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Gewählte Master / Diploma Thesis:

Tania Patricia Sosa Jirón (2020): The effects of different DOM sources on stream microbial activity.
Master / Diploma Thesis - Institut für Hydrobiologie und Gewässermanagement (IHG), BOKU-Universität für Bodenkultur, pp 79. UB BOKU obvsg FullText

Data Source: ZID Abstracts
Microbial biofilms (coupled heterotrophic-autotrophic communities) are key sites of enzymatic activity, including organic matter (OM) cycling. Here, we focused on the effects of DOM composition from three sources (leaves, maize and dung leachates) on benthic microbial processes within a laboratory flume experiment. We predicted that dissolved organic carbon (DOC) uptake rates would be higher in flumes treated with dung leachate compare to other DOM sources, as it is known to contain more labile compounds. We further tested whether periphyton would stimulate microbial DOM degradation by having 11 flumes under 14/10h dark/light conditions, and 11 under dark conditions. Fed with nutrient-enriched groundwater in circulating flow mode, flumes were colonized for 4 weeks, and thereafter, DOM leachates were added in a single pulse. During the first 20 hours after additions, DOC uptake was highest in flumes treated with maize leachate (35% dark/light - 26% dark flumes - of the total initial concentration), leaves (24 - 19%) and dung (11 - 10%). Changes in DOM quality (e.g. increased Biological Index (BIX) and protein-like compounds) indicated that autochthonous DOM production was equally stimulated by the additions in dark and light flumes. Humic-like compounds and aromatic content (i.e. Humification Index and Specific Ultraviolet Absorbance at 254 nm – SUVA254) were significantly higher in dark flumes compared to light ones. Soluble Reactive Phosphorous was immediately taken up by periphyton after additions, demonstrating that periphyton benefited from co-transported nutrients. P-limited conditions in light flumes led to higher phosphatase activity, validating the influence of periphyton in DOM degradation. Overall, the study provides relevant insights into the effects of allochthonous DOM, coming from agricultural sources, on in-stream processes.

Beurteilende(r): Hein Thomas
1.Mitwirkender: Weigelhofer Gabriele

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