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.
Das Projekt "Contaminant-specific isotope analyses as sharp environmental-forensics tools for site characterisation, monitoring and source apportionment of pollutants in soil (ISOSOIL)" wird vom Umweltbundesamt gefördert und von University Stockholm durchgeführt. Objective: Conventional remediation-monitoring programmes, i.e. analysis of contaminant and metabolite concentrations over time and space, often provide inconclusive assessments due to inability to resolve among mixing of several contaminant sources, degradation, dispersion and other redistribution processes. The isoSoil objective is to firmly establish concentration-independent contaminant-specific isotope analysis (CSIA) as a novel, user-friendly and powerful tool for both degradation monitoring and source apportionment of organic contaminants in soil. The balanced isoSoil consortium with world-leading CSIA research groups, progressive remediation-focused and analytical services companies and experienced software enterprises will enable a) applications of multiple CSIA systems (13C/12C, 2H/1H, 15N/14N and 37Cl/35Cl) for improved site-specific characterization and monitoring of microbial and abiotic degradation, b) applications of CSIA ?isotopic fingerprinting? (14C/12C, 2H/1H, 37Cl/35Cl, and 81Br/79Br) for source apportionment of both regional diffuse and locally mixed contamination scenarios (i.e., environmental forensics) and, c) emphasis on development and demonstration of web-based commercial software to aid soil managers in sampling and interpretation of CSIA results. The CSIA concept provides a well-defined and improved tool to for assessment and monitoring of the 3.5 mill contaminated soil sites in EU. Application of multi-element CSIA enables enhanced power to resolve between the many co-occurring processes. CSIA-based DEGRADATION MONITORING answers to Call Topic ?improved tools for site characterization and monitoring of contaminated soils including chemical analysis?. CSIA-based SOURCE APPORTIONMENT answers to Call Topic ?development of tools for detection of local, primary, or secondary sources?.
