Das Projekt "SIRRO: Siberian River Run-Off" wird vom Umweltbundesamt gefördert und von Universität Hamburg, Zentrum für Meeres- und Klimaforschung, Institut für Meereskunde (IfM) durchgeführt. SIRRO is a bilateral German-Russian project funded by the BMBF and russian authorities. The project investigates the nature and the impact of Siberian river runoff from Ob and Yenisei into the Kara Sea. In SIRRO, the Institute for Oceanography, Hamburg, is responsible for the high-resolution circulation modelling of the Ob and Yenisei estuaries and surrounding areas of the Kara Sea. The simulated flow fields will be used for transport and dispersion modelling of dissolved and particulate bio-geochemical tracers such as dO18, C13, nutrients, suspended matter or DOC.
Das Projekt "Modelling the impact of global warming on the trophic state of the upper ocean" wird vom Umweltbundesamt gefördert und von Helmholtz-Zentrum für Ozeanforschung Kiel (GEOMAR) durchgeführt. The main aim of the proposed research is a quantitative evaluation of the potential impact of global warming on the trophic balance of the upper ocean. Primary production, as well as autotrophic and heterotrophic respiration are all expected to increase with temperature, and a number of experimental culture studies suggest that the increase with temperature is more pronounced for respiration than for production. This notion has been further confirmed on the ecosystem level in recent short-term mesocosm studies. According to these results, an expected direct effect of global warming is a weakening of the biological carbon pump. In contrast to indirect effects arising from changes in circulation and stratification, such a direct temperature effect has not yet been investigated quantitatively on a global scale. Using an Earth System Model of intermediate complexity, the proposed study will investigate the sensitivity of the model's biological pump to different parameterisations of temperature effects on autotrophic and heterotrophic processes, each calibrated by available experimental data from culture and mesocosm studies. The ability of different parameterisations to closely reproduce regional patterns of biogeochemical tracer distributions will first be evaluated for pre-industrial steady-state solutions. In a second step, the model will be forced with IPCC-type CO2 emission scenarios over the 21st century in order to estimate the impact of direct temperature effects on the marine biota relative to indirect effects via changes in circulation and stratification.
Das Projekt "Quellen und Senken von Gasen in der Critical Zone: In situ-Sensoren und Isotopie (B03)" wird vom Umweltbundesamt gefördert und von Universität Jena, Institut für Biodiversität, Lehrstuhl Aquatische Geomikrobiologie durchgeführt. B03 erforscht, wie Gase und Isotope die Umweltbedingungen und die funktionelle Biodiversität der unterirdischen Critical Zone widerspiegeln. Wir entwickeln neue Technologien für hochfrequente Multigas- und Isotopenmessungen mittels Raman-Spektroskopie und wenden simultane Multigasmessungen im Feld und im Labor an, um die Gasflüsse mit den mikrobiellen Stoffwechselvorgängen in Verbindung zu bringen. Wir entwickeln neuartige 14C-Methoden, um die Raten biogeochemischer Flüsse zu bestimmen und den Kohlenstoffkreislauf zu erforschen.
Das Projekt "Dynamic (redox) interfaces in soil - Carbon turnover in microbial biomass and flux into soil organic matter" wird vom Umweltbundesamt gefördert und von Helmholtz-Zentrum für Umweltforschung GmbH - UFZ, Department Umweltbiotechnologie durchgeführt. Existing models of soil organic matter (SOM) formation consider plant material as the main source of SOM. Recent results from nuclear magnetic resonance analyses of SOM and from own incubation studies, however, show that microbial residues also contribute to a large extent to SOM formation. Scanning electron microscopy showed that the soil mineral sur-faces are covered by numerous small patchy fragments (100 - 500 nm) deriving from microbial cell wall residues. We will study the formation and fate of these patchy fragments as continuously produced interfaces in artificial soil systems (quartz, montmorillonite, iron oxides, bacteria and carbon sources). We will quantify the relative contributions of different types of soil organisms to patchy fragment formation and elucidate the effect of redox con-ditions and iron mineralogy on the formation and turnover of patchy fragments. The develop-ment of patchy fragments during pedogenesis will be followed by studying soil samples from a chronosequence in the forefield of the retreating Damma glacier. We will characterize chemical and physical properties of the patchy fragments by nanothermal analysis and microscale condensation experiments in an environmental scanning electron microscope. The results will help understanding the processes at and characteristics of biogeochemical interfaces.
