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  • 1
    Call number: AWI G3-16-90173
    In: Hamburger bodenkundliche Arbeiten ; 65, Bd. 65
    Type of Medium: Series available for loan
    Pages: XVI, 157 S. , Ill., graph. Darst., Kt.
    Series Statement: Hamburger bodenkundliche Arbeiten 65
    Language: German
    Note: Zugl.: Hamburg, Univ., FB Geowiss., Diss., 2011 , INHALT: Inhalt. - Zusammenfassung. - Abstract. - Abkürzungen. - Abbildungen. - Tabellen. - 1 Einleitung und Zielsetzung. - 2 Grundlagen. - 2.1 Die Bedeutung des Stickstoffkreislaufs. - 2.2 Die Nitrifikation - Ein Schlüsselprozess im Stickstoffkreislauf. - 2.2.1 Verbreitung Ammoniak oxidierender Bakterien. - 2.2.2 Verbreitung Ammoniak oxidierender Archaeen. - 2.2.3 Physiologie Ammoniak oxidierender Mikroorganismen. - 2.2.4 Bedeutung Ammoniak oxidierender Mikroorganismen. - 2.3 Psychrophile and psychrotolerante Bakterien. - 2.4 Grundlagen der methodischen Ansätze. - 2.4.1 Bodenklassifikation nach der US Soil Taxonomy. - 2.4.2 Charakterisierung der Ammoniak oxidierenden Mikroorganismen (AOM). - 2.4.3 Nachweis von nitrifizierenden Mikroorganismen. - 2.4.4 Denaturierende Gradienten Gelelektrophorese (DGGE). - 2.4.5 Fluoreszenz-in-situ-Hybridisierung (FISH) und Immunofluoreszenz (IF). - 2.4.6 Reverse Transkriptase RCR. - 3. Beschreibung der Untersuchungsgebiete. - 3.1. Untersuchungsgebiet im kalten Klimat – die Insel Samoylov im Lena-Delta. - 3.2. Untersuchungsgebiet im gemäßigten Klimat – Hahnheide bei Hamburg. - 4 Material und Methoden. - 4.1 Probenahme und bodenkundliche Standortaufnahme. - 4.2 Herkunft der verwendeten Anreicherungskulturen. - 4.3 Bodenchemische und -physikalische Laboruntersuchungen. - 4.4 Quantifizierung von gelösten Stickstoffverbindungen in Böden. - 4.4.1 Ammoniumbestimmungen. - 4.4.2 Nitrit- und Nitratbestimmung. - 4.4.3 Bestimmung der gelösten organischen Stickstoffverbindungen (DON). - 4.5 Nährmedien. - 4.6 Nachweis von mikrobiellen N-Umsetzungen in Böden. - 4.6.1 Bestimmung der potentiellen Nitrifikation. - 4.6.2 Bestimmung der potentiellen Mineralisationsaktivitäten. - 4.6.3 Bestimmungen der Temperaturoptima der Nitrifikation. - 4.6.4 Quantifizierung von nitrifizierenden Mikroorganismen mittels MPN. - 4.7 Kulturführungen von Anreicherungen und Reinkulturen. - 4.7.1. Anreicherung von Ammoniak oxidierenden Mikroorganismen (AOM). - 4.7.2. Kulturführung von Reinkulturen. - 4.7.3 Reinheitstest der Anreicherungs- und Reinkulturen. - 4.8 Mikroskopische Verfahren. - 4.9. Molekularbiologische Methoden. - 4.9.1 DNA Extraktion. - 4.9.2 Polymerasenkettenreaktion (PCR). - 4.9.3 Denaturierende Gradienten Gelelektrophorese (DGGE). - 4.9.4 RNA Isolation und Reverse Transkriptase (RT) PCR Anwendungen. - 4.9.5 Klonierung. - 4.9.6 Sequenzanalysen und Stammbäume. - 4.10 Statistische Verfahren. - 5. Ergebnisse. - 5.1. Bodenkundliche Charakterisierung der untersuchten Permafrostböden. - 5.1.1 Böden der Flussterrasse. - 5.1.2 Böden der jüngeren Überflutungsebene. - 5.1.3 Beschreibung des untersuchten Permafrostaufschlusses am Kliff. - 5.2 Bodenkundliche Charakterisierung der Vergleichsböden im gemäßigten Klimat. - 5.3 Gelöste anorganische Stickstoffverbindungen (DIN). - 5.3.1 DIN in den kalten Klimaten. - 5.3.2 DIN-Gehalte in den Böden der gemäßigten Klimaten. - 5.4. Mineralisation. - 5.4.1 Bestimmung der Mineralisationsraten. - 5.4.2 Mineralisation im Mikrokosmos Ansatz. - 5.5 Potentielle Nitrifikation. - 5.5.1 Gesamte potentielle Nitrifikation in den Böden der kalten Klimaten. - 5.5.2 Archaeale potentielle Nitrifikation in den Böden der kalten Klimate. - 5.5.3 Temperaturabhängige