Paradox reconsidered: Methane oversaturation in well-oxygenated lake waters

The widely reported paradox of methane oversaturation in oxygenated water challenges the prevailing paradigm that microbial methanogenesis only occurs under anoxic conditions. Using a combination of field sampling, incubation experiments, and modeling, we show that the recurring mid-water methane peak in Lake Stechlin, northeast Germany, was not dependent on methane input from the littoral zone or bottom sediment or on the presence of known micro-anoxic zones. The methane peak repeatedly overlapped with oxygen oversaturation in the seasonal thermocline. Incubation experiments and isotope analysis indicated active methane production, which was likely linked to photosynthesis and/or nitrogen fixation within the oxygenated water, whereas lessening of methane oxidation by light allowed accumulation of methane in the oxygen-rich upper layer. Estimated methane efflux from the surface water was up to 5 mmol m−2 d−1. Mid-water methane oversaturation was also observed in nine other lakes that collectively showed a strongly negative gradient of methane concentration within 0–20% dissolved oxygen (DO) in the bottom water, and a positive gradient within ≥ 20% DO in the upper water column. Further investigation into the responsible organisms and biochemical pathways will help improve our understanding of the global methane cycle

Wissenskommunikation – erhöhen Skills die Kommunizierbarkeit von Wissen?

Das Tagungsthema „Soft Skills – Alternative zur Fachlichkeit oder weiche Performance?“ wirft Fragen auf, die auch das eigene Thema berühren könnten. Die Formulierung lässt auf eine Alternative zwischen der Fachlichkeit und der sozialen Kompetenz schließen. Lehrer müssten in sozialen Kompetenzen ausgebildet werden, das Fachliche ergibt sich dann von Fall zu Fall. Oder umgekehrt: Fachlichkeit ist unersetzbar, auch nicht durch soziale Kompetenzen. Es gibt auch eine dritte Variante, beides bedingt sich im Lehrerberuf gegenseitig. Im Folgenden soll daher aus der Sicht der Kommunikation und ihrer Funktion im Umgang mit Wissen diskutiert werden, in welchem Verhältnis Fachlichkeit und soziale Kompetenz gesehen werden können und welche Konsequenzen sich daraus auch im Hinblick auf das übergeordnete Tagungsthema herleiten lassen. (DIPF/Orig.

Leistungs- und Persoenlichkeitsfoerderung durch sozialpsychologische und soziologische Mitwirkung bei der Arbeitsgestaltung

SIGLEUni.Jena, Inst.f.Psychologie - Ms. 234 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Leistungs- und Persoenlichkeitsfoerderung durch sozialpsychologische und soziologische Mitwirkung bei der Arbeitsgestaltung

SIGLEUni.Jena, Inst.f.Psychologie - Ms. 234 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

The short-EMBU in East-Germany and Sweden: A cross-national factorial validity extension

The factorial stability and reliability of the 23-item s(hort)-EMBU previously demonstrated to be satisfactory in samples of students from Greece, Guatemala. Hungary and Italy, were extended with 791 students from East-Germany and Sweden. Previous findings on factorial validity, internal reliability and correlations among scales were replicated. The 23-item form thus continues to be recommended as a reliable functional equivalent to the early 81-item EMBU, when the clinical and/or research context does nor adequately permit application of time-consuming test batteries

Microbial methane production in oxygenated water column of an oligotrophic lake

The prevailing paradigm in aquatic science is that microbial methanogenesis happens primarily in anoxic environments. Here, we used multiple complementary approaches to show that microbial methane production could and did occur in the well-oxygenated water column of an oligotrophic lake (Lake Stechlin, Germany). Oversaturation of methane was repeatedly recorded in the well-oxygenated upper 10 m of the water column, and the methane maxima coincided with oxygen oversaturation at 6 m. Laboratory incubations of unamended epilimnetic lake water and inoculations of photoautotrophs with a lake-enrichment culture both led to methane production even in the presence of oxygen, and the production was not affected by the addition of inorganic phosphate or methylated compounds. Methane production was also detected by in-lake incubations of lake water, and the highest production rate was 1.8–2.4 nM⋅h−1 at 6 m, which could explain 33–44% of the observed ambient methane accumulation in the same month. Temporal and spatial uncoupling between methanogenesis and methanotrophy was supported by field and laboratory measurements, which also helped explain the oversaturation of methane in the upper water column. Potentially methanogenic Archaea were detected in situ in the oxygenated, methane-rich epilimnion, and their attachment to photoautotrophs might allow for anaerobic growth and direct transfer of substrates for methane production. Specific PCR on mRNA of the methyl coenzyme M reductase A gene revealed active methanogenesis. Microbial methane production in oxygenated water represents a hitherto overlooked source of methane and can be important for carbon cycling in the aquatic environments and water to air methane flux