Das Projekt "Sources and reaction pathways of soluble Fe from the Western Antarctic Peninsula to the Southern Ocean" wird vom Umweltbundesamt gefördert und von Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung durchgeführt. During two campaigns on King George Island (Antarctica) in 2012 and 2013, numerous sediment and pore water samples were collected in Potter Cove and Maxwell Bay. Especially Potter Cove is strongly affected by glacier retreat, which is assumed to affect the biogeochemical processes in the area. Based on pore water profiles the degradation of sedimentary organic matter in the sediments in proximity to the marine-terminating Fourcade Glacier was found to be dominated by dissimilatory iron reduction (DIR). In contrast, sulfate reduction was apparent at shallow sediment depths in those parts of Potter Cove, where surficial meltwater streams discharge. Sediments in proximity to the glacier fronts contain significantly higher amounts of easily reducible (amorphous) Fe oxyhydroxides than stations in the central part of the bay or in discharge areas of surficial meltwater streams. Stable iron isotopes are considered a proxy for Fe sources, but respective data are scarce and Fe-cycling in complex natural environments is not understood well enough yet to constrain respective delta56Fe 'endmembers' for different types of sediments and environmental conditions. In order to enhance the usability of iron isotopes as proxies for iron sources and reaction pathways, we developed a new method that allows to measure delta56Fe on sequentially extracted sedimentary Fe phases and applied the new protocol to sediment from King George Island. We suggest that easily reducible Fe in proximity to the glacier front is mostly delivered from subglacial sources, where iron liberation from comminuted material beneath the glacier is coupled to biogeochemical weathering processes (pyrite oxidation or DIR). Our strongest argument for a subglacial source of the highly reactive iron pool in sediments close to the glacier front is its overall negative delta56Fe signature that remains constant over the whole ferruginous zone. This pattern implies that the supply with easily reducible Fe exceeds the fraction that afterwards undergoes early diagenetic DIR by far. The light delta56Fe values of easily reducible Fe oxides imply pre-depositional microbial cycling as it occurs in potentially anoxic subglacial environments. Interestingly, the strongest 56Fe-depletion in pore water and of the most reactive Fe oxides was observed in sediments influenced by oxic meltwater discharge. In terms of the potential of delta56Fe as a proxy for benthic Fe fluxes, the study demonstrates limitations due to a large variability of pore water delta56Fe deriving from DIR in the marine sediments at small spatial distances. The controlling factors are multi-fold and include the availability of reducible Fe oxides and organic matter, the isotopic composition of the primary ferric substrate, sedimentation rates, and physical reworking (bioturbation, ice scraping). Whereas delta56Fe may prove a valuable parameter to further investigate biochemical weathering of glacier beds, a quantification of benthic Fe fluxes bas