potentielle Ammoniakoxidation. - 5.5.4 Potentielle Nitrifikationsaktivität im gemäßigten Klimat. - 5.6 Quantifizierungen von Nitrifikanten. - 5.7. Molekularbiologische Befunde. - 5.7.1. Diversität des bakteriellen und archaealen 16S-rRNA-Gens. - 5.7.2 Nachweis AOB und AOA mittels der Ammoniakmonooxygenase (AMO) 5.8 DGGE Analysen der Anreichungskulturen. - 5.8.1 Anreicherungen bei 4 °C. - 5.8.2 Anreicherungen bei 10 °C. - 5.8.3 Anreicherungen bei 28 °C. - 5.9 Taxonomie der untersuchten Ammoniak oxidierenden Mikroorganismen (AOM). - 5.9.1 Taxonomie der AOB. - 5.9.2 Taxonomie der AOA. - 5.10 Charakterisierungen der Anreicherungskulturen. - 5.10.1 Morphologische Eigenschaften der Anreicherungskulturen. - 5.10.2 Lichtmikroskopische Untersuchungen der Anreicherungskulturen. - 5.10.3 Temperaturanpassung als physiologische Eigenschaft der AOM. - 5.11 Zusammenfassender Überblick der Ergebnisse. - 6. Diskussion. - 6.1 Permafrostböden und die Prozesse des Stickstoffkreislaufes. - 6.1.1 Stickstoffumsätze aufgrund kleinräumige Variabilität der Böden Samoylovs. - 6.1.2 Verteilung der gelösten anorganischen Stickstoffverbindungen (DIN). - 6.1.3 N-Limitierung in den Permafrostböden. - 6.1.4 Die Prozesse im Küstenaufschluss am Samoylov-Kliff. - 6.2 Die mikrobielle Diversität in den Permafrostböden. - 6.2.1 Diversität in Permafrostböden. - 6.2.3 Unterscheidung AOB und AOA. - 6.2.4 Wer ist wann aktiv? Die Bewertung der RT PCR Ergebnisse. - 6.3 Temperaturanpassung. - 6.4 Möglicher Einfluss des Klimawandels auf die Stickstoffumsetzung. - 7. Schlussbetrachtung und Ausblick. - Literatur. - Veröffentlichungen. - Dank.
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  • 2
    Publication Date: 2019-02-01
    Description: Nitrification, the step-wise oxidation of ammonium to nitrite and nitrate, is important in the marine environment because it produces nitrate, the most abundant marine dissolved inorganic nitrogen (DIN) component and N-source for phytoplankton and microbes. This study focused on the second step of nitrification, which is carried out by a distinct group of organisms, nitrite-oxidizing bacteria (NOB). The growth of NOB is characterized by nitrite oxidation kinetics, which we investigated for 4 pure cultures of marine NOB (Nitrospina watsonii 347, Nitrospira sp. Ecomares 2.1, Nitrococcus mobilis 231, and Nitrobacter sp. 311). We further compared the kinetics to those of non-marine species because substrate concentrations in marine environments are comparatively low, which likely influences kinetics and highlights the importance of this study. We also determined the isotope effect during nitrite oxidation of a pure culture of Nitrospina (Nitrospina watsonii 347) belonging to one of the most abundant marine NOB genera, and for a Nitrospira strain (Nitrospira sp. Ecomares 2.1). The enzyme kinetics of nitrite oxidation, described by Michaelis-Menten kinetics, of 4 marine genera are rather narrow and fall in the low end of half-saturation constant (Km) values reported so far, which span over 3 orders of magnitude between 9 and 〉1000 µM NO2-. Nitrospina has the lowest Km (19 µM NO2-), followed by Nitrobacter (28 µM NO2-), Nitrospira (54 µM NO2-), and Nitrococcus (120 µM NO2-). The isotope effects during nitrite oxidation by Nitrospina watsonii 347 and Nitrospira sp. Ecomares 2.1 were 9.7 ± 0.8 and 10.2 ± 0.9‰, respectively. This confirms the inverse isotope effect of NOB described in other studies; however, it is at the lower end of reported isotope effects. We speculate that differences in isotope effects reflect distinct nitrite oxidoreductase (NXR) enzyme orientations.
