Description: Das Projekt "Nitrogen effect on molecular dynamics in forest soils (end of thesis)" wird vom Umweltbundesamt gefördert und von Universität Zürich, Geographisches Institut durchgeführt. Atmospheric nitrogen deposition affects many forests and their ecosystem functions, including organic matter cycling in soils of temperate forests. But it is not clear how, and what the underlying mechanisms are. Here we asked the question: Do compounds with high intrinsic nitrogen content (typical for microbially-derived biomass) respond differently to atmospheric nitrogen deposition than compounds with low nitrogen content (such as plant-derived biomass)? Two facts delayed the progress of the project in the first year. From May 2010 to June 2011 the PhD student Marco Griepentrog successfully completed make-up classes for the recognition of his Fachhochschule degree by the University of Zurich. His workload (30 credit points or 900 working hours) was 50Prozent of the annual workload of a full time student, and delayed the progress of the project. Furthermore the PI Dr. Alexander Heim has left research in November 2010 and started a new position in industry and the co-PI Prof. Michael Schmidt stepped in as PI. Despite the delay the project eventually progressed well thanks to the hard-working PhD student Marco Griepentrog, who worked in the lab and simultaneously compiled a detailed methodological literature review on preparative soil fractionation procedures. His review revealed striking discrepancies in the application of this frequently used method, and was submitted to a peer-reviewed journal and is still under revision. With a competitive travel grant from the European Science Foundation, Marco Griepentrog worked at the University of Ghent (Belgium) and could measure compound-specific isotope ratios of amino sugars reliable in soil density fractions for the first time, using a novel analytical technique. This was the first time that amino sugars were measured in density fractions, and we could show that especially bacterial amino sugars were associated with soil minerals. Furthermore, when combined with stable isotope labeling, it became evident that amino sugar turn over much slower when associated with soil minerals. Another unexpected result was that fungal residues turn over at the same rate as total organic carbon, while bacterial amino sugars turn over slower. The fact that fungal amino sugars turn over faster than bacterial amino sugars contradicts with previous assumptions, and our measurements are the first to show that. Results have been presented at several international conferences, and now a manuscript circulates between co-authors to be submitted to a high impact scientific journal later this year. For the final year, we plan to focus on another compound class and propose a change of the initially planned target compound lignin. Own results showed that the isotopic label might not be detectable in lignin but in fatty acids, since they have been shown to turnover faster. usw.
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Origin: /Bund/UBA/UFORDAT
Tags: Stickstoffgehalt ? Tierhaltungsanlage ? Bodenkohlenstoff ? Fettsäure ? Zucker ? Organischer Kohlenstoff ? Biomarker ? Kohlenstoffgehalt ? Humus-C ? Kohlendioxidkonzentration ? Arbeitszeit ? Humus ? Mineralstoff ? Stickstoff ? Belgien ? Temperater Forst ? Flüssigkeitschromatografie ? Isotopentechnik ? Schadstoffdeposition ? Kohlenstoffsenke ? Stickstoffverbindung ? Organisches Material ? Waldboden ? Waldökosystem ? Bakterien ? Bodenmikroorganismen ? Chemische Zusammensetzung ? Gesamter organischer Kohlenstoff ? Düngung ? Kausalzusammenhang ? Literaturauswertung ? Phytomasse ? Pilz ? Biologische Aktivität ? Biologischer Abbau ? Bodenprozess ? Biomasse ? Begasung ? Gefäßpflanze ? amino sugars ? fatt acids ? fungal biomarkers ? Isotopenverhältnis ? Aminozucker ? CO2 fumigation ? nitrogen deposition ? microbial biomarkers ? compound-specific isotope analysis ? plant biomarkers ?
License: cc-by-nc-nd/4.0
Language: Englisch/English
Time ranges: 2013-05-01 - 2014-04-30
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