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1983
Journal Article
Titel
Production and consumption of hydrogen in a eutrophic lake
Abstract
The vertical distribution of hydrogen was measured in the Loclat, an eutrophic and holomictic lake near Neuchatel, Switzerland, before and during summer stratification. H2 concentrations decreased with depth in the anaerobic hypolimnion and were often below the detection limit (2.5 nl of H2 liter E-1) in the water adjacent to the lake sediment. The highest H2 concentrations (bigger than 4 myl of H2 liter E-1) were observed in the aerobic water of the epilimnion and metalimnion. There, the H2 concentrations changed with time, indicating a turnover of H2. The possible role of cyanobacteria and algae for H2 production is discussed. Aerobic or anaerobic H2 consumption activities were observed at all depths of the water column, with highest activities in the hypolimnion. Aerobic H2 consumption activity was insensitive to azide inhibition, but sensitive to heat, mercuric chloride, or cyanide. It was restricted to a particle fraction of 0.2 to 3.0 mym in size, so that it must be due to single bacterial cells. Aerobic hydrogen bacteria, on the other hand, occured in clusters of bigger than 3.0 mym. Therefore, the hydrogen bacteria could not have caused the H2 consumption in lake water. The aerobic H2 consumption activity followed Michaelis-Menten kinetics, with a K sub m of 67 nM H2. This is an exceptionally low value compared with K sub m values of hydrogenases in hydrogen bacteria and other species, but is similar to that for H2-decomposing abiontic soil hydrogenases. (IFU)