    Type: Article , PeerReviewed
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  • 3
    Publication Date: 2018-07-05
    Description: Recent studies on permafrost organic matter (OM) suggest that a portion of previously frozen carbon will enter the active carbon cycle as high latitudes warm. Less is known about the fate of other OM components, including nutrients such as nitrogen (N). The abundance and availability of N following permafrost thaw will regulate the ability of plants to offset carbon losses. Additionally, lateral N losses could alter aquatic food webs. There is growing evidence that some N is lost vertically as N2O, a greenhouse gas 300 times stronger than CO2 over 100 years. Despite broad recognition of its role regulating both carbon and non-carbon aspects of the permafrost climate feedback, estimates of permafrost N remain uncertain. To address this knowledge gap, we quantified N content for different stratigraphic units, including yedoma, Holocene cover deposits, refrozen thermokarst deposits, taberal sediments, and active layer soils. The resulting N estimates from this one permafrost region were similar in magnitude to previous estimates for the entire permafrost zone. We conclude that the permafrost N pool is much larger than currently appreciated and a substantial pool of permafrost N could be mobilized after thaw, with continental-scale consequences for biogeochemical budgets and global-scale consequences.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 4
    Publication Date: 2015-01-22
    Description: Permafrost-affected soils of the Siberian Arctic were investigated with regard to identification of nitrite oxidizing bacteria active at low temperature. Analysis of the fatty acid profiles of enrichment cultures grown at 4°C, 10°C and 17°C revealed a pattern that was different from that of known nitrite oxidizers but was similar to fatty acid profiles of Betaproteobacteria. Electron microscopy of two enrichment cultures grown at 10°C showed prevalent cells with a conspicuous ultrastructure. Sequence analysis of the 16S rRNA genes allocated the organisms to a so far uncultivated cluster of the Betaproteobacteria, with Gallionella ferruginea as next related taxonomically described organism. The results demonstrate that a novel genus of chemolithoautotrophic nitrite oxidizing bacteria is present in polygonal tundra soils and can be enriched at low temperatures up to 17°C. Cloned sequences with high sequence similarities were previously reported from mesophilic habitats like activated sludge and therefore an involvement of this taxon in nitrite oxidation in nonarctic habitats is suggested. The presented culture will provide an opportunity to correlate nitrification with nonidentified environmental clones in moderate habitats and give insights into mechanisms of cold adaptation. We propose provisional classification of the novel nitrite oxidizing bacterium as 'Candidatus Nitrotoga arctica'.
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  • 5
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    In:  (Diploma thesis), Universität Hamburg, Hamburg, 119 pp
    Publication Date: 2015-04-10
    Type: Thesis , NonPeerReviewed
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  • 6
    Publication Date: 2019-02-01
    Description: Nitrous oxide (N2O) is one of the most important greenhouse gases and a major sink for stratospheric ozone. Estuaries are sites of intense biological production and N2O emissions. We aimed to identify hot spots of N2O production and potential pathways contributing to N2O concentrations in the surface water of the tidal Elbe estuary. During two research cruises in April and June 2015, surface water N2O concentrations were measured along the salinity gradient of the Elbe estuary by using a laser-based on-line analyzer coupled to an equilibrator. Based on these high-resolution N2O profiles, N2O saturations, and fluxes across the surface water/atmosphere interface were calculated. Additional measurements of DIN concentrations, oxygen concentration, and salinity were performed. Highest N2O concentrations were determined in the Hamburg port region reaching maximum values of 32.3 nM in April 2015 and 52.2 nM in June 2015. These results identify the Hamburg port region as a significant hot spot of N2O production, where linear correlations of AOU-N2Oxs indicate nitrification as an important contributor to N2O production in the freshwater part. However, in the region with lowest oxygen saturation, sediment denitrification obviously affected water column N2O saturation. The average N2O saturation over the entire estuary was 201% (SD: ±94%), with an average estuarine N2O flux density of 48 μmol m−2 d−1 and an overall emission of 0.18 Gg N2O y−1. In comparison to previous studies, our data indicate that N2O production pathways over the whole estuarine freshwater part have changed from predominant denitrification in the 1980s toward significant production from nitrification in the present estuary. Despite a significant reduction in N2O saturation compared to the 1980s, N2O concentrations nowadays remain on a high level, comparable to the mid-90s, although a steady decrease of DIN inputs occurred over the last decades. Hence, the Elbe estuary still remains an important source of N2O to the atmosphere.