Das Projekt "Der Einfluss der SML auf die Spurengasbiogeochemie und den Ozean-Atmosphäre-Gasaustausch" wird vom Umweltbundesamt gefördert und von Helmholtz-Zentrum für Ozeanforschung Kiel (GEOMAR), Forschungsbereich 2: Marine Biogeochemie durchgeführt. Labor- und Feldstudien zeigen, dass die Oberflächengrenzschicht des Ozeans (â€Ìsurface microlayerâ€Ì, kurz SML) die biogeochemischen Kreisläufe von klimaaktiven und atmosphärisch wichtigen Spurengasen wie Kohlenstoffdioxid (CO2), Kohlenstoffmonoxid (CO), Methan (CH4), Lachgas (N2O) und Dimethylsulfid (DMS) stark beeinflusst: (i) Jüngste Studien aus den PASSME- und SOPRAN-Projekten haben hervorgehoben, dass Anreicherungen von oberflächenaktiven Substanzen (d.h. Tensiden) einen starken (dämpfenden) Effekt sowohl auf die CO2- als auch auf die N2O-Flüsse über die SML/Atmosphären-Grenzfläche hinweg haben und (ii) Spurengase können durch (mikro)biologische oder (photo)chemische Prozesse in der SML produziert und verbraucht werden. Daher kann der oberste Teil des Ozeans, einschließlich der SML, verglichen mit dem Wasser, das in der Mischungsschicht unterhalb der SML zu finden ist, eine bedeutende Quelle oder Senke für diese Gase sein, was von sehr großer Relevanz für die Forschungseinheit BASS ist. Die Konzentrationen von CO2, N2O und anderen gelösten Gasen in der SML (oder den oberen Zentimetern des Ozeans) unterscheiden sich nachweislich von ihren Konzentrationen unterhalb der SML. Typischerweise werden die Nettoquellen und -senken wichtiger atmosphärischer Spurengase mit Konzentrationen berechnet, die in der Mischungsschicht gemessen wurden und mit Gasaustauschgeschwindigkeiten, die die SML nicht berücksichtigen. Diese Diskrepanzen führen zu falsch berechneten Austauschflüssen, die in der Folge zu großen Unsicherheiten in den Berechnungen der Klima-Antrieben und der Luftqualität in Erdsystemmodellen führen können. Durch die Verknüpfung unserer Spurengasmessungen mit Messungen von (i) der Dynamik und den molekularen Eigenschaften der organischen Materie und speziell des organischen Kohlenstoffs (SP1.1; SP1.5), (ii) der biologischen Diversität und der Stoffwechselaktivität (SP1.2), (iii) den optischen Eigenschaften der organischen Materie (SP1.3), (iv) der photochemischen Umwandlung der organischen Materie (SP1.4) und (v) den physikalischen Transportprozessen (SP2.3) werden wir ein umfassendes Verständnis darüber erlangen, wie die SML die Variabilität der Spurengasflüsse beeinflusst.
Das Projekt "Highly-resolved imaging in artificial and natural soils to yield dynamics and structure of interfaces from oxygen, pH and water content" wird vom Umweltbundesamt gefördert und von Universität Potsdam, Institut für Erd- und Umweltwissenschaften durchgeführt. In soils and sediments there is a strong coupling between local biogeochemical processes and the distribution of water, electron acceptors, acids, nutrients and pollutants. Both sides are closely related and affect each other from small scale to larger scale. Soil structures such as aggregates, roots, layers, macropores and wettability differences occurring in natural soils enhance the patchiness of these distributions. At the same time the spatial distribution and temporal dynamics of these important parameters is difficult to access. By applying non-destructive measurements it is possible to overcome these limitations. Our non-invasive fluorescence imaging technique can directly quantity distribution and changes of oxygen and pH. Similarly, the water content distribution can be visualized in situ also by optical imaging, but more precisely by neutron radiography. By applying a combined approach we will clarify the formation and architecture of interfaces induces by oxygen consumption, pH changes and water distribution. We will map and model the effects of microbial and plant root respiration for restricted oxygen supply due to locally high water saturation, in natural as well as artificial soils. Further aspects will be biologically induced pH changes, influence on fate of chemicals, and oxygen delivery from trapped gas phase.
