1,557 mass peaks indicate that numerous DOM molecules cycle on timescales much longer than the turnover of the bulk DOC pool (estimated residence times of >100 ka) and the range of validity of radiocarbon dating. Changes in elemental composition were determined by assigning molecular formulae to the detected mass peaks. The combination of residence times with molecular information enabled modelling of the average elemental composition of the slowest degrading fraction of the DOM pool. In our dataset, a group of 361 molecular formulae represented the most stable composition in the oceanic environment (“island of stability”). These most persistent compounds encompass only a narrow range of the elemental ratios H/C (average of 1.17 ± 0.13), and O/C (average of 0.52 ± 0.10) and molecular masses (360 ± 28 and 497 ± 51 Da). In the Weddell Sea DOC concentrations in the surface waters were low (46.3 ± 3.3 μM) while the organic radiocarbon was significantly more depleted than that of the East Atlantic, indicating average surface water DOM ages of 4,920 ± 180 a. These results are in accordance with a highly degraded DOM in the Weddell Sea surface water as also shown by the molecular degradation index IDEG obtained from FT-ICR MS data. Further, we identified 339 molecular formulae which probably contribute to an increased DOC concentration in the Southern Ocean and potentially reflect an accumulation or enhanced sequestration of refractory DOC in the Weddell Sea. These results will contribute to a better understanding of the persistent nature of marine DOM and its role as an oceanic carbon buffer in a changing climate

Major Role of Microbes in Carbon Fluxes during Austral Winter in the Southern Drake Passage

Carbon cycling in Southern Ocean is a major issue in climate change, hence the need to understand the role of biota in the regulation of carbon fixation and cycling. Southern Ocean is a heterogeneous system, characterized by a strong seasonality, due to long dark winter. Yet, currently little is known about biogeochemical dynamics during this season, particularly in the deeper part of the ocean. We studied bacterial communities and processes in summer and winter cruises in the southern Drake Passage. Here we show that in winter, when the primary production is greatly reduced, Bacteria and Archaea become the major producers of biogenic particles, at the expense of dissolved organic carbon drawdown. Heterotrophic production and chemoautotrophic CO2 fixation rates were substantial, also in deep water, and bacterial populations were controlled by protists and viruses. A dynamic food web is also consistent with the observed temporal and spatial variations in archaeal and bacterial communities that might exploit various niches. Thus, Southern Ocean microbial loop may substantially maintain a wintertime food web and system respiration at the expense of summer produced DOC as well as regenerate nutrients and iron. Our findings have important implications for Southern Ocean ecosystem functioning and carbon cycle and its manipulation by iron enrichment to achieve net sequestration of atmospheric CO2

Process studies of dissolved organic carbon and bacterioplankton in the ocean.

The oceans play an important role in the global climate system by mediating as buffer of heat and greenhouse gasses (e.g. CO). Oceanic water constirutes one of the largest carbon (C) reservoirs of the earth and the fluxes of carbon in the marine system affect the global biogeochemical cycle of carbon. Oceanic uptake of atmosphetic CO2 results mainly from photosynthesis by phytoplankton (primary production). A portion of this newly fixed organic matter is eventually transformed into a dissolved phase. The export of particulate and dissolved organic carbon, from the surface layers to deep water and eventually burial of carbon on the sea floor, results in a net reduction of the atmospheric CO2, concentration. To quantifit and understand the physical and biological controls on these fluxes is the primary objective of the Joint Global Ocean Fiux Study (GOFS). The research encompassed in this thesis was carried out within the JGOFS framework or related projects. ... Zie: Summary.