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  • 7
    Publication Date: 2015-10-27
    Description: The biogeochemical pools of fossil organic matter in permafrost, mainly the carbon pool, are subject in current research to estimate the quality, quantity and the potential release into the modern cycles maintained by permafrost thaw and accelerated by arctic warming. Organic matter freeze-locked in perennially frozen ground of the northern circumpolar region accumulated over tens of thousands of years during the last glacial and interglacial periods. A part of this permafrost region is composed of ice-rich silts penetrated by large ice wedges, resulting from sedimentation and syngenetic freezing accompanied by wedge-ice growth driven by certain climatic and environmental conditions during the late Pleistocene. These unique materials are called Yedoma deposits. This study focuses on the area of potential Yedoma deposit occurrence in Siberia and Alaska and on nitrogen which has mostly a subordinate role in current studies, but is also an important source of greenhouse gas N2O. Based on the most comprehensive data set of total nitrogen (TN) concentrations in permafrost, our study aims to estimate the present pool of nitrogen stored in the different stratigraphic units of the Yedoma region. Nitrogen stock calculations will be based on bootstrapping techniques using resampled observed values. The total mean pool size estimate will be derived afterward for every of the 10,000 bootstrapping runs, resulting in 1 mean calculated from 10,000 observation-based bootstrapping means. The conceptual formula for the nitrogen stock calculation is: TN budget [Gt] = (deposit thickness [m] × coverage [m²] × bulk density [g/cm³] × (100-WIV/100) × (TNwt%/100))/ 1,000,000,000; TN: total nitrogen; WIV: wedge-ice volume In conclusion, we expect a substantial amount of nitrogen sequestered in the Yedoma region, which is expected to be released after thaw, probably mitigating the current nitrogen limitation of Arctic tundra ecosystems.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed , info:eu-repo/semantics/conferenceObject
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  • 8
    Publication Date: 2016-07-02
    Description: The biogeochemical composition of fossil organic matter stored in permafrost is an important subject in current climate change research. Multiple studies on the quality and quantity of permafrost organic carbon suggest that there is a high potential for carbon release into the active carbon turnover cycle through permafrost thaw in a warming Arctic. Other components of organic matter that are important for biogeochemical cycling, however, are less studied so far, including the amount and distribution of nitrogen (Keuper et al., 2012; Mack et al., 2004; Rustad et al., 2001). Nitrogen from thawing permafrost could be a significant source of the greenhouse gas N2O. Given its high global warming potential (about 300 times larger than CO2 over 100 years), even small releases of N2O can affect the permafrost-climate feedback. This study focuses on the abundance and distribution of nitrogen currently freeze-locked in the Yedoma region of Siberia and Alaska. Organic matter in permafrost deposits of the northern circumpolar region accumulated over tens of thousands of years during the last glacial and interglacial periods. A part of this permafrost region, the Yedoma region, is composed of thick ice-rich silts intersected by large ice wedges, resulting from sedimentation and syngenetic freezing accompanied by ice wedge growth in polygonal tundra, which was driven by certain climatic and environmental conditions during the late Pleistocene. These unique materials are called Yedoma deposits. They constitute a large organic carbon inventory of the (sub)Arctic but are also known to be nutrient-rich due to burial and freezing of plant remains. Besides carbon inventory estimates, detailed quantification of total nitrogen (TN) stocks is lacking. Based on the most comprehensive data set of TN content in permafrost to date, our study aims to estimate the present pool of nitrogen stored in the different stratigraphic units of the Yedoma region, which are (1) late Pleistocene Yedoma deposits; (2) in-situ thawed and diagenetically altered Yedoma deposits (taberite); (3) Holocene thermokarst deposits; (4) Holocene cover deposits on top of Yedoma and (5) the modern active layer of soils. Nitrogen stock calculations are based on statistical bootstrapping techniques using resampled observed values. The total mean pool size estimate is derived for every of the 10,000 bootstrapping runs, resulting in an overall mean derived from 10,000 individual observation-based bootstrapping means. The conceptual formula for our nitrogen stock calculation is given below. We show that the deposits of the Yedoma region store a significant pool of TN. At least a portion of this nitrogen is expected to get mobilized