Das Projekt "International Surface Ocean - Lower Atmosphere Study (SOLAS)" wird vom Umweltbundesamt gefördert und von Helmholtz-Zentrum für Ozeanforschung Kiel (GEOMAR), Forschungsbereich 2: Marine Biogeochemie, Forschungseinheit Chemische Ozeanographie durchgeführt. Since 2004, the International Surface Ocean - Lower Atmosphere Study (SOLAS) project is an international research initiative aiming to understand the key biogeochemical-physical interactions and feedbacks between the ocean and atmosphere. Achievement of this goal is important to understand and quantify the role that ocean-atmosphere interactions play in the regulation of climate and global change. SOLAS celebrated its 10 year anniversary in 2014. In the first decade, the SOLAS community has accomplished a great deal towards the goals of the original Science Plan & Implementation Strategy and Mid-term Strategy (Law et al. 2013) as highlighted by the open access synthesis book on 'Ocean Atmosphere Interactions of Gases and Particles' edited by Liss and Johnson and the synthesis article in Anthropocene from Brévière et al. 2015. However there are still major challenges ahead that require coordinated research by ocean and atmospheric scientists. With this in mind, in 2013, SOLAS has started an effort to define research themes of importance for SOLAS research over the next decade. These themes form the basis of a new science plan for the next phase of SOLAS 2015-2025. SOLAS being a bottom-up organisation, a process in which community consultation play a central role was adopted. After two sets of reviews by our four sponsors (SCOR, Future Earth, WCRP and iCACGP), the SOLAS 2015-2025 Science Plan and Organisation (SPO) was officially approved.
Das Projekt "Biotic and abiotic factors that dive the function of microbial communities at biogeochemical interfaces in different soils (BAMISO)" wird vom Umweltbundesamt gefördert und von Helmholtz Zentrum München Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Abteilung für Umweltgenomik durchgeführt. Biogeochemical interfaces shape microbial community function in soil. On the other hand microbial communities influence the properties of biogeochemical interfaces. Despite the importance of this interplay, basic understanding of the role of biogeochemical interfaces for microbial performance is still missing. We postulate that biogeochemical interfaces in soil are important for the formation of functional consortia of microorganisms, which are able to shape their own microenvironment and therefore influence the properties of interfaces in soil. Furthermore biogeochemical interfaces act as genetic memory of soils, as they can store DNA from dead microbes and protect it from degradation. We propose that for the formation of functional biogeochemical interfaces microbial dispersal (e.g. along fungal networks) in response to quality and quantity of bioavailable carbon and/or water availability plays a major role, as the development of functional guilds of microbes requires energy and depends on the redox state of the habitat.To address these questions, hexadecane degradation will be studied in differently developed artificial and natural soils. To answer the question on the role of carbon quantity and quality, experiments will be performed with and without litter material at different water contents of the soil. Experiments will be performed with intact soil columns as well as soil samples where the developed interface structure has been artificially destroyed. Molecular analysis of hexadecane degrading microbial communties will be done in vitro as well as in situ. The corresponding toolbox has been successfully developed in the first phase of the priority program including methods for genome, transcriptome and proteome analysis.
Das Projekt "Redox processes along gradients" wird vom Umweltbundesamt gefördert und von Universität Bayreuth, Lehrstuhl für Hydrologie, Limnologische Forschungsstation durchgeführt. The relevance of biogeochemical gradients for turnover of organic matter and contaminants is yet poorly understood. This study aims at the identification and quantification of the interaction of different redox processes along gradients. The interaction of iron-, and sulfate reduction and methanogenesis will be studied in controlled batch and column experiments. Factors constraining the accessibility and the energy yield from the use of these electron acceptors will be evaluated, such as passivation of iron oxides, re-oxidation of hydrogen sulfide on iron oxides. The impact of these constraints on the competitiveness of the particular process will then be described. Special focus will be put on the evolution of methanogenic conditions in systems formerly characterized by iron and sulfate reducing condition. As methanogenic conditions mostly evolve from micro-niches, methods to study the existence, evolution and stability of such micro-niches will be established. To this end, a combination of Gibbs free energy calculations, isotope fractionation and tracer measurements, and mass balances of metabolic intermediates (small pool sizes) and end products (large pool sizes) will be used. Measurements of these parameters on different scales using microelectrodes (mm scale), micro sampling devices for solutes and gases (cm scale) and mass flow balancing (column/reactor scale) will be compared to characterize unit volumes for organic matter degradation pathways and electron flow. Of particular interest will be the impact of redox active humic substances on the competitiveness of involved terminal electron accepting processes, either acting as electron shuttles or directly providing electron accepting capacity. This will be studied using fluorescence spectroscopy and parallel factor analysis (PARAFAC) of the gained spectra. We expect that the results will provide a basis for improving reactive transport models of anaerobic processes in aquifers and sediments.
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