after thaw, affecting biogeochemical budgets and cycles of thawing permafrost-affected ecosystems. Possible effects include mitigation of the current nitrogen limitation of Arctic tundra ecosystems or a contribution of additional greenhouse gases in the form of N2O. In both cases, the permafrost-climate feedback will be affected by the amount and availability of so far not accessible nitrogen. Acknowledgements: This project is integrated into the Action Group “The Yedoma Region: A Synthesis of Circum-Arctic Distribution and Thickness” (funded by the International Permafrost Association (IPA) to J. Strauss). We acknowledge the support by the European Research Council (Starting Grant #338335), the German and Russian Science Foundations (DFG and RFBR “Polygon” project, DFG-HE 3622-16-1, and RFBR-11-04-91332-NNIO-a), the German Federal Ministry of Education and Research (Grant 01DM12011, and “CarboPerm” (03G0836A)), the Initiative and Networking Fund of the Helmholtz Association (#ERC-0013) and the German Federal Environment Agency (UBA, project UFOPLAN FKZ 3712 41 106). References Keuper, F., van Bodegom, P.M., Dorrepaal, E., Weedon, J.T., van Hal, J., van Logtestijn, R.S.P. and Aerts, R., 2012. A frozen feast: thawing permafrost increases plant-available nitrogen in subarctic peatlands. Global Change Biology, 18(6): 1998-2007, doi:10.1111/j.1365-2486.2012.02663.x. Mack, M.C., Schuur, E.A.G., Bret-Harte, M.S., Shaver, G.R. and Chapin, F.S., 2004. Ecosystem carbon storage in arctic tundra reduced by long-term nutrient fertilization. Nature, 431(7007): 440-443, doi:10.1038/nature02887. Rustad, L.E., Campbell, J.L., Marion, G.M., Norby, R.J., Mitchell, M.J., Hartley, A.E., Cornelissen, J.H.C., Gurevitch, J. and Gcte, N., 2001. A Meta-Analysis of the Response of Soil Respiration, Net Nitrogen Mineralization, and Aboveground Plant Growth to Experimental Ecosystem Warming. Oecologia, 126(4): 543-562, doi:10.1007/s004420000544.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 9
    Publication Date: 2016-12-14
    Description: Fossil organic matter (OM) stored in permafrost is an important subject in climate research. Such OM represents a huge reservoir of carbon (C). Multiple studies suggest its source potential for C release into the active C cycle through permafrost thaw and subsequent microbial turnover in a warming Arctic. However, net ecosystem OM balance in the permafrost region depends on more than just carbon. The abundance and availability of nitrogen (N) following permafrost thaw will influence plant growth, nutrient delivery to aquatic and estuarine ecosystems, and N oxide (N2O) emissions. Despite its central importance to predicting permafrost impacts and feedbacks to climate change, relatively little is known about permafrost N stocks and composition. In this study, we present the most extensive dataset to date of permafrost N in the Siberian and Alaskan Yedoma domain. The Yedoma domain comprises decameter thick ice-rich silts intersected by syngenetic ice wedges, which formed in late Pleistocene tundra-steppe environments, as well as other deposits resulting from permafrost degradation during the Holocene. Together, the deposits in this region constitute a large C inventory storing several hundred Gt C, but are also known to be nutrient-rich due to rapid burial and freezing of plant remains. Hitherto, the total organic C pool of the Yedoma region was quantified, while the total N inventory is lacking so far. Based on the most comprehensive data set of N content in permafrost to date, our study aims to estimate the present pool of N stored in the different stratigraphic units of the Yedoma domain: 1) late Pleistocene Yedoma deposits, 2) in-situ thawed and diagenetically altered Yedoma deposits (taberite), 3) Holocene thermokarst deposits, 4) Holocene cover deposits on top of Yedoma, and 5) the modern active layer of soils. To quantify measurement uncertainty, we estimated nitrogen stocks with bootstrapping techniques. We show that the deposits of the Yedoma region store a substantial pool of N that is expected to get mobilized after thaw and, at least partially, affecting biogeochemical budgets of thawing warming permafrost ecosystems.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 10
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    Alfred Wegener Institute for Polar and Marine Research & German Society of Polar Research
    Publication Date: 2019-07-17
    Description: Das „Permafrost Young Researchers Network“ (PYRN, http://pyrn.ways.org) ist ein Netzwerk von und für junge Wissenschaftler, die sich sowohl durch ihren beruflichen Werdegang als auch aus privatem Interesse mit dem Thema Permafrost beschäftigen und mit dieser Motivation, lokale bis internationale bzw. individuelle bis organisierte Kooperation betreiben.
    Repository Name: EPIC Alfred Wegener Institut
    Type: "Polarforschung" , NonPeerReviewed
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